83 SC engine dies when hot

walt83sc · 06-01-2009, 07:48 AM

I've been having trouble for a year or so with this. After 20 minutes of driving, the engine shuts off and won't start.

After it sits for 15 minutes or so, it usually starts back up.

I replaced the fuel pump 3 years ago.

I replaced the fuel pump relay 2 years ago, and again last year.

I just replaced the fuel pump *again*.

I have swapped relays among my growing collection of used ones.

Yesterday, I drove it 4 miles to the store and back, and it died 200 yards from my driveway. Towed it home, pushed it into the garage, and it started back up.
I let it run for 30 minutes without further issue.

Any suggestions would be appreciated.

Bryan A. · 06-01-2009, 07:52 AM

Try a coil. They can act strangely when hot when they start to break down internally.

walt83sc · 06-01-2009, 01:11 PM

Well, here's the strange part. It would not start at all prior to replacing the fuel pump on Saturday. After I replaced it, it fired right up.

And after I got it put back in the garage, it started up again, and I let it run for at least half an hour. It got really hot. I stuck a furnace blower behind the car to keep from setting fire to the carpet. (Yeah, it's old crappy carpet, but hey, a carpeted garage is cool.)

The fuel line was under pressure when I removed the old pump, as it sprayed when I unscrewed the cap nut, so the (3-year-old) pump was pumping... I kind of assumed it wasn't pumping up to full pressure or something.

So, I'm kind of thinking it's a fuel related issue. Is there anything that might cause it to shut off the fuel system after it warms up?

Thanks in advance... I'm really bumming that my fav ride is out of commission.

mca · 06-01-2009, 01:20 PM

Could also be a sign that the CDI is failing. I tested one for a buddy and after the car reached normal operating temps the CDI quit.

teenerted1 · 06-01-2009, 01:31 PM

Quote:

Originally Posted by Bryan A.

Try a coil. They can act strangely when hot when they start to break down internally.

+1
being hot i would check all the electronics.

hows that carpeted garage when you spill fluids on it?

not sure i would like that one bit

Mookster · Mookster's Garage

Remove the rev limit relay (in the left side of the dash, I believe behind the fuel gage). If your engine stalling problem ends, replace it. This test is free.

Check the relay under the passenger seat. If you unplug it and the vehicle runs like garbage when disconnected, the relay is good.

Rotor and cap still good? Cheap replacement but not sure of its age?

It the problem continues, I agree the coil and CDI may be going bad.

Just for funzies, do you have the original black ignition coil or has it been replaced with a silver ignition coil? If you have the silver ignition coil, made in Brazil, it will go bad. I had 3.

Electrical gremlins suck. Do not throw parts at the problem.

I feel your pain. Good luck.

Aurel · Aurel's Garage

When it won`t start, have you tried to lift the airbox meter flap to give it more gas? Also, a faulty fuel accumulator would cause hot start issues (but usually only after the engine has been shut down).

Paulporsche · 06-01-2009, 06:07 PM

Quote:

Originally Posted by mca

Could also be a sign that the CDI is failing. I tested one for a buddy and after the car reached normal operating temps the CDI quit.

There have been quite a few reports on this BB of this happening, especially to Permatune CDIs.

Hoffmanmotors · 06-01-2009, 06:23 PM

Quote:

Originally Posted by mca

Could also be a sign that the CDI is failing. I tested one for a buddy and after the car reached normal operating temps the CDI quit.

Exactly my thoughts. My car did this same thing. replaced it with a MSD, Problem fixed. Or send it off to be rebuilt...

After it shuts off, run back and open your engine lid and see if you can hear the CDI box "whining". If you cant hear it, and a few seconds or min pass by and it starts whining again then the box is failing. This was the case In my 79SC.

Good luck,
-Jeff

walt83sc · 06-01-2009, 07:01 PM

Thanks for all the feedback, much appreciated.

I have the original coil, I believe. It's black, looks really old.

I had the distributor rebuilt a few years ago, and that did wonders for the wear rate on the cap and rotor. Didn't make much difference with the engine though.

Spills on the carpet aren't fun, but it was free used office carpet, and I have extra, so it gets thrown out if it's too bad. Fortunately, I haven't had a major spill since that one nasty incident with the oil drain plug falling into the funnel and plugging it up. :-P

I noticed a couple of whining noises when I lifted the airbox meter flap. Seemed to be coming from the airbox and somewhere to the left side of the engine, although I thought it was near the distributor... No noise aside from that.

There was a nasty "dieseling" sound a few seconds after it died, lasting for a couple seconds... No idea what that might be.

Thanks again... Walt

schoward · 06-01-2009, 07:26 PM

Could be CDI or coil, probably most likely.

Dont forget Mookster's first tip above. The rev limiter is an obscure failure point but can cause issues as it cuts the fuel pump power. When those go bad they can intermittently cut power to the fuel pump when not supposed to. I had one that constantly cut the pump on and off very quickly causing less than optimal fuel flow and performance. Simply unplug it to see if any improvement; you can run forever with it unplugged - you just wont have any rev limiter.

As a further check open the trunk when running and listen to the fuel pump to see if constantly running or any change before motor cuts out. The strange sound of mine cutting on and off (sounded like gravel going thru pump) told me something was not right related to the fuel pump.

Paulporsche · 06-02-2009, 05:49 AM

Your dieseling might be due to incorrect timing, too hot engine temps, or a too rich mixture. I don't know if it's related to your other problem.