This is a question that came up on a mailing list I'm on, and it has me really baffled. A lot of flatfender guys run buick 225/231 motors, and it seems that most of these guys have blocked off the return from the mechanical fuel pump with a piece of hose and a bolt.


On mine, the return just loops back into the fuel filter since there's no return on my tank.
Now it seems to me that blocking off the return line will cause excessive fuel pressure and decrease the life of the fuel pump wouldn't it??

Thanks

Originally posted by oldjeep
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Now it seems to me that blocking off the return line will cause excessive fuel pressure
Thanks

maybe this is why they did it.
one of the ways to increase fuel pressure, if you do'nt have a pressure regulator, is to fully/pertially block the return line.

Are You talking about a regular old engine driven fuel pump on a carb?

A regular old engine driven fuel pump is two check valves and a diaphragm. The reason for the return line is to keep the fuel cool, not to change the pressure.

Originally posted by Old Scout
Are You talking about a regular old engine driven fuel pump on a carb?

A regular old engine driven fuel pump is two check valves and a diaphragm. The reason for the return line is to keep the fuel cool, not to change the pressure.

Yes, that's what I'm talking about.

Thanks for the info. So basically the only downside to them plugging the return is a greater chance of vapor lock?

Originally posted by Old Scout
Are You talking about a regular old engine driven fuel pump on a carb?

A regular old engine driven fuel pump is two check valves and a diaphragm. The reason for the return line is to keep the fuel cool, not to change the pressure.
I was wondering that also, but then again i have never seen a carb with a return line, they must of just stopped doing it

This is why when you go to get a new fuel pump the counter guy will ask if it has AC or not.
AC=harder working engine=more heat under the hood=vapor lock

What you can do if you want to go through the trouble is install a T fitting in the line where it come out of the tank and run the bypass line to it but it won't have the same effect as dumping the heated gas back into the tank and pulling out fresh.

So I guess what I'm saying is if you have to replace the pump tell 'em it doesn't have AC and you'll get a 2 line pump.