Motor issues

Hey yall,

My father in law has a 72 Mercury 650.
Idles and runs in gear when on water muff.
Idles fine in he water, but stalls when put in gear.
Anyone have an idea of what would cause this?
Any help would be great.

Thanks, Fisherfore

Had a older one do the same thing. It is probably that the carb is gummed up. I was told that and did not believe it to start with because it idled so good. The jets get clogged up enough that it idles fine until you apply a load. It shuts off immediately just like you hit a kill switch. Take it out of gear and it starts right back up. I rebuilt the carb and it fixed my problem.

Thanks for the info. Cwright

Take it to Angier, NC Pitstop Marine

Going to try to adjust the idle jets first and if that don't work rebuild the carbs. Then if that don't work he may check on a newer motor. I'm pushing for a newer little bit bigger boat!!! LoL

Have you tryed new spark plugs?

Before doing a lot of carb work I would do a compression test on it. Low compression will cause a motor to do the same thing. If low compression is the problem look for a new motor.
If compression is okay then do the carbs and plugs.

Thank yall for all the helpful tips.
I'm not a motor guy, but father in law is a jack of all but this has him stumped:yikes... so I'll have him do a compression test first now and see how that goes.
Thanks again everyone.

Anyone know what the compression should be?

Bad news for the poor old Mercury.
No compression on #1 cylinder.
Guess we are now looking for anot her boat or motor.
Thankso all for all the input you gave us.

Sorry to hear that but at least you didn't spend a lot of time and money on other things. Hope you can find another before long.

I would still try rebuilding the carbs and changing the fuel lines and plugs; no fire no compression

"no fire no compression" Whaaaatt??????????????????

I second that on Pitstop. However, a problem that only appears on the water can be problematic since they are land-locked and have to schedule lake diagnostics. But, they might be able to diagnose this in the shop - I don't know. But, they do good and honest work.

"No compression on any cylinder" = broken rings,scored cylinder,or blown piston = motor overhaul....$$$$$$