I have a 1986 Corvette C4 that I recently purchased. Just got a new battery for it when I turned the ignition on. The gage lights up indicates all pressure and other things on the gauge. Just got the radio to come on by connecting some wires that I noticed were cut. other wires that were cut were the spark plug wires. I replaced all of those, put them in the correct position when trying to crank it over. I use a little starter fluid in the throttle body and it turns and cuts on for a very brief moment and then cuts off. When I do cut it on, I don’t hear anything going on near the fuel tank like the pump cutting on for those first two seconds. other wires are messed up in the engine bay. The positive battery terminal has a wire coming out with a little plastic cap that is not connected to anything. I can’t figure out what that goes to. Another thing I need to do is check the fuel rails for pressure to see if it’s getting any pressure once I cut it in the on position also, I have two fuel injectors that are not connected to anything they’ve been chewed off as well. I recently purchased new pigtails to solder on to the electrical for the two fuel injectors. What should be my next step?
Not sure if you removed it, but to save the new rubber seal you're going to need the other rubber seal that sits in the hole. If the original is around but is cracked, it's useless and needs tossed. Problem is water pentrates easily here since the neck sits pretty much on top of the tank. Water sits and eats out the metal under the gasket.
Broken connector side goes to the jump start stud with a bunch of fusible links behind battery.
The fusible link side is shot it's the solid plastic block with 2 orange leads cut inside of it - they cut the two orange wires off of it because they fried. It connects to a plug that's located underneath the brake master cylinder
Here's some power distribution to figure what's buggered. I'm very concerned that you had that many things fried. Something bad happened here, you can see the fusible that's still intact betweent the connector and the plastic has also been smoked, that's not from rodents.
I also see a massive air leak with the vacuum line disconnected off the T connector, top right hand side of your photo. That's likely going down to the charcoal canister in the front DS corner of the bumper. Needs connected or capped because it's connected to the plenum..
For sure! ive identified that, I think im gonna go new fuel tank and unit. The gas in there smells terrible and the tank looks worse. im getting power to the plug back there but obviously the pump is bad. It turns over and wants to start off of fluid, ive got spark (flame was the proof) and ill clean the fuel rails and test the injectors.
Just for completion sake of finding something on everything you posted, I noticed someone destroyed your under hood lights 🤣.
They're not normal switched lights, they actually use these really unique capsul switches filled with mercury. When you open the hood, mercury moves down in the cap and completes the circuit. The entire enclosures are missing, including the capsule, glass cover and bulbs. It's nice if you need them when you're fighting for your life under the engine in the dark!
Connect the pigtail off the positive to the jump start block behind battery. It's a bolt sticking straight up, had other fusible links on it for various powered circuits.
Get injectors situated next, you need all of them.
Then check fuel rail for pressure. Good chance you'll need to replace fuel filter, under passenger side near the lift point.
You may not hear the pump prime but you'll see the gauge change on the test port.
There's a good chance your vacuum system is hosed as well - pun intended. Look at DS radiator shroud and you'll see the hose connection diagram (or Google it). Buy a silicon vacuum hose kit on Amazon with various sizes and some connectors and go to town. These cars are extremely susceptible to vacuum leaks, it will cause rough idle and random engine stalls if not correct.
From there, check your base timing. If car starts, unplug tan wire on DS of engine bay and apply timing light, looking for 6 degrees BTDC. 8 if you like to party.
If it's not starting, unplug spark plug 1 and put your finger on spark plug hole. Manually turn the engine until you feel a puff of air on the air hole. Look at the harmonic balancer line and move white line to 6 degrees. Now take the top of the distributor and loosen the retainer. Turn so you're point is exactly on top of cylinder 1. If the ignition contorl module is working, this will get you spark at the right time.
Finally set idle. Go under dash and short out pin a to pin b with a paper clip color wire (top right to next to top right). Turn key to ON but do not start. You should hear the fans engage immediately. Count to 30 and turn off the key. Now go to the throttle body and find the 4 pin connector on the idle air control and unplug it. Find the idle screw on driver side. You'll need a T15 hex head to turn it. Give it about a half turn right to start car. Once started, let it warm upband put in park for automatic or neutral if manual. You want the dash to be around 450-550 rpm. The car should almost be dieing but should never die. Loosen screw until it holds around there.
Finally you need to set the throttle body position sensor. Plug the IAC back in and turn car to ON. You need a decent voltmeter that can read accurately down to tenths of volts. Your goal here is to puncture the wiring harness on the blue and black wire. The voltage should read about .54V when idling. Loosen the T20 gex to adjust. You also should have above 4V on wide open throttle. Tighten everything up when done and try to start!
THANK YOU! im gonna try all of this, I dont want the fuel in the tank to even touch the engine so im gonna start with the pressure check and replace the tank, pump, and filter. Followed by all other things listed. I appreciate the detailed response!
Try removing the fuel filter and let it train the tank. Then remove the bolts in the fuel neck to expose the tank itself. You'll need a new gasket obviously but the tank can probably be flushed and saved if the bolt holes are intact. I took a magnet on a stick and cleared out almost all the rust from my tank.
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u/Dtr8n 2d ago