Fuel pump Relay problem
 

I have no voltage to my pump. Last night i started trying to trace it back to figure out what was the problem. I have a stock wiring right now for the fuel system so both my relays are in place. Here is what i have found with the two relays,open circuit and fuel pump relay, it seems i am not getting the ground trigger to induce the coil. I get power to both the trigger wire and the supply wire on the circuit opening relay but the relay doesnt click to transfer the voltage to the fuel pump relay.:scratch: You would think its just a bad open circuit relay but when i remove the relay and run jumper wires to the relay it clicks like it should and it ohms within spec so the relay isnt bad. The only thing i can come up with is the computer isnt giving the trigger circuit a ground to active the coil. I dont know where to go from here. I put a jumper wire on each of the two relays and got power to the pump so i know its got to be in this area. Is the computer not giving the ground? Where do i go from here?

I had the exact same problem with the circuit opening relay. Relay was fine, chased wires for months, and finally ran a stand alone wire from the relay to the 1T pin at the ECU. No change so I decided to crack open the ECU and found a burnt resister at that pin location on the PC board. Replaced the ECU and the same thing happened. Now, instead of pulling the entire front harness, I just run a jumper wire in place of the relay. Works just fine with no problem. I chased this short for many, many months testing wires from the relay box all the way to the ECU but couldn't isolate the fault. The only difference running a jumper wire in lieu of the circuit opening relay is that it makes your fuel pump run with the key in the "on" position. With the factory set-up, the pump doesn't come on until you start cranking the car. I actually prefer the jumper wire now because I can hear the pump running before I start the car.

Steve

Thanks for the reply. Yea i am kind of stumped with this one. The only thing that is left is the computer not giving a ground. I didnt know that the pump wouldnt turn on unless you were cranking, I thought with the key in the On position it would pressurize. My only problem is I would have to replace both the open circuit relay and the fuel pump relay with jumpers to make it work. Maybe its a good time to do the "fuel pump rewire" and use a switch to energize the fuel circuit. I just hate removing the interior to run wires.

Yep. The ECU grounds the circuit for the Circuit Opening Relay at the 1T terminal when it detects engine rotation from the crank angle sensors.

Steve

Did you check the front harness for damage at the [usual] location in the forward area of the left front wheel well? Damage to this harness is common when oversize wheels and/or tires are used.

Mine had no damage at the wheel well. The OP should check for this though.

Steve

always something hunh?

Derek you got that right.

Thanks for this feedback, I was beating my head on a wall for over a week to see why mine wouldnt start, I tried this and it fired right up the second I pull out the jumper it shuts off again. I'll have to swap out the fuel pump relay and see if that fixes things for me.

Mispost

did swapping out the fuel pump speed relay under the front cover fix this issue for you?