Engine dies after long freeway run. - Chevelle Tech
Engine General Engine Discussion.

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post #1 of 15 (permalink) Old Apr 8th, 19, 3:30 PM Thread Starter
Glenn
 
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Engine dies after long freeway run.

Engine 350, carburetor ( Holley 650 Spread bore vacuum secondary), HEI, Automatic, dual exhaust.
When I run at freeway speeds for long time (more than an hour) (RPM about 2000)( engine temp 190) ( electrical at 13 volts )when I get off the freeway and come to a stop the engine continues to idle. When I accelerate off of stop the motor does not respond, then starts to die then finally dies. Motor will start right back up and then continue to have a problem for a couple of more minutes. Smooths out then runs fine around the streets from then on. This only happens after running at freeway speed and coming off the freeway. Short trips on freeway( 20 minutes or so) no problem. Good acceleration. Last time this happened was a two hour run and when I coaxed it from a stop the motor back fired and blew out my muffler. Never had this problem until I changed Distributor, may be a coincidence. Any Ideas.
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post #2 of 15 (permalink) Old Apr 8th, 19, 3:55 PM
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Ed
 
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Re: Engine dies after long freeway run.

Only guess I can come up with is floats sticking or set too low. Or does the temps climb after coming to a stop?

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post #3 of 15 (permalink) Old Apr 8th, 19, 4:24 PM
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Rick
 
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Re: Engine dies after long freeway run.

Trapped vacuum in a non vented fuel tank or tank with a clogged vent? The vacuum would prevent the tank from letting fuel out.

This would be an insidious problem depending on how much fuel was in the tank. It would occur sooner in a full tank, later on a lower fuel level.

Rick

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post #4 of 15 (permalink) Old Apr 8th, 19, 9:23 PM
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Re: Engine dies after long freeway run.

May be distributor. I've also seen mechanical fuel pumps stop pumping when they get above a certain temperature. I've seen it twice, in fact.
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post #5 of 15 (permalink) Old Apr 8th, 19, 9:57 PM
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gary
 
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Re: Engine dies after long freeway run.

Possible vapor lock. What year car? Is a fuel line near an exhaust pipe?
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post #6 of 15 (permalink) Old Apr 8th, 19, 10:33 PM
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Re: Engine dies after long freeway run.

A hot engine at 190F coming to an extended idle with little air flow could boil fuel in the carburetor and cause an overly rich condition until it cools down. I would reduce the level of the floats and check the fuel pressure is not too high for the carb model.
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post #7 of 15 (permalink) Old Apr 9th, 19, 6:30 AM
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Geoff
 
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Re: Engine dies after long freeway run.

If boiling fuel or vapour lock, would not expect engine to start up straight away.

Check tank venting.
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post #8 of 15 (permalink) Old Apr 9th, 19, 8:58 AM
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Re: Engine dies after long freeway run.

Next time it does this, feel how hot the carburetor is.

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post #9 of 15 (permalink) Old Apr 9th, 19, 9:10 AM
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Jeff
 
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Re: Engine dies after long freeway run.

Its spring and you are experiencing ethanol stumble. Hot weather with winter fuel in the tank can be a pain. Does your fuel system have a return line? I think the best set up is the 1970 454 filter that's close to the carb and has the 1/4" return port in it.. The early Pontiac big car 389 with AC also has this filter arrangement..

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post #10 of 15 (permalink) Old Apr 9th, 19, 6:06 PM Thread Starter
Glenn
 
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Re: Engine dies after long freeway run.

1970 El Camino mechanical fuel pump
Temperature stays at 190 all the time.
I will check the vapor lock, Charcoal canister has been removed.
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post #11 of 15 (permalink) Old Apr 9th, 19, 7:25 PM
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Re: Engine dies after long freeway run.

Next time it does it, see if there is suction when you remove the gas cap.
Maybe the tank is not getting enough make up air.
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post #12 of 15 (permalink) Old Apr 9th, 19, 10:42 PM
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Re: Engine dies after long freeway run.

Quote:
Originally Posted by chevyjeep View Post
1970 Charcoal canister has been removed.
So how is you tank vented? If all the lines were plugged, you probably don't have a tank vent.
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post #13 of 15 (permalink) Old Oct 18th, 19, 5:11 PM Thread Starter
Glenn
 
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Re: Engine dies after long freeway run.

Well it has been 4 month and the El Camino just got worse. Drive it 5 miles the then stalls when coming off from a stop. It will start right back up then shut back down when back in drive coming off a stop. Shut it down and wait a half hour and it works for anther 5 miles. Runs rich.
Changed coil and cap on HEI, no change.
Carburetor has been on for 30 years. HOLLEY 4160 650 cfm vacuum secondary with a divorced choke.
Did a lot of reading and choice to change the power valve. Put carburetor back together and it would barely run, supper rich.
Opened up the primary side and the accelerator pump transfer tube o'ring had dries out and would not seal.
Put in new o rings and El Camino is running like a charm again.

Thank you all for your advice but sometime it just cannot be trouble shot over the internet, just have to put in the work.
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post #14 of 15 (permalink) Old Oct 24th, 19, 1:58 PM
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Re: Engine dies after long freeway run.

I was going to say accelerator pump and just saw your response
My father had this issue with his edelbrock.
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post #15 of 15 (permalink) Old Oct 24th, 19, 6:00 PM
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Re: Engine dies after long freeway run.

Ugh this gas....how is your fuel pressure?
Runs like a top also if its under 190, 185. Otherwise the idle gets lazy just isnt "right". Almost worth it to save and keep a drum of good gas around.

Seen guys wtih TBI type systems have issues also that fuel in the body gets too hot. Maybe cool cans will make a comback

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