Engine hesitates at beginning of acceleration

[juicejug]

I have a 1984 Mercruiser 140. The engine runs fine for the most part. However, it hesitates when accelerating. If I slowly push the accelerator to full speed it doesn't happen. However if I immediately put it into gear and fully accelerate it will hesitate shortly and then it will either get up to speed, or it will completely stall.

When it does stall, the only way to get it started again is with the use of starting fluid. Once it's started back up it will resume with the same operation.

What things should I check? The fuel filter was changed last summer but I don't know how regularly that should be done.

 

[thumpar]

Sounds like a carb problem. Most likely the accerater pump. Get a rebuild kit for it. The carbs on those are super easy to work on.

 

[Jmunk]

Have someone pump the throttle and watch in the carb for a stream of fuel to shoot. If there's no stream then it's the accelerator pump that's bad, however if you change that do a rebuild on entire carb.

 

[juicejug]

Thanks for the replies. I was considering rebuilding the carb.

I should also mention that this behavior only happens when it's in gear/driving. It works as expected when not engaged.

 

[thumpar]

There is no load when not in gear.

 

[juicejug]

Probably a silly question, but how do I determine what model carb I have and, do you know what the kit part # is? I believe it's the MerCarb, but am not positive and want to get the correct kit.

 

[thumpar]

If it is a Mercarb there is only one mixture screw. If there are 2 it is a Rochester.

 

[gm280]

I think thumpar hit the nail on the head with the accelerator pump. You are experiencing the lack of fuel when you hit it quickly. When you riv it up slowing, it doesn't utilize that accelerator pump as much and you can cover up for the lack of it.

 

[juicejug]

Thanks all

I'm going to do the rebuild of it and then will post the results.