Electric fuel shutoff

[rally 1]

Symptom:

Engine runs fine for 15-20 minutes, fuel pressure (gauged) starts to drop off until it is at zero, engine then stalls.
After five minutes, I can restart with the same sequence of events.
The electric shutoff (purchased from Snyders) was installed about five years ago, and has been trouble free to this point.
What has been the experience out in the "A" world.
Does this sound like a failing shutoff.
The engine is equipped with a downdraft carb, and an electric pump.
Pump has been replaced with a new spare unit.

Thanks
Ken

[Tom Wesenberg]

Have you tried a loose gas cap, just in case the vent is plugged?

Also be sure to use the small filter in the tank valve.

[oldbike99]

I believe the Tom nailed it with the gas cap suggestion. Please give us a follow up on the problem.

[rocket1]

I definitely think you are pulling a vacuum in your fuel tank,not vented properly.

[1931 flamingo]

It's possible that the "crap" gas has gummed up the inside of your fuel shut-off. Dis-assemble (I can dis-assemble mine) the shut-off and clean with any good spray carb cleaner, re-assemble. Even after thoroughly cleaning your problem may re-occur + re-clean.

It almost acts like vapor lock doesn't it??
Let us know if this works.

Paul in CT

[Brianfrench65]

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Paul; could you please explain "vapor lock" and what causes it and how to avoid that problem?
Thank You Very Much

[1931 flamingo]

Brian: Ck your e-mail.
Paul

[Mitch//pa]

cmon paul i want to learn to

[rally 1]

Follow-up.....
Checked for a blocked fuel cap vent, not the problem
Removed the cap when I saw fuel pressure starting to drop, no increase in pressure.

However, while working on the running car, the coil was blistering hot.
Suspecting that to be the actual problem, I shut the car off, let it cool down for a couple of hours.
Hooking a Ohm meter to the coil terminals, at cold start it measured 28 Ohms, as it warmed up increased to over 50 Ohms, plus the coil was very hot after only ten minutes of running.
Coil used is a Mallory 29219,been in there about 5 years, 14k miles.
Anyway, ordered a new coil, should have it Tuesday for install.

More to follow.

Ken

[SeaSlugs]

coils should have low low resistance(like less than 10ohms) so i think you found an issue.

[Mike V. Florida]

Originally Posted by Mitch//pa

cmon paul i want to learn to

STOP IT!

Look up via search, perhaps the nastiest discussion on this forum, vapor lock.

[Mitch//pa]

im wondering what the coil has to do with the fuel pressure gauge going to 0
could it be a power supply issue to the pump?
i would first get to the bottom of the no /// losing fuel pressure..i think were starting to jump around..
1. supply issue // clogged tank pick up or line restriction // bad auto shut off etc etc.
2. fuel pump issue
3. losing voltage or ground to the pump itself
are you losing voltage to the pump when the car stalls acts up?
even if the coil is bad why are we losing fuel pressure after running it

[Tom Wesenberg]

Also when a coil gets too hot it's either the wrong coil, has internal shorts, or is triggered on for too long (lots of dwell). Have you checked your points adjustment? Also make sure the lower points plate wire isn't shorting to ground, or the wire from the key to distributor shorting to ground, or a repro switch terminal hitting the gas tank.

[rally 1]

Mallory dizzy with E-spark conversion. No points.
Voltage to coil is constant @12v.
I'll check the voltage to the running pump next.
I'm thinking that the pump might be on the same circuit as the coil.

This coil has an internal resistor, no ballast resistor required per Mallory.

I agree that it appears to be two separate issues.

Repeatable, run the engine for ten minutes (+/-), fuel pressure drops off and the engine eventually stalls after the gage shows zero pressure.
Let the engine cool down, and repeat.

Thanks for the feedback.
Ken

[Mitch//pa]

Originally Posted by rally 1

Mallory dizzy with E-spark conversion. No points.
Voltage to coil is constant @12v.
I'll check the voltage to the running pump next.
I'm thinking that the pump might be on the same circuit as the coil.

This coil has an internal resistor, no ballast resistor required per Mallory.

I agree that it appears to be two separate issues.

Repeatable, run the engine for ten minutes (+/-), fuel pressure drops off and the engine eventually stalls after the gage shows zero pressure.
Let the engine cool down, and repeat.

Thanks for the feedback.
Ken

and ground side

[Tom Wesenberg]

Since the pump and coil are on the same circuit, when the pump pressure falls off, check the coil by holding the coil wire 1/4" from a head nut while cranking the engine with the key on.