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Kent,
I took it to a mechanic (because I havent had time to work on it for a long time) and they tested the pumps and found them both to be bad. They were only putting out a max of ~5 psi. They wanted a little over $300 to replace the front fuel pump and over $400 for the rear fuel pump becuase they were going to have to cut the trailer hitch off to pull the rear tank off the van. So I told them to replace the Fuel return valve in front of the carb and replace the filter in the carb and I will either replace the pumps in the tanks or put some kind of booster pump inline.
Do you think this is feasible? Could I put an inline boosterpump in the fuel line to raise the fuel pressure and volume to an acceptable level? or do you think this would overrun the carb with fuel?
JOhn MOnroe
John, no pressure regulator in the carb. engine, just the later F.I. ones, pump design determines pressure. I'm going to send you an email with the pump(s) volume and pressure check proceedures. In trouble shooting a problem, it's best to start at a source, in this case, the fuel pumps, and work outward from there.Two things that haven't been mentioned are the heated aircleaner, (not modulating and getting too hot), and the fuel level in the fuel bowls,(check via the plug in side of bowl casting).
John, the fitting before the carb that has the fuel return line to the tank is merely a "Tee" with no moving parts, just an orifice for the bled-off fuel to return to the tank.
John, I have the same year and model chassis under my Class C. First, have you replaced the little Engine Stopper filter in the carburetor inlet? I added a clear plastic inline filter in the feed line from the select valve to the carb, right at the select valve. Used a loop of fuel line to keep from having to cut and bend the steel fuel lines. Line diameter was 5/16". Then I replaced the little ceramic filter in the carb inlet. Mine has a feed-to-carb-to- return tee right at the carb, so remember, any blockage in the carb inlet filter will just send the fuel back to the tank. NOW, at about the speed you describe, on a hot day, with a/c running, after I'd been shut down half an hour to go eat, the engine stuttered, missed, and shut down. I ended up replacing my ignition coil. No problems since. A friend tipped me that the ignition "brain" (aluminum box on driver side fender liner) can also cause problems in these trucks. I actually bought both parts at Autozone and changed only the coil. Thinking I'll get a second coil to be able to carry new spares for both. Cost of both was well under $30 total and there were "lifetime warranties" on at least the module, maybe coil too. Camp happy and God Bless, jd |