Mercruiser 140 dies once accelerated under load

[tcooke]

The culprit is a 1978 Mercruiser 140, new block, new head, manifold, riser, etc... The carb was just rebuilt with a new kit, new distributor cap, condenser, points, wires, plugs....

The engine runs fine in nuetral, idles and revs. You kick it into gear and it idles fine at 700 rpm. The second I give it a touch of gas in gear it dies. Starts again no problem, into gear, a little gas and dies again. I have tried adjusting the carb and chocke to no avail. I do hear a hissing when its running, does this mean it is a vacuum problem? Help please!

 

[fishrdan]

Re: Mercruiser 140 dies once accelerated under load

Sound like the accelerator pump isn't working right. With the engine off look down the carb's throat and have someone pump the shift control as if you were accelerating, you should see a stream of fuel discharge into the carb bores. If you are working solo, disconnect the carb's throttle from the linkage and pump the carb's throttle by hand. Either way, you should see a steady stream of fuel as the carb's throttle is moved open.

When you replaced all of the ignition components did you set the dwell and timing correctly?

Hissing is most likely carb noise, air being sucked through carb. Could be a vaccumm leak, but probably normal noise.

 

[tcooke]

Re: Mercruiser 140 dies once accelerated under load

Ok, what is the accelerator pump? Not listed in the manual.

 

[fishrdan]

Re: Mercruiser 140 dies once accelerated under load

Ok, what is the accelerator pump?

part in the carb, if the carb was rebuilt, it should have been replaced.

 

[tcooke]

Re: Mercruiser 140 dies once accelerated under load

part in the carb, if the carb was rebuilt, it should have been replaced.

Would they just call it the pump in the manual? If so yes it was replaced. I talked to a mechanic today and he thinks it is my shift interrupt switch. Seemed to make sense to me, I will be out later to take a good look at it.

 

[tcooke]

Re: Mercruiser 140 dies once accelerated under load

Just got back in from taking a look, turns out it is the shift interrupt. The cable weren't adjusted properly tripping the switch as you try and give it gas. A little too much extra glide in the shift cable

Looks like she'll be getting the full water treatment tomorrow