Engine/Transmission (1998.5 - 2002) lift pump has delayed start

[JMcrae]

When I first turn the key on ,the lift pump used to come on right away . As of this morning it takes about 10 seconds before it will come on. I just disconnected the batteries to see if resetting it would help. Has anyone heard or had this happen ?
thanks

 

[FourBarR]

I would check the plug where the lift pump plugs into the harness. with the key on check for 12 volts. clean the plug with contact cleaner and apply silcone grease. If that doesnt work ,if the pump is still located on the engine key on tap the pump with something and see if it starts.

 

[JLandry]

JMcrae,



The lift is only supposed to turn on for 2 seconds when you first turn the ignition key to the run position. If you bump the starter (without starting the engine) and leave the ignition in the run position, the lift should immediately turn on and run for approximately 25 seconds.



If the above isn't happening, then the first thing to do is measure the voltage present at the lift pump wiring harness to try and determine whether you have a problem with the lift pump itself or its supply voltage. The Yellow/White wire should have approximately 12 volts when you bump the starter. The Black/White wire is the ground.



If you don't have 12 volts present on the lift pump wiring harness when you bump the starter, then you either have a problem with the wiring harness between the ECM and the first pump, the ECM connector, the ECM itself, or the ECM grounding. There's no fuse or relay between the lift pump and the ECM.



If you are measuring 12 volts on the lift pump wiring harness when you bump the starter, then the lift pump is the problem. If you decide to replace it, go with an Airtex replacement. It's only $150, a better design from the original Carter, fits in the same location as the original, and works *great*!



Good luck,



John L.

 

[Ram4Sam]

"

If you don't have 12 volts present on the lift pump wiring harness when you bump the starter, then you either have a problem with the wiring harness between the ECM and the first pump, the ECM connector, the ECM itself, or the ECM grounding. There's no fuse or relay between the lift pump and the ECM. "





On my 01. 5, there is a fuel pump relay in the elect box under the hood, next to the brake master cylinder. There is one in there labeled "fuel pump circuit" or something like that. Try changing that relay. My original pump died and killed the relay. I had no voltage when I changed the pump, swapped relays with the fog light circuit(which uses the same relay) and off I went.



Sam

 

[JLandry]

On my 01. 5, there is a fuel pump relay in the elect box under the hood, next to the brake master cylinder.

Sam,



In diesel vehicles, the relay marked "FUEL PUMP" in the PDC (Power Distribution Center) is actually for the VP44 fuel injection pump and not the lift pump. Your experience with swapping out the VP44 relay and then having the lift pump start working could either be a coincidence, or maybe it's possible if the VP44 isn't getting adequate power the ECM won't make the lift pump run.



But the lift pump is wired directly to the ECM.



Best regards,



John L.

 

[Ram4Sam]

Sam,



In diesel vehicles, the relay marked "FUEL PUMP" in the PDC (Power Distribution Center) is actually for the VP44 fuel injection pump and not the lift pump. Your experience with swapping out the VP44 relay and then having the lift pump start working could either be a coincidence, or maybe it's possible if the VP44 isn't getting adequate power, the ECM won't make the lift pump to run.



But the lift pump is wired directly to the ECM.



Best regards,



John L.

That's kinda weird, didn't know that, I figured it was referring to the lift pump. About a year ago, I got a check engine light, truck stumbled a bit, then cleared up and made it home. Pulled the code which I think(IIRC) was p238, not sure but code book said something about fuel pump circuit. Hooked up pressure gauge,pump made no noise with key on and zero pressure. I figured the original lift pump finally went tits up. Plugged in new pump I had and new pump didn't run with key on either. Damn I said, had a beer and went looking,starting with the power center and saw the relay labeled "fuel pump". Swapped it as I said and went key on again and the new pump ran briefly like it is supposed to. Changed out lift pump and with the new relay in place, truck ran fine. Hooked up test gauge again to check pressure, showed 15 lbs at idle. This was about a year and 10,000 miles ago, no CEL's or stumbles since.



Sam

 

[duckcarvr]

JM do you have two fuel pumps like one on the engine and one on the frame? or just one. the reason i ask is i have that sytem and the one on the rail is a BD pump and does not come on till oil pressure comes up. its so you dont get the hard starting issue. robert

 

[JMcrae]

I am going to test the voltage at the pump today , but I suspect that it will show low.
I have also noticed that my wait to start light also is delayed . From doing a search on that symptom it may point towards a ecm problem.
Also noticed the last few weeks that upon start up my check guages light has come on for a few seconds at start up . It would always go out once the voltage gauge on dash would read around 14 volts , usually a few seconds later.
I always thought this was the grid heaters cycling and didn't think much of it.

If I try to start the truck before the lift pump and wts light come on it wont start. But after they come on (around 5 seconds later) it starts fine and runs fine .

John L how do I check the ground of the ecm ? Is it grounded by being bolted to the engine or is there a wire ?

Robert I just have the one pump on the frame rail.

Thanks for all replys so far , they have really helped point me in the right direction.

James

 

[blacksheepdiesel]

Wasn't there something about the original ECM software from the factory making the lift pump run continuously when the key is on and re-flash softwares changed that to a "momentary on" when the key is on and then "run" for 20 secs when the starter is bumped? If so and you had a re-flash this could be the reason for the change.

Godspeed,
Trent

 

[JLandry]

John L how do I check the ground of the ecm ? Is it grounded by being bolted to the engine or is there a wire ?

James,



The ECM itself is grounded through the engine block, but the lift pump is grounded through the wiring harness.



To make sure the ECM has a good ground, unplug its multi-pin connector, remove the ECM from the block, clean it well with some non-harsh solvent like WD40, clean it's mounting location on the block, then put everything back in place. When you have the multi-pin connector off, examine the pins on the ECM carefully for any signs of corrosion. You can clean them if needed with alcohol on a Q-tip... nothing stronger. If any of the pins are making weak contact, just the act of removing and reinstalling the connector can sometimes work wonders.



A couple of other things you might also check if cleaning the ECM doesn't solve the problem. First let me say I'm not sure if these items could cause your delayed wait-to-start, or no start condition if you don't wait for the wait-to-start light to go out, but it's worth a try...



1. If you haven't already, replace the IAT (Intake Air Temp) sensor. It's relatively cheap and some TDR members have reported obtaining better fuel economy after changing it out on high mileage engines. It's used to control the fuel/air mixture after all.



2. Check the intake heater elements for an open or grounded circuit.



I'll let you know if I think of anything else. Please keep us posted on how everything works out.



Regards,



John L.

 

[JLandry]

Wasn't there something about the original ECM software from the factory making the lift pump run continuously

Doesn't sound familiar to me. If I get time today I'll search through the TSB's to see if I can find anything.



Regards,



John L.

 

[AKAMAC]

James,



The ECM itself is grounded through the engine block, but the lift pump is grounded through the wiring harness.





John L.

The ECM is actually grounded through harness.

You can run the engine with the ECM hanging from zip straps.

 

[JLandry]

The ECM is actually grounded through harness.

You can run the engine with the ECM hanging from zip straps.

I sit corrected...



AKAMAC is absolutely correct. In glancing at the wiring diagrams, pin 30 on the ECM connector and pin 6 on the VP44 fuel injection pump connector share a common ground line which ultimately leads back to the main battery. The main battery is of course grounded to the chassis and engine.



When other TDR members have reported removing and cleaning their ECM to get their lift pump to start working properly, they must've just been improving contact on some of the ECM connector pins, or possibly jarring something inside the ECM.



Quite interesting.



Regards,



John L.

 

[AKAMAC]

John,

I pointed this out as a probable trace that the OP can use to find his ECM problem. I didn't even get my hands dirty.

 

[KCanepari]

I sit corrected...



AKAMAC is absolutely correct. In glancing at the wiring diagrams, pin 30 on the ECM connector and pin 6 on the VP44 fuel injection pump connector share a common ground line which ultimately leads back to the main battery. The main battery is of course grounded to the chassis and engine.



When other TDR members have reported removing and cleaning their ECM to get their lift pump to start working properly, they must've just been improving contact on some of the ECM connector pins, or possibly jarring something inside the ECM.



Quite interesting.



Regards,



John L.

I know this is old post, but the tech manual states to remove the ecm and clean the back of it to make sure it makes a good connection, so maybe part of it is grounded through the harness and the rest through the block. it would make sense because they run any high voltage noise producing components through a separate ground and noise filter.