Rosiesdad Posted February 10, 2011 Share Posted February 10, 2011 My '50 special boils the fuel in the Carter fuel filter mounted next to the carb.Even after a short drive on a mild day the fuel is boiling inside the glass bowl and forcing past the float bowl needle and dripping out the throttle shafts and elsewhere. I am hoping to find a pressure relief valve that would work with a return line to the tank.Anyone tried this????Thanks,Phil Link to comment Share on other sites More sharing options...
Fr. Buick Posted February 10, 2011 Share Posted February 10, 2011 Sounds like several possible problems before you conclude that the fuel is boiling, i.e. vapor lock.First is to check that there might be a leak in the fuel line. The fuel pump would then draw air into the system, making it look like boiling. I would disconnect the fuel line at the carb, have a friend apply air pressure at that point in the line, then trace the the fule line all the way to the tank and listen for a leak. Or better yet apply soapy water with a small brush and look for bubbles at all the fittings along the line.Next, I would rebuild the fuel pump. It is not hard to do yourself.Lastly, I would look at the carb. It sounds to me like the throttle shaft is worn out and the carb needs a rebuild.Happy wrenching! Link to comment Share on other sites More sharing options...
Ben Bruce aka First Born Posted February 10, 2011 Share Posted February 10, 2011 Phil, I may be wrong, but i would think the last thing you want to do if the fuel is in fact boiling is to reduce the pressure. This would allow it to boil more. Fr. Buick is correct on the carb. If it has not been rebuilt, perhaps it should be. I have a '50 Super with the Carter carb and filter that does not have this problem. Another thought- have you perhaps managed to get a tank of E-85 gas? Just some thoughts. Bye the way, what part of the world are you in? Ben Link to comment Share on other sites More sharing options...
Don McClair Posted February 10, 2011 Share Posted February 10, 2011 (edited) I have a friend with a 38 Century that kept dying on the highway. He kept saying that it was vapor locking because there was bubbles in the fuel bowl and he thought the fuel was boiling. I put my hand near the fuel bowl and could not feel any heat so I wrapped my hand around it. It was not hot so the fuel could not have been boiling. His problem was the sock on the end of the pickup tube in the tank had deteriorated and was sucked up into the fuel pump blocking the fuel. Apparently the fuel pump had created a vacuum and resulted in the air bubbles in the fuel bowl. Possibly the carb needs to be rebuilt and I can suggest putting some Stabil for Ethanol in the tank. It is the blue stuff that is also for motor home/marine applications. Edited February 10, 2011 by Don McClair (see edit history) Link to comment Share on other sites More sharing options...
Rosiesdad Posted February 11, 2011 Author Share Posted February 11, 2011 Thanks Guys,I have a Carb rebuild kit but have not installed yet. Don't think that will help the fuel boiling though. I have a glass fuel filter bowl so can see the problem. I don't think I got E-85 but its possible. Here in the S.F. CA area its hard to get good gas. The fuel pump looks new/rebuilt and also have a 6V electric pump at the tank. I have no leaks in the line but as the pressure builds it forces out of the carb. Link to comment Share on other sites More sharing options...
Guest NikeAjax Posted February 11, 2011 Share Posted February 11, 2011 Um, if it is boiling, look for a heat source; your line could have come loose somewhere and now it's on something hot, or very warm, like the exhaust pipe. An old trick that people used to do is ad a bit of diesel fuel to your fuel mixture to keep it from vapor-locking: yes I know I'm a dirty dog for even mentioning it and it will kill everyone in a 12-mile radius if you do, oh, and it will cause you to grow a second head too, and that will keep you up all night arguing! I've done it, and know it works! Just a thought...JaybirdPS, you may want to wrap your line in something to insulate it from the heat. Link to comment Share on other sites More sharing options...
MrEarl Posted February 11, 2011 Share Posted February 11, 2011 and it will cause you to grow a second head too, and that will keep you up all night arguing! now THAT's funny. will need to remember that one:D Link to comment Share on other sites More sharing options...
Guest Jim_Edwards Posted February 12, 2011 Share Posted February 12, 2011 This really does sound like a very small pin hole in a fuel line or a connection not being tight. Might even be a crack in a rubber fuel line. I think a vacuum test of the line from the tank to the fuel filter is in order. Steel fuel lines can develop minute holes that do not drip whether the engine is running or not and old flex lines can ooze fuel and/or suck air through cracks. Certainly deserves immediate attention before a fire takes out the entire car.Jim Link to comment Share on other sites More sharing options...
Rosiesdad Posted February 12, 2011 Author Share Posted February 12, 2011 Thanks All!,But wouldn't I SEE a leak in the line when the fuel boils and pressurizes the system??? or is there a check valve in the pump and the leak possibly before that point?p Link to comment Share on other sites More sharing options...
Guest Jim_Edwards Posted February 13, 2011 Share Posted February 13, 2011 (edited) Thanks All!,But wouldn't I SEE a leak in the line when the fuel boils and pressurizes the system??? or is there a check valve in the pump and the leak possibly before that point?pWhat makes you think the fuel is actually boiling. Bubbles in the filter bowl doesn't mean the fuel is hot enough to percolate. Even if it was it would have to be fighting the 4 to 6 psi the fuel pump generates. Your fuel system is sucking air from some place and that is what is causing the bubbles in the fuel filter bowl. Replace all old flex lines and if that doesn't solve the problem then it's time to test the metal fuel line, which I'd go ahead and do while replacing any old flex lines.Jim Edited February 13, 2011 by Jim_Edwards (see edit history) Link to comment Share on other sites More sharing options...
Guest NikeAjax Posted February 15, 2011 Share Posted February 15, 2011 No, I doubt it if you'd actually see the leak; they act rather counter-intuitively! Gasoline has such a low flash-point it wouldn't take a very big hole to make it bubble: it would probably just look like a very slight metal imperfection, or a piece of dirt smaller than a fly-spec--really! It could be anywhere and you'd never see it.Jaybird Link to comment Share on other sites More sharing options...
Rosiesdad Posted February 15, 2011 Author Share Posted February 15, 2011 Well.... I did find some loose rubber gas line down under the car. Also the gas line touches the upper radiator hose. I pulled off the intake manifold and found the riser baffle stuck in the middle position so I forced it closed. The carb has a pressure relief ball in the bottom that was stuck closed. Now time to put it back together..... Link to comment Share on other sites More sharing options...
Rosiesdad Posted March 8, 2011 Author Share Posted March 8, 2011 FYI. Seems like the main problems I corrected were a loose hose clamp down under and I put a rubber sleeve around the fuel line where it was in contact with the engine. I also removed the intake manifold and forced the heat riser flap all the way off from it's stuck half open position. So far no fuel boiling in the gas filter. I rebuilt the carb too but don't think that was related to this remedy.Phil Link to comment Share on other sites More sharing options...
buick5563 Posted March 8, 2011 Share Posted March 8, 2011 Thanks for the update Phil. It is always helpful for folks in the future to post the results. Link to comment Share on other sites More sharing options...
60FlatTop Posted March 8, 2011 Share Posted March 8, 2011 Here is a link that may be of value:Carburetor Tune Up Guide - The Carburetor DoctorBernie Link to comment Share on other sites More sharing options...
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