fuel pressure question

[fredws]

What should the fuel pressure be at with the engine running?

I set up a presure gauge just before entering the carb, with it running, had about 4 psi, but as soon as I shut the engine off, it drops to zero. Shouldn't it hold pressure? I checked before the filter, and it has about 7 psi, and holds it after cranking.

My guess is it has something to do with the bypass line. Should it hold pressure? Can you just bypass the bypass? :)

[Torque]

The key is to have steady pressure when motor running,when you shut off the engine the pressure gauge needle should slowly return to zero when measured between the filter and carb.THe book say the guage should resd between 2.5-8psi with a mechanical fuel pump

[Don S]

Originally posted by fredws:
What should the fuel pressure be at with the engine running?

I set up a presure gauge just before entering the carb, with it running, had about 4 psi, but as soon as I shut the engine off, it drops to zero. Shouldn't it hold pressure? I checked before the filter, and it has about 7 psi, and holds it after cranking.

My guess is it has something to do with the bypass line. Should it hold pressure? Can you just bypass the bypass? :)..
fredws:...
What you described sounds OK to me. I would not want over 7 psi.. I had to add a fuel(& vapor) by-pass to my Wagoneer to help prevent vapor locking.

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[graham]

Originally posted by Don S:
[QUOTE]I had to add a fuel(& vapor) by-pass to my Wagoneer to help prevent vapor locking.
Don, Sure would be interested how you did this as this is a prob I sufer some times.