1989 4.2: What could be causing air to clog my fuel line?

J

JonT

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Aug 19, 2024
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North Florida
Hi everyone,

I have a 1989 Sahara with a 4.2 and a Weber 32/36. Every few miles, particularly in stop and go traffic, my YJ will starve for fuel and quit running. I coast to the side of the road, and I'll pull the line coming from the tank to the fuel pump and suck on air until I taste gas. Reconnect line and then it fires up and runs perfect as before.

I thought maybe I had introduced air into the system after replacing my fuel pump and dropping the tank to replace a rubber fuel return line, filler, and vent hose. Maybe the Jeep could be burping out that air? But it keeps doing it, four times actually over a maybe 20 mile drive. FYI it has the fuel filter plumbed with the return line (picture attached); I've heard not doing so can cause issues.

Maybe I need a new sending unit, or could it even be as simple as a gas cap? I really don't like firing the parts cannon when I can't diagnose. What do you think could be the problem?

IMG_5779.jpg
 
could be a few things;
looks like those rubber lines are reaching the end of their service life. what do ALL the soft lines look like, including under the jeep?
cracked, collapsed or kinked fuel lines can cause all kinds of problems.

did you get a bad fuel pump? (it happens) I recommend hooking up a fuel pressure gauge.

is that fuel pressure regulator working properly? why do you have an aftermarket regulator?

how old is that filter? I have used those return filters with good results before, it prevents the fuel from "deadheading"which can cause vapor lock. were you having vapor lock problems? is that the reason for the return filter and the regulator?

my suspicion is a deteriorated rubber fuel line somewhere in the system. I would just replace them all including the ones on top of the gas tank.
while the tank was down, I would inspect the inside of the tank and the pickup/sending unit. replace any sus parts.
 
Stoopid Jeep said:
could be a few things;
looks like those rubber lines are reaching the end of their service life. what do ALL the soft lines look like, including under the jeep?
cracked, collapsed or kinked fuel lines can cause all kinds of problems.

did you get a bad fuel pump? (it happens) I recommend hooking up a fuel pressure gauge.

is that fuel pressure regulator working properly? why do you have an aftermarket regulator?

how old is that filter? I have used those return filters with good results before, it prevents the fuel from "deadheading"which can cause vapor lock. were you having vapor lock problems? is that the reason for the return filter and the regulator?

my suspicion is a deteriorated rubber fuel line somewhere in the system. I would just replace them all including the ones on top of the gas tank.
while the tank was down, I would inspect the inside of the tank and the pickup/sending unit. replace any sus parts.
Click to expand...

I didn't see any cracks in the soft lines. I think the pump is working because it sprayed fuel everywhere when I forgot to tighten the hose clamp on the supply line from the pump. The regulator was there when I bought it; I think all Jeeps with the Weber conversion use it since the Weber can only take about 3.5psi. The filter is brand new as of a few weeks ago.

And I'll probably go with your suggestion to replace all the lines and the sending unit while I'm there, eliminates all the variables that are hard to get to.
 
JonT said:
I didn't see any cracks in the soft lines. I think the pump is working because it sprayed fuel everywhere when I forgot to tighten the hose clamp on the supply line from the pump. The regulator was there when I bought it; I think all Jeeps with the Weber conversion use it since the Weber can only take about 3.5psi. The filter is brand new as of a few weeks ago.

And I'll probably go with your suggestion to replace all the lines and the sending unit while I'm there, eliminates all the variables that are hard to get to.
Click to expand...

Admittedly, I'm not familiar with with the Webber conversion, I'm pretty familiar with carburetors though. I was a boat mechanic for a while and saw a lot of fuel line issues.
Do you know what the fuel pressure is without the regulator? (that's just me being curious)
fuel line is cheap and eliminates a variable, I recommend Gates Barricade fuel line, it has a vinyl liner that stands up better to crappy gas (all gas is crappy these days, even the over priced non ethanol stuff)
I exclusively run non ethanol gas in all my motorcycles and I usually end up replacing fuel lines every 4 years or so.
 
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