gpwhite7

I hadn't run my 1991 Pickup in a few months so I started it and let it run a few minutes and it shut off by itsself. After a few more times of that I pulled the connector from the fuel pump and measured the voltage. It was pulsating DC, between 0 VDC & around 5 VDC on my Fluke (DC selected). This was with the key turned all the way on without trying to crank it. The voltage read the same during cranking. The battery connectors read a good steady 12.4VDC.

I followed the wiring harness underneath to the first connector inside the truck and measured the same pulsating DC voltage. From there took the glove box down and tried to follow upwards but I am not sure what to check now. Kinda sounds like I might have a loose ground wire vibrating. Do ya'll have any ideas for me to try? Thank You Very Much for any help.

rustypigeon

Put an ammeter between DLC terminals FP and B+. Make sure you ammeter is capable of measuring up to 20 amps, since most fuel pumps will draw about 13 amps.

This will bypass much of the electrical system and help narrow your search down a bit.

Post back with your results and we will go from there.

gpwhite7

Hey, I'm a noob when it comes to automotive. The voltage that I was measuring was the fuel gauge sensor and it was pulsating. I've got a steady 10.5 VDC going to the fuel pump. I couldn't get the truck to start today. I will re-evaluate the problem and get back on here. One thing I did notice was no gas smell after trying to start the truck for a while, which might mean it isn't getting any fuel. I need to trace out the fuel lines coming from the pump and see where it is and isn't. Sorry about the stupid first post and thank you for helping. I will still put an ammeter on FP & B+.

INFINITY

the COR controls the fuel pump on that truck. read under fuel pump tricks.
http://www.4crawler.com/4x4/CheapTri...shtml#FuelPump