Hello Everyone...This is my first post on your site. I've read over 35 pages of past threads and several questions have been addressed without ever being asked formally. I have owned nine Corvettes but only one C4.
My current project is a 1986 coupe with 8300 miles original. The car was wrecked by the original owner when it had 700 miles and it went on an Arizona salvage title for the second owner who re-built and drove it for the next 7600 miles. He moved to Missouri and parked the car behind his house where it languished for years. I bought the car nine years ago and stuck it in my garage occassionally tinkering with the cosmetic issues. During this period I drove a 78 Anniversary model.
Now my dilemma. One one hand..this machine has sat too long and would best be parted out. On the other..it starts and runs. Looks decent. Sinister appearance. Four speed plus 3 transmission. Barely worn interior. Its a CORVETTE.
My fuel injection experience is limited and comes from my boat (twin 454s). I emptied all possible fuel (sludge) from the tank. Added five gallons...emptied again..three times to eliminate and dillute the old gas. Added injector cleaner. Emptied again. More gas. More injector cleaner. I next replaced the fuel pump and associated parts on the pick-up tube.
Next I removed the distributor and cleaned contacts and rotor. Charged the battery. Turned the key.
She runs better than I expected however fuel pressure is a little higher than 37 (more like 45).
I'm wondering if pumping fresh fuel and cleaner thru these old (low mileage) injectors can be expected to clean them out or do I need to remove and soak them in cleaner?
I do not hear anything that sounds like a vaccuum leak while it idles. However the age of the regulator has me worried. Removing, cleaning, and replacing the injectors would also replace O rings thereby eliminate more old rubber.
Removed spark plugs for inspection and gap check. Nos 1 and 3 had wet appearance suggesting (to me)leaking injectors.
If injector removal is required..can it be accomplished without removing intake plenum and runners. I read a thread where very complete instructions were given for this process and it kinda scares me. If the four bolts on the fuel rails will give enough clearance to remove the injectors I'll clean them just to remove suspicion.
When the engine runs..it has a miss (expectedly) and if additional fuel is applied...the engine hesitates before spooling up and occassionally will backfire thru the intake (I think).
I let it run on a couple tests till the fans kicked in (224) and all electrical systems seemed to function better than anyone should expect given the car's history. The radio sounds lousy but I rarely use one anyway.
What do you think? Work out the bugs and drive the thing, or resist the impulse to throw good money after bad and let it go for parts. Thanks for your time (and your advise) NineBall

 

Sounds like a keeper to me. Welcome to the site. From what you said it could be a really nice ride. I say bring it back and drive it. Cheers

 

Lord no, don't soak injectors unless you want ruin the coils in them.

No, it cannot be done that way.

Have the injectors professionally cleaned in the car with an injector cleaning service and see if that helps. Have you checked for any codes?

 

Ihave NOT checked for codes. Once again..I read a thread that makes this procedure sound stupid simple. No special equipment required. Is it really a matter of completing the circuit with a wire and counting flashes?
I put the fuel pressure guage back on and checked again. Don't know where I got previous readings but today it was a rock-steady 39 at idle and after settling down after revving.
Also put a timing light on. Didn't suspect any issues here since I've NEVER messed with it's timing.The timing mark was way above the timing tab. I didn't know it would idle that far off. Made a slight adjustment to get the mark ait the top end of the tab. Seems to idle better and doesn't back-fire when I rev it. Still stumbles when I rev it though. Rotating the distributor to move the mark further into the tab seems to want to kill the engine. I'm beginning to think maybethe distributor isoff a tooth..
Thanks for the injector knowledge. If I coulda got the things out I would have soaked them for sure. I did start removel of the plenum a couple weeks ago but backed off and put it back together when I realized two of the torx bolts were BEHIND injectors. I know I didn't breech the vaccuum system unless removing the torx bolts I could get to effectively did it. Again .. there are no vaccuum noises.
Just how lousy does an engine run with a bad MAF? I may have trashed mine a couple years ago squirting engine starting fluid thru the thing an an aborted effort to start it when it was out of gas. Stupid..I know.

 

Hey guy iv'e had my 86 for 20 yrs and their ain't much i don't know LOL.put a new fuel pump and filter on it.might have to change the filter a couple times. believe me iv'e canged a couple and the fuel pressure reading don't mean ****.ithe system looses pressure under load and you can't tell what it is.The l 98 is an excellent motor.The only issues iv'e ever had with the car is fuel and that is because i let it set a lot.notice the filter onthe pump you'll see if it is gettin crap from the tank.It only takes abo;ut an hour to change the pump.good luck.Dave

 

Thanks Dave...I just did replace the fuel pump and all the related hardware on the fuel pick-up pipe. The old one sat so long withlittle fuel in the tank that the float assembly froze in position with rust. That and the fact that the pump also quit led me to make the switch. I may get in there again after a couple months to see if anything collects on the filter screen. When I had it opened I emptied and flushed the tank pretty thoroughly. I visually siphoned all flecks of anything out with the old fuel three times. Now the system is steady at 39 lbs and stays at least 10 lbs up to 15 minutes after I shut it off.

 

Hello. I had a similar situation when I picked up an 85 with 31,000 miles on it last year. When you set the timing, you need to disconnect the electronic spark control, a gray and black wire on the drivers side near the firewall. I didn't catch if you changed the fuel filter. Sounds like your pressure regulator wroks like a champ. Don't be afraid of the fuel injection, the whole system comes on and off pretty easy, just a little tedious. I would definitely check the codes and grab a Haynes manual or use the internet to read them. The car sounds like a keeper. I have a 1979, 1985 and a 2003, and I actually like driving the C4 more. Good luck.

 

Electronic Spark Control ... Looks like I'll be doing that task again. Seems like whatever knowledge I accumulated over all these years just isn't applicable when I raise the hood on this car.
Thanks for the clue. It's almost as good as having a pro watching over my shoulder.

 

It occurs to me I might be missing something obvious...

Is there a fuel filter in addition to the one located in the tank? It seems kinda primitive to rely on that sock thing as the only filtering system for eight injectors. If there is another in-line type filter..I haven't replaced it or even seen it .. yet.

 

Passenger side, inside frame rail, behind RF tire.