Engine/Transmission (1998.5 - 2002) Help with lift pump

[C4gan]

Lift pump only runs when i bump the key. When i start the truck i makes now pressure. Any ideas??????

 

[C4gan]

Oh, let me add that i just installed this pump today cause i thought that my old one quit on me. Is it possible that the ecm is not working properly? I am at a loss with this one. It works when i bump the key but does not work when i start the truck... ... ... . hum

 

[Cummins724]

Lift pump only runs when i bump the key. When i start the truck i makes now pressure. Any ideas??????

Possibly try running a hot wire directly from battery to the pump & see if the pump stays running & builds pressure. Do you have antigel in the tank?

 

[C4gan]

I have not put any additives in the tank. Just run the fuel at the truckstop that is suppose to have it already. The truck is in the garage with heater running. Can i use the harness that you get with the lift pump and just wire it up hot and ground to a switch and run it like that?

 

[Cummins724]

I have not put any additives in the tank. Just run the fuel at the truckstop that is suppose to have it already. The truck is in the garage with heater running. Can i use the harness that you get with the lift pump and just wire it up hot and ground to a switch and run it like that?

You should use a wire tap on the red wire going into the pump & run it to battery + & see if that helps, but don't cut the wires. It isn't recommended to leave it hooked to a switch, but you can do it to test it. It may be possible that your fuel pump relay is bad..... maybe try that first. Just switch the relay with one of the other relays in the fuse box under the hood & see if that helps.

 

[C4gan]

changed out the relays and nothing. hooked up the wire from battery to red wire on the pump and it builds pressure 14. 5 lbs but as soon as i start the truck ... pressure goes away. if i turn the truck off (with key in on position (electric gauge)) pressure builds back up..... can it be the ecm?

 

[C4gan]

Changed out the ECM and still the same problem. I am at a loss. Anybody have this problem before? Anyone with some different ideas? Does the glacier lift pump setup run through the same wiring or does it require its own wiring?

 

[KTobin]

Your ECM delivers between 12 and 13. 5 VDC to your lift pump. Check it out with a meter while running, if voltage is steady, between these numbers, you can pretty much rule out your ECM as the culprit. Was this a new lift pump that you installed? Was your old lift pump doing the exact same thing? Where are you picking up your fuel pressure from? How old are your filter/filters?



Kevin

 

[C4gan]

Yes, it was a new lift pump. When i first started the truck after the new pump was installed it was fine. Once i shut the truck off then it started doing this all over again. The pump works whenever it wants to. I could go out there right now and it may work. Or it may not work for 20 or 30 starts. Every time i bump the started the lift pump will run and build pressure. it is only when i actually start the truck that it does not run. The old pump was doing the exact thing. I figured that it took a crap and it was time for a new one. Filter is around 5000 miles old and i am picking up the pressure off the shrader valve on the firewall side of the filter assembly.

 

[KTobin]

I gather you have a Glacier lift pump and I assume therefore, that it must be mounted on the frame rail in front of the tank. If my previous suggestion checks out and you have solid voltage to your new pump, I'd start troubleshooting your flow. Run a piece of fuel line from a fuel can to your pump input and try to reproduce your symptoms. Look very closely along all lines for any signs of fuel leakage and thus air entry. Do the cheep and easy things first and get back to us.



Quote: "Does the glacier lift pump setup run through the same wiring or does it require its own wiring?"



You really should run your pump through a small 12VDC ISO relay, with #16awg rather than directly off the stock pigtail. However, it should still work without.



Kevin

 

[Cummins724]

Do you have a isolator on your gauge..... cause sometimes they can freeze up & give bad readings. I saw this on my brothers truck just last week. He would only get a quick movement then nothing until the truck got up to temps. I know that you said that it is in the garage now, but only mentioning everything that I can think of.

 

[eacallan]

Replace your filter. The life of the filter is contamination not milage. Same thing happened to me 2 times. My theory is the restriction causes the ecm to turn the pump off because of increased current flow. key off causes the ecm to reset. Hope this posts ok, my first attempt.

ec

 

[GarrettPetersen]

Did you check the fuel pressure with a manual gauge?? Dielectric grease the connections at the lift pump. Ive also had some pump right out of the gate be bad.

 

[C4gan]

Thanks for all of the extra things to check.

EAcallan,I am going to stop and get a filter (If my genos order did not come in today) and get a new filter. I will also pull the line off and check for proper flow. I think that it is 50 ounces per minute? I do not have an isolator on the gauge. will head that direction if all others dont solve the dilema.

KTobin, I do not have the glacier kit yet. I am wanting to install one and was just wondering how and where it gets its power source.

Will post results tonight... Thanks for the help.

 

[Joe Mc]

C4gan - The Glacier "Kit" comes with wiring and it's own relay to get things going, may I suggest the GFS-392 and the 2 micron spin on filter systems? See links in my signature.



Reading the whole thread I think you are seeing good pressure when you "jog" the key to the start position. This should last for 30 seconds, maybe 45 - I forget exactly. So afterwards you start the truck and there's "no" LP pressure? I think when you "jog" the key this by-passes the LP relay for a period of time (30 or 45 seconds) but when you start the truck power comes from the relay. I'm confused here because you changed the relay and it still does the same thing. Now you mentioned that it'll work sometimes and then it won't, I'm thinking ground somewhere? But, the pump should be grounded to the motor which is grounded to the body/frame . . . . I'd check the grounds anyway they are tempermental little buggers. I'll keep thinking. LEt us know what you find out - this is a good one . . . ?????

 

[C4gan]

Joe Mc, The black wire that hooks to the pump, is that a direct ground? If so then i can tap and run a ground back to the battery?

 

[Cummins724]

Checking the grounds is a good idea, but the fuel filter can be the problem as stated. The dirt can be settling to the bottom & this is why he gets pressure only sometimes. Both are good ideas & this is why TDR is so great..... multiple ideas quickly. Seperate we've been called dumbies, but together we are as smart as a guy who failed his SAT by one point. LOL

 

[C4gan]

LOL... .....

Cummins724- What do you find to be a good combo as far as smarty to drag box settings.

Not to jump subject but when i get this straightened out i am going to start adjusting the two of them. And if i get this figured out then i can install the Vaporizer stage 3's that i have sitting on my kitchen table... ... ... .

 

[Cummins724]

LOL... .....

Cummins724- What do you find to be a good combo as far as smarty to drag box settings.

Not to jump subject but when i get this straightened out i am going to start adjusting the two of them. And if i get this figured out then i can install the Vaporizer stage 3's that i have sitting on my kitchen table... ... ... .

I usually drive around with smarty on sw2 & when I want to play... . 5x5 comp gets me down the road. It stacks well on my truck in any even number setting, but sw8 smarty & comp on 5x5 is just rediculous on my ride. It kinda feels like something wants to break... . I run this in the summer when I want to give my friends a ride. :-laf

 

[C4gan]

Ok so here is what i have come up with.

13. 1 volts running with no fuel pressure

if i pull the fuel line off before or after the filter (stock location) and by bumping the key it will push around 46 to 50 oz of fuel in its cycle.

I hook the line back up and fuel presure will either be 0 or it will bounce between 4. 5 to 7 lbs and you can hear the pump trying to build pressure and then it will "free rev" and then it sounds like it is trying to pull fuel again.

Then it may jump up to 14 or 15 and then it will fall off again... .

I think that i may have bought a lift pump that is bad. What do you think?

Oh yea, garage is 70 degrees and i had the heater pointed at the fuel tank... at a safe distance.....