Packard Forum Index » Pre-War (1899-1942)

I have a 41 120 and fought vapor lock car alledgedly had a nos new pump on it. I ordered rebuild kit from then and now automotive installed and still vapor lock

Put six volt ac pump sold by great pla8ns Packard on car r8ght in front of rear axle with filter before pump. Ran wirinv through toggle zwitch on dash to ign switch. Took all guts out of pump
Xcept gaskets. Made block off plate and also took out pump actuating arm. Pump on engine has fuel flowing through it but is a dummy. My vapor lock problems are over. The toggle switch
Is a safety feature.

Sounds like a practical and all but invisible solution.

Many of us use a variation on that setup with a pulse type electric pump in the line near the tank and just run thru the mechanical pump.. Electric is switched on when used for priming or if the vapor lock condition occurs but otherwise is switched off and mechanical pulls thru the electric 99% of the time.

There have been a couple of installs where owners didn't want to risk a damaged diaphragm in mechanical pump dumping fuel into the crankcase. In one install the owner ran a very discreet and mostly hidden parallel line near the top of frame rail. It contained a check valve and fed by the electric to a tee and another check valve in the output line just after the mechanical pump. The connection was under the heat shield and not too visible.

The electric can still be used for priming and emergency but check valve at mechanical pump prevents pressure on diaphragm. The electric pump has its own valves and probably didn't need the extra check but the owner felt it was just added insurance to prevent mechanical from pushing fuel back into tank.

Another option is the bulb type hand pump commonly found on boats. I have one plumbed in just before the mechanical pump. Of course this requires you to open the hood to prime the engine, and offers no benefit for vapor lock. However it is quick and easy to install and could be easily removed as well. No additional plumbing or wiring required.