thoth@tellab2.UUCP (Marcus Hall) (06/13/84)
I have a Fiat X1/9 that is exhibiting a weird problem. Every now and
then the engine will die. When this happens, there is no fuel in the
fuel filter in line from the pump to the carb. After sitting for a
while (sometimes a few minutes, other times several hours), it runs
fine. Once when it had failed, I disconnected the fuel line and cranked
the engine and the pump didn't output any fuel. I sucked on the output
from the pump and was able to easily get some gas out, so the lines are
not clogged. Blowing back into the line I could not force the fuel
backwards, so the valves in the pump were ok and it didn't have a leak.
Although I am not absolutely sure, it seems to happen only when the
engine is rather hot (long trips on hot days), so perhaps it runs after
it has cooled down?
Do these symptoms make sense to anyone out there? I have not run
pressure and capacity tests on the pump, but I intend to as soon as I
get a chance.
marcus
..!ihnp4!tellab1!tellab2!thothrls@ihuxf.UUCP (Richard Schieve) (06/13/84)
I have no experience with Fiats so I'll relate a similar problem I had with my 1980 Mustang. My symptoms were very much the same, loss of fuel pressure (particullarly when the engine was hot), no fuel line restrictions and disconnecting the fuel pump at the time of failure (many failures) showed no output of gas. The fuel pump itself pumped plenty of gas from the tank to the pump and right back down the return gas line back to the tank!!! It seems that many newer cars have fuel pumps with internal regulators that are supposed to keep a constant fuel pressure to the carb by routing excessive fuel back to the tank. This is much easier on the float valve in the carb. In short, my fuel regulator was shot!. To make matters worse the first replacement pump was also bad leading me to distrust my own diagnosis but the second replacement solved the problem. A second guess may be a problem with your gas tank venting system causing more vacuum in your fuel tank than the pump can overcome. This is easy to test by just listening as you remove your fuel cap next time your car fails. Rick Schieve
mikey@trsvax.UUCP (06/15/84)
#R:tellab2:-13000:trsvax:55200068:000:469 trsvax!mikey Jun 15 09:17:00 1984 Check if the fuel line runs over/near any hot parts of the engine, i.e. exhaust manifold, pulsair pump pipes, etc. This can cause the gas to actually boil to a vapor in the line, and the fuel pump gets high pressure fumes instead of liquid locked inside it. You can reroute the line or do what I did on my 68 Mustang, I wrapped the fuel line with a sandwich made from a sheet of paper on a sheet of aluminum foil. This will insulate VERY well. mikey at trsvax