2 lift pumps in 3 weeks...

[Docfranco]

HI all
I have apparently gone through 2 lift pumps in 3 weeks. The first was a "new" one from ebay which quit in a week, the second was an AC Delco from the stealer. There was maybe 1 hour run time between the two of them They both were wired direct to the ignition switch to rule out any OPS problems. I at first was believing i am having problems with my ECM , i am working on my 3rd one, the first ones were not programmed for the 4L80E and now the engine has been stalling badly which now appears to be the lift pump. Anyone have any ideas about how/why i could go thru 2 lift pumps so quick? Can the pump burn out if wired direct? I am thinking it should be able to run as long as there is power for more that an hour?
omething else i am overlooking?

[BobND]

They always claim the biggest cause of these pumps failing is from foreign material in the fuel, and running a filter ahead of the pump is recommended.

No harm in running direct power to them. My 1994 has about 80,000 miles on the pump, to prove that.

[rameye]

Doc,

How did you verify the pump is DOA?
Did you change the filter?

I ran mine direct to eliminate a wiring issue both ground and hot feed. I suggest you do the same to eliminate all possibilities..

No it wont burn it out to run direct,however..

1) your direct line needs to be fuse protected
2) realize you have lost the safety of the pump shutting off in case of an accident..more of an environmental concern with a diesel than fire.

[Docfranco]

How did you verify the pump is DOA?
by listing to it feeling it and nothing out of the brass t- valve while the engine is running & the engine quickly dies.
Did you change the filter?
the filter is 2 hours old

[Hubert]

I have had to replace mine and its no fun. I still read most posts on the LP. I Dislike to be obvious but what about any restriction before the pump?

Anyone know for sure if running the the LP sucking hard is what kills them early sometimes?

The pump isn't submergered in the tank but I have heard its still not a good idea to run diesel tanks down all the way.

[rameye]

Doc,

Just for fun..bench test the unit direct to a battery...just for fun..it's DOA anyway.

Before installing the next one, apply suction to to the inlet hose and drop to a bucket to siphon, check the flow.

Also..really reaching here, undo the fuel cap..maybe it's plugged, causing vacuum.

Upon new winstall put a gage at the T-handle take a pressure reading.

Also take a voltage reading at the pump while it operating after install. Low or high voltage will kill a pump.

Ram..

Ps I'll trade you a IP replacement for a lift pump problem.

[ogrice]

To eliminate the lift pump problem on my truck, I installed a Holley Black fuel pump in its place. 14psi unregulated and 140 gph flow. It out does the stock lift pump like a sumo wrestler ordering everything on the menu when he eats dinner. Totally night and day.
Its noisy, but its a good noise to hear.

[Barry Nave]

I follow this lift pump and OPS issue for many years. Bought my 95 in 98 with 45k miles on OD.
Done many Mod's, though have yet to need to change Lift and OPS. Changed about every thing else. (knock on wood)
Truck now @ 137k. Something is making the pump work to hard,getting to hot not have good fuel flow to get the pump cool.
When the pump fails,is it hot.

[Docfranco]

do most of you guys have a filter before the lift pump?

[charliepeterson]

If the fuel tank cap is plugged up the lift pump will work harder than it should.

[rameye]

I dont have a filter before the pump but I've seen marine type filters installed.

Live dangerous..undo the fuel cap.

[Docfranco]

i think i found what probably did my pumps in. i found some alega appearing clumps in the pump. my tank is 7 months old, but have not run the truck in as many months. will i need to remove the tank to clean it ?

[rameye]

Yes,
If that is the case, you will most definitely have to drain, remove and clean the tank, in addition you will have to change out the filter sock at the bottom of the sender assembly.

I would blow out/clean all the lines from the tank to the pump, additionally after re-assembly you need to add a biocide agent.

How did you find the problem?? I know you were persuing a bad IP.

[Docfranco]

Rameye
I found it by removing the lift pump and seeing clumps of green algae in the inlet/outlet of the pump. them i dropped the tank and cleaned it. i put an pre-pump filter and will be replacing my new plugged 6.5 filter. i was having stalling issues that i thiought were related to heat, but now turns out it was not heat but fuel starvation from plugged filters. My learing curve is steep....

[rameye]

Good for you!

Wish my problem turned out to be algae!..

try GMpartsdirect.com for a cheaper Delco pump.

ram