masterprice33

in response to mr. kidd........I do not have access to a good ECM to test with, we replaced the fuel pump relay already, had no effect. One thing I thought was rather peculiar was that the mechanic noted that the fuel pump fuse was blown before, and when he put a new one in there it also blew eventually. But even with a new one in now it is still having the same problems, according to my mechanic. Does this lead any of you to change your opinions on what's going on? And what exactly would the oil sending unit have to do with these problems? is it pricey to replace?

RRT vette

Have the mechanic run a hot wire from the + battery to terminal G of the ALDL. It should run the pump continiously until the wire is removed. You might have a short in the tank, connector, or anywhere inbetween the fuse and the pump.

masterprice33

another question.....could any of these specific symptoms i've described have to do with messed up oxygen sensors or a bad catalytic converter?....I can't get a hold of the mechanic so until then I can't give an update.

RRT vette

I didn't see in any of your posts that the O2 sensor or cat would be the problem. A clogged cat will usually glow when hot and make your car feel like there is no hp when giving throttle, but not stall unless it is completely blocked. If completely blocked it probably wouldn't start, kinda like a potato in the muffler type thing. The O2 sensor doesn't start sending signal until the exhaust temp reaches 600* and/or the engine temp reaches 140*. With a faulty O2 sensor it will make the car run rough and either tell the ECM to add more or less fuel, associated with rich or lean exhaust smell and exhaust color. The O2 sensor can be tested for volts....ranges from .1v lean to .9v rich. The numbers will vary every second depending on engine load. Did you get the ignition module tested yet? More things would be to check the color and smell of the spark plugs and ohm the wires.

masterprice33

a little update here........I will be definitely getting the module checked tomorrow, another thing I wasn't aware of until now was that at its CURRENT state, when I got together with the mechanic, the fuel pump WILL NOT turn on with the ignition key on 'ON', at least that's what happened today. I swear this is getting crazy. At least after I get the module checked we can eliminate one of the things many on here think would be the problem. The wiring is all jacked up in the car I swear, but still I got this car a couple years ago and it hadn't ever continuously and intermittently stalled like this until after I brought it into the shop and had oil change done, codes checked, and had the radiator replaced. I forgot to mention RRTvette's advice about seeing if the pump would run with a hot wire from the battery to ALDL port G to the mechanic, I think I'll tell him tomorrow to do that and then I'll report back

masterprice33

PROGRESSS!!!, I just had the ignition module tested at Napa and, after the first run the guy there said it passed, but once hot, started failing over and over, so we may have our culprit. I will write another post once I have the mechanic put the new module in and see what's happening from there.

LD85

I guess I was lucky, the mechancs I took my car too, when I first got my 85,, told me straight away, its the HEI,,, and he was correct.

I could be driving along & depress the clutch and the car would die, turn it on, then die, let it cool for a bit, then it was OK.

masterprice33

update.....well we THOUGHT the ignition module cured everything, it only made it better, now it will stall less often, and after stall it will start RIGHT back up, so I'm thinking there were a couple of problems. So the stall is still there. Upon stall fuel pressure maintained, so at a loss here once again, advice anyone?

RRT vette

O.K. you fixed one part that was bad...good. Now describe what it is doing all over again. If fuel pressure builts and holds then the pump is probably good. Have you checked the spark plugs and/or PVC?

rick lambert

I hope your mechanic is using a factory service manual or Helms manual. I'm thinking he should be checking the voltage at the TPS=throttle postition sensor.Accoding to the FSM, this is one of the most important sensors on our cars!

masterprice33

Ok, i'm back from Redding CA to report what happened the other day with the installation of the ignition module. So before the new one was installed, the car would have a hard time starting, and even when it did turn over, it would stall in park/idle pretty quickly, and every start thereafter took longer and longer, until eventually not being able to start at all. So after seeing that the old ignition module was bad, we replaced it with the brand new one. Although it took awhile to start and actually died rather quickly (mechanic says he 'thinks' he saw the check engine light come on right before it died), we tried it again and it started right up and held good strong idle for quite some time, shifting from park to drive and back and forth, idle held very well for about 5 minutes, so we decided to take it for a drive...

Drove it around pretty good for about 10 minutes around time, everything seemed back to a no stall condition, at idle, cruise, acceleration...So we bring it back to the shop and let it idle for awhile. Idle was still holding very well, engine was all warmed up. Then....as I almost expected to happen, it died. When we tried to start it back up it started up RIGHT away, good strong start, but the idle seemed a tad jumpy on this go round, and then it died again a minute later, but would start right back up quickly. The thing is...sorry this is taking so long I must explain everything here....This was the problem IN THE FIRST PLACE, I believe the ignition module actually failed maybe a few days AFTER, as my car overheated because my radiator went out, which I have since replaced, which is why the problem appeared to be getting worse, so now its back to the beginning. So there it is RRTvette, if you have any more questions, let me know....I'll have to have the mechanic check that TPS voltage and maybe the code that the first stall may have created. Mechanic was wondering what types of things make an ignition module go bad...

masterprice33

Mechanic is not using an FSM, just the Haynes manual, I know I should get the FSM I was hoping I wouldn't have to but it seems like a GREAT idea now. I'll have to see about the TPS tonight and see if he can test it tomorrow.

RRT vette

Well you seem to have this problem only after it warms up. The SES light came on but does it stay on? If you try and pull the codes it might not show up if the SES light isn't on. I would try and put a fuel pressure guage on while driving and at idle hot to see if there is any drop in pressure causing this...to rule out fuel problems. When it stalls the pressure should hold between 36-40 psi and not drop much at all. It seems to crank back up everytime when hot so the new ignition module should be o.k. I know this is an aggravating situation for you. Could be so many things, so the only other thing I can think of besides guessing, is to run a scan on the car until it happens again to see what the ECM is seeing.

masterprice33

The SES light does not stay on, and it only came on right before the FIRST stall RIGHT after we installed the ignition module, and it did not stay on. After the ignition module was replaced and we drove it around awhile, then stalled, there was no SES light on before it stalled. We checked the fuel pressure right after it stalled and the fuel pressure remained constant at around 40 psi. We have not noticed drops in fuel pressure BEFORE any of the stalls we noticed during all this time when working with the vette. Like I said in the past, there were a few odd times when the fuel pressure would drop very fast, but this did not happen very often, and it hasn't happened since placing the new ignition module in. Thanks for your help I really appreciate it everyone.

86Pacecar

I have to ask if the mechanic installed the ignition module properly with the proper heat transfer grease between the module and the distributor. If the grese is not applied correctly it will not transfer heat properly away from the module and it will heat up and quickly start to fail again. This sounds like what is happening, and it is a common misstep when the module is replaced. My money is still on the module, but hey I'm a long ways away and cannot see what is happening.
Seems too coincidental that it ran good for awhile after the module was replaced and that it has now gotten back to the same point. Not unheard of for a new part to fail even if installed correctly.

Blownfuel1

One other possibility on this, I've had a HEI that acted exactly like it had a bad module, but it turned out to have a bad wire on the inductive pick up (the little, round, pointed (kinda like a throwing star, but shorter points) star looking thing down below the module. You may havew to remove a plate in the base of the Dist. to see this, can't remember for sure right now. I know if you have to change it, you have to drive out the roll pin that holds the gear on the bottom of the Dist. on, and then knock out the shaft to change it (you've pretty much got to dissassemble the complete Dist. to change it), or you can just order a performance Hei Dist. with a better than stock module, etc... for Summit for about $130.00. Before you do that though, make sure you've traced the problem to the Dist.

masterprice33

I personally watched him do everything with the transfer grease on the ignition module, and he was very careful about it, so I doubt it was installed incorrectly. In response to Blownfuel1, it was proven that the old module was in fact failing, as I had it tested at Napa. Will report back when I can rule out the TPS, that's my next move, if that doesn't do it I'll look back at the module

masterprice33

I just received a message from another member saying that he strongly felt it may be the pick-up coil causing these problems. If I could get some backup on this one I would greatly appreciate it, it this could also be a culprit in this.

rick lambert

Very well could be the pickup coil...that's what Blownfuel was refering to. I'm at work so I don't have my FSM...but your mechanic should be able to ohm the pickup coil....just make sure to tell him to wiggle the wires while he is checking it, that is an important part of the test.And, I'm thinking if the pickup coil is bad it could explain why the fuel presssure dropped....unit fails, no signal to the ECM to fire the injectors.

Blownfuel1

Yes, that's what I was refering to, should be two wires leading to/from it (orange and white, if I remember right). they are the two wires that plug into one side of the module and the disappear underneath it. Mine failed just outside the entrance to the Like Like tunnel in Ohau, Hi! That probably doesn't mean much to most of you, just picture driving up the side of a volcano on a two lane road with no shoulders! At least it failed JUST before I entered the tunnel (instead of waiting till I entered it, cause I would have had to roll backwards back out against traffic, cause it's a steep uphill, and there's NOWHERE else to go! ) and there is a maintenance vehicle pull off right at the edge of the tunnel! Feild stripped and repaired it right there on the side of the road, was back in action in about an hour.