have 87 firebird with holly carb 305 5.0l

getting really frusterated everytime i crank the engine to my car over it blows my ch fan 20 amp fuse fan works direct fine just changed the relay over today what or where could the problem be

ps when i turn the ignition on not cranking it with ac on fan runs and doest blow fuse but when i crank it itdoes

 

Power = Current x Voltage.

When you crank it, what happens to the voltage and thus the amp draw for the fan motor?

Your stock fan should NOT have a 20 amp fuse in line with it. It should run through a fusible link from the starter terminal through the relay. Bottom line here is, maybe, a hack job?

 

is there any other way id hate to half to flip a switch everytime my cars hott

 

you can install a derele fan controller or a cylinder head temp sensor and wire to the ground side of a relay like tbi cars use.

 

where is this 'fuse' it's blowing?

 

What do you mean "flip a switch" ? Does that mean your fan is being controlled by a switch in the car ? From what you have said so far about your fan fuse blowing at start up means your fan is wired directly and is on at start up even when its cold. If that's the case get rid of that and run this simple basic no-frills adjustable thermal fan switch.Its what I use and works perfectly.
Side note = that controller is running my large 16" front pusher fan and only uses a 20 amp fuse.

http://www.autozone.com/autozone/par...artNumber=true

 

Why is it when asking a question that, for the people trying to help, it doesn't require a cap'n crunch decoder ring to figure out what is being asked ?

If you can state your question in a clear and concise format with punctuation, it really helps everyone else to help you.

 

 

The stock fan will pull more than 20 amps on start up, maybe not every time, but eventually (when the voltage drops). I've done a few electric fan conversions using the stock setup and have found that a 25 A fuse is needed.