Update 94 Jeep GC 5.4L Fuel Pump?

A close contact who runs a large repair shop with a large fleet account informed me about the Jeep fuel pump Problem?. Seems the vehicle would stall out and was told by another shop that the pump needed replacement. When we tested the vehicle it would always start and run without a problem. Replaced the fuel filter but then stalled again after about 20 mile drive. Would not start. Again tested vehicle later and it started and ran without difficulty over about 10 miles of test. Dropped the fuel tank and checked the strainer sleve (very clean) and bench tested the electric pump and it operated without hesitancy.

Contact informed me that young people (owner of the vehicle)tend to run the vehicle down to near empty and on questioning of the owner, he admitted waiting till the warning light went on about low fuel. Seems that the pump when not immersed in the fuel(when tank is near empty) the electric motor overheats and then will bind up. Waiting a short interval, such as 1 hour and it will unbind and operate.

I then tested the fuel pressure at the Strader Valve (30 +psi) and ran it several miles and rechecked the presure. I then let it idle for about 1 hour with the gague near empty and it then started to sputter and the pressure sank immediately to zero. No other trouble lights activated and the oil pressure was 6o. It would not restart immediately but an hour later it started again and ran with the pressure back to 30 psi. There was sufficient fuel to let it continue to run.

Our options were to let the owner opoerate as is but to keep fuel gague at no lower than 1/2. Second option was to replace with a salvage yard pump at $50. Third option was to replace the pump with a new one at $190. What would you recommend? We pretty much assumed that there was no other malfunctioning sender(although realizing anything was possible).

Thanks Again for your comments.

Never even consider a used pump. They’re simply not worth the risk, and especially not at 50 bucks for a used one. Always go new in my opinion and keep in mind the fuel filter should be changed on a regular basis; about every 15k miles and even more often if contamination is suspected. Even partially clogged filters on vehicles that run fine can shorten pump life.

You’re being told wrong about the overheating fuel pump scenario. Running the tank down low will not cause the pump to overheat for the simple reason the pump itself is full of cooling, circulating gasoline as long as there is enough fuel to run the engine without stalling, etc.

Running it down so low the engine cuts out and stalls is a different matter. A pump can suffer some damage if this occurs on a regular basis.

When pumps age they can overheat and quit even if the fuel tank is full. They can also be hit and miss. They may work fine for a week, month, or whatever, stall out, and then work fine for another undetermined amount of time.

You gave an old fuel pump more than the benefit of a doubt. I think you did everything you could to confirm a diagnosis, rather than just “guessing”. Kudos to you. I’ll agree with going new. Electric motors do wear, and it is difficult to access and time consuming ti change the fuel pump twice.

Thanks OK4450 and hellokit: So far so good, 3 days operation and no calls of distress.