Hot Rod Forum banner

what causes hard starts

5K views 8 replies 6 participants last post by  001mustang 
#1 ·
ever since i changed my carb intake fuel pump, if i remember correctly, i've been having trouble with starting the car... for instance i go for a drive and then shut off the car and let it sit for 10 min... when i come back to start it i have to crank it for a good 5-10sec unless i press the pedal... if i shut it off and start it within a couple minutes... i barely have to crank it... so what causes this prob

its a 305 with edelbrock rpm intake edelbrock carb and fuel pump... i also have the fuel line insulated
 
#2 ·
abas_abas said:
ever since i changed my carb intake fuel pump, if i remember correctly, i've been having trouble with starting the car... for instance i go for a drive and then shut off the car and let it sit for 10 min... when i come back to start it i have to crank it for a good 5-10sec unless i press the pedal... if i shut it off and start it within a couple minutes... i barely have to crank it... so what causes this prob

its a 305 with edelbrock rpm intake edelbrock carb and fuel pump... i also have the fuel line insulated
Edlebrock aluminum carbs are famous for boiling the fuel. Try one of the thick insulator gaskets between the intake & carb. If that doesn't work block the exhaust heat crossover in the intake as the holes are very large.
 
#3 ·
Is the Edelbrock fuel pump a mechanical one? An electric fuel pump would probably help because it would prime your fuel bowls and fuel pressure, plus wouldn't be as suspectable to heat soak. It'd be a pain installing one though. Some fuel filters like stock rochesters have a anti-drainback check valve that and I think some fuel pumps have one and that probably helps some. Even with an electric fuel pump and check valve, like the other poster said fuel percolation from heat soak sounds like a big factor here, and his advice sounds good.
 
#4 ·
cruiser1 said:
Is the Edelbrock fuel pump a mechanical one? An electric fuel pump would probably help because it would prime your fuel bowls and fuel pressure, plus wouldn't be as suspectable to heat soak. It'd be a pain installing one though. Some fuel filters like stock rochesters have a anti-drainback check valve that and I think some fuel pumps have one and that probably helps some. Even with an electric fuel pump and check valve, like the other poster said fuel percolation from heat soak sounds like a big factor here, and his advice sounds good.
its mechanical... and i wont go for electric... i have a edelbrock performance fuel filter and already have an insulation for the fuel line..
 
#7 · (Edited)
hard start post hot shutdown

Minimize carb evaporation loses by installing 0.3" thick rubber heat insulator gasket (verify hood clearance), use nylon washers under the 4 metal washers that attach carb, remove gasket between carb and breather so metal breather can serve as a heat sink.

Minimize fuel boiling in fuel pump by installing 1/8" thick fuel pump gasket, grind the shoulders off the two fuel pump bolts and insert 3/4" long 3/8" od tubing on the bolt shoulders. Use nylon washers under metal washers on fuel pump bolts.

When you have extra time measure fuel psi during idle and post shutdown. Fuel pumps should hold pressure for a while post engine shutdown which minimizes fuel evaporation in the fuel line. To hold the fuel pressure post engine shutdown the pump valves must seat well and the carb float needle must seat well. You can disassemble and inspect some fuel pumps just remember to tension the spring during reassembly. You can replace or inspect the carb float needles and verify float is set per edelbrock instructions.
 
#8 ·
The first thing I would look at is your choke operation. Wehn you come back after the car has been off for 10 minutes, if the choke is closed again, this could cause your hard start. Everything else mentioned in the above posts are possibilities but until you verify the choke is working properly you cant move on to the other things.

Please before you fix something, make sure it is broken.
Dont assume your fuel is boiling out, check it. most all carbs have a bowl vent, stick a small piece of wood of a plastic stirer or something in the bowl vent to see if there actually is fuel in the carb or not.
 
#9 ·
Check fuel bowl level edelbrock carb.

Good suggestion. You can verify fuel is in edelbrock carb by removing a rod assembly and inserting a WD-40 red plastic nozzle tube into carb rod well. If it comes up wet then fuel is in the carb. I like to do this test about an hour following hot shutdown.

I have seen empty glass fuel filters post hot shutdown on a few applications; is that typical?
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top