Fuel Filter gas boil

[Brad H.]

In my newly done 58 283 230 single four the gas in the filter bowl boils or percs, what causes this, naturally too much heat directed to the manifold, am told that this is not unnatural in cars of this age and setup. Im thinking back to the heat riser valve and how they barely open even with engine hot so naturally mine is wired open im thinking 1/2 way(guessing), does this direct too much heat to the manifold instead of out the exhaust so heat is exiting the upper end? If not what is the cure or don't concern with it . Thank you, Brad

[Roy B.]

Re: Fuel Filter gas boil

I think you have air trapped in the bowl (not heat related) , While at idle loosen the bowl clamp letting the air out ,I've done this many years ago and the bowl has no air gap but filled all the way to the top with gas.

[Brad H.]

Re: Fuel Filter gas boil

Roy, this is the clamp underneath the bowl that holds the bowl tight to the housing?, naturally loosening this will leak gas on to manifold till air is out and gas fills the bowl?, is this correct and I guess put a rag underneath, yes my bowl is always only half full, is it supposed to be full? Thanks again Brad

[Roy B.]

Re: Fuel Filter gas boil

Roy, this is the clamp underneath the bowl that holds the bowl tight to the housing?, naturally loosening this will leak gas on to manifold till air is out and gas fills the bowl?, is this correct and I guess put a rag underneath, yes my bowl is always only half full, is it supposed to be full? Thanks again Brad

Yes it's should be full, yes put a rag under the filter , you can do this when the engine is cold . it just take less then a second and the air is gone.

[Christopher R.]

Re: Fuel Filter gas boil

Roy, Are you sure? The glass bowl in mine and many that I've seen over the years run just fine with the bowl half full. The bowl is never full.

Brad, Look again. Are you sure the gas is boiling? That bowl doesn't touch anything. So any heat conducted to it is from the air. Air that was so hot to boil gas would also scorch the paint on the hood. What looks like boiling may simply be the gas gurgling in the bowl as it's pumped in.

[Roy B.]

Re: Fuel Filter gas boil

That's right the gurgling is from air pressure so you see the gas moving in the bowl ,but again if you just break the AIR seal in the bowl then you have gas fill the bowl . If you need I can take a pic. Of the bowl full of gas when running or not.
Many people install the filter empty of gas then the fuel pump tries to fills it but cant displace the air , that's why I break the bowl seal to let the air out then you don't see any air trapped

[Brad H.]

Re: Fuel Filter gas boil

Hi guys again, yes mine was about half full which shows the gas slopping around in their with air bubbles and what not, Roy I did what you had noted and that worked but then noticed the air starts coming back in several hours later, does this matter and where does the air come from when there are no gas leaks anywhere, air in bowl I guess does not affect the gas going into the carb with air and cause missing? Thanks, sorry for late reply to all Brad

[Roy B.]

Re: Fuel Filter gas boil

Hi guys again, yes mine was about half full which shows the gas slopping around in their with air bubbles and what not, Roy I did what you had noted and that worked but then noticed the air starts coming back in several hours later, does this matter and where does the air come from when there are no gas leaks anywhere, air in bowl I guess does not affect the gas going into the carb with air and cause missing? Thanks, sorry for late reply to all Brad

1 the float needle leaks when sitting
2 the fuel pump loses pressure
3 the filter seal not tight
4 the fuels line not tight
One may be miner and dosen't effect the running if there is air trapped

[Michael H.]

Re: Fuel Filter gas boil

Hi guys again, yes mine was about half full which shows the gas slopping around in their with air bubbles and what not, Roy I did what you had noted and that worked but then noticed the air starts coming back in several hours later, does this matter and where does the air come from when there are no gas leaks anywhere, air in bowl I guess does not affect the gas going into the carb with air and cause missing? Thanks, sorry for late reply to all Brad

I wouldn't be loosening that fuel bowl when the engine is running. That's NOT a very good idea. It's possible, likely in fact, that gasoline can/will spray in almost any direction during this process and the result is often a dandy blaze.
You will never permanently fill the bowl by bleeding off the air anyway. As mentioned, when the engine is shut off for a few hours, you will once again have air in the top of the bowl.
The air isn't causing any problem.

The fuel boil issue isn't new but it's been getting worse in the last few years as the folks at the oil companies have been changing the formula/ratio.

[Clem Z.]

Re: Fuel Filter gas boil

the air in the filter will go out the carb bowl vent as the engine is running. on race cars we always put any inline fuel filter in a vertical position to keep out the air pockets.

[Brad H.]

Re: Fuel Filter gas boil

Thanks again guys , Brad