If anyone read my '60 Pontiac Bonneville start up thread, everything from there has worked out and it's like 90% ready for the road. Tons of new parts, etc, etc. My new "all of a sudden" issues. 1.) After running perfect for a couple weeks, it all of a sudden doesn't idle right. It'll stay running giving it gas and you can also drive it. But soon as you let off, it cuts off. Never did that until recently. 2.) After you take it up the road or let it run a bit, all the fuel bleeds back thru the fuel line. I'm guessing it has something to do with issue 1 also. To get it to start back after a day or so I gotta put a little gas in the carb. After that it starts right up and gas is running back thru the lines. Any solutions to these 2 issues? To keep in mind, the gas tank and sending unit it brand new. Fuel filters been replaced. Fuel lines cleaned and blew out. The carb has been untouched on the count that it's ran fine without doing anything to it. Maybe something in there has took a crap?? Pump? Time to rebuild it?? Fuel pump? Add a inline fuel pump??
I would check all fittings, hoses, any place that could have an air leak. May not leak fuel but the pump could suck air. Friend had a '40 Chrysler that would run fine but would die if it went up a hill. He found a loose connection.
stock mechanical pump? Could be weak and not pulling enough at low RPMs or a pinhole/crack in the line sucking air- exactly how soon after returning to idle does it need a tickle from your foot? Hold it at a high IDLE RPM for several seconds to make sure the bowl is full- if it dies right after returning to idle, then you've got a tuning issue or maybe vacuum leak/other. If it idles for a bit while it drains the carb bowl, then you might need to freshen the pump. -rick
Yeah it's the stock mechanical pump..... Not long at all after letting off of it, I've gotta pump the gas pedal a bit. I replaced all the vacuum lines but it will fill the bowl. But as soon as I completely let off of it, it boggs off. Seems like it's also making a sucking noise at times when I'm revving it up keeping it running...
you could just have some trash in the carb from old or new parts- maybe she can only feed off the main circuit or the accelerator pump (the idle circuit could be clogged up).Vacuum leaks can come from fittings or intake manifold gasket, too- not just vacuum lines. Check to see that float level hasn't changed and then might want to pull carb apart for thorough cleaning, then also check intake and other vacuum leak possibilities. -rick
Old pumps do not have the correct rubber compound for ethanol blended gas. The ethanol breaks down the pump diaphragm and the crap plugs the carb up. You need a new, (not NOS) fuel pump and clean out the carb.
Man that makes tons of sense! I was just talking to a guy tonight about the ethanol in this new gas crappin out these old cars. Didn't even think of this! Thanks a ton man!
If the carb doesn't have a metal float, ethanol can ruin those too. New floats are made with material that will work with alcohol.
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