# Warmed engine have to floor to start?



## KowalskiCW (Jul 11, 2016)

Hey everyone, new to the Pontiac world after just getting my first 69 Lemans with some mild engine work(cam, edelbrock intake and carb) and GTO appearance upgrades. 
It's got a tired 350 but still runs fine, but when the engine is warmed up it won't start once shutting it off without flooring it. It starts perfect after two pumps when cold and idles great. It's got a Edelbrock Performer 4 barrel w/electric choke on it. I thought the gas line might be getting hot as it was pretty much sitting on the intake so I raised it off the block and manifold with a support, but still has the same issue. What should I check next? Can I adjust the float levels on a Edelbrock Performer carb? Would a carb spacer help?
Thanks in advance. There are several small annoyances so far but otherwise a great car!


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## PontiacJim (Dec 29, 2012)

My experience with such is that the carb is leaking/flooding the engine. By putting the pedal to the floor, you open up the carb to let more air in and purge the excess gas. Problem is that should you have a back fire through the carb with excess gas - might burn the car down. 

When it won't fire up for you wen hot, using extreme caution, I would pull the air cleaner off and see if I smell a strong odor of gas. If you do, it is flooding. I would NOT try to start it without the air cleaner in place as the air cleaner also acts as a fire arrestor should you have a back fire. Now if its visibly leaking gas, look where the carb bolts to the manifold and the throttle shaft at the base of the carb as excess gas will typically follow the shaft or even leak out from a bad carb gasket and drip on the manifold. You may only see staining as gas can evaporate pretty quick on a hot manifold.

Here is a silly question, and just a random thought. How is the condition of the air cleaner? If it is plugged up due to age, it can sorta act as a choke does and your car starts OK when cold, but when hot, it chokes off the needed air until you put the pedal to the floor to get the additional air flow going. Once its going, there is enough suction to keep it running, but you may see black exhaust coming from the tail pipes, especially when you first fire it up when hot.

Now there are other things as well, fuel filter, fuel pump going bad, electrical problem, timing is off, etc.. From what you describe, I'd look first to a leaking/flooding carb issue.


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## KowalskiCW (Jul 11, 2016)

Well thanks. I'll check the gas smell next. The air cleaner is brand new. I was thinking about replacing the fuel filter as I have no idea how old it is and fuel pump too but I'm not very confident working on carbs so I thought I'd ask about that. I've heard poor things about Edelbrock carbs so I'm thinking about saving up for a Rochester quadrajet by SMI Carbs, that's been recommended by my buddy with a 427 chevelle that he swears by, but would like to figure this issue out first before I go that route.
Thanks


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## chuckha62 (Apr 5, 2010)

Guys,

One contributing factor here is the ethanol content of today's gas. It vaporizes fairly quickly and causes a hard restart when warm. Mine starts great within five minutes. After ten minutes and for nearly an hour, it's hard to start just like you describe. After an hour cool down or so, it starts right up again. Lot's of us old school muscle car guys are experiencing similar symptoms. My buddy's '70 Challenger T/A does the exact same thing.

Chuck


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## Goat Roper (Oct 28, 2014)

^^this^^

I blocked the crossover then added a thin phenolic spacer on my '67, you could watch the gas boil over on my QJet when the engine was hot.
Same flooded condition and not a good thing to have it vaporizing and running into your oil.


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## KowalskiCW (Jul 11, 2016)

Interesting. I could only find 91oct gas near me. I was thinking about trying a 1/2" spacer to see if that helps too. Also Goat Roper what crossover are you referring to? I'll try everything. Last night unfortunately it was pouring here so I didn't want to take the car out and get it warm to check for strong gas smell which I just will assume is there.


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## chuckha62 (Apr 5, 2010)

'67 Specific manifold (and maybe others) has a passage under the carb mount which allows diverted exhaust heat to warm the carburetor. There are two 11/32" holes which you plug (and I have) to keep the gases away from the bottom of the carb.


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## KowalskiCW (Jul 11, 2016)

Ok I'll check for those too.


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## KowalskiCW (Jul 11, 2016)

Well I installed a 1/2" carb spacer and saw the crossover hose referred to but I didn't eliminate that yet. But it doesn't matter because I was about to drive it to work today and it kept dying before even getting out of the driveway. It started back up 2 times but on the 3rd time it just made a loud crunching/grinding noise while the engine turned over but refused to start.  I checked the intake plenum before closing it up so I don't think anything dropped in there. I have no clue what happened but she sounded very unhappy. An hour later it was on a flatbed being towed to the shop. I'm sitting here waiting anxiously at what they find out. Had it all of a month before it was deemed un-driveable. Gotta love cars.


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## chuckha62 (Apr 5, 2010)

Whoa... That sucks! Keep us posted as to what you find. Hopefully it's nothing too bad.


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## KowalskiCW (Jul 11, 2016)

So the shop called this morning and said that the car started fine and ran "decent" with no engine noise like I described! The gremlin was in my head? They said they tuned my carb a little and checked the timing and all was fine. They feel the cam in it is too big but doesn't appear to be shot and no spun bearing either. Me and the guy walking his dog past my car yesterday morning sure thought otherwise! I've never heard that kind of crunching/grinding noise before. Could I have been sheering off starter gears? I'll check that when I get the chance but otherwise the car is "fine" Guess I'll pick it up after work and see for myself. Weird


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## chuckha62 (Apr 5, 2010)

One other thing... If your manifold is like the '67, there is a right and wrong way to install the gasket under the spacer. One way opens up a vacuum passage to the atmosphere, the other way doesn't. I've seen very experienced mechanics get it wrong.


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## Lemans guy (Oct 14, 2014)

K. first thing that comes to mind when you describe symtoms,....with Pedal to the floor on hot start is that your choke and fast idle are not set right.

When you push the pedal to the floor, down and up you set the choke, when you leave the pedal down and crank you hold the throttle open to clear a flooded condition.

So your choke may be set way to rich, and when you go to start hot it is partially closed, which causes the fast idle cam and throttle plate to be positioned wrong for temperature as well.

you also might want a new electric choke spring mechanism, something in there may be funky. So go to basics on the choke and fast idle screw set it all, or make sure it is all set to proper specs. a choke set to rich will cause a hard start when hot (floods) clearing with pedal down is the way around a flooded condition.

all the other guys advice still holds, bad float, etc.

Pontiac cooled the gas in AC cars by adding a 1/4 inch fuel return line to the tank. The condenser dropped a lot of heat in the engine compartment. It can return from a fuel filter that has two nipples on the carb side, and a line run back to the tank. some fuel pumps have a return line, but it is better closer to the carb for cooling.

also you might want to make sure your distributor isn't sticking inside...it it sticks the centrifigal weights advanced, it will be hard to start and will kick back or grind the starter which may be what you are hearing.

When shop says they checked the timing was that only base timing? with a timing light or did they open and inspect dist...considering centrifigal and vacumn timing as well.

sounds more like the choke fast idle set-up ......


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## KowalskiCW (Jul 11, 2016)

Well I got super busy at work so I'm just getting back to this. The shop called me the next day after searching and tinkering and found NOTHING wrong. They tuned the carb a little and put a missing cap on a vacuum port otherwise they couldn't find any evidence of what I explained. I've had it back over a week now and have had no issues since. So dumbfounded but so thankful. After the tune the warm starts got better but still aren't fixed. So I guess I keep digging into the issue myself. Got my new Cooper Cobras though and so far so good!


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