Can't disconnect fuel line at carb

[smithjw]

OK. How about looking at something unrelated to the fuel system for a minute. Before all this started, I was checking out the heat riser. There was a vacuum line that turns into a steel line and goes into an actuator that controls whether the heat riser valve is opened or closed. I had read during the winter that the valve sometimes can get rusty and seize,so I put a some p-blaster on it to try and keep it free. I then worked it back and forth by pushing the actuator arm. Seemed like it freed up some, so I was not concerned. Now have gone back and looked at this again. Seems that the steel vacuum line was disconnected from the actuator by a previous owner. My question is, when this is disconnected, the actuator arm seems to be at full extension. Is this opened or closed? Can my idle problem be attributed to the valve being either fully open or fully closed? I am thinking that when I first started to play with this it was stuck in an in between position, and when I freed it up, it either went fully closed or fully opened.

 

[vettenick]

By default, it should be open. This way if there's a failure with the temperature switch, it won't hurt performance, just cold driveability. Now, if someone moved it into the closed position and it was stuck.........then it won't matter if the system is controlling it or not because the valve is stuck.

 

[smithjw]

Let me see if I understand this. You say that it should be open by default. So when the car has not been driven, engine is cold and not running, the actuator arm is fully extended and that should be open, correct? Then, when the engine is started, it is cold and the thermostat sends a signal for vacuum to the actuator, which retracts the arm and closes the valve? When the engine is up to operatting temp, the vacuum is stopped and the actuator arm is extended again and the valve opens?

You did not mention this, but if the valve was say stuck at half way open, could this cause the idle problem?

 

[smithjw]

I got a chance to test the heat riser last night. After engine gets to normal operating temp, I tried moving the riser valve to both full open and full close. I did not see any change in the idle when doing this. Not sure if this is a good or bad thing.

Anyway, looking at the fuel delivery system again, I opened up the fuel tank to have a look inside. Removed the line that has the 'fuel sock' on the end. Looked very clean. The inside of the tank was spotless. No visible rust or dirt. I then disconnected the fuel line at the carb and blew compressed air back to the tank. I then reversed and blew air from the tank feed line back up to the carb. While doing this, I also put my finger over the carb fuel line which caused the air to divert back to the tank through the return fuel line. Put everything back together and started the engine. Much improved. The idle seems like it might stabilize afte the computer has time to get used to the new readings it gets from the sensors. If I hold the gas peddle steady at 2000 RPM now, the surging is much less than it was before. Just a little now. So, now I suspect that I might have some clogging or dirt or something in the fuel pump itself which I might have partially cleared out. I already know that the carb, the carb fuel line, and tank are all clean, so that is why I suspect the pump. I really don't know what the pump looks like inside. Might there be some filtering done there? I suppose that some dirt could have accumulated in it once the fuel filter in the carb got so dirty that no more dirt would stick in the paper folds and the dirt would have gone back down the line and into the pump. Can anyone comment on this theory?

 

[SMKN97GP]

i had the same problem about a week ago with the fuel line going into the carb. i had to get the exact size line wrenches, use alot of pb blaster and have my friend hold the wrench on the big nut while i smacked the smaller wrench with a hammer. it finally broke lose and the fuel line didnt get bent.


since you guys are talkin about air pumps im gonna jump in here with a question. next week im doing a cat back setup and im gonan remove the cat, the pipe that come from the a/p that goes into the center of the cat, can i just connect that to exhaust pipe, and then just take the belt off the a/p? in MA you dont need to pass emissions on an 81. thanks

 

[smithjw]

When you say remove the cat, do you mean permanantly? I just removed the whole air pump, so the hose that went to the tube that goes to the cat was removed. There is a one way valve there, and mine is still connected from that valve to the Random Tech cat that I use. If you are permanantly removing the cat, then you don't have to do anything with that line. It would be disconnected at both ends. If you are still going to have a cat, you can plug the pipe that comes out of the cat. Mine came with a plug to do this.

 

[smithjw]

Another update: I spent the day replacing my fuel pump, as I suspected there may be a problem with it. After removing it, a one inch long, very thin nail poped out of the fuel intake of the pump. This was probably causing a partial blockage, as well as putting a small hole in the diaphram. I could blow into the intake of both the old pump and the new pump and there was a big difference. So where do you think a nail came from?? My thinking is that a previous owner replaced the pump before and used this nail to prop the pushrod up instead of using the longer bolt tip. After the new pump was in, the nail stays in there. I'm not sure if it's possible for the nail to find it's was inside the pump from there, but a nail got in there somehow. Anyway, the car is idling great now. There is still a bit of surging at mild acceleration, but I am hoping that this is just the computer learning again. I'll have to drive it around a bit and see.