Lift pump failures

[arveetek]

Why do the lift pumps on the 6.5L fail so frequently? They are a very simple design. I have a universal style electric pump on my 6.2L, and it's never given me troubles. The AC Delco pump on my 6.5L just quit again after 3 years and around 40,000 miles.

Casey

[simon]

cause they want you to keep coming back for more,makes good economy for every one involved but you.

[Hubert]

I think your year the power is relayed through OPS and thats been reported to have weak contacts. Kennedy use to offer a wiring upgrade might look at his website or do a search on here for it. There is no protection for the pump to pump small trash and crud through so tank delamination and dirty fuel is an issue. There is a sock in the tank but it aint much of a filter.

Its not really a heavy duty pump. Dodge had some problems too for some years. Probably just a poor choice of specs for the pump and the automotive bean counters tried to cheapen it up and cut cost a little too much in the mid 90's.

[Roachie]

Excuse my ignorance, but the pumps that have been failing....are they the mechanical lift pumps located on the front right hand side (passenger's side for you guys in USA), or are they an electric pump?

I've recently junked the mechanical pump altogether and just have 2 electric pumps. One of these was already there..... it's a black cylinder a bit smaller than a can of Coke and it is located near the intake "top-hat" at the back of the valley on the motor.

I've also added a Facet electric pump at the back of the truck, so that it lifts the fuel from the tank and pushes it forward, through a magnetic device called a Morison Debug ( see www.morison.com.au (http://www.morison.com.au) ), then through a filter, then on to the "Coke can" pump, then through a 2nd filter, then into the IP.

Cheers

Roachie

[DmaxMaverick]

The pumps of discussion are electric. The mechanicals generally don't fail often.

The rear of the engine valley area should be a fuel filter if it's an OEM 6.5L (vacuum pump location for 6.2L). Otherwise, if it's a pump, that's an awful environment for an electric fuel pump. WAY too much heat and vibration. You might consider moving it.

[Roachie]

Thanks for clarifying the type of pump you're talking about. Bear in mind that my rig is a Japanese truck (Nissan Patrol, which you don't get there in the states/Canada). The Chev motor has been installed as an aftermarket changeover, so the company that does the conversions has to modify a heap of things. The Patrol is relatively narrow compared to Blazers, burbs etc that these engines were designed to go into.
Also, here we have right-hand drives and we drive on the left side of the road..... not that that has any bearing on fuel pumps etc...:rolleyes:

Roachie

[Hubert]

Casey forgot to read your signature again. So you already have the Kennedy OPS harness. Uhggg

Here is some of my conjecture....

GMCTD has typed it is a self regulated pump. I am not really sure how it regulates I think it some kind of amp draw thing but never looked at the logic. I run an electric fuel pressure gauge and my pressure is almost constantly dancing over 0.5 +/-psi sometimes 1-2 psi. No not a tremendous amount of variation but its constant. Then during acceleration it dips and recovers constantly. Maybe all this variation is in the amp draw too. Never heard anyone measure the amp draw over time and see what it does. Maybe the constant speed changes of the mechanics of the pump is stressful. Acceleration (vibration) start up and stop etc etc is what really causes forces and stresses components. Force equals mass times acceleration. Usually if you can run something the same load and speed it will last longer.

Maybe the DS pump have more variation of fuel flow. The DS pump kinda pump all the time and the FSD controls the injection and fuel recirculation probably at a higher frequency. Whereas the DB's have more of a mechanical regulation of fuel flow????

But mostly I think its the overall quality of the units and again a poor spec for the pump. Your universal pump is probably just a better quality pump.

[arveetek]

Casey forgot to read your signature again. So you already have the Kennedy OPS harness. Uhggg




That's okay! But yeah, I do have the OPS harness, and this last fuel pump was operated its entire life by the Kennedy OPS harness and relay. So voltage issues shouldn't have been an issue.

Granted, the 6.5L has seen a lot more miles than my 6.2L, so that might play a part in it's longevity, but the 6.2L electric pump has been on for a longer period of time.

Casey