merc 650 bogging jerking

[brussell]

Hi all. I have posted this before but it has been a LONG time. Last summer I let my Bomber bass boat w/a 650 merc sit for 2 months. When I ran it again it idled and fast ldled fine. As soon as you try and go it runs all over the place. It seems like it's about to go then bogs down, goes again and so on.

Fast forward to this weekend. The boat sat for over a year. I get a battery, 1 gal or fresh gas, 1 pint of seafoam and a can of Deep Creep. It cranks right up and I do the de carb thing. It smokes like heck. Then I get off the dock out to the main channel and its bogs down again. Runs like it did last year(not that I expected it wouldn't). Where should I start?Carbs?(do they even make parts for it?)Some plugs and wires?One wire seems loose. I wanna fix what's broke not buy a bunch of parts for nothing(something I'm good at with cars and boats).

Much thanks for advice

 

[OBJ]

Re: merc 650 bogging jerking

Well brussell...long time and wrong forum....d

How about if I move your post over to the Merc forum?

You'll get the help you need there.

 

[emckelvy]

Re: merc 650 bogging jerking

Ser # ?

Is it a 3-cyl of 4-cyl ??

 

[brussell]

Re: merc 650 bogging jerking

3 cyl 1972 model, I'm looking for the tag receipt now. Or I'll half to walk down to the boathouse and clean off the VIN- seem s like it's something simple

 

[emckelvy]

Re: merc 650 bogging jerking

Throw a timing lite on each cyl to make sure it's firing on all three. Check compression since these motors are infamous for problems in #1 cyl. Or bad seal in #3 causing problems.

If you can't find anything obvious you may need to pull the carbs and service them. It's possible you have debris in the carbs or perhaps even something in the fuel pump check valves.

One thing you might try if you're back out on the water is to pump the primer bulb and see if that makes it go better. Or try hitting the choke button when it's just starting to bog down.

HTH & let us know what you find........ed

 

[brussell]

Re: merc 650 bogging jerking

In the past if the tank top was on tight it would bog, I just loosened it. Also, it never did idle very well. I just found a plug wire to be very loose. Plugs look ok. Alos, if the tank top was on tight you could keep it going by pumping the primer, up to a point then it would die. Some kinda vapor lock.

The powerhead was rebuilt in the 90's and it sat for a good while after. The foot is in ok condition.

 

[billybones]

Re: merc 650 bogging jerking

Sounds like a fuel pump to me. Car will do the same thing. eventually won't run at all. I know little on boats though. but loose cap makes it easier to pull fuel. excessive primming will eventually flood it out.. Thats what it sounds like to me. HTH.. I'm not even sure that there is a fuel pump. but it sounds like starvation under load.

 

[brussell]

Re: merc 650 bogging jerking

I haven't done a compression check nut I think its got to be fuel. I may just get the carb kits and go at it. My problem is the age of the boat. How hard are parts to fond for a '72?