whats a bad fuel pump like???

[predator]

i was just wondering if there was any way to diagnose a bad fuel pump, are there any characteristics of it??

91 explorer 4wd 4.0 5spd

 

[Jspafford]

The good thing about fuel pumps is when they go, they go. There is usually no signs, other than the truck not starting.

Listen when you turn the ignition on to hear if it primes.

Are you having problems?

 

[mkpecor]

take the fuel filter off and crank the motor over ,if fuel comes out of the line then your pump is doin its job.
, if you think its the filter take it off and try to blow through it, blow the same way the gas flows through it, there should be an arrow on the side of the filter.

 

[Hardwareman]

Yeah, the fuel pump either works or it does'nt. That's how mine went out. I went outside to start it one morning and it just kept cranking over but would'nt start. I could tell immediately though that it was my fuel pump because I could'nt hear it when I turned on the ignition.




Allen

 

[Jspafford]

take the fuel filter off and crank the motor over ,if fuel comes out of the line then your pump is doin its job.
, if you think its the filter take it off and try to blow through it, blow the same way the gas flows through it, there should be an arrow on the side of the filter.

You could just as easily test it at the fuel rail with an inexpensive guage. Lot less of a fire hazard. You would also not need to turn the truck over, just turn the ignition to on and the pumps will prime.

 

[mkpecor]

ya just turn it on you dont need to crank it over.

 

[Carlos Murphy]

Pumping

NOT TRUE!!! Not all pumps just fail.

My 88 Ranger Super Cab with 2.9 auto would die on the trail when climbing steep grades for 10 min.

The exterior pump would get hot a die (like flipping a switch) and after about 30 min of cool down time it would work again and would not die going down hill or on the road in town. After going through this in the mountains a few times and not finding the problem, I hooked up a fuel pressure gage, taped it too my windshield, went wheeling and when the engine started to die I looked at the gage and sure nuff, ZERO fuel pressure.

When I replaced the pump with a high flow after market unit, I removed and discarded the internal pump because if THAT one failed on the trail it would be a real bitch to replace. Ford used the internal and external pumps for only 2 or 3 years on the late 80's models that I know of.

Haven't had a problem since!

 

[predator]

well im getting a fuel system code, i start it and it runs fine, but when i start to drive it the check engine light will flash the the entire vehicle will lurch forward and start running like shit, almost sounds like its running really lean and starting to kill, it will continue lurching really bad while its driving too....cant really describe how it reacts, im sick of dumping money into this, i just want the fucking problem figured out and solved...

 

[mikhail]

i had a similar problem i couldnt figure out, the check engine light would flash and it would stall for a sec. it turned out to be a ground on the neg battery terminal. leave the truck idling and go around shaking wires to see if you can get it to do it.

 

[reno]

What is the fuel pressure supposed to be on a 93 4.0 4x4? I get a reading with KOEO @32psi and KOER @ 32-31psi and KOER RPM @ 2000 29psi. Truck does not seem to hesitate, and seems to handle hard takeoffs well (I usually drive easy and slow, but tried it to see). Had her up to 80 for 2 miles and no problems.

 

[almostclueless]

What is the fuel pressure supposed to be on a 93 4.0 4x4? I get a reading with KOEO @32psi and KOER @ 32-31psi and KOER RPM @ 2000 29psi. Truck does not seem to hesitate, and seems to handle hard takeoffs well (I usually drive easy and slow, but tried it to see). Had her up to 80 for 2 miles and no problems.

For crying out loud, buy a decent manual and look.

 

[97ranger4x4]

Well according to the factory service manual for a 97 ranger, the fuel pump is capable of 45psi. the internal pressure relief valve has a max pressure of 125 psi in case something gets blocked, then it will release. I could not find any info on what the fuel pressure is supposed to be

 

[Jspafford]

Pretty sure its supposed to be 40#.

 

[Southern3.0]

Befor the Pump went out on my old '91 Ranger the syptoms where Hard starting/ No start, hesitation, bucking and missing. A new pump solved all that. and remember when your testing fuel pump pressor at the fuel rail your also testing the pressor regulator. So even if you get a low pressor reading, theres a chance it could be the regualtor.

 

[james99]

my girlfriends jeep computer had forgot how much gas to send to the engine and it was doing the same thing. have you let the battie die in the last week or so if so that could be the problem
just my 2cents good luck