Can't disconnect fuel line at carb

[smithjw]

I think that the fuel filter has never been changed in my '81. I want to change it but I can't get to it at the carb. The fuel line seems to have a fitting at the carb end, which fits into another fitting that has the filter in it. When I try to remove the fuel line fitting from the filter fitting, the fuel line starts to twist with the fitting, so I stop before the line deforms and breaks.
Now, normally a fitting will spin around outside the actual fuel line. Is this not the case here or am I doing something wrong? Seems like the fitting is frozen to the line. The Haynes manual shows that you use two wrenches to do this. One on the fuel line fitting and the other on the fitting that holds in the filter. They don't go into detail but I imagine that you hold the wrench steady on the fitting holding the filter, and turn the other wrench counter clockwise to loosen the fuel line fitting. Can anyone give me any advice on what might be doing wrong, or if the line is actually frozen to the fitting, what can I do to free it? Thanks for your help.

 

[mikejpss]

Jeff , you are correct in all of your observations.

You have a couple of choices:
1. Spray anti-sieze/nut buster onto the fitting and let set overnight. Give it a few taps and try again. 50-50 chance it'll knock loose
2. Continue to try and stop short of twisting the metal line. Cut the metal line and continue, replacing the metal line with a new (aftermarket) one or a rubber,gasloine grade line. I took this option.
hope this helps

 

[smithjw]

OK, thanks Mike. I thought I might have to go one of those directions. If I use the rubber line like you did, will it run from wherever I cut the metal line right to the fuel pump, or do you make another cut near the fuel pump and run the rubber line sort of just between the metal line at the carb and the metal line at the fuel pump? Thanks again.

 

[mikejpss]

disconnect the metal line AT THE FUEL PUMP discharge fitting, get the correct brass fitting that will screw into the fuel pump and accept the rubber hose. DO NOT merely slip a piece of hose over the existing metal line and screw a band clamp down- if done like this you're asking for a hood compartment fire. !!!

In other words, you're deleting the metal line all together and replacing it with a rubber hose.

Back up all the way to the fuel pump and run one hose from there to the carb intake at the filter. You're auto parts store will have these brass fittings, you'll need one at the pump and one at the filter inlet. Be sure to secure the new hose down with a tie rap to something to keep it from moving about.

You're BEST bet is to buy another metal line, but that will be a time consuming effort.
good luck with whichever route you take.

 

[81 Corvette]

here is the deal. You need two wrenches. ONe for the fuel line and one for the fitting the line goes into. YOu have to do teh double wrench thing to keep from twisting your gas line. After the gas line is removed, use the big wrench and remove the fitting. Replace filter and reverse procedures. If memory serves, tehre is a spring in there, so make sure it goes back in.

Also, be very carefully with that fuel line. I was messing with mine, and somehow caused it to start leaking at fuel pump fitting. I'm still miffed by that one.

 

[vettenick]

If you do the two wrench thing...sometimes if you tighten it slightly at first, then try to loosen it may work for you. If you have to toss the line, I wouldn't use anything but a steel line to replace it.

 

[smithjw]

Update: I ordered a new line. Received it yesterday. Installed it last night. This job took a lot longer that I thought it would. The only way I could get the old line out and the new line in was to remove the A.I.R pump/system. While doing this I realized that the A.I.R pump did not have the pully on it. Therefore, although all the electrical connections and hoses were intact, I suppose it was not working. Would it be safe to say that I could just leave this thing out and not reinstall it? If so, what would I use to terminate the hoses, some of which are about 1 inch diameter?

 

[vettenick]

There's check valves at the end of the hoses. They prevent exhaust gas from coming back. If you disconnect the hoses, and you don't haer an exhaust leak when you start the car, then the valves are OK. If you don't have emissions inspections where you live, then you're probably OK.

 

[smithjw]

Thanks Vettenick. I assume that you mean I should remove the hoses entirely and that the check valves are in the ends where the hoses connect to the engine and not the ends that connected to the A.I.R pump. Is that correct? No emmisions check where I live.

 

[vettenick]

That's right. If you feel energetic, you can try to remove the tubes from the exhaust manifolds and replace them with plugs. I would only do this if there's not a lot of corrosion and you have time to do it .

 

[81 Corvette]

i removed my air pump last summer. the bubba in me connected the two hoses on passenger side in a loop. On the driver side, i plugged it with a wine bottle cork

its ok, headers go on next week.

 

[smithjw]

new problem: idle is very rough. I notice a very very high pitch sound coming out of the carb air horn at idle. Goes away and runs fine when you give it gas. I was wondering if when I was trying to originally get my old fuel line disconnected from the carb that I may have messed the carb up. I tried the spray with nut buster on the fuel line fitting and then gave it a few taps to try and loosen it up. Maybe my taps were a little too hard and I hurt something in the carb? I would say that the high pitch sound is a vacuum leak in the carb or something like that. I have read that a vacuum leak can cause a rough idel condition although I have not read where the vacuum leak is in the carb itself. Anyone have any suggestions? Should I take the upper portion of the carb apart and take qa look inside?

 

[vettenick]

You're right. A quick check for a vacuum leak is to use some propane around the carb base. If you notice the idle change...you've found your leak. By the way, when you use the propane, don't light the torch.

 

[smithjw]

I tried the propane and also the spray WD40 around the carb gaskets method and neither made a difference to how the idle was. If I let the engine run for quite a while the idle usually smooths out a bit, but if I turn the engine off and then restart, the idle is very bad again. I can then get it to smooth out by disconnecting the mixture solenoid electrical lead on top of the carb. Would this indicate that the solenoid might be bad? Or possibly that the ECM is not controlling the solenoid properly? I can't believe I'm having these problems all because I wanted to change the fuel filter! I should have left everything alone as it was running great.

 

[mikejpss]

Go back over all of your vacuum lines, sounds like u made one leak somewhere.

I had the same problem , fell out with a good case of the glow butt and changed the engine. Turned out to be a bad timing chain.Just my EXCESSIVE CUMPULSIVE disorder, your problem sounds simple enough. Did you try the spray at the throttle linkage where it enters the carb?

 

[smithjw]

Yes, I have sprayed around the linkage. I have gone over the vacuum lines a bunch of times. Most of them are already blocked off and not used. I'm thinking more like when I changed the fuel filter, which was extremely dirty never having been changed before, that some dirt was dislodged from it while was banging on the fuel line fitting a few weeks back. At that time, I could not get it off so I put everything back together and went for a drive. That is when the problem started. Maybe some dirt got into the carb either at the jets or possibly somewhere near the mixture solenoid since that seems to be suspect. I may have to take the carb apart and check this out. Not sure if you could even see dirt blocking anything. Anyone know the procedure for cleaning these parts in the carb? Soak parts in carb cleaner and then blow with compressed air?

 

[vettenick]

The fact that the idle got better when you disconnected the solenoid is an indication of it running lean. By disconnecting the solenoid, the rods pull up out of the main jets, which means more fuel at idle. At this point, I would disconnect and plug each of the vacuum lines one at a time. If you see your idle quality change, then that line that you just disconnected or whatever it's connected to is your leak.

 

[vettenick]

By the way, if that doesn't work, then I agree with you that some dirt did get into the carb bowl. You'd be surprised how much can get by, even with a filter.Either way you look at it , it's running lean, at least at idle.

 

[smithjw]

I tried pluging each vacuum line and none had any effect on the idle. I then took the air horn off the carb. There was quite a bit of very fine red colored particles coating the bottom of every area inside that contained gas. I cleaned this all out with cotton swabs. Actually, the carb was very clean other than that which means this carb looks like it was already rebuilt at some time before I owned the car. Anyway, I put it back together and it ran about the same as before and maybe a little worse. I did not do anything with the mixture solenoid when I had the air horn off because I wasn't sure how to get it out or if I could do anything to it anyway. So, my suspicions at this point are a bad mixture solenoid, or possibly the computer controlling the solenoid is not working properly. There is one other thing I noticed. If I hold the gas pedal steady at say 2000 RPM, the engine does not run steady. It pulses just a little bit, say down to 1900 and then back to 2000 every 3 to 4 seconds. Maybe this is another clue that someone else might identify with. Could the fuel pump itself cause problems like this?

 

[vettenick]

I'm concerned about that red stuff. It could be rust in your lines. At this point I believe a fuel system check is in order. That means the lines, sending unit and its filter, and the pump.