re: Spica car misfire

["Tony Sims" <simstony@domain.elided>]

Erik writes:

>Anyone care to comment?  My '74 GTV has developed a misfire that only occurs
>after driving the car for 15 minutes or so.  It doesn't seem like an ignition
>misfire because it isn't worse with full throttle (and increased resistance
>across the plug gap).  I'm wondering if it is a fuel pressure problem because
>the fuel pump is quite noisy and the fuel pressure light sender hasn't yet
>been fixed.  Is this type of misfire likely to occur with pressure down?

Seems plausible.  My 74 GTV was behaving similarly, and the functional low
fuel pressure light was glowing slightly when the stumbling occured.  I
started by replacing the rear fuel filter (Napa Gold 3299), at the same time I
discovered that the last time this filter was replaced the fuel line was also
replaced with 3/8 ID line (must have been a struggle to get it over the tank
fitting, it was starting to split...).  I replaced that with 1/2 inch ID.
Stumbling stopped, fuel pressure light went out, speed was enjoyed.

The fact that your fuel pump is noisy doesn't mean it's bad, it could be
cavitating -- but if you don't get that stopped it will go bad, because these
Bosch pumps are lubricated and cooled by the fuel and they don't survive much
dry running.

Cheers,
Tony
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