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1931 370A HOT STARTING PROBLEM

Started by rhr1931cad, September 02, 2013, 03:06:46 PM

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rhr1931cad

My V12 starts like a charm when cold  and when it cools down after running. Hot starting has always been a problem regardless of fuel or fuel additive.  I dont drive that much but i use VP racing  vintage leaded fuel only. Runs great on that. Car does not run hot. I can run all day and the temp stays fine. Would retarding the timing a little help or any other suggestions?
thanks Robert
ROBERT ROSENWASSER MD,MBA,FACS

Cooke

Robert, when I had my 30 Cadillac I had to use an electric fuel pump when it was hot, never had any problems on hot starts with the electric pump. If you mount them near the tank and use half inch or thicker rubber mounts its hard to even hear it. I don’t think a vacuum tank can overcome vapor lock especially with today’s fuel. I am now having the same issue with my 38 but I think I now have it solved with help from other forum members. Hope this helps. Martin

Martin Cooke

rhr1931cad

Martin,
thankyou for the tips. Do you worry about vacuum tank overflow or do you manually control the electric fuel pump.
Robert
ROBERT ROSENWASSER MD,MBA,FACS

Cooke

Robert,

I did worry about it although I think the tank can handle it. What I did was bypass the vacuum tank and went directly to the carb. I did install a fuel regulator (you can get them at any auto parts store, cheap) and set it to 3 Lbs. Works great always started. I put an electric shut off switch under the dash out of sight, its always good to be able to shut of the gas if a problem comes up.

Johan Boltendal #158

Make NO mistake, the Vacuum tank can't handle the electric pump, the gas will be all over the engine.  Johan

rhr1931cad

2 questions: 1. did you mount the electric pump near the vacuum tank or fuel tank. 2. is it possible to just use the pump to prime during hot starts and then turn it off. i.e.. use a push button switch that if off when released. that way it would not be continuous and hopefully avoid vacuum tank overflow?
ROBERT ROSENWASSER MD,MBA,FACS

Chris Cummings

Robert,

Are you sure that yours is a fuel problem, and not electrical?  These beasts need plenty of electricity, thick cables and solid connections.  My V-16 used to do what your 12 is doing until I got a new battery with 860 cold cranking amps.  I use heavy welding cable, too.

Chris Cummings

47bigcadillac

#7
Sounds like some percolation (fuel boiling in the Carb) due to heat build-up after the engine is stopped on a hot day.
The mixture is too rich to ignite - an electric fuel pump is only going to make things worse.

Do you smell gasoline ? does the car smoke just after having started ?

Try the following to narrow the issue: slowly depress the gas pedal and crank the engine with throttle fully open to see if it starts easier.

Heat Insulating fuel components (pump, lines, carb to intake etc) will help.
The other solution is to change the fuel mix back to how it was in the early 1930's by adding a heavier component such as kerosene or diesel in it.
R. Brandys

1932 355B  5 pass Coupe,  Fleetwood          
1935 LaSalle Coupe  5077
1947 Club Coupe      6207