carb starting problem

[OonDeanisS]

my engine turns over, but doesnt start. It's getting gas, and i believe spark, but the gas is getting blown out the top of the carb like the engine sneezing. It doesnt always happen though, sometimes it sounds like its starting, i can hear the exhaust for a second, then its off again. Whats the deal?

 

[86bluecobra]

i would say either you have the wiring wrong (i.e. H.O wired for a non H.O. or other way around) or you have a intake valve sticking open causing there to be pressure to blow gas the wrong way. does the car ever run? perhaps just the fact that it doesn't want to fire so the engine kinda kicks backwards and the fuel isn't getting pulled into the engine.

 

[EMW150]

If it's a pretty heavy cammed engine, and it's cold out they can be real tough to start. Mine is a real pain to start if it's been sitting for a long period and it's 40 degrees or less out. It "sneezes" through the carb like crazy (sometimes catching on fire), and tries to start like you said, you can hear it firing in the exhaust but just won't catch and go. Pump it about 3 or 4 times and then try it. Large duration cams have trouble because at low rpms they are very inefficient at pulling the mixture into the cylinder and the cold air makes it alot worse.

 

[88Stangboy]

If it's a pretty heavy cammed engine, and it's cold out they can be real tough to start. Mine is a real pain to start if it's been sitting for a long period and it's 40 degrees or less out. It "sneezes" through the carb like crazy (sometimes catching on fire), and tries to start like you said, you can hear it firing in the exhaust but just won't catch and go. Pump it about 3 or 4 times and then try it. Large duration cams have trouble because at low rpms they are very inefficient at pulling the mixture into the cylinder and the cold air makes it alot worse.

Agree'd, lots of overlap can cause a car to be hell to start when its cold.

 

[86bluecobra]

i had to back my dizzy off to get my car to start the other day. you may have to do that and then put the timing back in once its warmed up and idling.

 

[90_306powerhous]

if gas is coming out of the top of the carb i'm gonna guess the floats need adjusted. i'm not a carb expert so it could be anything. also what kind of carb do u have?

 

[OonDeanisS]

i also noticed that my fuel pump shuts off when i turn the key to start, and comes back on when i turn it back to on. would this cause it?

 

[OonDeanisS]

its a holley 750, and it was rebuilt during a dyno-tune a few months back, so the floats should be fine.