Need help - fuel problem with my 53
#16
There are at least two fuel pump/carb problems thread going, so I'm starting to confuse what was posted in each, so if I repeat post excuse me. Since you have starter fluid on hand, start the engine and with it running at as low a steady rpm as possible, spray some of the fluid around the carb base, the body gasket seam, and the throttle shaft where it exits the carb body. If the rpm increases you have a vacuum leak. Choking the engine richens the mixture and increases the vacuum the problem is finding the reason that is necessary to do that. The accelerator pump is supposed to richen the mixture when the throttle is opened, The idle screw(s) adjusts the idle mix. Since this has been an issue for some time I'd suspect that the carb has never been adjusted properly, has plugged passage(s), the timing is not set correctly, and/or there is a vacuum leak. A fuel delivery problem will usually allow the engine to run not at all, or only at low rpms, but not at higher rpms.
#18
#20
I would circle back to Ax's first suggestion. Get a low cost fuel pressure test gauge at an auto parts store. Test fuel pressure. You can disconnect the line from the carb and put in the test gauge. There should be enough fuel in the carb float bowl for it to run for a little while....see what the fuel pressure is. It should be around 1 to 3 psi (check the service manual).
After that, shut off the engine and do the flow test. Disconnect the coil wire from the distributor and ground it....now put the open fuel line in a can and crank for a few seconds (Ax suggested 30 seconds).
Usually a failing fuel pump has low pressure and very little flow. The surging that you experienced sounds like vapor lock which usually gets worse if the pressure/flow is not up where it should be.
I didn't catch what engine you are running, but it does sound like a big vacuum leak somewhere...check not only at the carb base, but look for an open or broken vacuum line....such as the line going to the vacuum wipers. Also check the intake manifold from end to end.
Dan
After that, shut off the engine and do the flow test. Disconnect the coil wire from the distributor and ground it....now put the open fuel line in a can and crank for a few seconds (Ax suggested 30 seconds).
Usually a failing fuel pump has low pressure and very little flow. The surging that you experienced sounds like vapor lock which usually gets worse if the pressure/flow is not up where it should be.
I didn't catch what engine you are running, but it does sound like a big vacuum leak somewhere...check not only at the carb base, but look for an open or broken vacuum line....such as the line going to the vacuum wipers. Also check the intake manifold from end to end.
Dan
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1973 - 1979 F-100 & Larger F-Series Trucks
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04-28-2017 07:53 AM