Packard Forum Index » General

A customer came in asking if we had a 6v electric fuel pump.
His car had been hard to start after sitting for a month so he added the electric last summer, problem cured. He thought the fuel was "draining back" and he needed the electric to fill the carb before tryng to start it after storage.He only uses the electric to start, then irt runs on teh mechanical. Now he was having the problem again and concluded that the ethanol had destroyed the electric fuel pump as turning on the pump did not allow the car to start

I said that I would presume that recently manufactured pumps were alcohol compatible. Then he asked for an oil filter, said he had to change the oil often as it has gas in it, happened before the electric also.

I told him the problem was that the diaphragm in the mechanical pump had a hole in it. That woudl account for it not being able to pump up fuel after storage and that would account for the gas getting into the crankcase. Brought his pump in, tested and inspected it, that was the problem.

His "suspicions" about ethanol led him to an erroneous conclusion. His failure to diagnose the original problem, which a pressure test would have shown, led him to a temporary cure for teh symptom but not a cure for the real problem.

His car runs and starts fine, my bet is that it will do so after stroage also.

This is a common and similar problem on older bikes, especially those with vacuum actuate petcocks.

The petcocks are left on (or the vacuum operated ones start to leak.) and the older worn needle and seat allow it to fill the carbs and slowly contaminate the crankcase oil with gasoline.

Someone gets the bike out, fires it and rides it and destroys the bottom end.

Cheap insurance, checking the oil for evidence of gas in any vehicle.

Fred, Thanks for the information. This has been my one big fear about sending gas through the mechanical pump with the electric. I only use the electric to start the car but also carry a long hose and fitting so in a roadside emergency fix I can bypass the mechanical pump if it should fail. I also carry a spare mechanical. The Packard Club website (http://www.packardclub.org/) under Tech Tips has a very nice article on installing electric pumps and recommends the Seagrave method used on it's fire engine many years ago. It is worth reading. If I were to install an electric pump to operate as my main pump I would use this method to bypass the mechanical pump so that either could be used safely.

To cortcomp

This is not at all similar to the situation with bikes as you describe. On the bike, the carburetor needle valve leak is, the fuel overflows the carb when the bike is parked, fill a cylinder , leaks past the rings and into the crankcase.

In the car I described fuel enters the crankcase via a fuel pump diaphragm that has a small hole in it. It flows down teh fp to carb line when parked, through the hole nad into the crankcase. Also when the electric pump is on teh entire fuel line/mechanical pump is pressurized and fuel leaks into the crankcase. When just teh mechanical pump is going the same leak occurs.

Completely different scenario.

That is why when one installs an electric fuel pump, it should always be installed in parallel. That is, with the output from the electric pump plummed into the output side of the mechanical pump. This requires a separate line to be run from the electric pump to the output side of the mechanical pump. Series installations, while they may work, are the lazy man's way.

(o{I}o)