I just picked up a 91 4-runner that isn't running but runs when throttle body cleaner is sprayed into the tube hole by the intake.

I lifted up the carpet under the right rear seat and removed the small plate on the floor. There is a fuel line connection and a wire connection easily accessible. The wire connection is only 2 wires. Is this the pump or fuel gauge connection?

There is no power on the incoming side and interestingly enough I get a ground on both spades going to the tank side.

Thanks for any help.

Jon

 

Online FSM - http://www.ncttora.com/fsm/1990-1995...emci/eng3r.pdf
Page 3

 

^^^Thanks. When I move the valve flapper above the air filter I can hear the relay in the passenger kick panel so I'm pretty sure I'll be pulling the tank but will use the FSM to be sure.

 

Before you pull the tank, you might want to check for voltage on the fuel pump connector. Do it both by moving the air vane (as you have), and by using the FP jumper in the diagnostic connector. If you get voltage (and the pump running!) with the FP jumper, the COR relay may be bad.

 

Pulling the tank is hours of work, broken/stripped bolts, possible breaking the fuel hose at the pump when dropping, etc. I changed my fuel pump in under 1 hour by doing the following:
I removed the access panel, and then used tin snips to cut the metal above the access hole enough, bent it back, and was able to remove and replace the pump pulling it through the hole. Once done, I bent the remaining metal back into shape, fabricated a seal around the cut areas with JB Weld, and insulated it along with the access plate with roofing seal insulation from Lowes for $15 a roll. Put the carpet back down, along with the seat, and project finished.
I would suggest the method above to gain access to your wiring, then pulling new wiring through from the top of the tank using the old wiring connected to the new, as needed.
Check continuity of the Lima (Blueish) colored wire between the Circuit Opening Relay in the Pass kick panel and the fuel pump to see if it is a shorted wire. Also, the white with black stripe wire grounds in the left front kick panel to the pump. Check continuity there as well, before any modifications or repairs to determine if it is wiring issue or the COR.
Most likely COR is the problem.

 

It's a motor, so as long as the brushes are touching, there will be a path from the 12v. source through the motor to the ground. The key is what are the resistance values (in ohms) for the ground side to ground and the hot side to ground. The path through the motor should have the higher resistance.

 

Thanks guys. Once I read that the pump is only on while cranking I retested and do have voltage going to the pump. So I went ahead and dropped the tank and pulled it. The whole assembly was pretty nasty with rust.

Also, my gauge was hurried on empty but no gas light was on (tank was 1/3 full). I pulled the sending unit out and played with it in the air while plugged in and got the gauge to show 1/4 tank. It definitely needs some clean up. Any idea if it is safe to use carb cleaner or brake cleaner on it? I can blow it out and wipe it down but I'm not sure if it will be enough.

Thanks for your help.

 

If your gauge assembly has only 2 wires instead of 3, you don't have the low fuel light option.

 

I picked up a new pump and filter this morning. I emptied the tank out and got as much of the rust particles out as I could by sloshing the gas back and forth. Tank looks decent inside but I didn't want to just stuff the new pump in and go. The old filter was completely gone, only the bones remained.

After blowing out the gauge sending unit and playing with it in the air and plugged in it is working and I do have a low fuel light. Response is a bit slow but a lot better than showing E all the time.

I put it back in and after about 20 seconds of cranking she started up and sounds great. That is a relief since I bought the truck after only hearing it run for a few seconds on throttle body cleaner. A/C even works and everything seems in working condition except for the clutch. Now I got to order a new clutch kit...