turk_myers

Hi,
I did a swap in an 85 Camaro, and have had this problem since it started warming up outside. Originally I had the 305/mechanical fuel pump, but had to go to an electric. The pump is an Airtex that puts out 7 p.s.i. to a 650 holley single feed carb,no regulator. The pump is mounted on the fender well on the passenger side by the strut mounts. I hooked a 3/8" line from the original fuel line to a filter, then to the pump. After 10-15 miles, in the warmer weather, it starves and dies. If I wait a few minutes, i can get it to re-start and off I go for a few more miles. when it dies, the filter is empty and the fuel is "Bubbling" in the glass filter. The return line is capped off. Essentially I am wondering if this is vapor lock, and other than moving the pump to the rear, what else can be done to prevent this. My fuel lines are literally right next to the headers on the passenger side under the hood. here is the link for the Vid. It's right when it died, and here is what the filter is doing.

Thanks for looking
Turk.

BTW, the car is off. That was my fan running.

five7kid

iTrader: (14)

What engine did the car come with from the factory? Curious if it has an in-tank electric pump that isn't working.

In-line pumps work much, much better back by the tank. Vapor lock occurs when the fuel heats up and changes from liquid to vapor in the fuel line on the suction side of the pump (type of pump is irrelevant). That won't occur if the pump is back by, or in, the tank.

If you have an inoperative in-tank pump, the problem will be much worse.

naf

iTrader: (7)

Your problem is very common for cars with headers and fuel systems that deadhead to the carburetor without a return. The fuel boils in the lines from the exhaust heat.

Using a return regulator will help keep the fuel from boiling while the pump is running. On hot soak it can still vapor lock with the pump mounted up front. Insulating the lines will help but probably won't alleviate the problem.

Your 85, if an original LG4, wouldn't have had an in-tank, unless installed later. Installing an in-tank pump is the best option, but you can get away with mounting your pump near the tank. On hot soak start, it will pump through any vapor lock provided a return line is present.

For a 7 PSI pump you should be able to get away with using a mechanical pump as your return. Even if it doesn't 'pump' it has a metered return orifice that will return fuel back to the tank through the stock return lines. The upside is it connects up front just as the stock setup did.

turk_myers

It had a carbed 305 (H vin code) and a mechanical pump.
Thanks for the info.
I will move that pump to the back.
I also saw a fuel filter that has a return line on it, I may try that to get some fuel back to the tank so the pump doesn't dead head.

turk_myers

The bummer is that the new block doesn't have a provision for a mech pump. I replied above that I did find a fuel filter that has a return line on it, and was thinking about running that under the hood by where my return line is.
It's just a thought.
I never had luck regulating a 7 p.s.i. pump with a regulator set at 7 p.s.i. (I've tried)
I guess I COULD get a higher psi pump, and regulate down to 7 with a return regulator? (Holley Blue)
Thanks for the info,
you're helping me figure out this nightmare!

naf

iTrader: (7)

You SBC won't even allow the fuel pump to bolt on?

Try regulating down to 5 at the carb, although a 7psi pump may not get to 5 psi at the carb.

turk_myers

Correct. It cannot be bolted on.
And you're right also. Regulating anything with a 7 psi pump is hard.