I've spent the weekend working on this !@#$%^&*! M38. I subsitutued a new
condenser, tried an electric fuel pump, used a temporary replacement fuel
line, rerouted the fuel line several ways, tried disassembling and cleaning
the carb, and still, ring-around-the collar. I finally put a translucent
fuel filter in line before the fuel pump so I could see what was going on
with the fuel supply. *Then* I made some progress...
I saw two things happening: When the engine was running moderately well,
there was only a little bit of liquid fuel in the bottom of the filter, but
there were numerous bubbles of vapor flowing out of the line from the tank,
and when the engine sank to the lowest depths of performance (or stalled
completely) there was no liquid in the filter at all -- just vapors! After
nursing the !@#$%^&*! vehicle home after midnight after the third failed test
drive (using gravity gas can & hose feed and looking around the hood), I
realized that I better go to bed before I hurt something or somebody.
This morning I pulled the stock filter and vent assembly out of the fuel tank
and looked at it again. Watching the fuel dribble quite slowly back out of
the filter element made me think it might be plugged up, tho it is pretty
hard to tell by looking. Since I had the see-thru filter up in the line by
the pump, I removed the rigid-yet-supposed to be porous filter element
completely. By the way, anyone know what it is made of? Looks like seashell
or some kind of ceramic...
It was then that I noticed that the dip tube was jagged on the end, like it
had been cut with the hacksaw instead of a tubing cutter. Then I measured
how far it extended into the tank. Not far enough! I bet someone cut it
short, perhaps to reduce intake of sediment (but it is *inside* of the filter
-- so I guess I don't know why it would have ever been shortened). In any
case, while I still had a 1/4 tank of gas, it was barely touching the surface
of the fuel!
Looking back on this madness, it looks like I fixed the problem but it may
have had several causes: weak pumping action, semi-plugged filter, and
perhaps a dirty carb. But running the engine so much for troubleshooting
lowered the fuel in the tank so that I was running out of gas - sort of
(thanks to the shortened dip tube). No wonder I was going crazy!
So after all this I'm back to the stock pump, stock line, no tank filter, and
the added inline filter. I put more gas in the tank (what a concept!) I took
it for an extended test drive this afternoon (I even risked going out on a
busy road -- amazing!) It performed well. I still see a few bubbles of
vapor coming into the inline filter, but it doesn't seem to be a major
problem, as the filter is about half full of liquid fuel. Much improved in
that regard.
Sigh -- I need a nap.
Steve Johnston
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