Gutted91

Please help me. My 91 pickup has a 22RE 154000 miles and manual transmission. The problem I am having is that at random it will start to sputter and the check engine light will come on while it does it then it will quit the light goes off and all is well until the next time. It will keep itself running most of the time but once in a while it will die. One time the efi fuse blew but only once. It will do it at idle and it will do it while driving but I haven't really noticed a pattern of any sort. I have replaced the fuel pump, fuel filter, spark plugs, wires, cap, and rotor. Cleaned throttle body with carb cleaner and rag. I need ideas

scope103

Uh, what's code 31? Do you think that just because your truck is BEGGING for help, that you should pay any attention to it?

http://personal.utulsa.edu/~nathan-b...85diagnosi.pdf
"At idling, open or short detected continuously for 0.5 sec. or more in volume air flow meter circuit." If it were my truck, I'd look at the VAF. The tests aren't difficult to do. http://personal.utulsa.edu/~nathan-b...33volumeai.pdf

Of course, code 31 doesn't have anything to do with the fuel pump, fuel filter, spark plugs, wires, cap, rotor. Is there a reason you replaced all those parts?

Gutted91

Yeah. I just picked this truck up and when I got it, it didn't run (fuel pump).. I did the filter for obvious reasons and the rest because it needed it. The previous owner said that the efi fuse would blow out often and he just quit driving it. I have put about 300 miles on it and it blew once. He claims it never did the sputtering stuff when he had it though.

scope103

Sounds like you've got your hands full.

The Fuel pump is on the EFI fuse. It wouldn't surprise me that you've got a serious wiring problem in that direction, your old pump was fine, but in the course of "repairing" it you moved the wires enough to protect them (very temporarily) from shorting out.

A more common cause of EFI fuse trouble is the O2 sensor. The wiring is hanging out in the dirt and spray, and if the sensor wire (or is it the heater wire?) shorts to ground it blows the EFI fuse. This one is so easy to check I would do it first.

Good luck!

Gutted91

The pump was shot.. I ran power straight to the pump and it had nothing. I'm wondering if there is a short in one of the VAF wires.. The efi relay under the hood gets pretty hot as well I'm not sure if it is supposed to. I would expect warm but it's hot enough I can't touch it more than a few seconds. I will definitely check the O2 wires though..

scope103

Yup, the EFI relay should not be too warm, and certainly not anything described as "hot." The EFI relay directly powers the fuel pump, the injectors, and the ECU. The ECU (indirectly) powers almost everything else, so a short in the VAF wiring would not only blow the EFI fuse, it's sure not going to do the ECU any good if you're pulling something like 12amps (EFI is a 15 amp fuse).

You could put an ammeter on the EFI circuit and disconnect items (VAF, O2 Sensor, TPS, injectors) one at at time until the current draw drops. I would recommend your regular multimeter, but it's hard to beat this gadget for convenience: http://www.harborfreight.com/30-amp-...ter-67724.html

Gutted91

Good call I will get on it in the morning and post results. thanks for the info!