2F fuel filter ( Is this normal?)

[oregonfj]

Im trying to troubleshoot an engine miss under load. I replaced the fuel filter with this clear one and noticed that gas barely trickles in while running. Is this normal? Im wondering if my fuel pump is failing?

 

[primer7]

Normal on my F motor.

 

[Fast Eddy]

Normal on my F motor.

I call shenanigans. It should be full of fuel; no air.

 

[splib]

I've seen lots of fuel filters operate like that. That could be a vacuum, not air, right?

 

[Pighead]

It's air, and I've seen fuel filters hold a bubble for a while...you could probably get rid of it by repositioning it for a bit.

 

[Sam Stewart]

My pickup was doing something similar and it had a blockage in the pickup tube. My fuel looked all nasty though and yours looks pretty good. Is that right after it has been running? When it's running it should be full. If it sits for a few minutes the pressure will likely bleed down and look like it does in the picture. Being that the fuel looks clean I would suspect the pump.

 

[Pighead]

Sure, half of the "Miss under load" problems are fuel delivery. Half of those are fuel filter. Could be half a dozen other places to check too...clogged pickup, bad fuel lines, non-venting fuel tank, bad fuel pump...
Try to isolate so you can rule out certain areas. Maybe undo the fuel line between the filter and the pump, should drain fuel easily by gravity, Maybe try running it without the gas cap. Of course, check the fuel level in the porthole window when it's cut out to be sure it's a fuel delivery problem. Maybe blow some compressed air back through the fuel line, see if that helps for a while.
Run the fuel line from the pump into a measuring cup and crank the engine, the FSM tells you how much fuel the pump should deliver over a given time. All kinds of fun things to do to figure this out.

 

[oregonfj]

Yep that running, revving the motor doesnt change it much. I'll maybe try to let the pump pull from a gas can to see if the pickups plugged.

 

[fj404life]

There is a spec in the FSM I believe that tells you what the pump should put out. Disconnect line at carb and turn motor over for x amount of seconds and you should have x amount of fuel.

 

[Shark56]

Both mine look the same as yours. One has new Fuel Pump and tank. Been like that for years, even after a filter change.

 

[fj404life]

Ya I forgot to mention...mine is sometimes full, and sometimes looks like that. New fuel pump/tank/line.

 

[oregonfj]

Oh I don't have a FSM. That sounds like a good Christmas present from the wife....

 

[Pin_Head]

There is a spec in the FSM I believe that tells you what the pump should put out. Disconnect line at carb and turn motor over for x amount of seconds and you should have x amount of fuel.

^ This

How much fuel it can pump out is what is important. IIRC, about half a cup in 15 seconds of cranking.

 

[oregonfj]

Well I found my problem. When I tested the flow rate of the fuel pump I got 8 ounces of gas in 30 seconds of cranking which should be plenty to keep the carb full. During further inspection I found a loose fitting on the fuel pressure regulator. I removed the regulator since I dont think I really need it anyway and she runs like a champ!
So in retrospect the filter just being half full of gas during running must be normal. Its just the first time I ever ran a clear filter. Thanks everyone for the help!!!!

Happy Wheeling

 

[Enigma]

Is that a plastic clear filter? I had been running some glass ones years ago (I think I bought them at some old hot rod shop, they were cheap) when I was having dirty fuel tank problems. I would have to take my filter off once a day and clean it out, but it was quite quick. Anyways a friend recommended I not use them, as glass tends to break quite easy..........

So do you have a brand name/part number handy for those?

 

[oregonfj]

Oops I threw the box away already. I just went to the local oriellys/shucks and asked for a filter for my 78 FJ.