Jump to content

72' Skylark Suncoupe -hesitates then lurches forward


Guest jamper

Recommended Posts

Hello, I am proud to be a new old Buick owner and a I am excited to have recently joined the BCA. I am looking for some ideas of what could be causing hesitation when I accelerate. My car is a 72' skylark suncoupe with a 350 2bbl, auto trans. When I first accelerate from a stop the car will hesitate and then jump/lurch forward and then continue to accelerate like normal. Any thoughts on what could be causing this?

Thank you!

Link to comment
Share on other sites

Could be several things:

Timing is retarded

Accelerator pump in the carb is failing (that is a very common response when this symptom is described, but I've never seen it personally).

Vacuum leak. There are a million places you could be leaking vacuum. Replace all rubber vacuum hoses and make sure all bolts on the carb are tight, as John said. Also, replace the hose going to the power brake booster.

Link to comment
Share on other sites

All good points so far. If it hesitates most when you 'punch' it, it is probably the accelerator pump. If there is hesitation with gradual acceleration then I would suspect a dirty carb. There are small and easily plugged passages in a carb that are responsible for the transition from idle to higher rpm.

Willie

Link to comment
Share on other sites

All good advice.

As for timing, don't be afraid to advance it a couple of degrees ahead of the factory spec. In '72, they were starting to retard timing for emissions, so most of us knew to push it up a little in order to help drivability.

As for the accelerator pump, you can check that by looking straight down the throat of the carb as you pull opent the throttle quickly. You should see two solid streams of gas shoot down both venturi of the carb.

Joe

Link to comment
Share on other sites

It hesitates mostly just when you ease onto the gas, not punching it. If I remember right it doesn't really do it when I first get going, but more so once it is warmed up to operating temp. When I first start it it usually wants to idle at a pretty high rpm, if I pump the gas once or twice and rev it the idle will settle down to what seams like "normal".

Link to comment
Share on other sites

Engines fueled by carburators ( as opposed to today's Fuel injection) are started with setting the choke. It's a manual process, pump it once and the choke should close. When the car starts it should automatically open a bit otherwise the air flow would suck too much gas and stall the engine. Once started the choke opens gradually, based on the operating temp of the engine. While the choke is partially closed that fast idle is helping the engine to warm up faster. Once warmed sufficiently a mere tap on the pedal should drop the engine to it's required idle RPM.

As for the hesitation, I would also suggest snugging the top screws on the carb. Sounds to me like there is too much air getting into the carb and upsetting your air/fuel mix.

Snugging the screws down means just that. Don't power torque these things and snap them off. They should be evenly tight with a regular hand held screwdriver.

Link to comment
Share on other sites

Guest Dans 77 Limited

To take it into a completely different direction........ have you checked to see if the tranny fluid is low ? It may not be a hesitation .... it may be a slip. They seem to do this as your just starting out. Usually all you need to cure it is a pint or 2 of trans fluid.

Not that the other points made arent valid , Im just trying to cover all bases

Dan

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...