'72, 55 horse Chrysler Fuel Pump

Priester

Recruit
Joined
May 29, 2003
Messages
1
This '72 Chrysler 55 horse runs great if you hold he choke almost closed but will not continue to run if choke is left open. (It starts up just fine with the choke closed but seems to run out of gas a few seconds after it starts.) I figure it's a fuel pump problem. I took apart the fuel pump but could not determine what could possibly be wrong with it. I checked to see that air was being forced into the ports in the pump and the diaphram seems to be fine. But, I'm not sure. What goes wrong with a fuel pump? What might need replacement?
 

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Fleet Admiral
Joined
Mar 25, 2001
Messages
8,217
Re: '72, 55 horse Chrysler Fuel Pump

The biggest problem with these fuel pumps is modern fuel formlations. Alcohol 'enhanced' fuels disolve the rubber diaphram. Other 'additives' tend to dry out the diaphram, make it brittle, or make alligator hide out of it. Look closely at the ruubber (neoprene proly) diaphram for small cracks. Stretch it by hand a bit, and see if you can make out tiny bumps (like an alligator viewed from a 4th floor window).<br />The rebuild kits for this pump are cheap(under 20buks), and it takes less than 30minutes for the first-timer, if he is good with a screwdriver.<br /><br />Remove the removeable check valves carefully tho, or not at all, and simply shoot some carb cleaner thru them and allow them to rapidly dry. Do not soak them in carb cleaner or allow them to remain wetted-down too long, as they will melt,warp or otherwise be rendered useless.<br />It's best just to ensure they are operating and clean, and leave them at that.<br />It could also be be that the pickup in the tank is clogged, or the pickup tube inside the carb is partially blocked.<br />But rebuild the fuel pump as it is the weakest link, install an inline filter with changeable element, clean/inspect the tanks, carb bowl, and try it again.<br />leme know if you need further help.
 
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