My uncles 94 chevy stalled in the road the other day.He replaced the fuel shutoff selonoid thinking that was the problem.Then it ran fine for about a week and stalled again this time it took about 20 mins to restart it.We put on a fsd cooler and a new pmd about 2 years ago,could it be bad already?last time it went out it set a code but this time there are no codes.any ideas would be apreciated

Did you mount the FSD cooler on the intake? If so, two years was a long time. The intake is much hotter than the IP, which has the fuel to cool it. Remote mounting seems like the best solution, but even this modification only saves the FSD so long.

Yeah its on the intake thought we were doin the right thing at the time plus we didnt want to mess with the pump to put it back there.

Sometimes, it's the engine harness connectors causing problems, sometimes grounds, sometimes the ignition switch. All things to check\verify.


Try removing the FSD, flip it over, remove the plastic covers from the transistors, and check that the four 4-32 nuts are more than finger tight. Heat compression causes them to loosen.


Using a 1/4" nut driver or equiv, back them off, run them down to finger-tight, then tighten 1/4 turn more - very important - only 1/4 turn. Breaks the oxides on the stainless transistor cases, restores electrical connection. Any tighter can break the ceramic hermetic seals in the transistors, resulting in open circuit(s).


Then check the fuel filter, and the air filter - either\both can cause the symptoms.Edited by: gmctd

Think your injection pump is bad. How many miles are on it?

Would the injection pump come and go like that?Where are the engine harness conectors you are talkin about?At the rear of the intake or where.Thanks for all the ideas.

Its a good idea to carry a spare FSD with you. The FSD doen't always go into complete failure. Sometime it will give you trouble several times in one day and then run fine for a week or two. Generaly when they first start to fail they will restart after cooling down. Take a look at my web site and see how I got home when mine went south.


I had 2 FSD fail on a cooler mounted on the intake manifold and now have it mounted under the front bumper were it can realy run cool.

You dont have any trouble with water getting in it mounted under the bumper?

The FSD is potted to the extent that you could run it under water. That's is part of the problem. If it was not potted to this extent we could take it apart and either fix it or redesign the weak parts to run under the conditions under the hood.


I have always washed my engine with Simple Green and lots of hot water and that never had an effect on the 3 FSDs that included the original mounted on the pump and the 2 that were on the intake mounted cooler. All of mine have failed on a nice dry day.

well maybe we need a water cooled fsd then.http://www.dieselplace.com/forum/smileys/Big Smile.gif

You could attach a strap to the a/c reciever/dryer and mount the cooler with FSD to it. It's cold to the touch when the a/c is on and when it's not it's usually cold outside. Ofcourse, it's right next to the exhaust side of the turbo. I mount mine to the side of the engine. If you trace the red loom to the upper intake, you can see where it ties in to the harness.





http://www.dieselplace.com/forum/uploads/5BE_fsdcooler.jpg Edited by: quantum mechanic

Just a thought...have you checked to make sure that your lift pump is running? Simple check, just open the petcock on the thermostat housing, if fuel flows then lift is working if truck stalls then lift is not working.


Graeme

I would say that the IP would not come and go as you said. More likely the FSD.

Thanks alot for all the ideas.I been a lil sick the last few days and haven't got to try them yet.But hopefully we will get it goin again soon.

OK we replaced the pmd and it seems to have cured the stalling.But now it seems like it has a miss on a pull.Not a huge load only a trailer with some mowing equipment on it.Anybody have any ideas?

Have you checked the fuel filter? Air filter?

If you open the fuel petcock and fuel comes out is the fuel filter ok?

If you open the fuel petcock and fuel comes out it means you have fuel pressure, and you can assume the OPS to lift pump opperation. You check the filter by unscrewing the plastic lid and checking it. I keep a new one in the truck. If you have a question as to how dirty the old one is, you compare the two.

My uncle said he pulled the fuel line off the injection pump and it had plenty of flow so id say that rules out the fuel filter.

That is a common mistake many folks make.


The lift pump must deliver 15 gallons per hour thru the fuel filter, to the inj pump. This volume\quantity will supply engine needs from idle thru max load.


That flow is under some pressure, when engine is off, somewhat less when engine is running, considerably less when engine is under heavy loading.


As the filter does its thing, the pores begin to plug, restricting flow more and more.


Long as pressure is greater than demand, the filter element is extended, and fuel can pass thru.


As demand becomes greater than filter can flow, the element collapses, restricting flow even further.


This is where bucking, hesitating, stumbling occur under load. Load can simply be hiway speeds, accelerating to pass, or hauling\towing heavy loads.


Open the drain, filter expands, passes fuel, and all seems ok....NOT!


Suggestion - pull the filter, compare it to a fresh one FYI, and while you're at it, clean the filter cannister of old dirt, water, rust, etc.


Peace of mind is only 12 bucks.

I drove about 400 miles this weekend and I put about 2 gal of green fuels (8%Ethanol/ethyl esters/ 1 1/2 ml THF for solvent) in on top of the fuel addative I normally use. This is the end result.


http://dieselplace.com/forum/uploads/8D7_fuelfilters.jpg


Notice that the paper apron around the bleeder valve on top is as dirty as the filter media ( your first clue). I run mixed fuels for power, but moreover to keep this build up solvated where it will flow through or build up on the filter media, not inside the fuel system. In the fuel system this will cause Optical sensor failure, clogged injectors/ fuel lines, resistance on the liftpump, ect.Edited by: quantum mechanic

Good demo, QM.


Show and Tell rules!!!


Most folks would consider the filter on the right to be useable, as some filter media for gasoline vehicles is brown.


Not so, as can be seen. Diesel fuel filters are IBM keyboard color to white.


A new filter can resemble the one on the right in very short order, depending on where fuel is purchased.


An 18-wheeler stop has excellent fuel quality, as will any station with high truck volume.


If many trucks regularly pass thru the station, the fuel will not be in the ground long enough to deteriroate into a watery, rusty sludge.Edited by: gmctd

Well it looks like we need to pull that filter out and look it over.It sure would be nice if thats all it took to fix it.

We pulled the fuel filter out and it looks like the one quantum mechanic has in his pic on the right.We looked at the air filter and it looks ok to me.Think that could be it?Or do we need to keep looking somewhere else?How can you tell if you have a bad injection pump?

If the filter looked like that, the filter bowl is probably just as bad.


I'd clean it out completely


Remove the fuel line from the inj pump inlet, blow it out with compressed air


Remove the inlet fitting ( think it's a 17mm socket) from the inj pump and clean the stainless screen. Blow from the outside in, then rinse in Diesel fuel, blow again.


Repeat till clean.


Even a used filter should look like the one on the left, at 12000mi.

When you remove the oil filter it is a good idea to lower the fuel level in the filter bowl before removing the filter. The outflow tube on this filter is in the center about midway up inside the filter. If you just pull the filter out while the bowl is full of fuel you will run the risk stuiring up sediment from the bottom of the bowl or dropping dirt off the filter as you withdraw it and it falling into the outflow tube. Even if you do not directly drop dirt into the outflow tube the oil in the filter bowl is stuired up enough that when you install the new filter there will be dirty oil on the inside of the filter.


To reduce this chance of contaminating the injection pump open the air valve on the top of the filter, open the drain hose pet cock. With a hand held vacuum pump or the good old turkey baster pull a vacuum on the drain hose ad remove about 4 oz. of fuel. This will lower the fuel level in the filter below the outflow tube and reduce the risk of contamination.

If you just pull the filter out while the bowl is full of fuel you will run the risk stuiring up sediment from the bottom of the bowl or dropping dirt off the filter as you withdraw it and it falling into the outflow tube.





I believe this is what happend to me. I posted much earlier about my truck stalling and removing the fitting on the injection pump and cleaning that out is what fixed it.


Yes guys, my truck is still running flawlessly. Thanks again

OK we put in a new fuel filter and cleaned out the bottom of the bowl and the screen.It seemed to help some but it still has a miss when your driving down the road.Got any ideas where to go from here?Is there any kind of test for the injection pump?

It is possible that the fuel pump is cutting out under load.


You can attach a pressure gauge to the drain hose and put it under the windshield wiper for testing. (open the valve)


If the pressure drops way down when it misses then it is a fuel supply problem.

Assuming no SES indicator, DTC codes (some are set without the SES, such as cylinder balance at idle, for air in the lines - need TechII to see those)


Could have air in the lines from the recent problem(s).


Try driving it awhile - see if it clears up.


Or - bleed the injector lines one at a time with engine cool and running.


Crack each line open until fuel seeps around the fitting with no bubbles, then re-tighten the nut.


Could be bad fuel (as indicated by filter)- try driving till it clears up


Almost fergot - very important


Top bleed on filter cannister is filtered fuel


Drain on t-stat housing is un-filtered fuel from bottom of filter cannister - allows water and sediment to flush outEdited by: gmctd

IP fuel inlet could be crudded up.

Is there any way to clean the IP fuel inlet?

Remove the inlet fitting and stainless screen - 17mm socket

Ok i think thats the one we already cleaned unless theres more than one screen.A local mechanic says he thinks its the injection pump and he says he can tell if its bad by hooking it up to a scan tool.Is that possible or is he just feeding a line of BS so he can charge him $60 to say its bad?It would be really nice to know if it was bad before spending the $ to replace it and see if it fixes it.Could a bad injector cause a miss?They were all replaced not long ago but they came from napa so i dont know what kinda quality they were.

No, that is the only inlet screen in the inj pump.


If the mech is good, he can interpret the info from the TechII in determining the failure.


Problem is, the inj pump doesn't always reveal it's mode of failure.


Failing injectors should give CYL BALANCE DTC(s) while engne is idling, but will not set SES indicator. PCM varies injection quantity to each cylinder to ensure quality idle under various conditions.


If missing at idle, crack each injector line open, engine cool and idling, where good cylinders will start missing. Injector on bad cylinder will no change.


Agaijn, bad fuel can cause missing, as can air in lines, or junk in lines\injectors.


Did you find anything in the inj pump inlet screen?

No we didn't see anything in the screen.If it does have air in the lines how long should it take to work it out?

Small amount in a line or two should clear at hiway rpm. Or, manually shift the transmission to stay in lower gearing, with higher engine rpm - run it up to 2500 - 3000rpm in 2nd and 3rd, hold it at max for a bit. Gets the fuel moving.


If it is 'missing' hard, or continues light 'missing', ease off and bring it back down. Want to 'cure', not 'cause'.


The injectors will require 'bleeding' to eliminate trapped air.

I think he's just going to replace the injection pump.Any tips or tricks to installing one?How hard is it to do it yourself?

Ok the new injection pump is on but it still has a miss at times.If it isnt timed just right or hasnt had the offset learn thing done could that be the problem?Would it still think it had the old pump on there without doing the learn thing done?What about a lifter bleeding down at times?Where have you guy's been anyway i hoped i would have gotten at least one person with help installing the pump:(

Come on guys i need some ideas.

If you're sure the injector lines are air-free, then you've accomplished all the mechanicals - now it's time for electrical.


It is a computerized system in a 10-year old vehicle, so -


Starting with battery terminals at batteries, remove, inspect, and clean all terminals, connectors, and terminations - you'll be looking for oxidation\corrosion, moisture, etc.


Sometimes just disconnecting\reconnecting a connector 'burnishes' contacts enough to restore circuit continuity.


This will include all the connectors in the engine\trans and PCM wiring harness.


PCM harnesss heads into the cabin from all those connectors behind the fuel filter.


Engine\transmission harness(es) distributes into the engine bay from those same connectors.


Loose ground terminations to engine block, loose power connections at starter, frayed wiring, scraped insulation exposing wire conductors. Etc.....


Some folks have cured similar by replacing igniton switch.


I suggest re-establishing contact at each connection, first - it's free, but for your time, and cheaper than a new switch.


And, a new switch will not fix it if poor-to-no continuity exists in harness connectors. Edited by: gmctd

So you think the timing is ok?I thought it needed to be set by a dealer but maybe im wrong.

PCM will log DTC's if anything is out of limits - pump was replaced and engine is still missing would seem to point to some other area of concern.


Any new codes?

No there arent any codes and no check engine light.Last night he drove it to a friends house and now it wont start at all.Where would be the first place to start looking since its not running at all now?

Jak,


Won't start, lets go back to basics, air, fuel, ignition


Air filter clear/no blockages it intake system


Fuel at filter bowl drain, power to fuel shut off solenoid, was PMD/FSD a new one, swap back to old to see if engine will even attempt to run the old one was only sometimes stalling right?? maybe a bad new one, it happens sometimes. water in fuel, fuel filt clean maybe some algae int the tank new filt is cruddy again.


Glows working okay, cranking speed okay.Edited by: Turbine Doc

Ok we spent most of the day fooling with it and the only way we got it home was to unplug the optical fuel sensor and it started up.It ran slugglish but at least it came home.If you try to start it with it plugged in it spits and sputters like it wants to start but blows black smoke out of the tailpipe.we moved the injection pump trying to change the timing and didnt help it a bit.When we started this morning it had a code 34 then we cleared it and after runing it home with the sensor unplugged it had 17 18 and 35 i think.We did the tests in the book for the code 17 and it had the 5 volts it should and it stays about 3 volts when your trying to crank it like the book says.The book says if it stays at 2or 3 volts then pcm is bad but i dont want to jump the gun or anything so any ideas on what else should be checked.There is nobody close to take it to that has a clue whats goin on with a 6.5.

Unplugging the Optical Sensor causes the PCM to run in the backup\limp-home mode - not much power, but it will get you home.


If engine runs better, the Optical Sensor is bad, or extremely dirty fuel is too opaque, causing erratic output.


Or wiring\connectors are faulty.


Seems like there was a recent post here in one of the other stalling-bucking-dying subjects about a web-site in Scandinavia detailing R&R'ing the Optical Sensor.

When your accelerating your pumping around 8 inches a second of fuel, I can see how worn contacts on the OPS could keep fuel pressure from building to demand.


If you wire in an auxillary relay where the OPS controls the relay and the relay powers the lift pump, the relay should be able to power the lift pump at full demand. if it is this problem you might want to start over with a new OPS.

the lift pump is on a toggle switch so i dont think lack of power to it is the problem.The pump is brand new so i guess the optical sensor in it is new too.I pulled the connectors apart and srayed WD 40 in them(Its all i had)Whats changing between backup mode when its unplugged and regular when its plugged in?I guess timing but what else.It really seems like its dumping alot of fuel in there when its trying to start with the optical sensor plugged in.Im pretty much lost what are the main circuits the pcm uses just to get the thing started?

Jak...,


I ran a toggle for a few weeks before I put in the bypass relay. I would always forget to turn it on or off, not a problem with the OPS switching the relay for me.


Hey listen,


If your running the liftpump off the OPS still, it isn't an optimal set-up. The lift pump is drawing 4 amps and the OPS is rated for 1amp. It is therefore drawing 3amps more than capacity to meet fuel demand.


A relay costs less than $5 and you can wire it in 30 minutes to carry the load. I put in a hd 30amp aux relay for aux lights. It could power two liftpumps without a problem if I felt I needed the fuel.





I'll tell you one thing I know. One bad tank of fuel can foul the optical sensor. On a scantool readout it looks like your timing is way off when it first starts (25 deg) and even if you move the IP on the stepper motor it doesn't change actual timing.


My '94 starts at 10 deg. advanced and comes down to 7.8 degs or so and a mm change gives 2.0 deg change. A truck I scanned with a bad optical started at 25 deg( a hard start) and ran at 14 deg and couldn't be seen to change with IP rotation either way.


It can also be an erratic signal from the crank sensor. With scantool it will count off cam pulses, crank pulses, show crank status on. Optical and crank sensor are similar in PCM variable relation.Edited by: quantum mechanic

Thats the trouble i dont have a scanner and i have no idea what the timing is.Or how many cam pulses or crank pulses.What exactly is a stepper motor anyway?Could this thing just need the timming set?Could it be out of time with the optical sensor plugged in and when its unplugged it changes the time enough to let it start?I dont think fuel is a problem it may be getting it at the wrong time though.

It's a four-stroke engine so the crank turns two revs to fire all eight cylinders - the Crank Position Sensor has 4 poles.


Inj Pump, driven at half crank speed, has 8 triggers on the Optical Sensor wheel, closely timed to the CPS, one for each cylinder.


OS also has High Resolution output, with 64 counts across TDC for each cylinder, for a total of 512 counts per revolution.


8 x 64 = 512, just like in Digital Computers. Which it is.


The PCM uses these timing signals, and other sensor inputs, to determine optimum injection event.


In backup\limp-home mode, PCM uses Crank Position Sensor and Throttle Position Sensor for some basic injection - no turbo, no power, just please get me home and I promise I'll be good, next time.


Won't run without the CPS, so backup mode sorta indicates that one is good.


You should get a DTC-88 if timing is too far off.


I still suspect wiring. The OPS connector is part of a short harness with an EMI suppressor molded in, and a larger connector behind that, and an even larger connector at the firewall, where it all joins the PCM harness.


Any possibility you could take a photo, with the Turbo Power cover removed, and post it here?Edited by: gmctd

Sorry no digital camera.We got tired of fooling with it so we loaded it on a trailer and hauled it about 50 miles to a guy that's supposed to know his stuff.(he talks a good game but i guess we will see)anyway we called about it the other day and he said the timing was off 14 degrees not sure which way it was off though.But i guess there is still more than that wrong so he said call back on monday to check on it.Ill let you know if he gets it fixed what he found wrong with it.Thanks for all the help

OK we called today and the guy says everything he is checking is pointing to the injection pump being bad.Plus he says it is a reman instead of a new one like it was supposed to be.Could it be possible that it was bad comming from GM?

Ask him for specific criteria he used in determining new from reman.......


Don't give him any hints - just get him to be specific.

I haven't talked to him myself but i think he went by the numbers on it somehow

OK i talked to my uncle today and he said the mechanic said the warranty on the pump could be void.He says they paint a white line where the fsd plugs in and if its been unpugged they void the warranty.Anybody ever heard of this?He's talking about putting another pump on it to see if thats the trouble.Then i guess if it is the pump they will try to get GM to replace it.

Jak,


OBD-I is a little out of my experience I'm OBD-II but something does not sound right, mine did not have a white stripe painted on it when it was replaced by the dealer, if it is a reman that is reason enough in itself to go back and get the dealer to fix it did they sell you a reman or new one if they did not specify it as a reman then somebody owes you some $$$, also if I remember correctly to policy GM follows says for them to scrap them, so there should not be a reman from GM.


Is your local mechanic trying to troubleshoot the IP with a "'suspect" PMD/FSD or has he swapped out to a new one, I've not heard of many bad IPs in themselves, GM replaces them as the consider the IP & FSD a intergral unit.Edited by: Turbine Doc

The dealer didn't install it,we put it on and it ran for a week and quit.It was supposed to be new but the guy we have working on it now says he thinks its a reman by the numbers on it.Kinda hard to walk in and say you sold me a bad pump without proof its bad.

I think if it ran for a week & now it stopped running that would make for a good case, but before you go back in to him run the checks you ran before, lift pump, fuel filt, something just does not sound right.


Describe again the failure mode it does not start at all, runs then stops then restarts, does the limp home mode that worked before work now, seqentially lay out what is happening now some of this is blurred in my minds eye as I try to interpret what was going on before into what is going on now.


Maybe start a new post from we swapped IPs it ran for a week now it does not _________ (fill in the blank with as accurate a description as possible), I think the inital diagnosis from 1st fail was wrong I'm suspect on the 2nd IP that "fixed" it for only a week.

well im not sure exactly how its acting right now but i know the day we dropped it off with the optical fuel sensor plugged in it trys to start but just blows black smoke.The only way we got it to run was to unplug the optical sensor then it started.It didnt have any power but we got it home.It was running on the old injection pump but it had a miss under a load.The day it quit after the injection pump was replaced he drove it to a friends house and left it for several hours and when he went to leave it wouldnt start.The lift pump is working and it has a new fuel filter so fuel delivery inst a problem.The guy did say the timing was off about 14 degrees though but it wont start with everything plugged in to see if it throws any codes or to see what its doing with a scan tool.

wow, sounds like a real bugger jack. I agree with GMCTD, I'm having a hard time keeping up with your story.


Quick thing to try, plug the optic sensor in, and unplug the crank sensor. it should start, you'll be in limp mode again, but if it works then you can be sure the optic sensor works and you might be getting a faulty crank sensor signal which would explain the 14 degrees.


if it wont start with the optic sensor plugged in, but it does smoke black then the pump is pumping, and the timing is out, either because the static (base) timing of the pump is way out or the optic sensor is at fault. if the new pump ran for a couple weeks and then this problem just started check the pins inside the plug for the optic sensor on your trucks wiring harness. They have a tendency to get a little weak over time. (there is an actual tool to check pin drag, but you may prefer the field expedient method, works just as well) if you see one that looks like its collapsed, or, even if you dont, try taking a seal pick and working it in behind the individual plugs and pushing the springy part that makes the connection in to increase your pin drag. If that doesnt work, then remove the glove box and unplug the PCM and do the same thing to the connectors there, pushing from the outer, empty rows to the tops of the individual connectors in each hole in the center rows, I've seen similair problems in these trucks caused by connections here (most commonly in the 6.5 vans because it sits right on the dog house). then try doing the same to the 3 large plugs on the bracket between the firewall and the fuel filter base. Edited by: Texas Diesel Guy

Thanks alot guys.Where is the crank sensor located at?Ill try that the next time i get my hands on it.

The plug for it will be routed right in front of the IP, and then down behind your A/C.

You could attach a strap to the a/c reciever/dryer and mount the cooler with FSD to it. It's cold to the touch when the a/c is on and when it's not it's usually cold outside. Ofcourse, it's right next to the exhaust side of the turbo. I mount mine to the side of the engine. If you trace the red loom to the upper intake, you can see where it ties in to the harness.





http://www.dieselplace.com/forum/uploads/5BE_fsdcooler.jpg

Where did you get that FSD harness extension? I have mine mounted on top of the intake and would like to move it.

Ok yesterday the mechanic thats working on it decided to pull the pump we got from GM off and try the injection pump off his personal truck on it to see if it would start.He got it running and we went last night to test drive it.It idles smooth and doesnt sound like its missing but it was kinda dead under 1700 rpm.Could it be low on power under 1700 because his pump came off a one ton and my uncles is a 3/4 ton?

The only ds4 pumps that are different are on '94 trucks. 1/2, 3/4 and 1 ton all use the same pump.


Does it have and codes stored in the computer?

I didnt check for codes but the service engine light wasnt on.This one is a 94 but im not sure what year the one ton is.

Did you happen to notice if the dashboard was different that yours? If it was the same then it is a '94. If different then it is at least a '95.


If it is newer, have him try swaping the chips and see if it makes a difference.

Well now we are in a real mess.The guy that was working on it for some reason decided to take a hammer and a chisle i guess using it to move the pump to set the time.So now we have a new pump that im sure GM isnt going to warranty even though we had trouble with it before we even took it to this guy.It seems to me that it must be the optical sensor or the connection right there at it because it ran when the guy put his pump on it.Is there anywhere a person could buy a new optical sensor and install it themselves in the pump that the guy beat up?I know im kinda grabbing here but what if the optical sensor was just not lined up right from the factory is there any lines to go by if you open it up and look to see if its where it should be?Any ideas are more than welcome.

You might want to shoot a PM to TDG & see if he can check it for you for a fair price may have to send whole IP, acutally I'd make hammer mechanic pay for the IP repair he voided the "new pump", he & you should invest in the proper tools for turning the IP, you can get them from Snap-On which is where I got mine.


Then once the IP gets repaired find a new mechanic or bite the bullet & let GM install it, hammer mechanic from what I read here, should not be allowed back under your hood, but that's me I'm a bit anal retentitve when it comes to folks working on my truck.

I would take it up with whatever garage this guy is with and get them to handle it, if their man put a hammer and chisel to your pump and voided your warranty then you put a hammer and chisel to them until they get it fixed, whether GM chooses to honor your warranty claim or not. I would say its pretty much impossible that the optic sensor was just incorrectly installed from the factory, they do calibrate these pumps not just assemble them. But we do see a few lemons out there that come back with extraordinaly low miles. Edited by: Texas Diesel Guy

I would like to know what you find out is the problem. Mine is currently doing the same thing. I have replaced PMD, IP (twice), ECM (twice) without fixing it. I first broke down on vacation.


The symptoms were first a drop in turbo pressure which then would max out and intermittant chugging/missing. I first replaced the boost pressure solenoid which helped even out the boost but still had missing.


It then started to severely miss and stall repeatedly. The codes were P0370, P0251, and P0606.


I then replaced the PMD with new longer remote cooler setup. Still no change. I took it to a mechanic and he first told me the ECM was bad, so I took it to GM and they had to replace it twice because the first one they installed was bad. Still no change.


The mechanic then checked again and only found codes P0251 & P0370 and told me the IP was bad due to a bad optical sensor. So I unhooked the optical sensor and drove back to Utah. Ran great other than long starting times and lack of power.


Once returned I installed a reman IP. It ran good for approximately 2 weeks then began again to stall and miss. The codes were P0370 and P0251. I tried another PMD with no change. I then installed another reman IP which still does not run, except with the new IP it will not run even if the optical sensor is unhooked. I haven't gotten the latest codes since the second IP was installed becuase I have to visit my local autozone for retrieval and it won't run that long.


I have tried checking the connection to the remote PMD and optical sensor for problems, I even replaced the short wire section that connects to the IP.


I love the vehicle but I am getting extremely frustrated with this. (Also I have replaced the fuel filter and checked the fuel pump).


My last guess is the crankshaft position sensor or the second ECM I have from GM may be faulty as well.


If I can't figure it out by myself I will have to tow to a diesel guy that timed the original one and see if he can figure it out. Please any help out there?

Well its home now.He went and got it after he found what the guy did to the pump.As far as i know GM sent it off and i guess they are waiting for a decision on it.The guy says he isnt paying for it so i guess unless he wants to take it to court thats the end of it.Its a shame this guy supposedly worked at a GM dealership and started his own buisness.Maybe thats why he doesnt work there anymorehttp://www.dieselplace.com/forum/smileys/Ermm.gif

I have a feeling the new IP will fix your problems...let us know.Edited by: Texas Diesel Guy

You owe it to the community where you live to sue this guy or he'll do that kind of work with out hesitation to the next guyhttp://www.dieselplace.com/forum/smileys/Big Smile.gif

We still haven't heard from GM about the damaged pump yet.Theres been alot going on here and the truck got shoved on the back burner.Ill let you know what fixes it when i know.