Hi guys, I'm new here. Been a mechanic for a while but new to Corvettes. Just bought my first, a 1984 that had an engine fire.
I replaced the burned wire harness, distributor, and throttle bodies.
Everything is in order. I'm not getting any fuel at the throttle bodies.
I open the fuel line and turned on the ignition and got nothing.
It seems like when the ignition key is turned on,the fuel pump comes on for a second then shuts off. And won't come on again until I disconnect the battery and reconnect it.
The car will start and run a while if I manually feed it gas directly into the throttle bodies but not on its own.
I was wondering if there is a fuel pump relay or a fuse that could be checked. Something that could have been triggered because of the fire like a safety shut off or something that would cause this that I may have overlooked.
Any help would be greatly appreciated.
Thanks

 

I am going to make an assumption the 85 works similar to the 90 type cars I am more familiar with but probably works the same.

The relay stays on for 2 seconds to pressurize the fuel system. When the engine starts it closes a oil pressure operated switch which keeps power (12 volts) to the fuel pump. Check for a broken wire or defective switch. I cant tell you where it is, sorry.

You can try jumping it out to see if the pump runs. If the engine keeps running the switch is probably bad.

 

Now would be a good time for a FSM (Helms)... would definately save you time and trouble...

good luck

 

What's an FSM?

 

Hope this can help you out a bit or at least get you pointed in the right direction. It's right from the Factory Service Manual (FSM). When you turn your ign on you should here the fuel pump charge for about 1-2 seconds then turn off. After the ignition being off for 10 seconds or more when you turn ign back on the FP should charge again for 1-2 seconds.

 

FSM stands for Factory Service Manual....get one. You need a fuel pressure gauge to see if you are getting fuel pressure when the key is turned on. I think the 84 uses a lower pressure than the later years (12-15 psi?). Make sure you have enough fuel in the tank. When the key is turned on, the ECM will energize the fuel pump relay for 2 seconds. You should have said fuel pressure after the pump stops. If not, I would look for kinks in the fuel line, fuel filter, leaks, or defective fuel pump/check valve.

 

wrap a rag around the shrader valve on the fuel; rail and push it in and if fuel comes out you got pressure.

 

You need the correct info/schematics for your 84 TBI. Not to be confused with the 85+TPI.
Sounds like the ECM is not firing your throttle bodies. Never messed with an 84, but if the ECM works similar to my 86, it will need to see a reference signal from distributor before it fires the TB's.
Where is CFI-EFI when you need him.

 

Right here. First of all, the following is incorrect, more like incomplete, for any C4 regardless of the year.When the key is first turned to "On", the ECM closes the contacts in the fuel pump relay and runs the pump for approx 2 seconds. It will do this every time the key is turned to "On" as long as the key has been "Off" for 10 seconds or more. When the engine is cranked, the distributor sends pulses to the ECM to tell it the engine is turning. When the ECM receives those pulses, it again activates the fuel pump. As long as the engine is turning, whether cranking or running, the ECM activates the fuel pump. Once the oil pressure reaches approx 4 psi, the oil pressure switch closes and provides back up power along a parallel path, to power the fuel pump in case of a fuel pump relay failure.

Since you hear the fuel pump running when you first turn the key, that rules out the fuel pump and the fuel pump relay as problems. Possibly some of the wires from the distributor got burned and the pulses aren't reaching the ECM. Also, those pulses are used to fire the injectors. Contrary to previous advice, you don't have a Schrader valve to hook a gauge to, but you need to determine if the fuel pump is activated during cranking. Then you need to be sure the injectors are receiving their pulses. Hooking up a pressure gauge could facilitate matters. The fuel pressure spec is 9-13 psi.

RACE ON!!!

 

That hurt, but that’s OK, makes me better. I didn't catch that sentence and was not aware of that piece of info. But I got it now on page 6E3-C2 (FSM).

The C4 gets cooler every day.

 

I'll check out this weekend. Thanks for the help !!!!
Ron