94 Chevy K1500 Fuel Pump Voltage

tdyer · 10-11-2007, 11:52 AM

1994 Chevy K1500, 305 cu in: Had to replace fuel pump in the Spring. When I picked up the truck, it ran terribly. I checked my fuel pressure gage and it was running about 10 psi. I need it to run around 13 psi or it hesitates from a dead stop. The shop put in another new pump which immediately was putting out 16 psi, but they said the first new one was also putting out that much pressure. I ended up turning down the pressure with my adjustable regulator and I was happy. The problem came back and I discovered they had pinched my harness between the tank and the box crossmember. After freeing the harness and inspecting the wires, it was all fine again. I then started getting codes. One was for a rich fuel mixture and the other was for low pump voltage. When I was getting full voltage/pressure, I was running rich. Then I would apparently lose voltage and get the other code, which would cause the truck to run poorly again.

I recently checked the harness that the shop had supposedly inspected after freeing it up. It looked fine. I also replaced the harness inside the tank, since they had replaced the pump only and not the whole assembly. The old one looked fine, but I replaced it anyway. I cleaned the ground really well and replaced the relay. I'm still getting intermittent performance. I checked the voltage at the three wire plug on top of the tank and it was 13.55V (plenty). I have not been able to check it while the pressure is low. It will be low one minute and normal the next. I'm not sure about the brand of pump they put in. Is it possible that I received two suspect pumps?? I hate to replace the whole assembly without knowing if that's the issue. It appears to be fine, but the leads coming out of it (that were pinched) could still be the problem. I'm planning to check my battery leads to make sure I have good contact. I'm also going to check the fuse to see if it's damaged in some way. Does anyone have any other suggestions? This performance issue has been a problem for a long time, so I'm not sure the new pumps are the issue. I seemed to have it fixed by tweaking the timing and bumping up the pressure, but it all started again, when my original pump went bad.

Thanks,

Todd

Hayden · 10-13-2007, 08:48 PM

Shoulda bought the good ole AC Delco Pump. Maybe the pinched wires screwed your new pump up.

nnunez · 10-15-2007, 11:44 AM

The pinched wire was my problem. Somewhere near the tranny mount.....i was told. I was also told that it was possibly done at installation.

Before replacing the pump. you might want to replace the relay......it may get hot and **** out.

I agree, you should have bought the AC "Chinese" Delco fuel pump......they last a little longer than the other brand "Chinese" pumps.

10-11-2007, 11:52 AM	#1
tdyer Full Member Join Date: Apr 2006 Posts: 16	94 Chevy K1500 Fuel Pump Voltage 1994 Chevy K1500, 305 cu in: Had to replace fuel pump in the Spring. When I picked up the truck, it ran terribly. I checked my fuel pressure gage and it was running about 10 psi. I need it to run around 13 psi or it hesitates from a dead stop. The shop put in another new pump which immediately was putting out 16 psi, but they said the first new one was also putting out that much pressure. I ended up turning down the pressure with my adjustable regulator and I was happy. The problem came back and I discovered they had pinched my harness between the tank and the box crossmember. After freeing the harness and inspecting the wires, it was all fine again. I then started getting codes. One was for a rich fuel mixture and the other was for low pump voltage. When I was getting full voltage/pressure, I was running rich. Then I would apparently lose voltage and get the other code, which would cause the truck to run poorly again. I recently checked the harness that the shop had supposedly inspected after freeing it up. It looked fine. I also replaced the harness inside the tank, since they had replaced the pump only and not the whole assembly. The old one looked fine, but I replaced it anyway. I cleaned the ground really well and replaced the relay. I'm still getting intermittent performance. I checked the voltage at the three wire plug on top of the tank and it was 13.55V (plenty). I have not been able to check it while the pressure is low. It will be low one minute and normal the next. I'm not sure about the brand of pump they put in. Is it possible that I received two suspect pumps?? I hate to replace the whole assembly without knowing if that's the issue. It appears to be fine, but the leads coming out of it (that were pinched) could still be the problem. I'm planning to check my battery leads to make sure I have good contact. I'm also going to check the fuse to see if it's damaged in some way. Does anyone have any other suggestions? This performance issue has been a problem for a long time, so I'm not sure the new pumps are the issue. I seemed to have it fixed by tweaking the timing and bumping up the pressure, but it all started again, when my original pump went bad. Thanks, Todd

10-13-2007, 08:48 PM	#2
Hayden Senior Member Join Date: May 2006 Location: Bay City,Michigan Posts: 378	Shoulda bought the good ole AC Delco Pump. Maybe the pinched wires screwed your new pump up. __________________ There Is No Replacement For Displacement

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10-15-2007, 11:44 AM	#3
nnunez Senior Member Join Date: Dec 2005 Posts: 307	The pinched wire was my problem. Somewhere near the tranny mount.....i was told. I was also told that it was possibly done at installation. Before replacing the pump. you might want to replace the relay......it may get hot and **** out. I agree, you should have bought the AC "Chinese" Delco fuel pump......they last a little longer than the other brand "Chinese" pumps.