MFP

84 crossfire. Starts fine when cold but once it's hot, and I shut it off, it won't start for about 15 minutes. It cranks, just no start. Also, it dies sometimes when it gets hot and won't restart.
Today I let it idle until it died, when I tried to restart it, I noticed the injectors were not putting out any gas(maybe a few drops but that's all).
After a few minutes of messing with it, the starter got where it wouldn't do anything. The dash lights up but no starter.
I've done searches but can't seem to find this particular problem.
Any ideas?
Thanks

Tom400CFI

1. When it does this, does it have SPARK?
2. When it does this, what is the fuel pressure?

Put a gauge on it, check spark, report back.

-Tom

MFP

I am trying to find somebody with a gauge.
I haven't checked for spark because I figure since I know for a fact that it is not getting any fuel, the spark really didn't matter(at least not at this time). That's the good thing about the crossfire, you can see the fuel being sprayed into the engine.
There is no problem with the fuel any other time, just after it runs for a while, then, once it sets for about 15 minutes, it starts right up.
It has a new fuel filter on it and I just replaced the pulsation damper on the fuel pump due to another problem I had.

CRUZN C4

Fuel pump is the culprit. When I had my 84 it did the same.

Tom400CFI

^Are you SURE??? Do you want the OP to spend his money on the wrong part? Diagnose, then replace.

You need to get a gauge (buy one so you have it) and you need to check for spark when the symptom is occuring. Why spark? Statisically speaking, the fuel pump is the likely problem; the '84 fuel pumps are junky. However, if your ignition pick-up coil fails, or your ignition module, (both items that when failing, are often aggravated by heat), you will also lose fuel. The ignition parts are what tell the ECM "Now-Now-Now-Now-", to fire the injectors. No "Now", no injector pulse="no fuel"....when your fuel pump may be working away like a champ. So you need to check for spark when the symptom occurs.

Additionally, if you have spark, then it still may not be the fuel pump. Before repalcing the pump, you should check for power at the pump, when the symptom is occuring, to make sure that you don't have a wiring or relay issue.

"Won't start/Die's when hot" isn't a common fuel pump symptom; that sounds more like electrical, which is all the more reason why I would test before replacing.

MFP

I replaced the ICM a while back hoping that was the problem but it wasn't. I might go ahead and put a new coil on it, they don't cost that much.
I didn't think about the ECM telling it not to pump fuel if there was no spark.
I really don't think it's the fuel pump. I think it would give me trouble other times.

Tom400CFI

It won't be an ignition coil, that prevents fuel flow at the injectors. It COULD be a pick-up coil. Test first. If the P/U coild is dead and you have no spark, the fuel pump will still run once you build oil pressure. But the injectors will not pulse, or fire -because nothing tells them when to.


I agree. But test.

MFP

How do I test the pick-up coil. I hope that's not the problem. That's more of a job to change than I can do. The distributor needs to be removed to replace it if I am correct. My knowledge and tools are limited.

Tom400CFI

If you have no spark when they symptom occurs, then that certainly narrows it down (to the Pickup coil and the module). You said that you recently replaced the module so...

You can test the pick up coil w/a DVOM. Do you have one? Also, you can replace the pick up coil w/o removing the distributor.

MFP

I don't have a tester and probably wouldn't know how to use it if I did

I am not saying that you are wrong but, according the my Haynes manual and the 84 Corvette shop manual, the distributor has to be removed to replace the pick up coil. Even if not, it still looks like a little more than I want to try. Like I said, I am very limited on knowledge, my expertise is more into computers.
Looks like I may have to give up and take it somewhere. The thing is, I see a lot of post on here about the same problem and nobody ever seems to find the answer, or if they do, they don't tell anybody.

RetiredSFC 97

Try shooting some ether into it and see if it starts. If it does it's most likely a fuel delivery issue. Or could be a coolant tmpe sensor as well.

A full and complete fule pressure test is the first thing to do though. Don't throw parts at it and pray

Tom400CFI

Dude. I'm telling you how to diagnose it! READ WHAT I'M TELLING YOU.

When the symptom occurs, does it have spark?
When the symptom occurs, does it have fuel pressure?

See post # 2 in this thread. You can check those things. Easy.

PS, you're right about the pick up coil; you DO need to pull the dist to replace it. BUT, we aren't that far yet. Spark and fuel. Do you have them?

MFP

Ok, here's where I'm at.
Let the car run today until it died. Tried to restart, no fuel.
Sprayed starter fluid and it started, then died, no fuel.
Sprayed again. Once it started, I revved up the engine, it started pumping fuel again and would then run without problems.
Shut it off, tried to restart, no fuel. Sprayed starter fluid, started then died. Same as before. It would run if I revved it after using starter fluid.
Did this senerio about five times with the same results every time.

After the car sits for about 15 minutes, it starts fine.

So, I am getting spark, just losing fuel. I don't have a pressure gauge but I am trying to find one to borrow.

Could it be the fuel pump?

Tom400CFI

It COULD be.

Why didn't you just check spark and fuel pressure like I told you to? Your "test" got you the answer...but what a arduous process. You could have checked for spark in 10 seconds, and had an answer.

If you're going to ask for advice, why not follow it? You need a fuel pressure gauge. Go buy one. If you own a CFI car, you need to own a pressure gauge. Go buy one. They're <$50, and you'll have it forever. Any time you need to diagnose, adjust for mods, etc.

Thus far, it sounds like you have an electrical problem in the FP circuit, or a bad FP...but you need to get a gauge on it, so you can SEE what is going on.

MFP

I don't have the tools or knowledge to do the testing.
I had to recreate the problem first by letting it get to the point where it won't start. Spraying the starter fluid was the easiest way I knew to test for spark at that point, and was also suggested by another user in this thread.
I also have limited funding for this so if I am going to pay $50 for a pressure gauge I will never use again, why not just go ahead and buy a pump?
I am not trying to be a smart a$$. I really do appreciate that you all take your time to try to help me. I just don't have the knowledge that you have.
I will continue to try to find a gauge that I can borrow, if not then I will go ahead and buy the pump. Even when I get a gauge, from the instructions I read it still takes a little while to get it hooked up and I only have a window of 10-15 minutes once this problem starts until it will start up ok. So that doesn't leave much time to hook it up and then test.
Once again, I appreciate all the help you are giving me. I know if I take it to a mechanic, it will cost a bundle.

Tom400CFI

Because if it's not the pump, then you just spent $$$ on a pump for nothing. Now how does spending $50 on a guage that you WILL use again, sound?


You can hook the gauge up any time. Hook it up as soon as you aquire it...then just start driving the car around. When the symptom occurs start observing the gauge to see what is going on. You can leave the gauge hooked up and functioning, for as long as you want. Days, weeks...whatever. You don't have to hurry and hook it up ONLY when the symptom occurs. Hook it up, leave it there. Observe when neccessary.

It will cost you a bundle if you take it to a mechanic. That is why I strongly advise you to follow a diagnostic procedure to SAVE money. I know about being tight on money. I don't want to see you "jump" at buying a part to end your problems...only to have that part not be the problem.

Keep us posted, and We (I at least) will help you continue down the diagnostic path, until the actual problem is located. Then you can fix it with a minimum of parts buying.

qws

Having a fuel pressure gauge is probably one of the best tools to have in your toolbox. I had actually set my gauge up as a permanent install on my car. Even now with my other intake I still have a FP gauge mounted on the fuel rail. You can always easily look down and see whats going on.
There very simple to put on, just locate between the two tb's using a tee fitting, and screw in the gauge.
Once you have it there you'll be very happy that you did it.

The problem with taking these cars to a mechanic, is that most look at in and say "cfi junk" get a carb. Because they don't fully understand themselves whats going on. Your better off learning how to diagnose it yourself than paying full price to a mechanic thats gonna need to learn how to fix it!

Listen to Tom400.

in-vette-uation

I agree. Tom is giving you very good help. If you follow what he's saying you're going to learn something about your car and pretty soon you'll not have to talk about how your skills are limited. It's a pretty easy car to learn on. Have fun AND save some green. Sounds good to me!

MFP

OK, here's where I'm at now. Still haven't got a pressure gauge yet, think I have a friend coming over next week with one.
Anyway, got a noid light from my local auto store on loan, let the car run for a while, shut it off, tried to start, no go, hooked up the light and it was very dim. So, I would say I am loosing power to the injectors. What could be the cause of that?

MFP

Finally got the fuel pressure checked. It shows 13 psi. even when it gets to the point where it won't restart. Pressure was still at 13 45 minutes later.
So now what? Is my ECM bad?