89 brought back from the litterally dead category. Couple issues but most are working themselves out nicely.

First issue was no start.. dialed it down to a fuel pump. Then it was a intermittent start/no start. That was a cracked coil.

Most recently is a no hot start issue. Just replaced the ICM and no dice. Key in ignition, turn it, fuel pump runs for a couple seconds, car starts immediately. Turn it off, and motor turns, but no fire.

Came to the conclusion that it will restart after 10 minutes or so of sitting. BUT.. what we noticed is that it will start again only when we hear the fuel pump cycle. Otherwise when you turn the key, no sound from the pump = no start. We also played with the fuel pump relay and there is a click when the pump cycles and no click when it doesn't. So... We know when it will start and when it won't just by if the fuel pump cycles.

When the fuel pump won't cycle with the ignition we checked and we are getting spark and we are getting pulse to the injectors (first we thought we weren't with a regular test light, but then we checked with a led test light and confirmed pulses) So we know that the ICM that we replaced today isn't the issue. (throwing parts is fun...)

We have not checked the fuel pressure (yet) but the plan is to replace the fuel pump relay ($17) and pick up a fuel pressure tester to confirm the pressure is correct.

Here is what is wierd. When it decides to run (fuel pump runs and relay clicks) it starts immediately. When we go to hot start it and no click or pump noise there is not even a sputter. Sometimes with enough cranking we get a quick sputter, but nothing more. I noticed that most of the time while cranking we are only seeing 3 psi (sometimes it bumps to 4 psi) on the oil pressure gauge so maybe that is what is giving a quick burst to the fuel pump to give us the sputter.

So question is..... Is there something else that will trigger the relay to give us this no relay click/no pump/no start issue that we are missing.

Vats comes to mind, but the security light comes on when the key is turned and then goes off again with the other lights. We have two keys and both produce the same exact results.

Any suggestions would be helpful. Thanks.

 

Check out my response to a similar problem posted on this forum:

Fuel Pump Help **PLEASE**

If you can verify that the fuel pump relay is supplying battery positive voltage to the fuel pump wire, usually the problem is a bad, rusted common ground attached to the tank assembly itself. (The common ground is for the fuel pump and the fuel tank float assembly inside the tank.)

Hope this solves your problem.

 

We are going to check the fuel pressure and abandon the relay for right now. After reading a similar post ...

http://forums.corvetteforum.com/c4-t...-turn-off.html

and the follow up...

http://forums.corvetteforum.com/c4-t...post1574723222


We have decided to throw a set of injectors at it. The first set yeilded 212k mi, so we think that our issue is with those. We suspect these since the car will start great, idle up, then down smooth, then after a few minutes develop a rather significant lope and almost misfire like condition. Then it pulls this no hot start crap.... But this rough condition is only present at idle and slight throttle, but it revs great and really smooths out as you stomp the pedal...

We've double checked all the vacuum lines, even double checked the one way T for operation etc. Vacuum gauge is showing good #'s and using propane gas we can't detect any leaks anywhere around the engine bay.

Decided that the next $$$ we throw at this car is going to be things it needs anyways...

 

Just checked the ohms on the injectors. Not a pretty sight. Cold...two or three were 16-17 one was 10, one was 9.9, and the others were not even numbers worth writing down.

After warmup a couple came up into the teens. Plan is to disconnect any below 10 and try to see if our no hot (or even 2nd cold) start condition remains. Injectors are definately being replaced, but we want to know if this other problem is related or not.

Should we be jumping the injector feed with a 16 ohm resistor while disconnected to test, or just disconnect and leave em?

 

You wouldn't happen to have a pic or a description of where that ground is located?

 

Sure enough... OEM injectors were causing the no warm start. Disconnected four of the "bad" injectors and wham... car started right up, plugged em back in, no start.

Ordering a set of the Bosch III now.

 

Started the install this afternoon at 1230. Everything came apart nicely except for getting the inside intake runner t-40 bolts out. I will say that having a t-40 bit or key will help a bit more than a socket type tool. Lots of tight places.

Anyone that says that this job can be done in an hour is either lying or one hell of a seasoned intake disassembler. I can tell you that we are at hour 4 with the fuel rail buttoned up and re pressurized. Still have to reassemble the intake parts, throttle body etc. But we are also dealing with 20 years and 200k+ worth of dirt and grime that we paused to address.

Also going to do a coolant bypass, those hoses are such a PITA. And what is up with the throttle position sensor bolts. One snapped at the head, went to grab it with vice grips and it snapped half way again. It's as brittle as a pretzel. I see having to drill and tap a new bolt before this job is done.

So far we have almost 2 hrs into disassembly, 1/2 hr into cleaning, 1 hr disassembling old injector, cleaning and reassembly of all the fuel rail o-rings, and 1/2 hr into injector and fuel rail reinstall.

Does anyone know where I can find a diagram showing which bolts go where on the intake runners? Towards the end of disassembly I realized I was dealing with different lenght bolts, as they all lay there in a pile

Update
Intake bolts are pretty straight forward. Just look at the thickness of the runner and you will see which ones go where. Only three lengths to deal with and as a hint... the two inside bolts have the short shoulder and the other two short shoulder bolts go on the right side of each runner. You have to look carefully, but you will notice it's slightly thicker. Anyone attempting this I would reccommend having a t-40 bit similar to the small #2 phillips bits you would use in a magnetic bit holder and use a 1/4 inch wrench to turn it when dealing with those two inner bolts.

 

We got it all buttoned back up yesterday. No fuel leaks. We did the TB coolant bypass and ran a 5' section of 5/8 hose straight out to the AC accumulator and back around with those lines. Only broke two bolts on the TB. One on the bottom and one on the TPS on the side. That one we had to drill and retap. Cleaned up the IAC valve (gooey) and replaced all the PCV hoses which all broke on disassembly.

It started up on the second try, hesitated for a second then came to life. Rolled to 1100 rpm, then settled down to 700 within 3-4 seconds. Fastest it's ever come down off of high idle. Shut it off and it restarted nicely. First time it's done that for quite some time now.

What we notice with the starting now is it will crank for 1 second then come alive. It used to start immediately. I'm sure this has something to do with the computer and injector monitoring.

multec ohm specs hot 17.3 14.5 6.5 6.1 10.1 16.6 9.9 16.9 Cold they all read .003 -.007 (I'm not sure if dad had his glasses on for those readings )

Loping is gone. It is still not as smooth as we would like to see, but this is also a car that sat for years and has numerous issues, some present, others presenting themselves daily. We noticed some initial slight poping sounds like a slight backfire, but they seemed to go away. On a test drive it was smoother than it has ever been. Pops wouldn't let me bury the go pedal so I only got a few burts in. Next time

Question though... Should there be any play in the rotor gear? What I notice is if you turn the inside contact wheel, you can feel the spline gear spin a few degrees (10 -15 degree window) and push the rotor upwards. Is that normal, or is it time to rebuild/replace that too ? I'm not sure if this is affecting the timing or not. That is the next thing we are going to check to see if it changes or bounces around. Timing light refresher course time.

 

your distributor shaft runs in two oil-lite bronze bushings, one at the bottom (just bove the dizzy driven gear) and another at the top (abt same elevation as the lower edge of the cap...the lower bushing is bathed in oil, but the upper bushing is not...the upper bushing lube/life depends on the 'pumping' action of the dizzy shaft moving vertically a tiny amount at each engine decel (inertia, beveled gears working together)...this does cause a spark timing change but since at this instant the engine is in decel mode with throttle closed/no fuel there is no harm/no fowl...some 'shim' the dizzy gear for reduced vertical movement and then wonder why the upper bearing in the dizzy shows excessive wear a short time later...raise one to those guys that came up with this idea circa 1952.

 

Thanks for the reply. I read shortly after I posted of a rpm based timing change and wondered if this is what it was. (still learning)

Now I just need to check the timing and reset the IAC TPS since I had to remove them during the process.