Fuel "sock"
Thread Starter
Drifting
Joined: Aug 2007
Posts: 1,838
Likes: 13
From: Kingman AZ
Fuel "sock"
What does it take to remove the "sock" inside the fuel tank? I have an 1976 L 48 THM 350 that has had a total tune, carb rebuilt, Distributor spring and weight replacement,fuel pump and filter replacement and still, upon WOT, Falls on its face at the point of shifting to second. If I let up on the throttle it recovers from the bog. If it shifts to second and stays at WOT it Seems to die off and on thru the range of RPM's as I accelerate. Cant think of anything else but lack of fuel. Since everything has been replaced I was thinking maybe the sock is full of crud. Any help is appreciated.
Timing is set to 10* at idle. Dont know what "all in" advance is at this time. Need to check still
Timing is set to 10* at idle. Dont know what "all in" advance is at this time. Need to check still
Le Mans Master
Joined: May 2002
Posts: 5,086
Likes: 786
From: Lebanon Township New Jersey
On my 77 I removed the tank to change the sock and hoses and to inspect the rubber bladder - which you probably have also. There is a cover plate on the top of the tank which has to be removed which brings the level float and pickup (and sock) out with it. I had to drop my exhaust to get the mufflers out of the way and remove the spare tire housing. There is also a big sheet metal enclosure around the top of the tank which comes out to give access to where the hoses connect to steel lines going to the front. Not too bad a job really.
Melting Slicks
Joined: Oct 2002
Posts: 2,317
Likes: 111
From: St Louis MO
Before you go to all that trouble, do a fuel volume check - it's in some of the shop manuals...
After running at idle to fill the float bowl, shut off the engine and then disconnect the fuel line to the carb and add a 6 foot length or so of fuel line to a bucket off to the side. Start the engine and run at idle for 1 minute, then shut it off. Measure the amount of fuel in the bucket and compare to the specifications. If your sock is clogged, it will be very apparent.
P.S. Be smart and safe, having an appropriate fire extinguisher available.
After running at idle to fill the float bowl, shut off the engine and then disconnect the fuel line to the carb and add a 6 foot length or so of fuel line to a bucket off to the side. Start the engine and run at idle for 1 minute, then shut it off. Measure the amount of fuel in the bucket and compare to the specifications. If your sock is clogged, it will be very apparent.
P.S. Be smart and safe, having an appropriate fire extinguisher available.
Burning Brakes
Joined: Mar 1999
Posts: 1,047
Likes: 3
From: CA
I've seen these go bad on a few cars. In each instance there was crap in the tank that caused the sock to clog up and restrict flow of fuel. In addition the fuel filter in the carb would also be filling up and clogging at the same time. So if your fuel filter is pretty clean and doesn't clog up after a short period of time, I would bet your fuel sock is clean and doesnt need replacing.
Pro
Joined: Jun 2007
Posts: 688
Likes: 1
From: Stevens Point WI
What carb are you running?
Could be even though its been (gone thru) your float levels are off?
If it was mine I would run a fuel psi gauge inline and see what its doing after you have verified float level
Could be even though its been (gone thru) your float levels are off?
If it was mine I would run a fuel psi gauge inline and see what its doing after you have verified float level
Thread Starter
Drifting
Joined: Aug 2007
Posts: 1,838
Likes: 13
From: Kingman AZ
Factory Q-Jet. It did it before the rebuild also. The rebuilder is a top notch guy. Been rebuilding them for years. Float level is good
Le Mans Master
Joined: Jul 2000
Posts: 6,001
Likes: 113
From: Saginaw Michigan
I had the exact same symptoms. I also noticed that with a full tank the car ran a bit better. Dropped the tank. It was the sock. Also the pickup tube was almost hitting the bottom of the bladder. We cut the tube back about 1/4 inch and installed a new sock - FIXED.
Jim
Jim
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Racer
Joined: May 2008
Posts: 318
Likes: 0
From: Wheaton, Illinois
fuel problem
I had similar problems with my Vette. I was told to check the fuel pump presure, lines, tank sock ect. It turned out that my S rubber hose that runs from the frame to the pump was very old and soft. The fuel pump was sucking the hose closed at wide open throttle and causing the bog. You can buy the S hose from Ecklers, aprox: $20.00. Al
Thread Starter
Drifting
Joined: Aug 2007
Posts: 1,838
Likes: 13
From: Kingman AZ
Just got back from OC GM performance. Danny put it on the dyno. Appears its not getting the required fuel. At 4000 rpm it just runs out of fuel Next step is the fuel line pressure test and check the lines. Thanks everyone and especially Danny and the guys at OCGMP
Melting Slicks
Joined: Jul 2004
Posts: 2,577
Likes: 2
From: Long Island New York
I had similar problems with my Vette. I was told to check the fuel pump presure, lines, tank sock ect. It turned out that my S rubber hose that runs from the frame to the pump was very old and soft. The fuel pump was sucking the hose closed at wide open throttle and causing the bog. You can buy the S hose from Ecklers, aprox: $20.00. Al
Burning Brakes
Joined: Jan 2007
Posts: 1,164
Likes: 1
From: Port Clinton Ohio
St. Jude Donor '08-'09-'10-'11-'12-'13
I had similar problems with my Vette. I was told to check the fuel pump presure, lines, tank sock ect. It turned out that my S rubber hose that runs from the frame to the pump was very old and soft. The fuel pump was sucking the hose closed at wide open throttle and causing the bog. You can buy the S hose from Ecklers, aprox: $20.00. Al
Burning Brakes
Joined: May 2006
Posts: 763
Likes: 0
From: FBO Florida
I had the same problem with bogging down. On the road it necessitated throwing in the clutch until the rpm's came back. Eventually it would bog down again. The tank/gas looked clean and clear when checked before driving but took on a more rusty turbid consistency after agitation from stop and starts which fouled the sock. I replaced the tank, the sender, the sock and cured the problem.
My tank does not have a liner (rubber bladder) but yours might. Frequently these have been known to collapse.
My tank does not have a liner (rubber bladder) but yours might. Frequently these have been known to collapse.
Thread Starter
Drifting
Joined: Aug 2007
Posts: 1,838
Likes: 13
From: Kingman AZ
I appreciate all the feedback. A forum member has a lift and were gonna take a look. Got plenty of good ideas from all. I'm hoping its the rubber hoses at the fuel pump. That would be the easy fix. But I'll be checking all your ideas
