How can i tell if my lift pump is going bad? i am recently having problems starting my truck. it cranks for a long period of time after sitting over night. and almost kills the batteries somteimes.
Nick

 

before you condemn the lift pump,next time you get a long crank, stop,....loosen the bleed valve above and to the left of the lift pump. pump the lever on the side of the pump and see how much air you get out of it and then tighten it!

If you can't get fuel out of it, it could be your lift pump. If you get bubbles and fuel......you have a leak in the suction side of the pump lines or in the(edit) TANK module it's self!!!


NOTE: if the pump lever don't pump, it my be becuse the cam lobe is holding the lever off the pump.............bump the eng over and try again and again untill you get the lever to work or you have turned the eng over a coulpe times!

 

i wasnt trying to condem the lift pump. how do you fix a leak on the suction side of the pump? cuz i think that might be what it is cuz if i park with the engine higher than the tank i have to let the truck roll til it is flat and then try to start it.

 

That depends on where the leak is located. In most cases I have found that a suitable patch in the line itself can be made using the right size fuel hose and a couple of hose clamps. In a pinch I have had to cut a piece of hose and split it lengthwise to cover a hole rubbed in a fuel line and secure it with a hose clamp right over the hole. That is called a soft patch. Then later on I replaced the worn line.
To test the line, try to pressurize it starting at the lift pump suction back to the fuel tank. Look for leaky fuel. But be very careful to NOT over pressurize the line or put any pressure in the tank. Use a pressure regulator and gauge and adjust it to about three to five psi after you take take the cap off the tank fill. Some one did it by using a rag and blowing air into the fill neck and it worked. Just be careful. Don't want you to blow up.

 

it cant be the line cuz the only leaks on the outsideo f the engine or anywhere else is oil. it just seems to loose prime or something. which is frustrating, cuz i dont know enough to figure it out.

 

It's ok just take a deep breath and then go back and read the previous statments and the go surching......you have to remeber that air is thinner the fuel.
what i'm trying to get at, is that the the slightist pin hole in the line will alow it to drain back to the tank but wont leak enuff,to evan drip!

if you put pressure in the tank, you will probably fined the leak!
But dont put to much in or it will only cause you more problems.

 

Inhale and hold.............................................. .................................................. .....................................
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.................................................. .................................................. .....Exhale.

but i just remembered that when i go to fuel my truck i always get suction out of the tanks when i remove the caps.
so if there was a hole wouldnt it release the pressure?

 

Ok now this bring up a diff idea...............are you shore that it is air going in or out when you remove the cap? if it is suction then you need to replace the fuel cap(cap should vent, but hold...a little pressure)

 

im not sure i have never put my hand by it to see if it is going in or out. most likely check it later tonight. but its on both tanks and i dont think they both would bo bad at the same time would they?

 

There is a neather thought,is it hard starting on both tanks?

could it be just one tank that giveing you the probems?

could it be geting air from the valve that switches the tanks?

 

im not sure cuz i have only been using one tank lately cuz the other goes through fuel faster than the one i am currently using. so i havent been able to check the other tank.

 

Was your Chevy a diesel before the Cummins? Gassers in '88 all vented through a charcoal canister. That may be a problem. Next time you stop, loosen the fuel cap. Let her sit overnight and then see if it will start in the morning. I'm thinking the tank is holding a negative pressure and between that and a minor air leak you are loosing prime.

 

Good call, Boatnik! For as sensitive as these fuel systems are, they will put up with a fair amount of 'wrongness', for lack of a better word, and still run quite well.

 

used to be a Gas hog 454. and im pretty sure that the charcoil cans are gondy cuz ive had the box off and didnt see any. im gonna run out now and loosen the cap. thanks for the info sir. much appreciated.

ill let yall know if it works cuz it will be sitting for the majority of the day and that is when i have the most problems.

Nick

I knew y i still love this site better than the Garage.:-D

 

so it started better this moring but not too much better. took 3 tries instead of long cranking period. so i guess im looking for new gas caps when im at home this weekend.