I have a ’90 Camaro RS in which I have swapped an LS1 with high flow heads/cam and everything is installed, including the wiring harness, etc. The car has the Racetronix hotwire kit installed with the brand new LS1 fuel pump. It has a new Corvette LS1 fuel filter/regulator also. For various circumstances, the car sat for 3-4 years before the install was complete, but the gas tank was cleaned out prior and there was just a trace of fuel in the lines, which mostly were replaced. For the startup, I placed 5 gallons of fuel in the tank.

I just had the car tuned for the first time with this swap and the car will not start. The starter turns over but the engine does not crank. The tuner said the crankshaft sensor is good and the VATS was disabled, and I also jumpered the two large wires on the starter relay to bypass VATS.

When I turn the key “ON”, you can hear the Racetronix hotwire relay click, but the fuel pump does not prime, which I was told I would distinctly be able to hear. Here are the diagnostics I have tried so far:

Fuel Pump Relay:
I directly connected 87 (battery) to 30 (fuel pump control) and the relay clicks but no fuel pump prime. I checked 30 and 85 (my ground) and I get 12V when the key turns “on” for the few seconds. The relay wiring seems to be okay?

Rear Wiring:
I checked the disconnected the connector coming out of the cabin in the rear and I get 12V upon turning the key to “on” at the grey (fuel pump control) and black (ground) wires. As I mentioned can hear the Racetronix relay click when I turn the key "on" or jumper. The wiring to the back seems to be okay?

I also connected the fuel pump connector (coming out of the fuel tank) to the connector (coming form the rear cabin) and tried to start…to no avail. I believe these connectors were originally connected together from the factory.

Does anyone have any other suggestions that I can check before removing the fuel tank? I have done much research, and it seems there may be some type of corrosion or such in the wiring in the fuel tank? Or for some reason the new fuel pump is bad?

- Ryan

 

No amount of fuel will make your motor turn over sounds like you got bigger issues.

Or you saying motor cranks but wont fire?

 

Yes, the motor cranks but won't fire (starter circuit works). There's something wrong with the fuel pump. Even when I directly connect 12V to the fuel pump connector going into the tank it does not prime. I'm thinking a loose connection in the tank or bad pump.

 

Sounds like you need to get inside the tank and see if you find the issue but I would pull the pump and test it if you dont find any other problems goodluck.

 

Are you using the metal 3rd gen fuel tank or the plastic fourth gen f-body tank? Make sure the pump itself has a ground wire to chassis.

Some of the descriptions in your troubleshooting sound fishy like your hotwire kit isn't hooked up right. Might be useful to share more about that.

 

I still have the stock third gen tank. I bypassed the Hotwire kit and still nothing. I’m going to have to pull the tank.

 

Before you do that, check the wire resistance through the pump, and check that the other side of the plug has literally almost no resistance to ground. At least you'll know whether there is an open circuit somewhere.

 

So which relay did you bypass? The stock relay or add-on Racetronix relay?

Stock relay drives the coil of the Racetronix relay (terminal 86). If you bypass the stock relay then you should hear a click from the Racetronix relay contacts closing.

However, bypassing the Racetronix relay should not result in a a click. It should just run the pump straight from the 10 AWG battery B+ wire.

Quote:

I checked 30 and 85 (my ground) and I get 12V when the key turns “on” for the few seconds. The relay wiring seems to be okay?

Yes that's my understanding too. Terminals 30 and 87 make up the circuit for fuel pump. Terminal 30 is the B+ directly from battery, and terminal 87 is the other side of the contacts (fuel pump side).

Terminals 86 and 85 make up the circuit for the coil wire. Terminal 86 is the switched high side (from stock fuel pump relay), and terminal 85 is the coil ground. I would not necessarily assume the relay was wired with the correct pinouts. I've had to swap wires around before with a fuse center I purchased.

You've got a strong handle on the wiring theory from what I can tell. Most people can't troubleshoot as well as you.

 

Thanks QwkTrip. I actually bypassed both as a test and also bypassed both. You are right that I heard the click when bypassing the "stock" relay and no click without the Racetronix relay. In no cases did I ever hear the fuel pump prime and I have no fuel at the rails. I'll check the resistance as well, but it looks inevitable that I will be pulling the tank. Yes, I'm a EE so the wiring isn't too much for me to understand.