Diesel Place banner

21 - 40 of 42 Posts

·
Registered
Joined
·
1,521 Posts
Hmm, you have me curious :idea:

Did you clean up your ground connection like i did underneath your rear bumper on the drivers side?
was it as simple as that and your LP and whole situation was fixed?

(so far for me, i did clean that ground and the other grounds up on the intake manifold, but still had my same bad situation the past 2 weeks of bucking and kicking and not drivable from stahling)
Wish I could give you an honest answer but too long ago to remember other than the lift pump turned out to be fine & that I had some difficulty powering the lift pump via the red lead .
The lift pump ground on my truck is via a short lead from the pump to the frame rail
 

·
Registered
Joined
·
154 Posts
Discussion Starter #22 (Edited)
By "12+ volt reading on the solenoid leg" you mean the Lift Pump Relay?

Another test, When the 12v. drops to 0 after the metal type sound, need to know what the voltage is at the ECM-B fuse.
yes, the 12+ volts i am referring to, is the Lift pump relay (i guess i have this brain block of saying a solenoid, instead of a relay, Doh lol, sorry )
 

·
Registered
Joined
·
154 Posts
Discussion Starter #23 (Edited)
By "12+ volt reading on the selenoid leg" you mean the Lift Pump Relay?

Another test, When the 12v. drops to 0 after the metal type sound, need to know what the voltage is at the ECM-B fuse.
I found ECM-B fuse diagram in the fuse cover decal, i see now, ok got it, i will check now...
 

·
Registered
Joined
·
154 Posts
Discussion Starter #24 (Edited)
By "12+ volt reading on the selenoid leg" you mean the Lift Pump Relay?

Another test, When the 12v. drops to 0 after the metal type sound, need to know what the voltage is at the ECM-B fuse.
ok, just did the test...

I have NOT changed the lift pump yet (the wife had dinner waiting :coffee:), so the perceived "bad" lift pump is still installed.
(also the Fuel heater is still unhooked, i will hook it up in 5 mins and try this test again)

Sooo, with the truck or LP nice and cool, i did the following:

1. Turned the key to on postion (no attempt to start) and leave the key on to allow the lift pump to run and get the pressure up from 0 to 6psi, the Lift Pump runs for 20 seconds (& the LP relay is showing 12volts), but at 20 seconds, the LP turns off and the LP relay voltage drops to 0 volts)

2. i can turn the key off, and immediately turn it back on and the LP runs and the LP relay voltage is at 12+volts, then 20 seconds, LP goes off and 0 volts.

What does this mean, just a safety mechanism built in case someone left the key on and didn't run the LP all day. or something more?
 

·
Registered
Joined
·
154 Posts
Discussion Starter #25
hooking up Fuel heater now and testing again, BRB...
 

·
Registered
Joined
·
3,941 Posts
That is proper operation. When the engine is running the LP should always have 12v.
I read your post again,
Does the PCM voltage at the LP relay ever drop to 0 when the engine is running?
 

·
Premium Member
Joined
·
9,478 Posts
Sooo, with the truck or LP nice and cool, i did the following:

1. Turned the key to on postion (no attempt to start) and leave the key on to allow the lift pump to run and get the pressure up from 0 to 6psi, the Lift Pump runs for 20 seconds (& the LP relay is showing 12volts), but at 20 seconds, the LP turns off and the LP relay voltage drops to 0 volts)

2. i can turn the key off, and immediately turn it back on and the LP runs and the LP relay voltage is at 12+volts, then 20 seconds, LP goes off and 0 volts.

What does this mean, just a safety mechanism built in case someone left the key on and didn't run the LP all day. or something more?
This is to build fuel pressure during the glow plug cycle.
 

·
Registered
Joined
·
154 Posts
Discussion Starter #28 (Edited)
hooking up Fuel heater now and testing again, BRB...
Hmmm, guess what, the Fuel Heater makes no difference.

Also i tested the resistance across the fuel heater element/connectors, and it reads nothing, which means it is open, fried, no good, wow...

I wonder how long i have had no fuel heater????
how important is the fuel heater??? (no issue in summer & maybe less fuel economy in the winter??? )

(would this not working also add to my bad fuel economy at 12+ mpg?)

** Hmmm, where is the cheapest price on a FFM Fuel heater?
 

·
Registered
Joined
·
154 Posts
Discussion Starter #29
Another test, When the 12v. drops to 0 after the metal type sound, need to know what the voltage is at the ECM-B fuse.
After 20 to 25 seconds with the key on and the LP goes off and the LP relay voltage drops to 0 volts, the ECB-B voltage stays at 12.5volts.

Also, i noticed the ECM-B voltage is always 12.5 volts with truck off and key out, which i suppose it would always be, but then again, you were asking, because it sounds like at times it could turn off? does the ECM send the voltage out to this fuse and sometimes go to zero (maybe from the ECM breaker blowing?) ?
 

·
Registered
Joined
·
3,941 Posts
The ECM-B fuse should always be 12v. and gets power directly from the battery.
This testing is done to make sure the power supply to related items having problems is good. With the LP pressure dropping to 0 and the engine dying at the same time I thought maybe you were loosing power somewhere. Since you did get it to run with 0 fuel pressure then you probably need a new lift pump. A shorted fuel heater or water in fuel sensor can cause problems with the PCM which will cause other PCM controlled items to act up also.
I gave up on the OEM LP after replacing too many of them. I never had one last more than 3 years, some only 6 months. I converted all 3 of mine to a Carter P4594 about 8 years ago and they are still purring along today.
 

·
Registered
Joined
·
154 Posts
Discussion Starter #31
The ECM-B fuse should always be 12v. and gets power directly from the battery.
This testing is done to make sure the power supply to related items having problems is good. With the LP pressure dropping to 0 and the engine dying at the same time I thought maybe you were loosing power somewhere. Since you did get it to run with 0 fuel pressure then you probably need a new lift pump. A shorted fuel heater or water in fuel sensor can cause problems with the PCM which will cause other PCM controlled items to act up also.
I gave up on the OEM LP after replacing too many of them. I never had one last more than 3 years, some only 6 months. I converted all 3 of mine to a Carter P4594 about 8 years ago and they are still purring along today.
Hey Thanks again Glagulator,

-Also, when you say PCM, is this synonomous with ECM?

- Now in my case, beings my fuel heater is "Open" (not shorted), does this cause any issues or anomalies ?

- Now for the water in fuel sensor diagnostics, how do i check it, i looks like it has 3 wires (vs the 2 on the fuel heater)...; which 2 would i check resistance across, and what is good resistance value?

-also, what is strange, is you would think it would stahl as it did before with the gas sock, or is that telling us, that beings the gas sock was restricting fuel supply that much, that the IP could not suck enough fuel to keep running? (vs now the IP can still suck enough fuel inspite of the Lift pump seemingly not working after a min or two?)
 

·
Registered
Joined
·
154 Posts
Discussion Starter #32
With the LP pressure dropping to 0 and the engine dying at the same time I thought maybe you were loosing power somewhere. Since you did get it to run with 0 fuel pressure then you probably need a new lift pump. A shorted fuel heater or water in fuel sensor can cause problems with the PCM which will cause other PCM controlled items to act up also.
I gave up on the OEM LP after replacing too many of them. I never had one last more than 3 years, some only 6 months. I converted all 3 of mine to a Carter P4594 about 8 years ago and they are still purring along today.
Oh a carter, i found it at Jegs, looks nice, and Jegs speaks good about it :thumb:
 

·
Registered
Joined
·
3,941 Posts
PCM = powertrain control module = engine and transmission control
ECM = engine control module = engine control only
TCM = transmission control module = transmission control only
All 6.5 electronic IP diesels have a PCM, even with a standard transmission.

Cool down your fuel heater to below 45 degrees F and then you should get resistance, if it is good. It has a built in thermostat.
The WIF sensor could probably be tested but the factory service manual just checks it for proper operation, otherwise replace it. It is solid state.
Here is the circuit -

View attachment 96wif.pdf
 

·
Registered
Joined
·
154 Posts
Discussion Starter #34
PCM = powertrain control module = engine and transmission control
ECM = engine control module = engine control only
TCM = transmission control module = transmission control only
All 6.5 electronic IP diesels have a PCM, even with a standard transmission.

Cool down your fuel heater to below 45 degrees F and then you should get resistance, if it is good. It has a built in thermostat.
The WIF sensor could probably be tested but the factory service manual just checks it for proper operation, otherwise replace it. It is solid state.
Here is the circuit -

View attachment 287121
ok, back to it... back home for the eve and i will now try to drive this beast with the fuel gauge & 2 voltmeters hooked up :thumb:
brb

After that, i guess i could park my truck outside for the night in the 35 degree weather and test it in the morning :HiHi:
What should the approx resistance be, something low i assume, couple hundred ohms, or really low like 50 ohms(what kind of current does it draw, couple amps, or higher like 5amps at 12 volts?)
 

·
Registered
Joined
·
3,941 Posts
Service manual does not have any specs on the fuel heater except that it has a built in thermostat that turns it on below 46 degrees F.
Another - Is it working? OK
Not working? replace it deal.
 

·
Registered
Joined
·
154 Posts
Discussion Starter #36
That is proper operation. When the engine is running the LP should always have 12v.
I read your post again,
Does the PCM voltage at the LP relay ever drop to 0 when the engine is running?
Ok, just back from my first successful run in two weeks :thumb:

For sanity sake, i still have the flaky Lift pump installed, but i am an engineering type, so i want to fix one thing at a time to know for sure what the heck the issue was.

Well, get this:
- at cold start in 55 degree garage, the Lift pump runs and pumps the system up to 5.5/6psi & truck started right up!!!
- i left the gas cap 3/4 loose to make sure i had no vacuum or pressure issue with it.
- then after backing out of garage i let it idle while i watched the fuel pressue and ECM-B voltage & the relay voltage.
- after approx 2 mins, it seems the flaky lift pump stopped working and sure enough the pressure slowly went to 0psi from the 2 min mark thru 4.5 mins. then i still let it run for another 6 mins idling, no issues, no hiccups, no bucking, ran great.

- Soooo, still having an 1/8 of a tank, i loaded my fresh spare 5 gal jug of diesel fuel (already treated with Stanadyne Blue (performance formula), and headed up the road. I drove a few miles to my favorite diesel filling station and brought her up to a 1/3 of a tank (and added Stanadyne blue & some Lucas treatment (Lucas Upper Cylinder Lubricant / Injector cleaner. i run it when i am out of 2-stroke oil or out of stanadyne blue, which was pretty much the past year, i assume it is perfect as an injection pump lubricant, you agree?)

--While i added fuel, i shut the truck off and the threw the switch to my newly installed & hidden switch up under the dash :bigglasse to test the lift pump, and sure enough, the lift pump is dead, just like the last night.
locking gas cap tighten all the way

-- after filling, this time i tightened the locking fuel cap all the way to see if by chance it would produce the bucking & stalling issue, but it did not, at least not in a 2 mile drive???

- Then drove home, no issues!! I even gave it WOT & got 11.5pounds of boost with 0psi still reading on the gauge, although it felt like it did the past year, didn't feel like a monster as it had the past few years...
-->>>So i am thinking the lift pump went bad this past year, would you agree?

-->>>but i let off the WOT after a few seconds, because logic tells me, that with 0psi, i suspect a LEAN condition and asking to blow up a good motor... does that logic make sense?

Stats
- The ECM-B voltage stayed on and high (14.5v)
- the LP voltage stayed on (14.5v)
- it stayed at 0psi after firing her back up at the pump and all the way home, go figure, wow :confuzeld


-->> Soooo, a new lift pump will be installed immediately :thumb:
*Now, does the lift pump type and brand really matter, if the truck actually runs on a broken lift pump at 0psi???



****MORAL of the story****
My gas fuel sock must of been the reason the truck was bucking and kicking and shutting off along side the road the past few weeks.
-> would you all agree???


IP FAQ
Would a bad lift pump for a few months to a year do any damage to the Injection pump, i assume a little lean on fuel, although i baby my truck and don't want to overheat it, because it felt weak and lean this past year at WOT, so i never pushed it....?
-Now i can say, that 98% of the time i used 2-stroke oil &/or lucas & more so this past year, so hopefully i kept the IP lubricated (along with everything else)
 

·
Registered
Joined
·
154 Posts
Discussion Starter #37
Service manual does not have any specs on the fuel heater except that it has a built in thermostat that turns it on below 46 degrees F.
Another - Is it working? OK
Not working? replace it deal.
Hmmm, i have no idea if it ever worked :confuzeld
So with me being ignorant of the fuel heater operation, what symptoms can i look for in the future to know if it suddenly goes bad?
Would it be those icy cold morning when she is harder to start and blows a ton of white smoke when first started up,

or
maybe slow to warm up on an icy morning, like really sluggish and slow and having to give it a little touch of throttle to get it going or keep it going the first 5 seconds after starting it on a freezing morning?
 

·
Registered
Joined
·
3,941 Posts
Hope you have it licked.
The fuel tank is a sealed system. As fuel is used and/or fuel temp changes so does the tank pressure. Normally there is a slight vacuum, the fuel cap is designed to cause that. When the fuel cap vent valve malfunctions you can get a very high vacuum and even collapse the tank. Happened to my burb. The burb had no symptoms of a problem until the collapse.
Running without a lift pump is said to put a strain on the IP, especially with the normal negative tank pressure. My 94 ran several years without fuel pressure before I
figured out the LP was running but not pumping. That IP has over 150,000 mi. on it now and is still running. Lube for the IP is very important.
AFAIK the IP is not going to cause a lean condition due to low or negative incoming fuel pressure but they will stumble under heavy load if fuel supply is restricted.
A 1993 lift pump is what most recommend.
 

·
Registered
Joined
·
154 Posts
Discussion Starter #39
Wow, my shiny new heavy duty lift pump from HeathDiesel.com pumped right up to 10 psi !!!
Thanks Bill Heath !

So hopefully tomorrow morning I'll take it for a spin and see if the pressure stays up the whole time & hopefull things are back to normal :)
 
21 - 40 of 42 Posts
Top