Car won't start when hot
Thread Starter
Burning Brakes
Joined: Mar 2004
Posts: 923
Likes: 4
From: Austin Tx
Car won't start when hot
Well, same problem as last year, and the year before. I made sure return line is working, it is, built a 5/8 wood carb spacer, carb is cool now, switched from Edelbrock back to QJet, it still does this to me. After a driving to store, friends house, turn car off, come back 15 min, won't start...turning over but no fire. I crank a couple times with pedal down and air cleaner off, wait a few min, and it always eventually starts, never has stranded me. I bought some starter fluid and it did it this morning, shot some starter fluid in there, started right up. If it is flooding, wouldn't the starter fluid not and have have another issue??? or not.
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
It is not flooding. Probly vapor locking, maybe the fuel pump letting the fuel in the pump to carb line siphon the fuel back out of the carb. I would look into that since you say the carb is cool.
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
hard to start when hot can be a starter prblem, usually it is because the starter is heat soaked, an electric motor that is excessively hot will be weak. In this case he said the motor was turning over so got to look at fuel delivery.
Le Mans Master
Joined: Nov 2004
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St. Jude Donor '07
Race Director
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From: Kansas City, MO ...I'd like to go fishing and catch a fishstick. That'd be convenient. - Mitch Hedberg
How well does the starter motor turn over? If it has to work hard, put a heat shield or heat blanket on the starter. If it turns over fine, I would say your problem lies with vapor lock.
I have a glass fuel filter that was too just above the head mounted horizontally. I moved the filter away from the head and that fixed my problem.
I have a glass fuel filter that was too just above the head mounted horizontally. I moved the filter away from the head and that fixed my problem.
Melting Slicks
Joined: Oct 2004
Posts: 2,662
Likes: 8
From: Knoxville Tennessee
I would look for a fuel line very close to a hot maniflod or exhaust pipe and is boiling when you stop. The air blowing across it while you are moving keeps it cool enough to not boil. When you stop the engine and exhaust actually get hotter causing anything close to them to heat up as well. When you find where it is getting hot put an insulating wrap on it and I believe your problem will be fixed. Hope this helps.
Bernie
Bernie
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Burning Brakes
Joined: Aug 2005
Posts: 1,126
Likes: 0
From: Hudson Falls, N.Y. 76 Vette Modified L-48
Originally Posted by Gage
Well, same problem as last year, and the year before. I made sure return line is working, it is, built a 5/8 wood carb spacer, carb is cool now, switched from Edelbrock back to QJet, it still does this to me. After a driving to store, friends house, turn car off, come back 15 min, won't start...turning over but no fire. I crank a couple times with pedal down and air cleaner off, wait a few min, and it always eventually starts, never has stranded me. I bought some starter fluid and it did it this morning, shot some starter fluid in there, started right up. If it is flooding, wouldn't the starter fluid not and have have another issue??? or not.
Thread Starter
Burning Brakes
Joined: Mar 2004
Posts: 923
Likes: 4
From: Austin Tx
Actually the carb is still getting pretty hot despite the wood space. The factory air cleaner holds a lot of heat underneath. I just got home after driving around and checked under the hood, the fuel line on the frame is hot to the touch, all the way up to the carb,and carb is too hot to touch. Its been sitting for 15 min, went back out to start, fuel in clear filter is gone, and when cranking it is not filling up with gas, aside from the occasional splash. It looks like it is sucking air, not liquid. When the car is cold, the filter fills quickly with gas...sounds like vapor lock to me, but what to do about it?
Pro
Joined: Nov 2004
Posts: 575
Likes: 0
From: Nice Lake Ontario
Originally Posted by SIXFOOTER
It is not flooding. Probly vapor locking, maybe the fuel pump letting the fuel in the pump to carb line siphon the fuel back out of the carb. I would look into that since you say the carb is cool.
Racer
Joined: Apr 2006
Posts: 477
Likes: 43
From: Millbrae California
if the gas cap is not vented to both let air in and out of the gas tank, the heat from the exhaust will create pressure in the gas tank that could cause the fuel to keep going into the carb as the fuel boils out of it and into the engine after you shut it off hot. we have had to add a vent to the gas caps on several corvettes to solve the problem you describe.
Intermediate
Joined: Nov 2005
Posts: 35
Likes: 0
I have the same problem. I have Jazz gas tank with vented line out of the tank. Under carb is wood 1" spacer. Carter hd (eleck) fuel pump. Still problem. Now i bought mr. gasket heat shield. Let's see what happenig...???? Any ideas?
Melting Slicks
Joined: Mar 2003
Posts: 2,512
Likes: 49
From: Franklin IN
Originally Posted by Gage
Well, same problem as last year, and the year before. I made sure return line is working, it is, built a 5/8 wood carb spacer, carb is cool now, switched from Edelbrock back to QJet, it still does this to me. After a driving to store, friends house, turn car off, come back 15 min, won't start...turning over but no fire. I crank a couple times with pedal down and air cleaner off, wait a few min, and it always eventually starts, never has stranded me. I bought some starter fluid and it did it this morning, shot some starter fluid in there, started right up. If it is flooding, wouldn't the starter fluid not and have have another issue??? or not.
Lars helped me out with this type of a problem with a pickup we have. When we'd go to start wed have to crank for a long time. He said to check the fuel pump as it has check valves to keep the fuel up to the carb. When those go bad the fuel will drain back to the tank. Then it takes a long time cranking to get the fuel back to the carb and fill it. My vote is to check the fuel pump.
Pro
Joined: Dec 2002
Posts: 560
Likes: 1
From: Mooresville NC
Originally Posted by 87bob
Lars helped me out with this type of a problem with a pickup we have. When we'd go to start wed have to crank for a long time. He said to check the fuel pump as it has check valves to keep the fuel up to the carb. When those go bad the fuel will drain back to the tank. Then it takes a long time cranking to get the fuel back to the carb and fill it. My vote is to check the fuel pump.
Burning Brakes
Joined: Aug 2005
Posts: 1,126
Likes: 0
From: Hudson Falls, N.Y. 76 Vette Modified L-48
Originally Posted by Gage
Well, same problem as last year, and the year before. I made sure return line is working, it is, built a 5/8 wood carb spacer, carb is cool now, switched from Edelbrock back to QJet, it still does this to me. After a driving to store, friends house, turn car off, come back 15 min, won't start...turning over but no fire. I crank a couple times with pedal down and air cleaner off, wait a few min, and it always eventually starts, never has stranded me. I bought some starter fluid and it did it this morning, shot some starter fluid in there, started right up. If it is flooding, wouldn't the starter fluid not and have have another issue??? or not.
Basically, did you modify it in any way that would help this problem to occur??
Thread Starter
Burning Brakes
Joined: Mar 2004
Posts: 923
Likes: 4
From: Austin Tx
No mods, this is stock 72 L-48, with the exception of alum intake, and a mild cam upgrade. Car runs 190 all day. I do live in Austin, Texas though, which doesn't help.
Heat riser valve is disabled
Heat riser valve is disabled
