Recently picked up a 1985 Corvette L98 as a Fall / Winter project. I'm a novice and this forum has already helped a great deal in my understanding of these great cars - thank you!

Would like some advice / direction on my no start issue. Initially the vehicle had no fuel pressure at the fuel rail. Replaced the fuel filter, fuel sending unit and fuel pump and now have about 40 psi at the rail.

Picked up a spark tester and observe spark during cranking. Sprayed some starter fluid in the intake and the engine seems to catch momentarily but won't run. Stuck a pin into a couple of the injector connections and my test light seems to flicker during cranking suggesting the injectors are getting a pulse.

It's my understanding from the previous owner that the car sat for years without running but I don't have much background other than that. Consequently I've cleaned the gas take and blew out the fuel lines. I suspect the fuel injectors need cleaning or replacing. Would like to pull the injector caps first to measure resistance but unclear how they come off. I see a metal clip at the injector base, will that release the cap from the injector?

Before I go after the injectors do you suppose Timing might keep it from starting? Also, even though I observe spark at the plugs could the ignition control module be an issue or does spark at the plugs rule that out?

Thank you for any direction / help!

 

Hi Kansas Brad,

when you did your fuel system work, did you replace the fuel pump relay?

 

Thank you for the response, Viking! No, I haven't changed the Fuel Pump Relay. I did jumper the OBD pin G to force the fuel pump on thinking if the FP was being turned off by something then the fuel rail would still get gas.

Do you think the relay could cause my no start? The Vette does sound like it's fuel starved when it catches and won't run.

Thanks

 

Kansas Brad, my 1985 was bought in 1992. Still using the same factory installed injectors. Had no problems with them about 19 years ago when I bought a kit to use a pressure can of injector cleaning liquid. Have not done any cleaning of the injectors since. The 85 runs great on low octane gas.

 

That's good to know, thank you ZZ! I don't want to pull the injectors without some good indication that they're causing my no start. Still reading and learning about what's probable and what's not. My understanding has a long way to go!

Thank you!

 

Another thing about my old 1985, I have replaced the fuel pump. There is a pulsator piece between the fuel pump and gas going to the fuel line. The pulsator piece can leak the fuel pumps pressure pumped gas back into the tank.
I also never turn the ignition key from off to start immediately, have learned to turn the ignition key from off to the run position first listening for the fuel pump to pump fuel and listen for the fuel pump relay on the firewall in front of the driver to click off, then I turn the key to start my 1985. It always fires up immediately using this method, the engine hardly turns over before it is running.
I use this method on my three other cars with the same results.

Another thing you can do is call Gordon Killebrew. He worked at the Corvette plant when your Corvette was made. Google his name and read about his services and Corvette experience. The cost of a phone call may save you a lot of money chasing your Corvette's no running problem. Back when I bought my 1985 there was a call in service at the Corvette Action Center at the Corvette plant that you could address your C4 problems with just a phone call, I used it.

 

Thanks, ZZ! I've been following your start procedure when I crank it but had only noticed the fuel pump kick on for 2 seconds. Just went and listened again and can hear the FP Relay now as well. Good tip.

Mr. Killebrew's site is quite impressive and the consultation fee is reasonable. Thanks for the lead!

 

welcome to the forum.....quite a few of us have 85's so don't give up on the forum and pay somebody....guessing you already have a fsm and fuel guage so you're halfway there.....make sure you're seeing fuel pressure when you're starting...fuel pump only runs two sec....if your fuel line is loose in the pulsator, your pressure will drop off and it won''t start...you wouldn't be the first to put a new pump in to have that happen
Also, check all your vac lines for cracks, (easier to do when running) make sure the egr valve is closed, and I'd pull the IAC and clean it and the port it goes into in the TB....i'm not that much of an expert but i'm sure the pro's will jump in and help....this is a great place for information...just be specific, always state your year...it helps alot...............good luck

 

Thank you for the warm welcome, Dixie! It's a great forum and I've already learned a lot.

I'll go check those items you mentioned, thanks. I do seem to maintain fuel pressure during cranking and it appears to be holding after key off. Today I pulled the distributor cap to check static timing and see the rotor pointing at plug number 1 when the timing mark is at the timing plate (...too corroded to read degrees though). Of course the battery is down now so my crank testing will be limited until I get my new battery charger next week!

I won't be paying anyone to troubleshoot as this is something I want to learn and am in no particular hurry. Takes time to assimilate the various systems on this vehicle. My dash cluster was also dark but thanks to this forum pointing me to batte.com I was able to get it back up.

Thanks again!

 

your 85 also has a9th injector a cold start injector.....When I got my 85, I changed most relays and the iac based on threads in this forum...couldn't believe how bad the iac/plenum/tb was choked with carbon...doubt it's your timing....set it after she fires up....make sure your tps is set right.
try a little starting fluid when cranking......here's what I finally did..

 

Impressive motor, Dixie! The only thing in common with mine is the Orange plug wires!

Did a resistance readings on some of the injectors this morning. Reading a consistent 16.3 ohms among four of them which seems roughly in range. I’ll check the others tomorrow and see if that holds. Adjusted the TPS up from 5.0 to 5.4 volts. Next check is the IAC valve and clean that up. I have been using starter fluid and it coughs a bit but hard to say if that constitutes running – but it wants to!

Borrowed a NOID tester and compression tester and will check that stuff tomorrow. If nothing obvious turns up I’ll return to square one and see where it leads.

Thanks for your input!

 

I hope you meant 0.54 volts...

 

I am assuming you have put a timing light on to verify the engine is firing? If not do that and verify you have fire. I have had tons of trouble in the last few weeks with firing on my "85.

Check your ignition coil and the distributor pick up coils. Test procedure here http://www.answers.com/Q/How_do_you_..._ignition_coil

Use an ohmmeter and check your pick up coil. Pull the 2 pin connector on your ICM and see if there is ANY resistance. Meter should show an open loop.

Only then would I go on to fuel.

Good luck.

 

There's only a few things a 4 stroke motor needs to run. Air, fuel, compression, spark, and timed right.

You have air, you've eliminated fuel as a problem with the use of starting fluid and you seem to have spark. Check the others and you should find your problem.

 

Thanks for the response! I've only been able to check the static timing since it won't run but it appears to be in the vicinity of timed. I do have spark but at some of the plugs (wires and plugs are new) it seems weak - not jumping the gap specs of my gap tester and orange-ish rather than blue. Consequently next steps are to run voltage and resistance checks at the distributor coils.

Since it was cheap and easy I replaced the ICM yesterday and the engine seemed to like it but not enough to continue running.

Thanks again for your thoughts - much appreciated!

 

Thank you! I do have those things and now looking at their quality. I'm also a novice so it's a learn as I go approach with its inherent mistakes and muddled thinking!

Thanks for your input!

 

Thanks Cliff! Yes, it's actually 0.54 volts!

 

Update: Replaced the fuel injectors and the 'Vette started right up!

Recap - This was a vehicle that had apparently sat unattended for years and happened to come across my path and although a novice in mechanics decided to take it on as a Fall/ Winter project.

The first issue (after installing a battery) was no pressure at the fuel rail. The fuel filter had previously been replaced as well as the plugs and wires.

Found that the fuel sending unit was leaking and replaced that as well as the attached fuel pump. This got me pressure (around 40 psi) at the rail and although the engine would catch it wouldn't run. Adding a little starter fluid would help it run for a second or two.

Looked like I was getting pulses at the injectors, spark at the plugs, and static timing seemed approximately correct. I jumped 12 volts to pin G at the OBD connector to force the fuel pump to remain on in case the oil pressure relay was shutting the fuel pump down but that didn't change the starting situation.

Still seemed like the engine was starved for fuel so ordered 8 Bosh III 24 psi re-manufactured injectors from ebay and installed them today. Vehicle started right up and idles fine. Took it for a couple of short rides and seems to run fine.

This Vette still needs lots of work to get it road ready but wanted to sum up this thread with the hope that it might help someone down the road. I've certainly gained much reading this forum and appreciate all the folks that relayed their issues and solutions.

Thank you all!

 

My dad's 86 had a complete no start problem exactly like yours. After replacing the dead fuel pump, we diagnosed everything and all was right on. The injectors had pulse, fuel pressure was great, etc...

Tapping on each injector with a block of wood and a hammer repeatedly freed up the injectors and the car started. It has run great ever since.