The Stovebolt Site Forums The Shop Area Engine Shop carb question

Hello.

I have a 1955, 235 chevy suburban engine with dual carbs. Over the last few months, it has gone from firing right up on a cold start, to needing gas to be poured directly into the carb for it to fire up. Once its going, it can turn off and on easily, but I am wondering what typically goes wrong in the carb on the initial start up which prevents fuel from getting to the carb. My fuel filter is not clogged, and I think my mechanical fuel pump is good. Do the floats get gummed up? Do the lines get clogged? I do not smell fuel at the carb when I prime it with the pedal, so I think gas is not getting from the tank to the carb upon initial startup.

Thank you.

Judson

Reasons: clogged fuel pick up, clogged fuel filter, clogged fuel line, rubber hoses (if any) swelled up due new type gas, bad fuel pump.
Test: with a helper, disconnected fuel line at carb. Remove start wire to ignition. With bucket, have helper turn engine over and see how much fuel you get over several seconds. Measure pumped fuel and check manual to see if you have pumped enough. If not, start trouble shooting your fuel delivery system.

Judson, it could be as simple as not choking it enough on a cold start. Not sure how your dual carbs are set up, but my suggestion for a cold start on a single carb manual choke would be to try pulling the choke out all the way and pump the gas pedal three times (some will say the gas pedal pumping isn't necessary, but it give me good luck!), then hit the starter. Push the choke in once it starts.

If my truck sits for more than a few days, regardless of the temperature, I always have to start it using the choke. That's not a bad thing...it's how they were designed to work.

Matt

That is generally caused by bad or weak accelerator pumps in the carbs. With the engine off, look down the carb throat & work the throttle linkage. A squirt of gas should go into the throat each stroke. This does the same as your priming. It also could be you don't pump the foot feed enough when you go to start it cold. We are used to these newer vehicles with FI. Pumping that accel. has no effect with starting. Like May says, when it sets for several days it may be necessary to crank it longer as the gas in the bowl has evaporated.

Not sure if California switch fuel grades for winter or not, but it could be as simple as that. Here in Missouri they switch to winter blends when it gets cold.

Does the truck run OK once its started? Bad accelerator pumps should have a dead spot when pulling away from stops. Not knowing which carburetors you have, it's just a guess on what can go wrong.

Thanks, guys. These are all good suggestions. I actually just moved to New Jersey, so perhaps part of what I am experiencing is having to account for the cold (choke)! haha! That would be funny! Ill try it out. Thank you! Judson