1990 miata with 6port 13b with holley 4 barrel carb
 

hi guys, i am thinking about getting this car as its pretty unique and i miss having a miata. the only problem with the car though is that after filling it up with gas, the car has a hard time starting and staying on??? after i guess cooling off, the car will stay on and start with no problems until it is time to fill up again... the fuel pressure on the holley 4 barrel carb is 6psi. is this a common problem with carbs? any tips?

thanks,

marlon from atl

it only behaves that way after you fill the tank? does it start and run fine all other times?

..

Its got to be the paint job!!!! lol

Probably a problem with fuel tank venting and fuel pressure.

The carb'ed rotaries are super sensitive to fuel pressure.

It probably needs the pressure that builds up in the warm gas tank to run right. Make sure the old fuel injection return line is open vented and then retune the fuel pressure up a bit to make up for the pressure lost to the carb from a non-pressurized gas tank.

How can you assume it is vapor lock

6 psi should be more than enough . Is there a carbon canister on the car ?

it only behaves after filling up yes. i dont know if there is a canister. this thing guzzles gas though!

just a shot in the dark but maybe could check if it does have a canister and if so make sure the hoses are routed properly .. just a thought but it won't cost anything to check it out .

i guess they aren't the easiest thing on fuel but it shouldn't be so bad that it keeps you awake at night .

If you decide to pass on the car, let me know ;)