Engine/Transmission (1998.5 - 2002) Why won't lift pump run?

[KWentling]

Truck is a '98. 5 with 106,000 miles that's dead. When I turn the switch to the run position, the lift pump runs for a second or so is all. If I bump the starter, it doesn't run at all. I have not been able to find a scan tool to borrow to pull codes. I may have to drag it to town (15 miles) to have someone scan it for me. The lift pump is new and the relay is OK. The truck was running one day and would not start the next. Anyone have any suggestions?

 

[ToolManTimTaylor]

I have seen NEW l. Ps up and dead out of the Box! You just may have one. Torque This as a matter a fact Had one live for 2. 4 seconds

 

[KWentling]

I guess I'd better check to see if the pump is getting power but not running then. Thanks for the reply.

Kim

 

[KWentling]

New lift pump is OK. I ran power direct to it and it run. Problem must be in the electrical control of it. Anyone?

 

[noland]

My LP stopped running last week and I bought a new one only to find out that it was not the pump but a bad connection on one of the power wires right where it goes into the plug. It was hidden by the tape that is wrapped over the end of the split loom.



Local Cummins dealer had a connector in stock



Part # was 4025182

 

[daveshoe]

Your lift pump will only run for a second or two when ignition switch is turned to ''run'' position. Some have reported no noise from pump when starter is bumped, but individuals could have hearing loss and not realize it. Mine is very quiet on '' bump the starter'' Bumping starter will run lift pump for 20 seconds or so.

If you have no fuel pressure gauge, the easy way to test function is to loosen the fuel filter housing and bump the starter-- do not blame me for the Diesel shower This also would probably work to open the fuel/water drain cock and bump the starter-- should result in larger volume fuel draining.

BTW -- to end diesel shower , switch ignition key off as soon as lift pump function is verified. This will proove function -- it will not proove pressure

 

[KWentling]

daveshoe, wish I could get a diesel fuel shower (not really) but pump isn't running long enough. When I changed out the pump I also changed the filter and would like to use the pump to fill it. I've got one plug out of the top of the filter housing, but have not got any fuel yet. I can hear the pump run when the key is turned to "on", but not when the starter is bumped, and I do have hearing loss and I know it. Guess I should check for voltage at the pump in case it is running and I don't hear it. Should have gotten fuel by now if it was though. Thanks for the reply. Anyone else?

Kim

 

[Tom W]

Kim, some have suggested pressurizing the tank to get fuel to the filter. If you have access to an air compressor, wrap a rag around the hose and give it a shot of air. Maybe your pump is air locked and will work if you get fuel to it. Good luck.

Tom

 

[Loren]

Kim,



I would guess that your problem is most likely not in the pump nor the control for it, but rather in the inability to prime the system following the fuel filter change.



I have primed mine by leaving the filter canister lid loose and running the pump, as suggested by daveshoe. Once I also loosened some of the injectors, although I suspect that I didn't really need to do it at the time. I think that #1 and #3 are the recommended ones, but I just used the ones that I could get to easily.



Before I spent much time or money trying to find a pump problem, I'd be sure that it wasn't just a priming issue.



To check the pump, you really do need a pressure gauge. My understanding is that the mechanical gauges that you connect right at the pump are not too expensive. It might be a good investment for you, especially if you find that your lift pump is not the problem.



Good luck with it.

Loren

 

[daveshoe]

Sorry about previous post . I have no idea if my advice even pertains to 12 valve Cummins. You have some good things to try from other members. I have read about guys having success pressurizing fuel tank to get prime. However , if memory serves, there has been advice to not put too much pressure on the tank.

clean exhaust from a vacuum cleaner would probably move the fuel.

You stated that you ran power direct to it and it ran. [I do not know if it was on or off the truck when you did this] Is there any way you could run power direct to it with it installed on the truck? then if you got it primed, and it pushed fuel, you could connect it back to stock harness. If it then did not push fuel, you would know you had a wiring issue. Sorry if I insulted your hearing, but an unprimed pump is more quiet than a primed one.

 

[TowPro]

Don't you have to turn the key off, then back to run, and "bump" the starter to get it to run? Once the pump has run, I don't think it will run again until you cycle the key back to off, then repeat the cycle.

 

[KWentling]

daveshoe. the truck I'm working on is the SO's Dad's, not mine, and it is a 24-valve. I tried the air in the fuel tank and got fuel as far as the lift pump banjo fitting. When I ran the pump it was off the truck. I checked voltage at the connector with it disconnected from the pump and there is a constant 8. 9 volts from the time the key is switched to "on" (longer than 60 sec) and doesn't change when the starter is bumped. Did the same with it connected to the pump and it had voltage for the 2 sec. that it ran and then went to 0 volts. That sounds like a bad connection somewhere maybe, opening up under a load. I don't think it can be air locked, because all the time I've been trying to get it to run I've had one of the plugs out of the top of the fuel filter canister. The pump should have run, air locked or not, shouldn't it? I may have access to a scan tool this weekend.

I talked to the guy (SO"s brother) who was driving this truck when it died. He was pulling an empty horse trailer from Cheyenne to Gillette and the last 100 miles or so it was getting hot on him (up to the edge of the red). He didn't recall ever hearing the fan engage, nor has the SO's Father ever heard it. Probably the fan clutch has gone south. He said he would slow it down to regulate the temp. Said the truck was guttless and running rough. When he got it here he unhooked the trailer and parked it. Next day it wouldn't start. It hasn't run since.

Kim

 

[daveshoe]

What next?

I stumbled on some stuff about how the ''run'' position and the ''start'' position work. Key on-- it is normal for a 24 valve to pressure up the lift pump for a 2 second duration and then quit. My fuel pressure guage verities this. When you crank the engine , ''The ECM pulses power to the lift pump on-off-on-off to get reduced pressures for starting-it does not reduce voltage to the lift pump'' Quote from Steve St Laurent.

The VP-44 fuel injection pump does not like full pressure at start up, so the engineers have elected to pulse the lift pump BY THE ECM. Now instead of looking for something simple like a bad connection , we get to wonder if a dern computer is involved!

KWentling. I think your abilities are way beyond mine. I hope that you can find some use of this.

 

[KWentling]

daveshoe, Thanks for the reply. You may be right about the problem being the computer. Would this be the one on the side of the block? I guess I'm done until I can get the codes read.

Kim

 

[daveshoe]

Go to first time cummins diesel owners forum. Sticky shows where everything is. As far as me being ''right'' about what problem is , I do not have a clue at this point. I think we went thru all the easy stuff already. Anybody else have this happen ?



Kim , keep us posted, we are interested in your problem and the solution. Dave

 

[KWentling]

Update: I got the codes read but I am having trouble finding what they mean. The codes are: P1693, P1689, and P336. I have found some info on 1693 and 1689, but nothing on 336. Scan tool said that the P336 and P1689 are pending. Anyone have a book for the '98. 5? I looked in my '98 and as I suspected they are different. Looked on an internent site recomended here for codes and it only shows a 1693. Help!!!



Kim

 

[dslmacdown]

Codes

P1689 = No Communication Between ECM & Injection Pump Module

P1693 = DTC Detected In Companion Module

P0336 = CKP Sensor Signal



The 1689 and 336 are pending, meaning that a flag has been set and the ECM is going through tests on these sensors. If the part or system fails these tests than a code will be set. OBDII is much more complex and complete diagnoses system than any OBDI system.



MAC

 

[KWentling]

Thanks for the quick reply! I believe CKP stands for crankshaft position sensor, but what does DTC stand for?



Kim

 

[dslmacdown]

CKP is crank sensor, DTC stands for Diagnostic Trouble Code.



MAC

 

[KWentling]

Thanks again MAC. Here's what I've done. I made a pigtale so I could run the lift pump to fill the filter and bleed out the air. Tried a couple of times to start it but no go. Didn't expect that it would, but thought I'd give it a try. Called Cummins Rocky Mountain for a crank sensor. She said they had 2 in stock. Got there to pick it up and I think she had a temperature sensor. We looked in the parts book and found the right one but they didn't have it so its ordered. Be here Tuesday or Wednesday. What a poor parts book. Sensors are only called "sensor" not "temp sensor" or "crank sensor" so you need to know the location of it. Hope that fixes it, but I'm thinking the VP44 may be tits up. I'm not sure that any of this explains why the lift pump doen't run after bumping the starter, unless the VP44 isn't sending a signal for fuel. Not sure how all that works. Sure would be nice to have a service manual. If he's going to keep the truck, and want me to work on it, he'll be buying one.

Anyone have any pointers on replacing the crank position sensor? I can feel it, and see it with a mirror, but I can only get one hand to it. Looks like it could be a PIA.

How does one bleed the injectors? Does the engine need to be cranking over to do it? I presume that I'll have to do this.

Kim