My 69 won't start when it's hot

TwoStangWmn · Jun 17, 2004

For many years now my 69 351W coupe doesn't want to start when the engine is got and the temp is warm outside. I end up flooding it and then having to floor it to get it started. Then it runs fine, but I am afraid to drive it anymore when it is warm outside any long distance. It has 70,000 orig miles on it and has done this for several years. Is that called vapor locking? Our friend with a 68 Shelby 500KR says his vapor locks a lot.

Any suggestions? Thanks....
Vicki

69Rcode_Mach1 · Jun 17, 2004

I hear you bro, My 1969 Mach1 with a 351 W is harder to start in heat than in the cold. In the cold it needs a tap on the key and it starts. Mine has never gotten as bad as yours though. I just have to floor it when starting it in hot temperatures. If you find a solution to this problem let me know. Maybe my carb is running too rich. Check your jets.

Snail50 · Jun 17, 2004

Sounds like vapor lock, but if the fuel line is vapor locked, would fuel still be able to reach the carb to flood it? (I don't know much about carbs, so if I'm way off on how the whole vapor lock/fuel flow thingie works, disregard any and all advice I might give.)

BTW, the old guy I bought my 67 from had the car vapor lock on him many years ago, and he stuck a wooden clothespin on the metal fuel line right before the carb, which supposedly absorbs heat out of the line. looks funny, but he says it never vapor locked again. I left it on there, I haven't had any problems yet.

6Stang7 · Jun 17, 2004

I had the same problem with my 67, and still get it on really hot days. I would have to hold the petal down about 1/2 way to get it to start up. It sounds like you are getting too much fuel to the motor, either from the carb getting too hot and it being on the verge of gas boiling out, or that you are running it a little too rich. Do you use the choke when you start your car cold? Another possiablity is that you have a small vacuum leak somewhere. Where and how small I have no idea but it wouldn't hurt to get out some carb cleaner and start spraying!

-Shaun

MustangMatt1966 · Jun 17, 2004

hey, maybe u guys have starter shock, it hapens to me if you are running long tube headers....the heat zaps the starter and the starter turns slow and the car is just almost impossible to start when it it hot....i think that is the problem i have....but i dont have any solutions, i have heard people talk about it on here before, but i dont remember them saying any solutions other than to go with a mini starter............but i can be wrong on all this........

68GEETEE · Jun 17, 2004

Several things: Your starter may be breaking down from the hot exhaust pipe and hot engine, try replacing it. Also check your cables, My starter cable got too close to the engine block and was breaking down when hot. A hot cable doesnt conduct very well. Also check your fuel line, it may be touching the manifold or block making your fuel temp too hot. Have you checked your engine timing, too far forward can cause this too. Hope these help some.

10secgoal · Jun 18, 2004

68GEETEE said:
Several things: Your starter may be breaking down from the hot exhaust pipe and hot engine, try replacing it. Also check your cables, My starter cable got too close to the engine block and was breaking down when hot. A hot cable doesnt conduct very well. Also check your fuel line, it may be touching the manifold or block making your fuel temp too hot. Have you checked your engine timing, too far forward can cause this too. Hope these help some.

These are good palces to start looking. I would lean towards vapor lock. Check the fuel line like the man said. If that still doesn't work, it may be the carb getting hot. Hot fuel take forever and a day to burn. You can put on a carb spcer(preferably phenolic). If you can't fit one you can also use an aluminum spacer that is very thin to seperate the carb and inatke. Or just use more than one gasket. If it is the line, the gas will boil and force it's way past the floats and into the bowl. Then it floods the motor, hence the flooring off the pedal to start. It needs more air to over come all the bloody gas. Good luck.

Cobra6 · Jun 19, 2004

I agree with everything in this last post - just remember - it is very inexpensive to check or replace the cables - you may need new ones anyway.
If the engine is very hard to turn over when hot, I would lean toward the timing being advanced too far or bad cables somewhere.
If the engine turning over but not starting, you will probably need a carb spacer or something over the fuel line.
I have seen several clothespins on fuel lines over the years, (I even tried it once) but I really doubt that it helps (there is no evidence to show that it does help).
My $.02

Hack · Jun 19, 2004

Cobra6 said:
I agree with everything in this last post - just remember - it is very inexpensive to check or replace the cables - you may need new ones anyway.
If the engine is very hard to turn over when hot, I would lean toward the timing being advanced too far or bad cables somewhere.
If the engine turning over but not starting, you will probably need a carb spacer or something over the fuel line.
I have seen several clothespins on fuel lines over the years, (I even tried it once) but I really doubt that it helps (there is no evidence to show that it does help).
My $.02

I also don't know whether a clothespin on a fuel line helps, but it stands to reason that something metal clipped to a fuel line would transfer a lot more heat away from the line than a wooden something - that is, if there's a place nearby that's cooler than the fuel line where the heat can be transferred.

69stang351 · Jun 19, 2004

Hack said:
I also don't know whether a clothespin on a fuel line helps, but it stands to reason that something metal clipped to a fuel line would transfer a lot more heat away from the line than a wooden something - that is, if there's a place nearby that's cooler than the fuel line where the heat can be transferred.

This was the problem on my 69 the clothespins on the fuel line helped alot, because before i could see my fuel boiling in my filter, then the wooden clothes pins (about 5 of them) cooled the fuel enough to aleviate the problem. Also you might want to relocate your coil... sometimes the coil can get a little hot and not want to send a spark but that is just one of the problems my friends 69 galaxie had. just my solutions to similar problems... try what you will, something has to work!

My 69 won't start when it's hot

TwoStangWmn

69Rcode_Mach1

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Snail50

6Stang7

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MustangMatt1966

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68GEETEE

10secgoal

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Cobra6

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Hack

69stang351

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