Trouble with warm restart
Thread Starter
Racer
Joined: Aug 2016
Posts: 271
Likes: 16
From: Raleigh NC
Trouble with warm restart
I’ll do my best to explain this, but wondering if anyone has the same issue. When I start my 69 L46 up cold, I slowly pump the gas peddle three times first and it usually takes 5 seconds to turn over and fire up with no problem. After a drive, if I stop (get gas, run an errand, etc) when I go to fire her up again it’s hit or miss. Usually I’ll slightly depress the gas peddle and turn it over and it starts, but sometimes it weekly starts and then fizzles out. When this happens, if I attempt to restart it just turns and turns but won’t fire. I don’t like knowing whether it will start again or not when warm, and am sure this isn’t correct. Can any experts out there give me some trouble shooting tips or advice?
Drifting
Joined: Jul 2015
Posts: 1,765
Likes: 254
From: Catlett VA
Since you are having trouble starting after the engine is hot and sits for a while, I would also check for whether there is fuel in the carburetor fuel bowl or whether the engine heat has boiled and evaporated some or most of the gas out while it was sitting there...... so you now have a dry carburetor. Take the air cleaner off, look down into the carb and move the throttle lever and note if gas comes out of the little jets for the accelerator pump. My 68 would boil out almost all of the fuel if the car sat for 15-20 minutes after the engine was hot. I had to crank it for 30-40 seconds before the fuel pump got enough gas back into the carb so it would start. I finally installed an electric fuel pump and now I just turn the key to "on" and let the fuel pump run for about ten seconds before I activate the starter. Now it starts immediately. Not sure if your car has the same problem, but it is something to check. Hope you get it fixed.
Drifting
Joined: Nov 2013
Posts: 1,806
Likes: 258
From: Dublin Ohio
That was me a few years ago. I would shut it off wait 5 minutes and listen to the fuel bubbles. Very hard to start.
I had Lars go through the carburetor (it was set a tad incorrectly with wrong jets) and (and I think this was a big issue) I got the heater hose away from the fuel line coming up from the pump to the carb. The heater hose was resting on the fuel line.
Now it damn near acts like a normal car.
I had Lars go through the carburetor (it was set a tad incorrectly with wrong jets) and (and I think this was a big issue) I got the heater hose away from the fuel line coming up from the pump to the carb. The heater hose was resting on the fuel line.
Now it damn near acts like a normal car.
Is my vette stock?? HAHA
Joined: Oct 2015
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From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
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what kind of carb are you running? Do you pump the gas when its warm? you shouldnt have to, it should fire without a pump, if it doesnt try one pump as you may be creating the problem by flooding it. if not carry a can of starter fluid and give it a quick shot down the throat to see if its a boiling/evaporating problem, a flooding problem or a coil issue. Before you give it a squirt look for gas soaking/sitting in the bottom of the intake by looking down the throat with the butterflies open. When you open them check for the pump squirt as mentioned above.
my issues with evaporating were similar and a pheonolic spacer solved most of the heat soak issues.
my issues with evaporating were similar and a pheonolic spacer solved most of the heat soak issues.
Le Mans Master
Joined: Jun 2019
Posts: 5,485
Likes: 2,193
From: Loveland
I have the same problem with my spread bore holley 4175. When it's hot I have to do a flooded start,,, peddle to the floor untill it starts. I have a carb shield and thick spacer. I have replaced the needle, seat, float, valve, fuel regulator, ETC no help! It still does it. I am thinking a fuel return line, to get cold fuel into the carb during start would help. Has anybody tried this?
Thread Starter
Racer
Joined: Aug 2016
Posts: 271
Likes: 16
From: Raleigh NC
what kind of carb are you running? Do you pump the gas when its warm? you shouldnt have to, it should fire without a pump, if it doesnt try one pump as you may be creating the problem by flooding it. if not carry a can of starter fluid and give it a quick shot down the throat to see if its a boiling/evaporating problem, a flooding problem or a coil issue. Before you give it a squirt look for gas soaking/sitting in the bottom of the intake by looking down the throat with the butterflies open. When you open them check for the pump squirt as mentioned above.
my issues with evaporating were similar and a pheonolic spacer solved most of the heat soak issues.
my issues with evaporating were similar and a pheonolic spacer solved most of the heat soak issues.
Drifting
Joined: Jul 2015
Posts: 1,765
Likes: 254
From: Catlett VA
I have the same problem with my spread bore holley 4175. When it's hot I have to do a flooded start,,, peddle to the floor untill it starts. I have a carb shield and thick spacer. I have replaced the needle, seat, float, valve, fuel regulator, ETC no help! It still does it. I am thinking a fuel return line, to get cold fuel into the carb during start would help. Has anybody tried this?
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Racer
Joined: Mar 2011
Posts: 490
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From: The South
When you have a warm start situation again, remove the air cleaner and watch the top of the carb as you attempt to start the car. If you see fuel spitting out of the bowl vent as you crank on the starter, then you have a dirty carb. Mine sucked up rust particles from the old fuel tank and gave me the same problem.
Le Mans Master
Joined: Jun 2019
Posts: 5,485
Likes: 2,193
From: Loveland
When you have a warm start situation again, remove the air cleaner and watch the top of the carb as you attempt to start the car. If you see fuel spitting out of the bowl vent as you crank on the starter, then you have a dirty carb. Mine sucked up rust particles from the old fuel tank and gave me the same problem.
Last edited by kodpkd; Sep 6, 2019 at 09:59 AM.
Drifting
Joined: Jul 2015
Posts: 1,765
Likes: 254
From: Catlett VA
kodpkd- If you have fuel shooting out of the carb when you have the no-start problem, obviously the carb is not dry, so your problem must be different from what I was experiencing. I removed the old mechanical fuel pump and used a block-off plate to cover the opening in the block. If you install an electric fuel pump, you should also do the return line as you suggested. This will allow the excess fuel pressure to bleed back into the tank. I would also install a pressure gauge and a pressure regulator. The stock needle and seat in your carb can not hold back much more than about 6 psi, so the regulator and gauge will allow you to control the pressure, otherwise the fuel will get past the needle and seat and flood out the carb.
Drifting
Joined: Jul 2015
Posts: 1,765
Likes: 254
From: Catlett VA
One additional thought. My QFT carb has four glass sight windows that allow you to see the fuel level in the fuel bowls and allow you to adjust the float height by just looking at the fuel level and matching it to a line marked on the carb while the engine is running. Not sure if your carb has glass viewing windows or not. Older carbs required measuring the height of the float while the carb was dis-assembled. Most rebuild kits have a cardboard template to use to get the float set at the correct height. If your float level is too high, it will allow gas to spill out into the intake manifold and flood the engine, especially when you shut it off and it sits there. Did you already check the float level?
Last edited by ronarndt; Sep 6, 2019 at 12:22 PM.
Le Mans Master
Joined: Jun 2019
Posts: 5,485
Likes: 2,193
From: Loveland
One additional thought. My QFT carb has four glass sight windows that allow you to see the fuel level in the fuel bowls and allow you to adjust the float height by just looking at the fuel level and matching it to a line marked on the carb while the engine is running. Not sure if your carb has glass viewing windows or not. Older carbs required measuring the height of the float while the carb was dis-assembled. Most rebuild kits have a cardboard template to use to get the float set at the correct height. If your float level is too high, it will allow gas to spill out into the intake manifold and flood the engine, especially when you shut it off and it sits there. Did you already check the float level?
Last edited by kodpkd; Sep 6, 2019 at 01:07 PM.
Drifting
Joined: Jul 2015
Posts: 1,765
Likes: 254
From: Catlett VA
Mine was running 6 psi. That's also what I set my electric pump to. Originally I installed a high pressure/high volume electric pump that ran 14 psi even with my pressure regulator. It completely overpowered the needle and seat and poured raw gas into the intake manifold. I took that pump off and installed a normal performance one that I could adjust down to 6 psi.
Le Mans Master
Joined: Jun 2019
Posts: 5,485
Likes: 2,193
From: Loveland
I should check the mech pump pressure. I can tell it's a new pump. No telling what someone added to the car. I did do a high flow, 180* thermostat, and fuel line insulation. I can tell the engine is running cooler. My last test run, it didn't hot start flood. It's going to be hot again today for another test. It will make my head explode if it is something as simple as a thermostat!
Team Owner
Joined: Oct 2004
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From: altered state
St. Jude Donor '05
More than enough. Phenolic spacer helped a little but going to put a holley heat shield on.
Todays gas sucks.. I see guys with TB type EFI that have the same issue too, just not quite as bad as they have an electronic fuel pump.
Seen talk about the possible removal of ethanol gas which would be great but who knows if it will happen.
Todays gas sucks.. I see guys with TB type EFI that have the same issue too, just not quite as bad as they have an electronic fuel pump.
Seen talk about the possible removal of ethanol gas which would be great but who knows if it will happen.
Last edited by cv67; Jan 24, 2020 at 12:15 AM.
Is my vette stock?? HAHA
Joined: Oct 2015
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From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
just make sure you have the hood clearance before shutting your hood. I run a 1 inch on my quadrajet and its great. But I have an aftermarket L88 hood
Burning Brakes
Joined: Dec 2008
Posts: 971
Likes: 45
From: Middlesex NJ
If its a holley you power valve diaphragm maybe cracked and leaking. You wont see it leak down because the vacuum port for the power valve is in the bottom of the throttle plate.. you wont see it leak from the boosters if it is in fact the power valve. The car will also run very fat with the power valve leaking.
This will effectively dump the fuel in the bowl down into the engine when sitting for a few mins like in the time it takes you to get gas and make it a real pain to start... just like its flooded... cause it is.
The ethanol in the fuel today rots the rubber components in our fuel system... fuel pump diaphragms and power valve diaphragms in holleys. I always put 3oz of marvel mystery oil per 10 galls of gas (this was recommended by edlebrock techs for their fuel pump diaphragms).
Most carbs dont like more than 6 psi before the needle is pushed off the seat. Mech pump cars dont like hot fuel lines... causes vapor lock at the suction side of the pump. Depending on your year and setup of your 69 i believe you could have a vented cap or a non vented cap depending on your tank, fuel line, and or fuel return line setup if you have them or if they have been messed with.
This will effectively dump the fuel in the bowl down into the engine when sitting for a few mins like in the time it takes you to get gas and make it a real pain to start... just like its flooded... cause it is.
The ethanol in the fuel today rots the rubber components in our fuel system... fuel pump diaphragms and power valve diaphragms in holleys. I always put 3oz of marvel mystery oil per 10 galls of gas (this was recommended by edlebrock techs for their fuel pump diaphragms).
Most carbs dont like more than 6 psi before the needle is pushed off the seat. Mech pump cars dont like hot fuel lines... causes vapor lock at the suction side of the pump. Depending on your year and setup of your 69 i believe you could have a vented cap or a non vented cap depending on your tank, fuel line, and or fuel return line setup if you have them or if they have been messed with.
Le Mans Master
Joined: Jun 2019
Posts: 5,485
Likes: 2,193
From: Loveland
I have the same issue with my 68 with a holley 4175. Does your fuel line to the carb have a return line from the filter to the tank? I am installing one today. I have checked ALL the carb fixes everyone is talking about and still get flooded,,"vapor lock" hot start. Float, needle and seat, heat shields and spacers, fuel line insulation, new diapham, ETC ETC! Mine even does it when it's 50* out and the front bowl is luke warm. I believe it is because there is expansion and excess pressure in the fuel line. Does your car have a return line?
I have a return style filter I am going to install, GF-432. I'm not sure the new ones are made correctly. The one I got doesn't have any restriction in the 1/4 inch return port. I'm going to put a restrictor in the line from the filter to the tank.
I have a return style filter I am going to install, GF-432. I'm not sure the new ones are made correctly. The one I got doesn't have any restriction in the 1/4 inch return port. I'm going to put a restrictor in the line from the filter to the tank.
Last edited by kodpkd; Jan 24, 2020 at 10:23 AM.