jrdrag

Hi all, I am new to this site. I have two Corvettes, One is an 87 and the other an 84 that I just obtained in a trade. I traded a junior dragster for it. The 84 is in good shape except it needs the driver's window regulator replaced. The window won't roll all the way up and it has a starting problem which I wanted to ask about. The 87 is well used but still drives good.

The starting problem on the 84 is this. It has to cranked over probably 8 or 10 seconds then it will start and will run fine after that. It does this every time it is shut off and restarted. I am not real familiar with the start system on this Vette but it must have an oil pressure switch bypass that is not working. It seems that the engine when cranking over finally builds enough oil pressure that the ECM finally turns on the fuel pump and it starts. Does anyone out there know what to look for that could be causing this problem and where it would be located ?.

Thx, Jrdrag

Dominic Sorresso

jrdrag,

The 84 fuel system works tthe same as the other C4s do. There's a fuel pump relay on the driver's side firewall hanging nearby the windshield wiper motor. Its the back relay witth the front one being a trans relay for the 4+3. With "key on" and no start, you should hear fule pump turn on for 2 sec or so then shut off. If that's not happening then the FP Relay ma not be working. The long crank time is happening because the FP circuit is now being energized by the Oil Pressure Sending unit with (I think) 7psi of Oil Pressure. While you're looking at the FP Relay, check the wire harness connector. Due to the age of the car, you will probably find that the insulation has shrunk leaving BARE WIRE. This needs to be fixed ASAP if not sooner. I'd also think about changing the fuel filter located under the passenger rail near the front wheel well and upgrade to an LT-1 pump.

jrdrag

Hi, Thanks for the info. My biggest problem is finding the relays on the car. There is so much electrical. I also have an 87 with a similar problem. When starting with the key it has to be turned off and on to the start position three of four times then it will start. The engine cranks over each time but not long enough to raise the oil pressure. Any ideas ?. The fuel pump on the 84 was upgraded to an 85 pump by the prior owner. I will certainly use your advice. I really appreciate it. Thanks, Bob L

RRT vette

Here is where the fuel pump relay is on my 86. I would check it first. Jumper the first and last connection on the relay connection at that should bypass what the relay does.