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A filter should not be used on the suction side or inlet side of the pump.
Would you explain why this could be a problem? I thought I was accomplishing "due diligence" by installing a filter on the inlet side. Is there a mechanical issue or safety issue with installing one as such?
I noticed the same problem with my '71, returned the lifetime pump to A-Z (10 yrs old-wow) for replacement and had same result. More intensified research (aka reading) revealed the pump would allow fuel to drain back as an emission feature. Comparison of the motorcraft and holley (miss that Holley) carbs revealed that once the needle valve opens on the motorcraft, fuel can drain out of the bowl. Past that it's just a hot start issue, with less fuel draining down the manifold. I'll probably be replacing starters more often.
Wow! I had not read that, Hypoid. This is taking on another interesting twist. Thanks for the input.
I had one of those clear filters on my truck for years. I had the same problem as you are having, took the filter apart and found that the rubber seal on the end was shot allowing air into the fuel line through the filter. Mine just unscrews, worth a look.
I had one of those clear filters on my truck for years. I had the same problem as you are having, took the filter apart and found that the rubber seal on the end was shot allowing air into the fuel line through the filter. Mine just unscrews, worth a look.
Mine is an inline filter with a hose on both sides of it. It's brand new; I'm hesitant to think it would be the problem. I have it installed between the pump and the carb. If it goes bad, it should spray fuel, not suck air...at least in my way of thinking.
A jam nut?...I'm not seeing what you are referring to here. My filter has a self contained element. It is a clear, plastic filter that you put inline with your rubber fuel line.
Would you explain why this could be a problem? I thought I was accomplishing "due diligence" by installing a filter on the inlet side. Is there a mechanical issue or safety issue with installing one as such?
Atmospheric pressure has to "push" the fuel thru the inline filter at a fuel pump inlet. A fuel filter is way too restrictive to use on a pump inlet. This interferes with the ability of the pump to pump fuel. A strainer with large openings to keep the big chunks out is the only "filter" allowed on the inlet side of a pump. Remove that filter and replace it with a piece of hose.
Multiple threads merged.
Last edited by Torque1st; Apr 11, 2006 at 04:04 AM.
I apolagize, I thought you had one of those glass filters that allow you to replace the element. As far as the filter not filling up with gas, I think that when the paper element gets soaked with fuel it swells just enough to create a restriction in air flow causing the fuel to be pushed up the line first leaving the air in the filter, I don't know.... just a thought?
I cut apart a filter at work that wasn't filling all the way, to find out why-
Turns out, inside the element, there is a tube that goes almost all the way to the end of the element. The fuel only fills until it starts going out the tube, then the air in the filter is trapped there. If you mount the filter upside down, it will fill more.
I wouldn't put a filter before the pump because of the possibility of vapor lock, due to the extra restriction in the line.
That's interesting info, Ford_Six. I may experiment with turning it upside down and test that theory. It makes sense! I definitely believe that air gets trapped in the filter...When I first started the engine after replacing all of the rubber fuel lines, I thought there might be some kind of air lock in the system. I thought it would be smart to remove the outlet side of the fuel filter while it was running. I got a good spray of air and gas when I removed the line from the filter, as it was under a little pressure. It didn't help with the symptom either. Thanks for the input. BTW, I'll remove the inline filter that I installed before the pump. I thought it would be necessary since I no longer have a filter sock in the tank.