Fuel pump pulse signal issue (video) any help would be great

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forcedinduction

move it like this'''''
Joined
Aug 10, 2013
Messages
76
I have been trying to chase down this problem since I bought the car. My fuel pressure is all over the place at idle.
I replaced the following:
Ecu
Fuel pump (mine was good but I found a nice deal on a used walbro)
Fuel pump relay (at least the pump primes now lol)
Fuel pump hotwire kit


That knocking sound is the pump starting up and stopping real fast. The clicking is obviously the hotwire relay.
It's not the pump because the pump works fine when I jump it to the battery.

I was thinking maybe I was sold a bad rebuilt Ecu with the same issue mine had.
I was about to change the crank sensor but mine looked new.
Could this be cam/crank sensor related?
This car also had an aftermarket alternator with an external regulator on it when I bought it that was blown. I replaced it with the correct stock alternator and a new pigtail. but there are a few hacked up wires in that harness. But the alternator is charging correctly so I figured that I installed it correctly. I'm not sure if that could have anything to do with this problem.

Any input would be great thanks
 
I noticed that you changed the fuel pump relay. Have you tried replacing the hotwire relay??
 
First to do is to check the fuel pump relay under the hood. See if it too is clicking on & off. If so then there is a wiring issue between it, the ECM, or fuse block. Be careful when trouble shooting as the ECM supplies +12 volts to enable the FP relay. Short it and the transistor in the ECM pops (easy to replace).

If the under hood FP relay is not clicking, then there is an issue in the wire/connectors that runs from the FP relay back to the connector at the hot wire relay.

The FP relay is on the passenger side under the hood. The two relays there, one for FP, the other for the A/C compressor.

Also, there is supposed to be an oil pressure switch that bypasses the relay. Since the engine is running and the fuel pump is starting & stopping, I'd say that switch is bad or has been removed.

RemoveBeforeFlight
 
First to do is to check the fuel pump relay under the hood. See if it too is clicking on & off. If so then there is a wiring issue between it, the ECM, or fuse block. Be careful when trouble shooting as the ECM supplies +12 volts to enable the FP relay. Short it and the transistor in the ECM pops (easy to replace).

If the under hood FP relay is not clicking, then there is an issue in the wire/connectors that runs from the FP relay back to the connector at the hot wire relay.

The FP relay is on the passenger side under the hood. The two relays there, one for FP, the other for the A/C compressor.

Also, there is supposed to be an oil pressure switch that bypasses the relay. Since the engine is running and the fuel pump is starting & stopping, I'd say that switch is bad or has been removed.

RemoveBeforeFlight
The relay under the hood clicks on with the ignition. I didn't check to see if it clicks on and off with the engine running. I will check that this afternoon.
I forgot to mention that I also replaced the oil pressure switch.
 
Ok the relay under the hood clicks on 3 seconds after the key is on and stays on. So it looks like the stock relay is working well.
Any ideas on how to tackle this problem. Is there a wire that runs from the stock relay directly to the pump pigtail? If so can I check if it is shorted? Anyone know what wire it is and how it's routed through the body.
Thanks
 
I removed the stock relay and jumped the tan/white and pink/black wires and the fuel pump starts right up. While the pump was running I jiggled the harness at the stock relay,Ecu,and hotwire relay and all the connections at the pump and sender and the pump stayed on with no problems. Once I start the engine that's when the clicking at the hotwire starts. So I'm pretty sure the harness is good.
Could this be my cam or crank sensor clicking off and on fuel and spark? Because I notice that the car will run for about 1 minute when I first start it before it starts clicking and choking. And once it's warm the clicking happens as soon as I restart the engine.

Also there is no change if I unplug me evap canister solenoid.
 
I just ran a new wire from the white/tan relay wire terminal all the way back to the pump and cut the white/tan wire. it runs fine now no more clicking.
I guess that wire was pinched somewhere.
thanks for all the input.
 
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