1937 Packard 12 still not running right

Posted by 1508 On 2015/10/17 17:09:40

Working on my 1937 Twelve. Car ran & drove great for many years. Starting around 2003 car was only started & driven a short distance once or twice a year with some fresh gas put in. Car still ran & drove great 3 years ago (key point here), but wheel cylinders started getting sticky from inactivity so I laid it up to go over through the brakes. At that time I drained the gas tank and had 13 gallons of varnish on my hands. I got the brakes put back together last October. During the down time I also installed a new electric fuel pump (normally used for priming only). The old one was one of those cylindrical ones from the 1960's with points in it. It didn't work anymore, so I replaced it with an new Airtex rotary type pump. I put fresh gas in the car, started it up & it still ran great. Since the engine hadn't run in two years I let it run for probably half an hour, also using the hand throttle on the dash to run it at higher rpm. Everything seemed fine.....until I tried to drive it on the road.

After pulling out of my driveway and driving it maybe a mile up the road it started to buck like it was starving for gas. It couldn't be vapor lock I thought. It wasn't hot out, and when I tried driving it, it wasn't even fully warmed up. It never had a vapor lock problem in the past either. I turned the electric pump on and that seemed to help. If I turned it off again it would start the same symptoms again after a short time. The car would also die on occasion when coming to a stop at a stop sign. One time I drove down the road without the electric pump and it literally ran out of gas. I pulled to the side of the road, stopped, and tuned on the electric pump and it had to run for a good 15-20 seconds before the car would start again.

My thought was that the fuel pump diaphragm had weakened from sitting for 2 years with our modern alcohol laden gasoline. The pump was last rebuilt in 1999 in preparation of driving it to Warren, OH for the Centennial. So, this spring I had the fuel pump rebuilt by Antique Auto Cellar in MA. Put the rebuilt pump back on, drove the car, nothing changed or improved. Car still acted like it was starving for gas.

My next thought was either the gas tank has crap in it and is clogging the pick up tube, or the carburetor is gummed up. Since it's a lot easier to throw a kit in a carb than it is to drop the gas tank, I did the carb first. My thought was maybe it's gummed up or the accelerator pump was bad. Upon taking the carb apart I found the fuel bowl part did have a bunch of loose crap in it, and the accelerator pump has largely disintegrated. The carb had not been apart since the 1960's. I thought for sure this was my problem. I took it all apart, cleaned it thoroughly, used compressed air to blow out all the passages and put it back together
with new gaskets and a new accelerator pump.

Got the carb back on the car today. Drove the car, same results. Still starves for gas after driving a short distance. Still runs out of gas & needs the electric pump run to get it to start again. If I keep the electric pump on while driving it, it will stay running & drive OK.

So now my thought is that it is the gas tank. I think there's crap floating around in there and it's getting sucked into the pick up tube when the car is driving at a higher rpm. I'll post a picture of the electric fuel pump too. I don't think it's blocking the flow of fuel as the car will idle in the yard all day long. It's just when it's under load at a higher rpm that the symptoms emerge. But why would it run in the yard OK with the throttle pulled out to say, 1500 RPM, and not starve for gas?

Before I put the car away for the winter & pull the gas tank I'll ask: What do you guys think? The gas tank was last done in the early 1970's. The Bill Hirsch treatment was used at that time: the tank was sloshed with rust remover, then sloshed with a neutralizer, and then some type of sealer put in. I'm wondering if the alcohol in the gas has loosened the sealer.