Fuel pump troubles

[mike327]

I have went through 4 fuel pumps in about six months time. I am running a LT1 that has a carb intake with stock TBI throttle body, Howell harness, EBL PCM. This is in a 90 Jeep YJ that orginally had a 4 cyl fuel injected engine. I used the original oem fuel pump to start with. It is suppose to put out 42 PSI but the engine would starve for fuel at WOT. Replaced with another oem replacement Airtex pump and had the same problem. Changed to a Airtex for a 92 Camaro, can't remember the number. It lasted about a week, replaced with another Airtex pump. It lasted about two months and now it has went south. I am running 20 psi with a aeromotive regulator in the return line. Are these pumps that bad or what? I have checked voltage (12 vdc), ground is good, changed fuel filter. I have read on the nets about people using the oem Jeep pump with no problems but mine seems to be the exception. Are Delco pumps any better? Any thing I need to check that could be causing the problem with pumps.

[gregs78cam]

I have never heard anything good about Airtex pumps. I have a few stock 20+ year old GM pumps that are still going strong.

Make sure the tank is clean, and the filter sock on the bottom of the pump is attached and functioning.

[jameslleary]

TBI pressures are 9-13 psi, unless you are using a 454 throttle body from a 94-95 Truck. Too much PSI will cause problems.
Throttle bog issues have been mentioned with Carb intakes and TBI adaptors, due to the sudden open space under the spacer.

[EagleMark]

Throttle bog issues have been mentioned with Carb intakes and TBI adaptors, due to the sudden open space under the spacer.

Easy AE fix...

[mike327]

TBI pressures are 9-13 psi, unless you are using a 454 throttle body from a 94-95 Truck. Too much PSI will cause problems.
Throttle bog issues have been mentioned with Carb intakes and TBI adaptors, due to the sudden open space under the spacer.

I used the instructions in the EBL manuel to figure fuel pressure based on 290 to 300 hp. It seemed a little high to me but I am new to this. When i get the fuel pump issues resolved, i will revisit fuel pressure again.

[JP86SS]

I would look at how many amps its pulling.
If it is a high(er) volume pump, the line from the pump to the TB/regulator may be a restriction causing load that you cannot see.
ie; needing 25-35 psi getting to the TB or point of restriction, then it relieves down after the restriction to keep the reading there at 20 psi.
A pressure reading at the pump outlet would give you the actual pump load, (psi X GPM) * 0.000583 = electric motor HP to drive the pump.
you may find that having the pressure at 20 (at TB) is more than the motor on the pump can handle.
The amps may be higher than you expect and too small of a feed wire would result in a large voltage drop under load.
Anyway, over amps tells you to turn the load on the motor down.
Jp

[mike327]

Ok, installed the new fuel pump. Checked voltage drop as per video and had a .8 drop with key on engine off. Checked voltage with the engine running and had a 1.5 voltage drop. If I check voltage at the fuel pump, engine running using the Fluke with red on power feed and black to chassis ground I get 12.5 vdc. The power feed wire is 16 ga. which is OEM Jeep. I thought that was kinda small but the Howell relay is 16 ga. also. I have not checked pressure at the pump yet but plan on doing so.

[phonedawgz]

Pumps will burn out if they are running on low voltage. This may be your problem, especially since you say multiple pumps went out. The problem with measuring the voltage at the pump is if there is no load at the time of the test (ie pump disconnected) the circuit isn't being taxed, and a high resistance connection in the wiring will not show a voltage drop.

http://www.youtube.com/watch?v=boAA6_saiSk

[mike327]

Pumps will burn out if they are running on low voltage. This may be your problem, especially since you say multiple pumps went out. The problem with measuring the voltage at the pump is if there is no load at the time of the test (ie pump disconnected) the circuit isn't being taxed, and a high resistance connection in the wiring will not show a voltage drop.

http://www.youtube.com/watch?v=boAA6_saiSk

Thanks thats not the way I checked the voltage. I will be replacing pump with a Delco pump and check voltage as in video and see what happens.