Re: Strange 4bbl carb problem ...
Many thanks for everyone who volunteered their opinions, but after
tearing the carb apart and finding NOTHING wrong, it has been quite a
witch hunt to find the REAL culprit. Here is what apparently happened:
The fuel pump developed a microscopic leak in its diaphragm, which built
up fuel behind it (the business side is on the bottom, so the gas
collected on the top of the diaphragm). There was a 1/4" hole in the
side of the pump to keep any leaking fuel out of the oil, so it leaked
out there and THAT is what we smelled for days preceding the
semi-disaster. When I removed the fuel pump, it dumped a teaspoon full
of gasoline onto my hand from that vent hole. Further, everything below
the vent hole was VERY clean.
When, we drove ~50 miles to town on a HOT day, loaded up our trailer
with a half a ton of stuff, and generally heated the engine block well
above the boiling point of the gasoline. With the PCV system in good
working order, the vaporized gasoline from the leak was sucked IN to the
crankcase, some went into the oil (that gained about 3 quarts in volume)
and the remainder went either through the PCV or the crankcase vent to
the air cleaner. I suspect that in the process the leak got a lot worse.
Curiously, once in this mode, we didn't smell any more gasoline -
because it was no longer leaking externally, but was all being sucked
into the engine!
In total, this hassle ended up including:
1. Tearing apart a perfectly good carburetor.
2. Changing the oil and filter.
3. Replacing the air cleaner.
4. Replacing the fuel pump.
5. Replacing the tank full of gasoline that was lost, this being the
biggest actual expense of them all!
I had just gotten back from a long trip in this vehicle. I shudder to
think how this story would have turned out if this had all happened on
the road. By the time some repair shop had replaced the carb, etc., I
could have been out a LOT of money.
Thanks again for everyone's comments.
> On my 1985 351 E150 with a Ford/Holley 4 bbl carb:
> For the last few days, I have smelled gasoline coming from the engine
> compartment when the engine warmed up. I just presumed that a vent hose
> had come loose so I wasn't worried about it. Then ...
> I drove to town about 40 miles away, and the engine started running
> TERRIBLY, like it was getting WAY too much gasoline. I immediately
> headed straight home, but I used an entire tank of gas in just 40 miles!
> Obviously a sunk float, or so I thought. I restarted the engine and
> pulled the two float level screws from the float bowls, but no gas ran
> out! Further, the engine now idles OK!
> I suppose that a temporarily stuck float bowl valve could have done
> this, but that wouldn't explain the smell, and besides, I don't like
> "bogeyman explanations".
> Any ideas what ELSE could have gone wrong to do this?
> Thanks in advance for saving my carb.
> Steve Richfie1d