Whiskey Tango Foxtrot

[007]

So I started my Jeep for the first time with the clear fuel filter installed. I had made NO other changes. NONE.

It barely ran. Was blowing black smoke and puking fuel out the top of the carb and making pools on the intake.

I had to set the fuel pressure regulator DOWN from 6psi to 3psi to make it run even half way decent. I also noticed that while it was running the clear fuel filter was in fact clear I couldn't see any gas in it if you can in the picture below.

Should I have put the fuel gauge in front of the filter meaning between the filter in the carburetor? What in the world else could be going on?


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[Peanut Butter]

I would say too much fuel due to no fuel return line, but have you been using this type of fuel filter before, this type of setup?

 

[007]

There's a return at the regulator. Anything past Xpsi goes back.


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[007]

The more I think about this the more I come to the conclusion that was the only thing that would create the situation is the float being stuck?


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[Posi]

is there a check valve in the filter?
Remove the filter and see what happens
From what you posted I'm assuming the float is working as it should.

 

[Posi]

The float is easy enough to check

 

[Posi]

Remove the air horn
Put a straight edge across the top machined surface
The needle should be seated when the float is 1/8" below the top surface
Disconnect the filter and drain
Blow into the line while gently lifting the float
You shouldn't be able to push any air into the carb with the float seated

 

[007]

is there a check valve in the filter?
Remove the filter and see what happens
From what you posted I'm assuming the float is working as it should.

Remove the air horn
Put a straight edge across the top machined surface
The needle should be seated when the float is 1/8" below the top surface
Disconnect the filter and drain
Blow into the line while gently lifting the float
You shouldn't be able to push any air into the carb with the float seated

Will do - I should be able to do all of this tonight when I get home. If it is the float, then that's a freak coincidence indeed - unless a plastic shaving from one of the filter ends (comes with 3 diff sizes) got in there, then went to the carb and got stuck at the needle valve...

 

[Torxhead]

I'm thinking the stuck float possibility is what you should check for first. I have run those filters and would suggest installing it prior to the fuel pump. This way you can check for water and debris in the fuel line. They are a very weak filter though and installing a conventional filter before the carb entry would work better. Good luck with finding the problem.

 

[007]

I'm thinking the stuck float possibility is what you should check for first. I have run those filters and would suggest installing it prior to the fuel pump. This way you can check for water and debris in the fuel line. They are a very weak filter though and installing a conventional filter before the carb entry would work better. Good luck with finding the problem.

Agreed - I do have my "good" filter right in front of the electric pump. From there the fuel goes to the regulator (with bypass), then to the PSI gauge, then to the clear filter, then to the carb.

As I type this though, I realized something I did that I think proves it is the float - before I shut the garage up for the night I turned the key on to activate the pump so see if the filter would fill - it didn't. This tells me that even with the engine off - fuel must be dumping within the carb. I will carefully remove the air horn tonight and see what the float position looks like - I'm really feeling like something has worked its way in there...

 

[Torxhead]

I did not know you had an electric fuel pump, and havn't seen too many guys have long term success with one along with a carb. So what fuel pressure do you run to the carb?

 

[Posi]

Should be running 5-6.5 psi

 

[Lumpy Grits]

How much fuel do you KNOW is in the tank?
You don't need that see thru filter. All that rubber hose makes a great source for v'lock.
While the engine is run'n, tap hard the carb's side to free the float up.
Make sure you haven't unplugged a vacuum line.
LG

 

[007]

I did not know you had an electric fuel pump, and havn't seen too many guys have long term success with one along with a carb. So what fuel pressure do you run to the carb?

Well to summarize, I have a new Holley electric pump mounted on crossmember above fuel tank (where front of tank attaches). It has a 50" dry pull and check valve. Fuel goes from there to OE steel line up to engine bay, then rubber to regulator set at 6psi., additional pressure is bypassed back to return line to tank. Fuel PSI gauge is just past regulator, then comes the clear filter, then comes the carb. The Jeep tour companies that use/used the J10/J20 have used these for years to eliminate vapor lock at altitude. This way you're pushing cold fuel as opposed to trying to pull potentially hot fuel.

How much fuel do you KNOW is in the tank?
You don't need that see thru filter. All that rubber hose makes a great source for v'lock.
While the engine is run'n, tap hard the carb's side to free the float up.
Make sure you haven't unplugged a vacuum line.
LG

I only have about another foot or so of rubber line than I did before the conversion...but we'll see tonight.

 

[Lumpy Grits]

Never 'dry-pull' test a liquid pump. The liquid is a coolant and lube for the pump.

 

[007]

Never 'dry-pull' test a liquid pump. The liquid is a coolant and lube for the pump.

I never have with the exception of the first time it primed the system. It has a check valve to keep gas in the line between itself and the pick-up.

 

[Torxhead]

A big issue of running an external electric pump is getting fuel to the pump. Siphoning seems to work pretty good, to get the fuel to the pump. This requires the CJ fuel tank vent system to be working correctly, if not a vacuum will create in the tank and have an effect on the siphon to the pump. Having a high volume low resistance filter before the pump is a good way to protect the pump from the pick up screen lets thru. Make sure the pump does not get warm to the touch indicating poor cooling from fuel passing thru. When I was running the oem carb on the AMC 258 i6 / 4.2l , 4 p.s.i. from a mechanical pump worked just fine. My impression of using an external electrical fuel pump is that it can get pretty complicated, but doable.

 

[Lumpy Grits]

T'head has a good point here!
Try run'n the Jeep without the gas cap in place.
LG

 

[007]

I have an open vent to the tank. It goes up in the fender well above the filler tube and 180's back down. No leak. Plenty of vent. The reason I bought the pump I have is because of the pull power. It only sits about 14" above the bottom of the tank and has a built in check valve so it doesn't prime every time you turn the key. I have NO problems getting fuel out of the tank and up to the carb. I used the bypass regulator to control PSI AND return excess fuel back to the tank to keep the fuel headed to the carb as cool as possible.

The filter that came with the pump (and attaches to the IN side of it is 74 micron filter. The clear filter between the regulator and the carb is for a simple eye-check for the existence of fuel.

I'll be shocked if my float isn't stuck.

 

[Lumpy Grits]

Ele. fuel pumps are not 'pullers'. They are 'pushers'. That pump should be mounted no higher than the top of the tank and as close to it as possible.
LG