# Hard start when warm - 67 Pontiac 400



## jday240 (Feb 10, 2007)

I have a 67 Tempest with a 400 that starts every time when cold but is hard to start after its warmed up. For example, it takes 3 pumps of the pedal and it starts easily when cool, but if I stop for fuel, parts, etc. it will not start until after a 10 to 15 minute cool off period.  I have a Holley electric fuel pump, Holley 750 double pumper w/ mechanical secondaries (no choke), and the standard 14 x 3 air cleaner. After the cool down period it will start if you hold the gas pedal all the way down when you first try it. That works most of the time, but it is less than ideal. The engine temps run between 180 - 200 depending on traffic and outside temps after a 160* thermostat, fresh coolant, and a bottle of Water Wetter. The starter is close to the headers but wrapped with a Summit heat shield and has a remote Ford (gasp) solenoid mounted on the fender. I will soon be wrapping the headers to better control the under hood heat. I've removed the air cleaner when the engine won't start and can see fuel evaporating sometimes. I suspect the 1" aluminum carb spacer may be transferring too much heat and will be ordering a 1" or 2" phenolic depending on clearance.

Note: A friend told me about a truck he had that did the same. He was told to clip old style wooden clothes pins on the fuel feed lines and that seemed to work for him. I "installed" these this morning before leaving for work but have not had the time to "test" this method.

Any thoughts or ideas would be appreciated.


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## BearGFR (Aug 25, 2008)

Sounds like a heat issue as you've already figured out. Check the routing of the fuel line and make sure it's not close to a heat source as best you can. Since you've got an electric pump, I assume you also have a vapor return line and regulator? 

I just noticed you're in Robertsdale. I've got a cousin who lives in Elberta 

Bear


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## geeteeohguy (Feb 2, 2008)

I'm confused. It won't start because it won't crank, or it cranks fine but won't start up?? No crank would be a starter/electrical issue and cranks fine but no run would probably be fuel related. Need more information, please.


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## khinton (Jun 22, 2008)

:agree


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## jday240 (Feb 10, 2007)

Sorry, it turns over every time but will not always start. It acts like its flooded to some extent. I have a phenolic spacer on order and header wrap to install to address the heat transfer that I believe is part of the issue. Bear, I do not have a regulator in line and no vapor return either. I actually live in Foley now...even closer to Elberta.

On a side note, the clothes pin mod to the carb feed line did help. I left work and drove to a monthly Cruise In and after parking needed to move the car a few feet to squeeze in another car. After sitting only a minute or two it started up on the second try. This further leads me to believe it's related to the temperature.

BTW, it ran up to 210* in traffic on the way to the event.


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## chuckha62 (Apr 5, 2010)

If you were running a Quadrajet, I'd say that you're suffering from a well documented issue with early Quadrajets. The float bowl drains out through the leaky plugs. You're running a Holley though and my guess would be the temp from the manifold (and exhaust crossover) could be overheating and boiling the float bowl dry. If this is the case, the phenolic spacer should help. The other thing you can do is plug the crossover. I did this on mine by putting 11/32" (I think) "freeze" plugs in the holes directly under the carb. In addition, on the '67, you should have a stainless steel shield under the carb sandwiched between two carb gaskets.

Good luck and let us know what you find.

Chuck


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## jday240 (Feb 10, 2007)

Thanks Chuck, 

When I put in the spacer I will see if the crossover has been blocked and check for the shield under the carb itself. I will see if I can find pictures online of these areas so I have a better idea of what to look for.


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## FlambeauHO (Nov 24, 2011)

I have the same issue on my 68 with a Holley single feed. Be interested to hear a resolution.


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## geeteeohguy (Feb 2, 2008)

If that stainless steel spacer plate is missing, that's most likely the problem. They are often missing on '67's, and it's the only year that uses them due to carb and intake design. Exhaust directed to the underside of the carb=evaporated fuel!!


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## 05GTO (Oct 6, 2004)

Sounds like vapor lock to me, how are the fuel lines routed from the tank to the carb?

If the fuel lines are too close to the exhaust system the fuel changes state from liquid to gas while still in the fuel delivery system. While the car is running the fuel flows and prevents vapor lock, when the car is parked after running, the remaining heat from the engine will vaporize the fuel and prevent the car from being started until the engine compartment cools.


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