PMO carb starting issue

[Jim Dunham]

I now have finished a second car with PMO carbs.... and am fighting another case of cold "hard starting". It takes me 10 minutes to get it to start and I'm baffled as to why. Identical issue with last car. First car is a 3.0L and second is a 3.2L both with PMO's. 46mm / 36mm chokes on the 3.2L

Fuel levels prior to cold start are perfect. squirters work. Ignition has been carefully gone thru. (Car starts and runs fine when hot). I figured it should at least stay lit with pumping the throttle; working off the squirters if need be but it just coughs/sputters. Takes too many tries to get it to start and stay running.

I'm about to throw a pair of old 40 webbers on to see if its a signal strength issue.

[tom1394racing]

Hey Jim

I agree that a PMO carbureted car can be difficult to start especially in cold weather if the car’s been sitting for a while. My 3.0L with 46 mm PMO’s does not start as quickly as my MFI car does. However, I can always get it fired and running in less than 5 minutes. My process is as follows:

1. Turn on the key and let the fuel pump run for 10-15 seconds to fill the float chambers
2. Pump the throttle 2-3 times to squirt fuel through the accelerator pumps
3. With my foot off the gas pedal, run the starter for 10 sec
4. Repeat steps 2 and 3 until the engine just starts to fire. It usually takes 3-4 tries when the car has been sitting for more than a week
5. Once the car has started to fire but died, depress the gas pedal while cranking and the car usually will fire up.
6. Repeat step 5 until you can keep the car running with the gas pedal. It may take 2-3 tries.

I have found that trying to get the car to fire with the gas pedal depressed takes much longer. It also makes a big difference to make sure the battery is fully charged so you have plenty of cranking power. I do have a high torque starter in the car as well.

Hope that helps.

[PMNorris]

Tom's process works for me too. It always starts, it just takes a while.

Paul

[CheckBookChuck]

My car is a 1971T with Webers that I only drive once a month. My standard starting procedure regardless of how long it sat are: 1.) Turn ignition key to on and wait for the fuel pump reach resistance in the fuel line (the pump sound will change), 2.) Floor the accelerator pedal three times, 2.) Turn key to start while feathering the throttle just enough to get it running. This works every time, even for the 10 years I had the car in the Phoenix heat.

GOOD LUCK!

[al agustin]

Thanks CheckBookChuck, I have had the same starting problems too...I thought I was alone. The car runs absolutely magnificent otherwise (rebuilt Webers). Does reaching fuel pump resistance in the fuel line cause any harm? I find that my electric pump makes a ticking noise on start-up, is this the noise that changes and to what? Thanks again to everyone.

[CheckBookChuck]

Thanks CheckBookChuck, I have had the same starting problems too...I thought I was a alone. The car runs absolutely magnificent otherwise (rebuilt Webers). Does reaching fuel pump resistance in the fuel line cause any harm? I find that my electric pump makes a ticking noise on start-up, is this the noise that changes and to what? Thanks again to everyone.

The fuel pump pressure resistance is there all the time the pump is running and is perfectly normal and does no harm. The change is sound (ticking) seems to go away after the fuel line is pressurized and the pump is in its normal running condition.