Graham Man Posted May 9, 2021 Share Posted May 9, 2021 Ok this is one of my new cars, well actually a 1977 Ford truck. It has a 400 CID carbureted 2 barrel engine with a mechanical fuel pump. It gets driven weekly but normally only short trips. It ate a fuel pump a couple years ago, so I replaced it, about a year ago I lost another one, this spring I am on number two, so 4 in total. I had a clear fuel filter in line before the carburetor, no evidence of any garbage, pulled the carburetor fuel filter, spotless, pulled the fuel sender to look in the tank, looks clean. Last time I replace all the rubber lines. I did not blow the lines backwards, that is next on the list, all 3/8 inch lines, in cab fuel tank, it could almost be a gravity system. At first I blamed it on old shelf stock fuel pumps. If I put on a new pump, it fires right up. I only use nonalcohol fuel, and yes the gas cap is vented. It has to be garbage in the tank pick up? Looking for any ideas? Last resort is put in a electric fuel pump? (I hate electric pumps) Link to comment Share on other sites More sharing options...
zeke01 Posted May 9, 2021 Share Posted May 9, 2021 Are you buying aftermarket pumps? If so, try one from the dealer. I had the same problem with a non Ford product years ago. Factory pump worked for years after installation. Zeke Link to comment Share on other sites More sharing options...
Graham Man Posted May 9, 2021 Author Share Posted May 9, 2021 I was told they are no longer available from Ford Link to comment Share on other sites More sharing options...
joe_padavano Posted May 9, 2021 Share Posted May 9, 2021 Define "ate the fuel pump". That's not exactly an informative description of the failure mode. Link to comment Share on other sites More sharing options...
Graham Man Posted May 10, 2021 Author Share Posted May 10, 2021 Must be a ruptured diaphragm, just stops pumping. No fuel leakage, no noise, lever looks new. If I put a new one in the truck fires right up. Link to comment Share on other sites More sharing options...
Larry Schramm Posted May 10, 2021 Share Posted May 10, 2021 Any smell of fuel in the engine oil? Sometimes with mechanical fuel pumps you can smell the fuel in the oil. Also do you have any of the old pumps? What is the brand you are buying? If you have an old one, you might want to take one apart to see exactly what the failure is. Is it the diaphragm or one of the valves? That may help you diagnose the root problem. Just some thoughts. 2 1 Link to comment Share on other sites More sharing options...
Frank DuVal Posted May 10, 2021 Share Posted May 10, 2021 11 minutes ago, Graham Man said: Must be a ruptured diaphragm, just stops pumping. This usually puts gasoline into the crankcase. Not what you seem to have. Loose check valves stops pumping without leaking fuel anywhere (internal or external). I know loose check valves are an issue on new Corvair fuel pumps (for several years now). Lucky, those are screwed together, so one can open them up, re-stake the valves, and continue using them. All the pumps assembled with crimp edged are hard to open and even harder to reassemble!😲 Link to comment Share on other sites More sharing options...
Graham Man Posted May 10, 2021 Author Share Posted May 10, 2021 All local parts stores (China stuff), one Carter pump (still import). No fuel in the oil. I will cut up the Carter and look for the failure. The pumps are just the right age, could be lots of shelf years. Link to comment Share on other sites More sharing options...
carbking Posted May 10, 2021 Share Posted May 10, 2021 The gentleman I believe to be the authority on fuel pumps does not post on social forums. Try "Then & Now Automotive" in the Boston area. Ask for Tom. (781) 335-8860 Jon. 2 Link to comment Share on other sites More sharing options...
joe_padavano Posted May 10, 2021 Share Posted May 10, 2021 10 hours ago, Graham Man said: Must be a ruptured diaphragm, just stops pumping. No fuel leakage, no noise, lever looks new. If I put a new one in the truck fires right up. Could be bad check valves at the inlet/outlet ports. Could be trash in the tank or lines that holds these valves open. Take a failed pump, hold it in a bench vice, and actuate the lever to see if you get any suction. Consider an inline fuel filter on the INLET side of the pump. 1 Link to comment Share on other sites More sharing options...
ojh Posted May 10, 2021 Share Posted May 10, 2021 Sounds like a restriction on the supply side where a new pump will overcome it but it causes early failure in the pump. I'd replace the tank and lines. You say the 'tank looks clean' without conviction, I read a little doubt into it. Link to comment Share on other sites More sharing options...
Graham Man Posted May 10, 2021 Author Share Posted May 10, 2021 Yes the tank is another obsolete part, did I say it was an easy problem? Will the inlet side filter be OK? between the tank and the pump? Link to comment Share on other sites More sharing options...
Charles259 Posted June 5, 2021 Share Posted June 5, 2021 👍 Link to comment Share on other sites More sharing options...
Graham Man Posted June 7, 2021 Author Share Posted June 7, 2021 Yes all good fuel pumps, factory style mechanical pump, replaced all the rubber lines. This last time again with a new fuel pump I blew the line backwards with compressed air. My only guess is small sediment plugging the factory fuel pick up sock? Running good again, we will see how long this one lasts... Link to comment Share on other sites More sharing options...
Billy J Posted June 7, 2021 Share Posted June 7, 2021 Just curious. Could it be Ethanol that's causing the problem ? I put on a new old stock ( really old ) fuel pump on my '35 which lasted about 100 miles. Replaced the fuel pump diaphragm with one made from Nitrile which is supposed to work with the ethanol in the gas. Link to comment Share on other sites More sharing options...
joe_padavano Posted June 7, 2021 Share Posted June 7, 2021 6 hours ago, Billy J said: Just curious. Could it be Ethanol that's causing the problem ? I put on a new old stock ( really old ) fuel pump on my '35 which lasted about 100 miles. Replaced the fuel pump diaphragm with one made from Nitrile which is supposed to work with the ethanol in the gas. NOS pumps will likely not be ethanol compatible. Link to comment Share on other sites More sharing options...
Graham Man Posted June 8, 2021 Author Share Posted June 8, 2021 I have not put alcohol fuel in any of my carbureted cars for about 6 years, it is wonderful, don't have to rebuild carburetors every spring anymore. You are correct incorrect fuel pump diaphragm dies quickly. I use this kit for most of my pre-war cars work great in all early Graham-Paige cars https://store.fillingstation.com/detail/FS-908/Chevrolet_192933_FUEL_PUMP_REPAIR_KIT.html Link to comment Share on other sites More sharing options...
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