Trouble starting when hot
Thread Starter
Instructor
Joined: Jul 2007
Posts: 150
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From: Lewisville Texas
Trouble starting when hot
I have a recently built modified L-82. It starts right up when it’s cold but after I drive it and then try and restart it it acts like it’s not getting any fuel. It turns over and over about 3-4 times longer than it does when it’s cold and then finally starts. I talked to a local guy that build a lot of race engines and he said that it sounds like “The hard starting may be fuel boil out, engine is hot when you kill it, and it evaporates the gas in the bowls.” He said that if I switched out to an electric pump it should eliminate this. Does this sound right?
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Sounds more to me like the starter solonoid is getting hot and wearing faster.
The fix is a new solonoid or even a GM mini starter like the ones found on the later model V8s up to the LS engines.
The fix is a new solonoid or even a GM mini starter like the ones found on the later model V8s up to the LS engines.
Thread Starter
Instructor
Joined: Jul 2007
Posts: 150
Likes: 0
From: Lewisville Texas
It has a Proform 3 hp ministarter on it. It was new when the engine was rebuilt.
Race Director
Joined: Nov 2002
Posts: 12,142
Likes: 54
From: Taylor Michigan
Could be correct, You need fuel to have ignition. Appears you have a very good starter to be able repeatedly crank it for up to four times longer than when cold. Vapor lock is another name for the fuel starvation issue present more often when hot. Common among AC equipped cars with out the third return line.
Instructor
Joined: Mar 2007
Posts: 183
Likes: 0
From: Corpus TX
I have the same problem starts fine when cold and if i shut if off and try right away it fires up , but when its been running awhile and i let it sit for more than say five min. it cranks a few times before starting .
I too thought it was because of the heat in the bay ,maybe a spacer on the carb base would help a little ?
I too thought it was because of the heat in the bay ,maybe a spacer on the carb base would help a little ?
Melting Slicks
Joined: Aug 2004
Posts: 2,220
Likes: 6
From: www.Z16.org North/West Pennsylvania
I have a recently built modified L-82. It starts right up when it’s cold but after I drive it and then try and restart it it acts like it’s not getting any fuel. It turns over and over about 3-4 times longer than it does when it’s cold and then finally starts. I talked to a local guy that build a lot of race engines and he said that it sounds like “The hard starting may be fuel boil out, engine is hot when you kill it, and it evaporates the gas in the bowls.” He said that if I switched out to an electric pump it should eliminate this. Does this sound right?
Yes that sounds right. Your starter is cranking ok...right?
I just added an electric pump, back by the tank,that I use for just such reasons and to fill the bowls after storage. I used a Holly pump that the mechanical pump can draw fuel through. That way I only turn it on when needed. Been working just fine for more than twenty years.
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Okay I mis-read. I thought you were saying it was having trouble cranking, and a revolution was taking 3 or 4 times longer than when cold. You mean it cranks normally, just longer.
Yep, I was wrong, probably not the starter.
Yep, I was wrong, probably not the starter.
Instructor
Joined: Jul 2006
Posts: 208
Likes: 0
From: Hamden CT
St. Jude Donor '12
I have a recently built modified L-82. It starts right up when it’s cold but after I drive it and then try and restart it it acts like it’s not getting any fuel. It turns over and over about 3-4 times longer than it does when it’s cold and then finally starts. I talked to a local guy that build a lot of race engines and he said that it sounds like “The hard starting may be fuel boil out, engine is hot when you kill it, and it evaporates the gas in the bowls.” He said that if I switched out to an electric pump it should eliminate this. Does this sound right?
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Le Mans Master
Joined: Mar 2004
Posts: 7,499
Likes: 1,507
From: Little Rock AR
The carb is probably empty. Probably a heat/fuel issue. You can try to diagnose this by warming up the car, shut it down, wait long enough to recreate the problem and pour some gas into the bowls right before you try to restart it. If it starts easy, you probably had empty fuel bowls.
Check to see if the heat riser valve is stuck closed. If you have an aluminum intake you might want to get rid of the heat riser and block the drivers side heat pasage in the intake. I use a thin strip of stainless steel sheet metal between the 2 center intake bolts on the intake gasket to block the passage off. I would look for some very thin stainless steel sheet metal or just cut up a piece from one of your stainless steel kitchen bowls that has a large flat bottom. I have some dimensions if you need them just PM me.
If it is a Q-jet you might benefit from a different fuel filter element. There are filters both with and without the anti backflow valve on them. In some situations you might be better off with the anti backflow filter element. That would be a long shot here.
-Mark.
Check to see if the heat riser valve is stuck closed. If you have an aluminum intake you might want to get rid of the heat riser and block the drivers side heat pasage in the intake. I use a thin strip of stainless steel sheet metal between the 2 center intake bolts on the intake gasket to block the passage off. I would look for some very thin stainless steel sheet metal or just cut up a piece from one of your stainless steel kitchen bowls that has a large flat bottom. I have some dimensions if you need them just PM me.
If it is a Q-jet you might benefit from a different fuel filter element. There are filters both with and without the anti backflow valve on them. In some situations you might be better off with the anti backflow filter element. That would be a long shot here.
-Mark.
Last edited by stingr69; Apr 8, 2008 at 09:15 AM.
Thread Starter
Instructor
Joined: Jul 2007
Posts: 150
Likes: 0
From: Lewisville Texas
Yes that sounds right. Your starter is cranking ok...right?
I just added an electric pump, back by the tank,that I use for just such reasons and to fill the bowls after storage. I used a Holly pump that the mechanical pump can draw fuel through. That way I only turn it on when needed. Been working just fine for more than twenty years.
I just added an electric pump, back by the tank,that I use for just such reasons and to fill the bowls after storage. I used a Holly pump that the mechanical pump can draw fuel through. That way I only turn it on when needed. Been working just fine for more than twenty years.
Quick Fuel 850 (4150 style)
Melting Slicks
Joined: Aug 2004
Posts: 2,220
Likes: 6
From: www.Z16.org North/West Pennsylvania
That is correct. I have left it on without knowing. Never had a problem, both on, electric off....runs the same. Sure saves allot of cranking in the spring. I turn it on and listen to the motor...you can tell when the bowls are full. Then a couple cranks and its running.
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
That is correct. I have left it on without knowing. Never had a problem, both on, electric off....runs the same. Sure saves allot of cranking in the spring. I turn it on and listen to the motor...you can tell when the bowls are full. Then a couple cranks and its running.
That's how my electric pump is. It's a bellows style pump, that actually stops pumping when the pressure in the fuel line tells the pump that the bowls are full. I can turn it on, prime the carb, and then his start and it takes a lot less cranking to get it started.