Losing Fuel

Can you help me? I am new and just picked up a 80 bullnose with 4.9 l6 and 5 speed. Motor is new as well as carb. It is acting like it runs out of gas in second. Starts fine but when you shift into second it loses power like it's starving for gas. I have electric fuel pump with regulator turned all the way up. It also has a return line. I have not check the fuel pressure but its getting plenty of fuel on startup. Does any one have any advice on fuel starvation with these l6 engines.

This isn't specific to the I6, but it does sorta fit Carter carbs - which is probably what you have.

It sounds like you may have float level problem.  It might be too low, but in my experience a Carter has both a float level and a float drop setting and if it the drop is set too high you run out of fuel in 2nd gear.  I did exactly that in '58 Chevy with a 348 and a WCFB Carter carb.  Took off, hit 2nd, and it bogged.

I don't know that the float drop is your problem, but I know it can do that.  However, there are probably other reasons for it to bog that way, although most of them have o do with fuel and carburetion.

So I'd recommend rebuilding the carb as your first step.

Have the rubber fuel lines been replaced yet?
They can look good on the outside but be bad on the inside and stop fuel flow.
Fave ----

tykemp wrote

Can you help me? I am new and just picked up a 80 bullnose with 4.9 l6 and 5 speed. Motor is new as well as carb. It is acting like it runs out of gas in second. Starts fine but when you shift into second it loses power like it's starving for gas. I have electric fuel pump with regulator turned all the way up. It also has a return line. I have not check the fuel pressure but its getting plenty of fuel on startup. Does any one have any advice on fuel starvation with these l6 engines.

Ok I see a few things that could be the cause.
1 is the electric pump and regulator turned all the way up.
Why was this used? Who makes the pump?
Where is the pump mounted?
There is nothing wrong with the motor driven fuel pump and new rubber hoses between tank & hard line and hard line to pump.

Is this pump wired with a relay and have safety switches in place if the motor should stop running in a crash? Thinking not on both?

2 is the return line? Our trucks did not come with a return line so where dose it pick up the fuel for return and where dose it dump it into the tank?

Have you tried to run the truck with out the fuel cap in place for testing?
The factory tank should be vented but if something has been changed and yours had been it not not be vented as needed.

Being you have the regulator turned up I take it you have a fuel psi gauge somewhere?
Any way you can mount it on the windshield to see it when driving to see what happens when it falls on its face?

If it was me I think I would return the fuel system back to factory as it is a known good system.
My 81 F100 has a 300 six and manual trans and it has no problems with fuel from the coldest to hottest days. Lately been in the high 90's and have had a little fuel boiling in the carb when shut down to run it a store.

More so with the nose of the truck pointing down and coming back to the truck I can smell gas. I hold the throttle to the floor and after a little cranking it fires up and clears out. That is the only issue I have with the factory fuel system.
Dave ----

I just brought the truck in this manner and l needed advice on what to do. The pump is not wired to a relay but to the switch. it has a return line from the carb to the tank. I will troubleshoot and see what happens

Can you post up a picture or 2 of this return & regulator.
It could be this setup that is the cause.
Dave ----

Yes l will