I have a 94 6.5l TD with 100,000. I have what I believe is a fuel supply issue. My truck is becoming harder and harder to start in the mornings and runs quite rough. I can not hear my lift pump before engaging the starter. I started to replace it but before I did I tried to supply power directly and it appears to be working fine. I did replace the OPS last Februry but I suppose it could be bad again. My reason for replacing it the first time was that my oil gauge went to zero after warming up. I traced the power wires from the lift pump into the engine compartment and jumped power from the battery to the pump via these wires (quick disconnect present) Interestingly, it only needed power from the positive lead. A short in the ground wire??? Also, interestingly to me the fuel gauge goes to full deflection right when I disconnect the 'quick disconnect'. Is this a source of my problem. . . A ground failure? When should the pump run? Should it always run? Are there any tests? There are two relays mounted on the firewall (pax side). They appear to be a very similar relay if not identical. One is the fuel pump relay. . . What is the other? It only indicates 'Optional' Can they be interchanged? The wiring harness plugged into each of them are slightly different. Which harness (color of wires and number of wires) is the fuel pump relay harness? I am certain that I also need to replace some glow plugs if not all. . . . I will do this soon but I am sort of dredding doing the pax side with the turbo being in the way.


Thanks ahead for any help you might be able to offer.

I'm no pro but if its running fine after the warm-up it sure sounds like glow plugs to me. Pass side isn't too bad with stock exhaust if you remove the right front tire and splash guard on the inner fender well. But i'd test them first before removing them. I've had 1 bad plug, noticably hard to start, 2 bad plugs and she really don't want to start.

Fuel pump relay is on the left, optional relay, I'm not sure what it runs. The grey wire from the OPS connector is the lift pump wire, no ground at the connector, the yellow goes to the dash and the orange is a common power wire for the switch.Does your fuel bleed put out fuel while running?


Get a 12v tester and find out your glowplug situation first. I usually have someone turn the key while I testlight them. behind the turbo isn't so bad with the engine cold.

Thank you to quantum mechanic and CanadianRigger. Sounds like I need to throw some new G Plugs in first and go from there. . . . . . but. . . . I am quite certain I have an issue with the lift pump. . . . To answer your question, quantum mechanic, the fuel bleed does NOT put out fuel as it should while running. . . . It does put out fuel if I jump power to the pump. My truck never runs right but is particularly bad in the mornings when it is cold. ( Alaska is already around 32 in the mornings) The 'service engine soon' light comes on and then goes away intermittently. Is the Lift Pump supposed to run continously while the engine is running?

The 2 relays have slightly different #'s on the top. . . (3266 and 3285) I took them off (stupidly) and I am afraid I may have confused them. . . which is which. . . In other words which one should be to the left.. . . which one is the fuel pump relay?

Thanks again for any assistance. . . . I am being forced to become engrossed in this because I just can't find a mechanic that is willing to find the problem through diagnosis rather than just replacing all the parts until it works. http://www.dieselplace.com/forum/uploads/35A_relays.jpgEdited by: arctflyr

FLYER


Based on what you've said, I'd geuss the OPS has burned it's contacts. TDG suggests you power it off an ignition wire. It's the grey wire on the OPS connector.

Those are the oem date codes - you'll notice the part numbers - 14089936 - are identical.


Fuel Pump relay will have gray wire(s).


Other relay may be optional dual headlamp circuit - wire colors will tell.


Lift pump is powered thru START circuit at crank.


Lift pump is powered thru OPS when engine is running.


LP will vibrate when running, but can produce no to minimal fuel supply when valving has deteriorated.


Should produce 4psi at max engine loading to 7.5psi against full head at idle.Edited by: gmctd

Is lift pump powered from crank on a 94 for sure? Which year was it that they started to have the lift pump come on during the wait to start period?

That would be the '96-up OBD-II systems - PCM controls Lift Pump at START, and OPS when engine is running.

Alright . .. . . I got the glow plugs replaced. . . . Thanks to CanadianRigger and quantum mechanic the rear two plugs on the pax side were replaced easily enough as well. . .. turns out they both had burned off tips. . . . no telling how long they had been in there. . . . . Obvious to me the prior owner did not know how to get to them because they were the only two that had burned tips. I also got my lift pump working. . .. not sure exactly how. . . .. but I think it must have been a bad connection somewhere because it now works fine. . . . I am able to get fuel out of the fuel bleed while running.


The truck still seemed not to be running on all cylinders at start until giving it a bit more throttle. and. . . . . still hesitated / lurched quite a bit while driving. I thought I ought to change the fuel filter even though it had only 7000 miles on it and this seemed to make the truck run well . . . .the service engine soon light continues to come on intermittently though now only at higher rpm.


According to the dealer my vaccuum pump is bad and therefore my turbo is not working. . . . I planned to replace it and figured this may be why the service engine soon light was still on. This was a project for this weekend.


Three days of driving with out the lurching/ hesitation and it is back again. The lift pump is still working. Any ideas?


When I had it at the dealers they told me my 'app' was bad. . . . At the time (In a 1 month period) the service throttle soon light had come on two times and I lost all throttle. I shut the truck down and started it again and it worked fine. I have not had the problem for at least 2 months. Could a bad app cause my hesitation problem? Are these symptoms of the notorious PMD problem. The IP with a PMD were replaced last October so I really doubted it would be bad again.


I am thinking I am way above my head now and am fixing to just take it in to the shop. Any ideas out there?

Flyer welcome to the forum;


Before throwing in the towel for some serious $$$ of dealer trouble shooting go by auto store and have codes read for free and post back what is there,


also update your signature so we know what equipment is on your ride and what kind of ride it is so we can better assist you.


On the sig update I went back to your original post you have a 94 which is OBDI, with a paper clip across pin A&B IIRC (Help my memory guys) of the diagnostic port located lower left of dash above parking brake. With key in run and engine off the SES light will blink in a sequence, count and record the sequence, it will tell which codes the PCM is seeing/faulting and tells us what to look at 1st, they are supposed to but not always log worst problem 1st, and lesser problems after that.


1 word of caution on dealers, the 6.5 is an "old" engine to them unless they have some Diesel techs that have been around for a while take their recommendations with guarded skepticism, their current training is on DMAX.Edited by: Turbine Doc

Thank you, Turbine Doc. Thanks mostly for the encouragement. . . . Taking my truck to the dealer is the LAST thing I want to do AGAIN. I only took it there the first time because I was relatively confident at the time that I had a bad PMD which was and still is under warranty through Oct. I got a bill for 175.00 with a laundry list of things wrong with my truck but never touched the IP nor the PMD. I have their list of codes they pulled and will post them when I get home tonight. . . after confrming them using your above mentioned method. I can attest to the "OLD" engine idea you spoke of above. For example, the dealer told be that my lift pump would not run at all. I don't know much about anything but I jumped power to the pump and it worked fine. Turns out. . . looks like there may have been a bad connection somewhere cause that part of the system appears to be working. So rest assured I am skeptic. The 1600.00 they wanted me to pay beyond the 175.00 I already paid to 'fix' my truck. . .. to me. . .. really amounts to a mechanic and/or dealer that believes the best method to fixing a truck is to replace ALL the parts. Of course this method also works well for their pocket books. If I need to take it somewhere it WONT be the dealer.

Edited by: CanDieselTech

I'd really like to hear you defense on how that reading in particual will tell your that you have a bad Hydraulic Head. More likely cause would be worn/broken FSol dragging. If the head itself were worn, you'd have hard start hot condition, and you would see idle fuel deliveries on the high end like 12+. A bent/broken data disk would give cylinder contribution codes along with extremely rough idle and 0370/0251 codes. Are you saying you've trained shops?

CDT, TDG


Flyer probably has no scan tool is there a laymans test he can perform to try and isolate his problem.


Flyer something you can try to see if APP is having problems, get up to cruise control speed, set it, and see if surge happenes in CC, if problem still there, then APP isn't a player, CC does not use the APP to regulate speed.


Edited by: Turbine Doc

OK, ArcticFlyer, so far you've isolated and confirmed that your fuel supply system is working properly. Lets talk about turbo, a gauge would be best, but you don't have to get all fancy, unplug the connector to your Wastegate actuator solenoid with the two vacuum lines, one orange one black. Check with the engine idling to ensure there is vacuum from the orange, if there is plug them back in. Then unplug the black line from the wastegate atuator located under the inlet pipe between the airfilter (good idea to check/replace this if you havent already) and turbo, again check for vacuum while the engine is idling. If you have good vacuum at both places then you know that your vacuum pump and actuator switch are atleast somewhat functional. Next, take the truck for a good spin and watch the tailpipe for smoke. Its very normal to see some white smoke at startup, particularly in colder climates, but it should clear up in under 30 seconds. If not, then you possibly have glowplug, injector or compression problems. With the truck fully warmed, assuming the white smoke is gone, watch carefully for black smoke, you should see some black smoke when you hit the throttle, but it should clear up quickly as the turbo spools. If black smoke is continuous or excessive then you most likely have air/turbo problems. If black smoke seems to come and go, then its possible you have a faulty WG actuator switch, wouldn't hurt to change it anyway if you have doubts.

Really need to pull those codes, hooking a scanner up would be even better. Need to see what your TDC Offset is, CTime, History Codes etc...

Edited by: CanDieselTech

Hey man, I I'm not saying you don't know your stuff, I'm just saying I've never heard anyone diagnose one that way. I'm curious, not condecending.


Besides, we don't know what codes he's got, neither does he, were all kinda shooting in the dark until he can tell us that aren't we?Edited by: Texas Diesel Guy

OK. . . . I went out this morning to get the codes checked. . . . . and the only place that had free testing could not check a 94'. The other places ranged from $80.00 to $120.00 to test. I went to the internet and this is what I found:

<font color="blue">Turn ignition switch on but do not start engine, "CHECK ENGINE" or "SERVICE ENGINE SOON" light should glow.

Locate diagnostic connector under instrument panel near steering column (on most vehicles - the Fiero has it in the center console by the cigarette lighter, for example). It must be a 12 pin rectangular connector as shown below, or this method will not work

Take a jumper wire: a piece of stiff wire or even an unbent paper clip - and insert the two ends into the A and B terminals shown in this diagram. Note: If your diagnostic connector does not look like this (i.e. if it has 16 pins instead), you cannot use this method to read codes, you will need a scan tool.

http://www.dieselplace.com/forum/uploads/4F4_gmaldl.gif


<font color="blue">Note, if there are no metal contacts in either or both of these holes (as on some 1994 and 1995 vehicles), codes cannot be read using this method - a scan tool will be required. On some vehicles, the engine cooling fan will turn on when you insert the jumper, this is normal.

The Check Engine/Service Engine Soon light should begin blinking out trouble codes. To read the codes, you count the flashes of the light. The light will flash a number of times corresponding to the first digit, then pause, then flash a number of times corresponding to the second digit, then a longer pause before the next one. For example, code 12 would be flash, pause, flash flash.

Code 12 will always be flashed out, this does not indicate a problem. Following that, any additional stored codes will flash out in ascending order by number, and then start over at 12 again. Each code will be flashed 3 times.

When finished, remove the jumper to exit diagnostic mode.
</font>

<font color="black">I did this and this is what I get:

22 Accelerator Pedal Position (APP) 1 Circuit Low

23 Accelerator Pedal Position (APP) 1 Circuit Range Fault

25 Accelerator Pedal Position (APP) 2 Circuit High

27 Accelerator Pedal Position (APP) 2 Circuit Range Fault

34 Injection Timing Stepper (ITS) Motor Circuit Fault

35 Injection Pulse Width Error (Response Time Short)

36 Injection Pulse Width Error (Response Time Long)

57 PCM 5 Volt Shorted

63 Accelerator Pedal Position (APP) 3 Circuit High

71 Set/Coast Switch Fault

78 Wastegate Solenoid Fault

84 Accelerator Pedal Position (APP) Circuit Fault

NOTE: When I took it to the dealer in July they only reported 23,27,36,78, and 84.

Appears things are getting worse. One thing I find odd. . . Many of the codes indicated faults with the APP but I have not seen a "Service Throtte Soon" light for at least 2 months. Sure seems like this light ought to come on. . . . I wonder if I need to reset the codes and drive it for a day and try it again?????

Thanks again for any help.Edited by: arctflyr

You should be able to clear up some of those codes.


Code 78: Check out the WG solenoid for vacuum ~25"before and ~15"after. most likely a leak or the solenoid.


All the other codes: get a new pump. the fuel solenoids shot and causing all this.

I would reset them to see what comings back after a reset. And for about 25.00 the WG solenoid might solve one or two also.

You said the IP was replaced last OCT? I'd be contacting them for warranty if I were you. That 5v reference short could be the cause for your intermittent APP and other problems. The short might be in the APP itself. Try and get your pump warrantied, clear the codes and see which ones come back, but I think your going to need an IP/APP and wastegate solenoid at the very least.

Hey,


On the plug above, you can also jump A to G for the lift pump. and another one for the tranny.


http://www.dieselplace.com/forum/uploads/2BB_Aldl.jpg


Also, blueridgediesel.com sells vac pumps for $84 USD.Edited by: quantum mechanic

I just reset the codes and drove about 3 miles. . . . came back and all I get is code 36. I am pretty certain I have turbo issues though. . . . I have not yet had a chance to do the tests that TDG suggested so I will check it out. Maybe I need to drive it a bit more to see if any more codes pop up.


I don't mind getting greassy working on vehicles but the mystical stuff is giving me a headache.

Code 36 is the fuel solenoid sticking or side loading.


My last pump had code 36 when new. It was only a matter of time (15,000 miles)and it surged( read "ran away"). My cruise control didn't work right, surges as it shifted into R or D.

Hey QM What plug are you talking about for the lift pump?


Here what I did to run my lift pump with the key on. nice, easy and clean and the cover still fits toohttp://www.dieselplace.com/forum/uploads/64B_DCP_0471.JPGeh








http://www.dieselplace.com/forum/uploads/89F_DCP_0470.JPG

Hey QM. . . . When you say Fuel Solenoid is this the same as the PMD or Pump Mounted Driver?

No, the fuel solenoid is driven (opened,closed) by the Driver (FSD/PMD) but is internal and essential to fuel delivery on the system.


http://www.dieselplace.com/forum/uploads/BA8_50681.jpg


http://www.dieselplace.com/forum/uploads/6E5_armature.jpg


The cap, terminals and internally the armature and rod.

With all those DTC's intermittent, I would suspect the wiring harness as contributive - grounds, connectors, etc, all need to be checked for oxidation, corrosion, etc.


The 5volt Ref Shorted would cause most of the codes, and that DTC sounds like really bad wiring problems


Start with both Positive and Negative battery cables, then harness grounds to engine block, then harness connectors.

I just got home a bit ago JD beat me to it, that many codes you got some electrical gremlins going on on top of your real problem which may be the Fuel sol, you suspect the turbo, why, have you had a chance to run any of the checks TDG suggested, if so post what your results were, gives us a little more to go on to help you.Edited by: Turbine Doc

The only practical way to change the Fuel solenoid is to replace the pump. TDG and others can tell you, once code 36 starts, The fuel solenoid has problems that won't go away. Exchanging the pump is the best case scenerio to fixing code 36, because you will excange The F Sol when you exchange the pump.

Flyer,


I moved your reference material from The Diesel Page to the Mod forum for discussion if it is appropriate to post copyrighted material from another site here, I wasn't sure but rather than get the site in trouble, pulled it just in case, if it can be posted I'll move it back, it isn't public domain IIRC it comes from the members only paid area, not sure what TDP's policy is in posting their articles in another site, I'll ask them.

Ok TD. . . . Sorry for the trouble.

Guess I will drive my truck a couple more days and see if code 36 is still the only code. . . . . Then I guess I will go fight the dealer for warranty work since the IP was replaced last OCT under warranty. I am not looking forward to the fight.

When my IP was replaced in May under the extended warranty program (120,000k) I was told the replacement came with a 12/12 warranty. Shouldn't be a fight.

Flyer,


No trouble you didn't know &amp; I'm not even sure myself, it's a good link and I'll repost it if we can use it, just want to make sure 1st though we don't get any unwanted grief from using stuff that is a DIRECT copy from a copywrtitten/protected source, now if you want to edit what you have learned elswhere in your words that is another story.

yea come on flyer put it in own words so we can learn from what you know

Flyer, as for the warranty fight go to the members area at TDP there is a letter there for GMs special policy for IPs replacement, burn a copy of it and carry to your dealer, they should not have charged you the $175 the 1st time. I'd post it but haven't got a clear copy of it to scan into a Word document. If your dealer gives you a hard time about honoring warranty and not having a IP code he can act on


Here is how to set one (at least it works on OBDII, not sure about OBD I) Pull the center plug on the IP, try to start the engine, it won't start but will set an IP specific code I don't don't remember which, plug back in and drive to the dealer, they should see the code optical sensor fault IIRC. It may take several trips as they just may reset it.


Before doing that though do all trouble shooting you can, lift pump, fuel filter, rust in bottom of filter bowl, OPS, crud in tank, they can and will charge you for that, some not all will look to everything else before looking to the IP, and so should you, but you need not pay dealer prices for the basic troubleshooting, you can do for free.

Hey QM What plug are you talking about for the lift pump?


Here what I did to run my lift pump with the key on. nice, easy and clean and the cover still fits too eh





Bowtie &amp; others doing any of the different jumps around OPS to power lift pump, I caution you to not do this as a permanent fix, this is for get home or troubleshooting purposes only.


Beside knocking out fused protection for the circuit in some cases, you can also disable safety feature of the OPS upon a crash to kill power so you don't pump fuel and feed a fire as result of a crash. Protection is; if engine quits so should lift pump on loss of engine oil pressure even with the IGN key in on positionEdited by: Turbine Doc

yea come on flyer put it in own words so we can learn from what you know








Bowtie since you are adept at posting pics PM Flyer, &amp; exchange info and collaboatively make a new post with pics I can link to the FAQs, it's one of the things I was going to do but not enough hours in the day for me to do it all by my lonesome, plus it's not TD's 6.5 forum it's OUR place to hang out and share stuff. http://www.dieselplace.com/forum/smileys/Big Smile.gif

go to the members area at TDP there is a letter there for GMs special policy for IPs replacement, burn a copy of it and carry to your dealer

Turbine Doc- I tried to find this area to no avail. Where is the member's area?

Hey QM What plug are you talking about for the lift pump?


Here what I did to run my lift pump with the key on. nice, easy and clean and the cover still fits too eh





Bowtie &amp; others doing any of the different jumps around OPS to power lift pump, I caution you to not do this as a permanent fix, this is for get home or troubleshooting purposes only.


Beside knocking out fused protection for the circuit in some cases, you can also disable safety feature of the OPS upon a crash to kill power so you don't pump fuel and feed a fire as result of a crash. Protection is; if engine quits so should lift pump on loss of engine oil pressure even with the IGN key in on position





i guess it's noted BUT I ran elec fuel pumps for long times on my street cars and never had a problem should as that and I believe gas is far more flammable then diesel. And the mod I used is fused protected by design, This is the exact reason I went this way. Sorry but I plan on running it this way till something better comes along to run it with a OPS. Edited by: bowtie

SAY WHAT ? Explain TDocEdited by: bowtie

go to the members area at TDP there is a letter there for GMs special policy for IPs replacement, burn a copy of it and carry to your dealer




Turbine Doc- I tried to find this area to no avail. Where is the member's area?




Try in reference section

SAY WHAT ? Explain TDoc


The photos you too of the fuse block were good, right image size to fit the forum, and clear.


Combine photos with the right words to make a post that does not cross into copywritten territory.

SAY WHAT ? Explain TDoc


The photos you too of the fuse block were good, right image size to fit the forum, and clear.


Combine photos with the right words to make a post that does not cross into copywritten territory.


could you explain what was copywritten bout what i did?

Casey,


What I was referring to was the post that I moved had copywrite notes all over it, I asked for permission to post here have not gotten a reply yet, not that what you had was copy. What I was suggesting for good of all in case we don't get permission to use it that you and Flyer combine efforts and write our own article with photos of topic at hand under a new thread we can link to the FAQs

I took the fuel filter out and was feeling around the bowl for sludge / rust etc. Did not find much but oddly when I put the filter back and started the truck up and ran it up the street the truck ran MUCH better. . . In fact ZERO lurching. This is exactly what happened when I replaced the fuel filter last week. . . . It will be back to itself in a couple days. Why would this be happening?

Fuel Solenoid is worn out, condition and codes may come and go temporarily, but you need to get your truck to the dealer while its showing a code 36.

I am just trying to arm myself with as much info as possible because when I took the truck into the dealer in July for them to look into replacing the IP they pulled code 36 themselves . . . .. They gave me a laundry list of things that needed fixed but didn't touch on the IP. I have fixed all the other items and so maybe it is time to take it in again.

Here is what I had moved until I got permission to use it from the site it came from, in today's ever litigious society wanted to play it safe. link is at the bottom of the thread



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<TD class=smText noWrap>Posted: September 26 2004 at 1:40am | IP Logged | Report Post (http://www.dieselplace.com/forum/report_post.asp?PID=167856&amp;FID=38&amp;TID=15669&amp;TPN=1) </TD>
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<TD class=text vAlign=top background="" bgColor=#fefefc>Ok. . . . I'll be checking all the connections and so forth. . . .. I suspect I may have caused some of the codes by screwing around with the wiring to the ECM while it was running.

I have not had a chance to do the turbo tests yet but will.

Turbine Doc- I only think the turbo may one problem not the only problem. . . . First, I have never heard the Turbo whine I would expect (I have owned this vehicle since Jan 04') Second, The dealer said it did not work as a result of no vacuum when I had it there in late July.

After I nail it down and assuming 36 is still the only code. . . . QM- Are you saying I need to replace my Fuel Solenoid? I hate to ask again. . . but I am still not sure I understand what this is. . . . Is it the Fuel Injection Pump. . . . If so I will have to battle with the dealer because it is still under warranty. Only they charge $170.00 just to talk to them. . . so I want to be pretty sure.

I did see this article that leads me to believe it may be the FSD/PMD:
http://www.thedieselpage.com/reviews/FSDCooler.htm


Thanks for ALL your help.

__________________
94 K3500 GMC Crew Cab 6.5L TD Everything stock to date. 101,000 miles </TD></TR>
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Just a bit more advice. I was experiencing multiple codes and problems on my 96 suburban and eventually found a short in the PCM wiring harness after replacing the IP twice, the PCM twice, wastgate solenoid, and several other parts and three shops couldn't find the problem. Here is the post with the progression. It is an OBD II but your problems sound similar. The advise I got from this forum helped in narrowing it down.


http://www.dieselplace.com/forum/forum_posts.asp?TID=11488&amp;KW=chevydave


Good luck!http://www.dieselplace.com/forum/smileys/Big Smile.gif

Flyr,


The code 36 is reason enough for the dealer to change the injection pump. Take it to them knowing that you have it coming.


Fuel is not being delivered because the F Sol isn't closing in time for delivery of the injection event.Edited by: quantum mechanic

Quantum Mechanic and Turbine Doc-


Two things before I take this truck into the dealer:


1.) When I brought the truck to the shop in July. . . remeber that it was throwing a code 36 at the time (documented on their receipt) the paperwork also shows this info: Injection Pump Data; PULSE 1.90, TAC 1. 76, TIMING 9.0, 8.8A Does this mean anything to either of you. Does it support my claim that the fuel solenoid is bad?


2.) I called today to make an appointment and the manager verified that they would be testing my fuel for metal. Would it make sense to flush my system somehow first. Any recommendations? Any tests I can do myself to ensure that my gas is clean before taking it in?


Thanks again for your help,


t.

1.78 closure time? This time see if TAC isn't ~2.0+ indicating it's dragging longer.

He's showing CTime of 1.90ms, which is the outer limit of spec and pump will definitely vary outside that window and set code 36. +/-0.02ms variance is a 'solid' CTime, 1.90 on a new solenoid is too long. All the pumps we sell leave with a bench CTime in the 1.55 - 1.70 range, we set them to the lower end because they normally drop a couple hundreths on the truck, and they have a natural tendency to wear and set a long CTime code rather than short. Long usually means worn/scarred solenoid, Short usually means broken solenoid or worn out poppet valve spring, but not always.

Ok this is almost comical. . . .

I went out to start my truck today and it sounded as if it was not starting
on all cylinders and smoked horribly. . . . This has been happening but it
is getting much worse. . . . It is not nearly as bad in the mornings with
the truck plugged in (block and oil pan heater). Anyway. . . I shut it
down and tried again and repeated this sequence 4 times when it finally
started and ran relatively normal. I drove off with the now typical severe
hesitaion and bucking until it gets warm where it is a bit better

and then. . . . The throttle started to change without my input. At one
point it went to full throttle without my foot on the pedal. I stopped the
truck and pulled the codes. This is what I got:

23***Accelerator Pedal Position (APP) 1 Circuit Range Fault

35****Injection Pulse Width Error (Response Time Short)

36****Injection Pulse Width Error (Response Time Long)


First, I have not seen any problems with my APP for at least 2 months. . . .
Today it was horrible and thus the code 23. Could this be a
gremlin problem somehow attached to an injector/solenoid problem? I
have a friend who has a 94 6.5td and this weekend I will try swapping out
the APP to test the situation (apparently this is very easy to replace but a
very EXPENSIVE dealer only item. My other (injector) problem is so severe
now that I thought maybe it could be causing this problem. I find it odd
that I experieced problems with the throttle two months ago and had
NOTHING for two months.

Second, How could I have a code 35 and 36? Don't these conflict?

I have an appontment on Monday the 4th and my warranty on the pump
expires on the 7th.

I am extemely FRUSTRATED!!!

Code 35 and 36 do often appear together, means your fuel solenoid is probably broken, closure time is very erratic, and the solenoid is binding and your pump can no longer properly meter fuel. Take your truck in, with those codes and your complaints they can't possibly turn you down for warranty. Did they do your injectors same time as the pump? If not, you might want to invest in a set while your truck is down. Do this first, then see what your app does, a faulty PMD has been known in some cases to cause other electrical gremlins (thats the technical term we use).Edited by: Texas Diesel Guy

My APP hasn't given me any trouble since replacing my pump. Previously it would surge all the time and make driving a pain.


Don't let fear rule you, flyer. Go to the stealer with the intention that you are going to have your pump warrantied out and don't except anything less. They owe you this one. Smile and enjoy the experience.Edited by: quantum mechanic

The games at the dealer begin. . . . . First they say my fuel is contaminated and before they will replace the pump I must have the fuel tank dropped and flushed and the lift pump replaced. . . .. All this for 700.00. and. . . . He says my front exhaust pipe at the motor has been hit and it needs replaced for 200.00. I am having the fuel tank issue done and I will try to find a pipe in town and do it myself. . . . so far I am havinig trouble finding a pipe. Does anyone know if it is a 3" pipe or 4". Midas has 3" but no 4".

How did they detemine contamination, dings in pipe have NOTHING to do with your problem, They are jacking you around, make them show the contamination, you would have seen crud in the bowl if that was the cause.


They are getting reinbursed from GM for the IP swap and are jacking you for the fuel tank drop, if they haven't started that yet do it yourself, do before &amp; after pics of the tank, or carry the "cleaned tank to them before reinstalling. This chaps my butt real bad, with all the known problems and extended warr how many Stealers turn this into a money maker off of the un informed.

The only pipe up front that counts is the crossover. You could get one from a salvage yard or have a local shop make one. It's a 2 1/4" collector off the exhaust manifold but the pipe you use can be 2 1/2".


As for the dealer. The code 36 isn't caused by contaminated fuel. It is a worn/sticking armatre on the fuel solenoid. No way he can say other wise.