need some help/ideas

car and background so you know some of the details:
66 vette
383 stroker
4 core be cool radiator with twin electric fans
650 holley with a spacer between intake and carb.
new mechanical fuel pump (thought this was the initial problem)
fuel lines have heat protection
msd distributor
strong aftermarket alt (don't remember name)
ceramic coated headers.
no air conditioning
2speed powerglide.
engine only has about 3k-didn't have this problem last year.

what it's done:
first started missing coming of the interstate off ramp: occured twice

drove fine on a warm morning and to lunch but on way home after about 10 miles, 9 interstate at ~70 and then to gas station off exit. cranked up after gas station and went about 100 yards, spudders and I can't keep it running. Towed home.
changed fuel pump after this.

yesterday:
drove to work fine. ~12 miles
drove down interstate 9miles fine. got off exit, after two stop lights cruising about 45 starts spuddering and stalling again, give enough gas to get to side of the road. car cools down, get a jump because the electric fans have been used to cool down and it cranks up again.
haul butt home about 2 miles and pull in driveway and let sit at idle, about 10 minutes later slowly dies out. let sit, and cranks up, idles for about ~10-15 minutes and it starts to die, try giving gas and it starts backfiring again.

take carb cleaner off and push on spring and there is fuel in the bowl injecting fine.
electric fans quickly cool down radiator but without running it's not flowing through motor. fluid level is fine.
battery level is fine, alt is fine.

SOmething has be heat soaking and creating the issue upon sitting in heat for a while, but what? no wiring looks burnt.

IDEAS?

 

Could be the coil breaking down. Heat affects their performance. When they cool off they may perform fine until they get hot again.

Also could be a fuel delivery problem (clogged filter, weak pump, trash in tank) but the fact you seem to have fuel at the carb and it has backfired a few times would lead me away from that. Might be a carb problem however - bad float or something.

Does it seem to be flooded or running rich when it dies out?

 

I literally just went through a lot of the same frustrating symptoms on my '67 Chevelle. Turned out to be a loose distributor clamp down bolt. The timing was drifting all around a few degrees and made the car run like cr@p...

Might not be your problem but it only takes 10 seconds to check it.

 

It doesn't seem to be flooding. when driving and it starts to die I've had to bump the accelerator to keep the engine going while trying to find a safe place to pull over.
I was thinking distributor and we all know this style vette has poor to no flow across the top of the engine unless you have a cowl hood, which I don't. what would a coil going out look like vs one that is just getting to hot?

 

Jeff - My 65 did the exact same thing years ago. It turned out the ballast resistor would heat up and shut everything down. I replaced it and all was well again.

John

 

Your problem could be related to your ignition system. I have used a can of compressed air on ignition components to cool them down fast. If the car starts up after you spray down the ignition, you have the problem narrowed down. Jerry

 

A bad coil can have various symptoms from a running miss to breaking down at high RPM to a complete shutdown. They are the dickens to troubleshoot as they may only intermittently fail under the heat and vibration conditions of extended driving. Best to replace it with a known good one and see if your problems clear up...

 

tampa jerry, awesome idea.

 

Sounds like what I experienced last year. Rust flakes in the gas tank contaminated everything fuel-delivery related. Ran ok for a good while until a flake broke free and did its thing- like a blood clot does nothing until it breaks free. Needed new tank, new lines, new fuel pump, blah blah blah- now all is ok.

 

could be the sintered bronze in line filters installed inside the fuel bowl connections, if you are running them.
they are very effective in trapping bs but clog up easily.
i clean mine yearly because i do not like an in line filter, although they will take a lot more crud before they clog.......jmo......

 

I just fixed my 66 after letting it sit for 6 months due to a frustrating stalling problem.....

After much diagnoses and part replacement....(fuel pump, new steel lines....ruber line between chassis feed and pump)
I finally took the sender out and the rubber line back there....and there it was- rotted internals in my 47 year old rubber hose (body has never been off frame)....replaced it....blew out sening unit...and steel line running from front to back...bought new sock from Gulf Coast Corvettes (very nice guy) replaced the rubber hose and Viola'!!!-Back in Business...I now love my Vette again and decided to join the forum!!!

This would let just enough fuel through to let it run...then under demand it would lose prime....let it sit...it would reprime and fire right back up.

Peace,
Jebby

 

You are right! When my '66 sat around unused for a while, the brake calipers needed replacing- thing was I was about to enter a show and I don't trailer the car to shows. Gulf Coast Corvettes were so obliging. Fast shipping, got exactly what I needed and was able to get the car to the show.

 

Same here....had a big cruise to go to...and I knew if I ordered inside Texas...I could get it in a day or two...this was Tuesday....it came the next day....
I forget the fellas name...(Maybe Dale?) but he knew Corvettes very well.....I ordered somee other stuff from him too (washer pump repair kit, E-brake light switch). He was less than the others to boot!

Not a very elaborate website....but good deals!

www.gulfcoastcorvette.com

Jebby

 

I'll go one step further. I ordered while in NY on my way to FL and the calipers were on my doorstep in FL when I got there. I dealt with Greg.

 

Check the RH bulkhead plug for corrosion on the red wire contacts. Check for solid ground on the distributor. If you have the original distributor, put it back in the engine to test the electronics.

 

ok, didn't have compressed air but I took my lil pancake compressor and let it idle till it shut down. took the top off and blew air across the coil and under about 6 or 7 times. compressor is a little slow to refill. didn't do it.
Inline fuel filter is still clean.
not leaning towards trash because it i can replicate it regularly with letting it get hott for a while.

how about starter getting hot-it is close to the headers-ceramic coated headers to side pipes.
how about neutral safety switch? is it close enough to a heat source or does it build heat with current etc.?

 

and magic, original distributor had points, would have to put the resistor back in and do some tuning, set the dwell, then set timing, etc. would be alot of work to go that route. i don't have a spare aftermarket sitting around. everything else we drive is newer except this car. i'm being to love fuel injection. it gives you lil codes and fancy annoying flashing lights.

 

The OP said he is using an MSD, so he should not use the ballast resistor.

 

update:
not spark related. made it shut down and when I pull a wire off the distributor, I can see spark.
not neutral safety switch. wiring diagram shows starter wouldn't even try to turn over if that was it.
found:
Carb bowl was low looking through side sight. pulled lines and found that the flow of fuel is very low at the fuel rail and somewhat decent right at the fuel filter, which is clean.
keep in mind this is a new mechanical fuel pump:
inline filter is clean.
my quesses:
1. the russell steel braided lines are collapsing between pump and fuel rail.(original engine setup had hard tube lines)
2.hard tube lines entering engine compartment to fuel pump are getting too hot.
3. fuel pump is too hot.

also,
does anybody know if the carb pulls a vacuum on the fuel line besides the fuel pump just pumping? this might answer collapsed lines or maybe we don't have enough pull helping the pump. In theory, the fuel is being pumped upward so with such low pressure, i didn't know if a vacuum exsist in this type of system?

 

Do you have a vented fuel cap? If so, is the vent clear? Jerry