Keeps killing fuel pumps.

kevinbmx77 · Mar 1, 2015

My 1994 3.0 keeps killing fuel pumps. I've searched the internet for about three days now and im at that point where ive worded it in everyway i can and still have no answer i understand. Its killed about 5 fuel pumps now. I put a new one in and it runs good for about a month or two.
Im not using airtex anymore so im not sure what cause be killing them.
The truck will run fine and excelerate like it should for like the first five minutes of driving but then it gives out and wont speed up even with the pedal floored and will even stall out while going 40.
I dont want to end up having to get rid of this truck. I did alot to it.

kevinbmx77 · Mar 1, 2015

Ive heard something about a second fuel pump/booster being somewhere but cant find any info?

Mazda · Mar 1, 2015

No second pump in these trucks. Do you have a extended cab and if so are you using a extended cab pump. I'm sure you are putting on a new strainer/sock on the new pump. Have you checked all wiring to the pump, might be getting to much voltage or a surge from the relay. Have you replaced the fuel filter and if so is the flow arrow in the right direction.?

kevinbmx77 · Mar 2, 2015

Single cab, we put a whole new pump assembly with hanger and all. Havent checked the wiring. And yes i replaced the fuel filter, the flow arrow is facing the front of the truck

black_demon69 · Mar 2, 2015

check alternator and make sure it is reading within specs (not too much or too little voltage / amps). check wiring to pump and make sore there are no shorts or a break where most of the strands are broken (it can raise resistance on wire) replace fuel pump relay..

are you sure it is the pump? whats fuel pressure when all is running fine and when it is acting up?

rebelkid · Mar 2, 2015

Not sure about the 94s, but do they have the fuel cutoff switch in the passenger foot well? My 03 had the same issue, traced it back to a smashed fuel cutoff switch, u can hook wires from switch together to diagnose.

downer · Mar 2, 2015

also make sure the tank vent tube is not blocked or pinched.

black_demon69 · Mar 2, 2015

rebelkid said:
Not sure about the 94s, but do they have the fuel cutoff switch in the passenger foot well? My 03 had the same issue, traced it back to a smashed fuel cutoff switch, u can hook wires from switch together to diagnose.

yes they do....

adsm08 · Mar 2, 2015

Have you considered the possibility that you are just buying junk parts?

Andy D · Mar 2, 2015

Does the gas tank release a vacuum when you open the cap? Do you run out of gas a lot? 5 bad pumps is too many to be a run of bad pumps. I'd say your truck is killing them.

kevinbmx77 · Mar 2, 2015

black_demon69 said:
check alternator and make sure it is reading within specs (not too much or too little voltage / amps). check wiring to pump and make sore there are no shorts or a break where most of the strands are broken (it can raise resistance on wire) replace fuel pump relay..

are you sure it is the pump? whats fuel pressure when all is running fine and when it is acting up?

I replaced the fuel pump today runs good not but still want to know what may be killing them. We put a pressure gauge on the fuel rail thats going to just stay there. When it was running normal on at idle it had 30 psi. 40 psi with truck off and pump on. When acting up we pulled over to check and it dropped to 0 psi as if the fuel pump just shut down

kevinbmx77 · Mar 2, 2015

adsm08 said:
Have you considered the possibility that you are just buying junk parts?

Yes switched from the airtex shit the first time it died

black_demon69 · Mar 2, 2015

kevinbmx77 said:
Yes switched from the airtex shit the first time it died

what brand are you running now?

Big Jim M · Mar 3, 2015

Jeep had a similar problem a few years back. Turned out to be the ground wire from the tank cluster went to the emergency brake frame inside the cab. As the brake was used a few years the frame got just a LITTLE loose and the fuel pump sometimes wouldn't come on or went off at other times. Just say'n.
Big Jim

94RoadkillRanger · Mar 3, 2015

If you have 0 psi then check the regulator if the pump is still running, which purges excess pressure back to the tank.
My factory nylon fuel line on my 94 seamed restrictive so I replaced it with a new steel line.
There was also a problem with the wire connection inside the tank that I had to address.

Keeps killing fuel pumps.

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