86 Merc xr2 choking when bogs cures problem

[inlgmouth]

Thanks for advice on other threads. I have an 86 Merc 150 xr2. I'll start from the beginning. Boat has ran great all year and recently started bogging and dieing while going to WOT, still started and idled great. Now it is hard starting and idles bad (spits and sputters). I found yesterday that if I hold choke in for about 10 seconds while slowly advancing throttle it takes off like it should. Temperatures seems to increase to 1/2-3/4 on gauge as well, even with good pee stream. I assume this is evident of a lean condition. The following has all been done in the last 6 months.
1.local boat shop (great mechanic) installed new stator and tuned up
2.carbs cleaned and rebuilt. even double checked floats after problem. all set at 1/16" per manual
3.fuel pump rebuilt.
4.water pump rebuilt last fall
5.new fuel hoses,inline filter, checked pickup tube and vent tube- both were clean
6.new primer bulb. i checked and only has flow 1 way
Today I found the enrichener valve is defective, but from what I have read this shouldn't affect running performance. I traced all fuel flow and fuel it getting to all carbs with good flow. Does anyone have any suggestions
Thanks

 

[quebec#1]

Re: 86 Merc xr2 choking when bogs cures problem

I have the same motor ! But not your problem, However a few years back we had a 70 hp johnson and i had the same problem, if i wanted to gun it , i would have choke it.
We spent lots of money on that problem. carbs rebuilt, fuel pumps redone, ignition systems ect....
I was young at the time but i remember my dad being fed up with the dealer so he tried another and all they did was to rebuild the fuel pump for the third time and the problem was solved.
It turns out that the other dealer used the wrong kit .

 

[inlgmouth]

Re: 86 Merc xr2 choking when bogs cures problem

Thanks quebec#1 for responding. I had thought that maybe the diaphragm in the fuel pump rebuild kit was bad. I'll try another. For everyone else, I forgot to mention, compression is consistent at 115-118.

 

[inlgmouth]

Re: 86 Merc xr2 choking when bogs cures problem

I just found that one of my main jets in the top carb is a .074 and the other five are .064. I assume to correct a lean condition at some point. With the problem I am having would it matter if the .074 was installed in cylinder 1 or 2 of the top carb after a rebuild. My thinking is it should be in 1.

 

[quebec#1]

Re: 86 Merc xr2 choking when bogs cures problem

In some cases some engines have stagered jetting because one cylinder always run's a little hotter.
I dont have my shop manuel to check for you but im sure someone here can help you out .

 

[inlgmouth]

Re: 86 Merc xr2 choking when bogs cures problem

Thanks Quebec. My manual shows all should be .064 Figured the .074 was installed before I bought boat to cure a lean problem. Also, for anyone out there, how do I know if check valves in fuel pump are bad. If they are bad, would this be the cause of having to hold choke in for approx. 10 sec. while advancing throttle to get mt boat to open up. Maybe a brand new Ranger Z20 is the way to go!!!