Fuel Problem

[sxviper1982]

I recently changed out all the fuel filters on my 1967 M35A2 after I did this the truck is hard to start and when I turn the fuel pump off the engine rpms start to drop and then quits. Before I did the filter change I could turn the fuel pump off and it would stay running. I did purge the air on top of the secondary filters. Anyone got any ideas on what I could try?

 

[steelandcanvas]

Did you verify the in-tank pump is running, (visually, audibly) or just turn the switch on?

 

[m-35tom]

you have an air leak. go back and re-do what you replaced, did you use new gaskets?

 

[M35A2-AZ]

Sounds like an air leak to me.

 

[sxviper1982]

Yes, I can hear the pump running and fuel dumping into the tank from the return line.

 

[sxviper1982]

Thanks for the info. I will go out today and see what I can find. I did replace the gaskets on the cans.

 

[Jeepsinker]

Sounds like an air leak to me.

X2. Funny how them suckers will suck air in a pressurized system, but won't leak sometimes...

 

[doghead]

Did you get about 3-5 psi and good flow out the purge valve at the top of the secondaries?

 

[sxviper1982]

Did you get about 3-5 psi and good flow out the purge valve at the top of the secondaries?

I have not pressure tested it. I didn't get a chance to work on it yesterday or probably today but I started it up yesterday and it ran fine. When I turned the fuel pump off it stayed running unlike before it stalled. I still want to find out what is going on so I will check for "air leaks" and do a fuel pressure test as well.

 

[sxviper1982]

Did you get about 3-5 psi and good flow out the purge valve at the top of the secondaries?

I did a fuel pressure check at the purge valve

and got 6.5PSI. Before I put the pressure gauge on I purged it w/ fuel pump running and some air came out of it but not a lot, would this be enough to give me trouble? How many times should you purge the system after a filter change? The truck seems to be running the way it did prior to the filter change now. I can turn the fuel pump off and the truck will stay running.

 

[doghead]

Once.

Your probably fine.