Fuel Issues?

[VeeTwin60]

Hey Guys - The other day, my truck started stuttering as if it were out of gas.  It is very intermittent, as it will go back to normal just a little bit later.  When it is stuttering, if you push the accelerator it will cough and act like it would if it had too big of a carburetor.  When it is normal, it works just fine.

Could this be a blockage in the fuel filter?  Could it be a fuel pump going out?  Any other ideas?

350 cu.in. w/Holley 600 CFM 4bbl Street 1850C

Thanks!

[77 step]

Holley,

Power valve is my guess.

[DnStClr]

Sure could be a power valve. Always start checking with the easy stuff. Air filter. vacuum lines. fuel filter. plugs. Look inside of the distrib. cap and see if it's cracked.

[Blue 82]

are you using E10?

[VeeTwin60]

Not knowingly.  Would it be labeled on the pump?

I think I'm going to rebuild the carb and replace the plugs and wires - It won't hurt, I know they both need it.

[TexasRed]

Replace the plugs and plug wires first and see if that helps.

E10 is usually found on the pump, it would say, "Contains Ethanol" or "Contains upto 10% Ethanol".

[VeeTwin60]

Okay - I've replaced the plugs and wires (which it needed).  I've rebuilt the Holley.  After reinstalling the carburetor, I turned the truck over.  Now, I know the bowls are empty, so it will take a few tries to fill them up and fire it off.  However, it never fired.  So, I disconnected the fuel line and diverted it into a container.  I then turned the truck over - nothing came out of the hose 

So, I go back to the fuel pump question - is it possible for a fuel pump to operate intermittently?

[77 step]

Is your pump mechanical, or has it been changed to electrical?  My guess is that the mechanical one works or doesn't.  An electrical one could be intermittent.

How about a suction leak?  Could the fuel pump be sucking air through a cracked/rusted/loose line?

Could the pickup tube in the tank be broken?

How about a blockage in the lines?

If you have access to a HAND OPERATED vacuum pump, or brake bleeding pump, you could try to draw a vacuum on the line to check for a leak or blockage.  If the gauge won't come up off 0, it is probably a leak.  If it goes up and up as you pump, and holds but you get no gas - blockage.  If it goes up, but slowly falls as gas is drawn to it, fuel pump is not working.

I stressed hand operated because of the dangers of mixing electricity and gasoline.

Hope this helps... good luck!


I

[VeeTwin60]

It is mechanical - and I had the same thought as you... a mechanical one works, or it doesn't - no in between.

But... it was the fuel pump.   I changed it and it runs like new again.

[77 step]

Good job!