Fuel Filter/Pressure Issue

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Paladin06

Paladin06

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OK, I replaced my fuel filter with the clear type a couple days ago. All seemed well until today, I stopped at the local shop when I noted the car seemed to be fuel starving. We open the hood and the filter was nearly dry. When I revived the engine there was barely a trickle of gas coming from the inlet side.

OK, easy right? We replaced the fuel pump. Car started fine, filter filled about half way up, so I thought good to go and drove home.

Once home I opened the hood again and noted the filter was a little less then half full. I let the car set for 15 minutes and the filter is now BONE dry. WTF????

Couple questions with my setup that is the OEM mechanical pump. Please note I have not identified any evidence of leaking!

1. When the car is off, how much fuel should be in the filter?

2. With the car running how much fuel should I see in the filter?

3. Why would the filter go dry after setting for such a short time? Could this be a gas cap issue?

Please advise!!
 
try running it without the gas cap. your tank vent could be clogged. you could have gotten a bad pump. it happens. i have a clear filter as well. sometimes its full , sometimes its partially full. i think it just depends where the pump arm stops.
 
I had the same problem with a clear filter. You can watch it cycle air in fuel out, fuel in air out repeatedly. Did fuel pump, etc..
I bought a filter that I couldn't see through ( steel ) and moved it to vertical below the alternator.
I also corrected the bent accerator pump linkage so the bowl vent would open like it should.
Fixed
 
Can you please provide pics of your corrections.

RedFish said:
I had the same problem with a clear filter. You can watch it cycle air in fuel out, fuel in air out repeatedly. Did fuel pump, etc..
I bought a filter that I couldn't see through ( steel ) and moved it to vertical below the alternator.
I also corrected the bent accerator pump linkage so the bowl vent would open like it should.
Fixed
Click to expand...
 
OK, when I run it with the gas cap off the the filter gets almost completely full and stays that way. How do I unclug the vent tube? Assuming that's the problem.

73AbodEE said:
try running it without the gas cap. your tank vent could be clogged. you could have gotten a bad pump. it happens. i have a clear filter as well. sometimes its full , sometimes its partially full. i think it just depends where the pump arm stops.
Click to expand...
 
Paladin06 said:
OK, when I run it with the gas cap off the the filter gets almost completely full and stays that way. How do I unclug the vent tube? Assuming that's the problem.
Click to expand...

What year/ model is your car? If its a 72, you can download a 72 shop manual for free right here:

http://www.forabodiesonly.com/mopar/showthread.php?t=132309&highlight=manual,+download

Judging from the photo, it's one that has the evaporative emissions controls (originally) I.E. the "carbon canister"

If so, these don't HAVE a vent except through the carbon can system. You need to get the proper year shop manual, and see how it's all set up.

If it's gone, there are "other ways." The original, earlier, "non" carbon can cars had a 1/4" or so line welded into the fuel filler tube up high inside the trunk just before the filler tube goes through the quarter panel. This tube then goes up high in an upside down "U" and then runs down along the filler, through the floor gasket, and ends (open on the end) inside the rear frame rail.

Like this:

2cmugso.jpg
 
Paladin06 said:
OK, when I run it with the gas cap off the the filter gets almost completely full and stays that way. How do I unclug the vent tube? Assuming that's the problem.
Click to expand...
that may be the problem then. do you have a line running to the front of the car for the canister? if so, you can take an air line and hook it to the vent tube and blow some compressed air back through it with the cap off. i think its a 1/4 inch line. if not , 67 has you covered with his pic
 
The line is at the canister but it appears to be closed off. I attempted to stick a small nail in the end and it does not go deeper then 1/4 inch. hummmm. The car is a 1972, 340 car.
 
According to my manual, there is a limiting valve in the line with a release pressure of 2 psi. It must be froze. it's part of the old emissions crap. Perhaps I can just drill it it?
 
I could be wrong but I think if you'll leave the fuel door open and let it run long enough the same air/fuel cycling in that filter will appear.
 
OK, the filter was almost completely empty this morning. I did note the inlet line to the pump was hard as if full of fuel but the filer was empty. Perhaps the accerator pump linkage that "RedFish" noted is the issue. Or the accelerator pump itself?

Thoughts?
 
RedFish...plz advise on bending of the accelerator pump linkage. Also is your linkage still in the factory set center hole?

Thx
 
On my carter 2 brl , The bowl vent is opened when the accelerater pump shaft returns all the way to the top.
I might have streched that link when I had the carb off. Anyway..
All I did was bend the linkage rod a tad so the accerater pump was all the way up when off throttle.
 
OK, forced pressurized air through the vent line, and made a minor adjustment to accelerator pump linkage. I drove the car for 20 minutes and when I stopped/shut down to check the filter it was completely full. I let it set for over an hour and it remained full.

Then I drove the car again, shut down and within 45 minutes the filter was half full.

I'm stumped.

Thanks all.
 
my filter is half full sometimes, completely full other times. when its out of gas, there is only a tiny little puddle in the filter. the car works and drives fine, unless there is only a little puddle lol. is your car running and working?
 
Yep, running and working just fine.:prayer:

73AbodEE said:
my filter is half full sometimes, completely full other times. when its out of gas, there is only a tiny little puddle in the filter. the car works and drives fine, unless there is only a little puddle lol. is your car running and working?
Click to expand...
 
The filter in a horizontal position can often be less than totally full. In fact you would have to go up a very steep hill to get the last bubble out to the bowl.

Those plastic see through filters are a fire hazard as much as worrisome.
 
ive heard stories about the clear filters. mine are always up and away from anything hot . been running them for years , never had a problem with them
 
Could it be heat soak...the gas getting hot and evaporating in the filter and fuel bowl after a good run. Had this problem with my slant..Just another possibility to consider...

Good Luck
 
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