mercury 125 hp elpto 2 stroke dropping cylinders

[pursuit 3800]

I have a 125 mercury saltwater classic with a feature of only 2 cylinders firing when under a certain rpm and the other 2 picking up when throttle is applied. However when in forward the motor will not pick up the other cylinders, but when in reverse there is no problem. Before handing this thing over to a shop I was wondering if there was simply a module or sensor I need to replace? Thanks in advance for any help anyone can give me.

 

[north40]

Re: mercury 125 hp elpto 2 stroke dropping cylinders

Do a search on "link and sync" on this board. Make sure your accelerator pump is adjusted and check to see if there is spark on all 4 cyl. All should fire at all times...the bottom 2 only get enough fuel to "run" above 1800-2000 rpm. A decarb with seafoam or carb rebuild may be in order as you may have trash or varnish buildup.

 

[pursuit 3800]

Re: mercury 125 hp elpto 2 stroke dropping cylinders

Ok I have fire in all 4 cylinders and I think I see the accelerator pump. let me see if I am looking in the right place, Its just between carbs 2 & 3 with a solinoid that is operated by a cam lobe as you advance the throttle? It is being actuated by the cam lobe but I cannot be sure if fuel is going through. What besides horrible fuel usage would be the result if I temporarily bypassed this and ran it straight? I am just trying to get a feel before bying parts or going to a shop. Thanks again for your reply.

 

[north40]

Re: mercury 125 hp elpto 2 stroke dropping cylinders

3800,<br /> The accelerator injects fuel into 3 and 4 to smooth out transition between 2 and 4 cyl operation through 2 nozzles in #3 and #4 cyl. Before you start disconnecting things, check your fuel pump to make sure it is pumping a good stream of fuel, change fuel filters and make sure you have no leaks in your fuel lines especially the primer bulb. If this all checks out, you could have high speed jets stopped up in carbs. Get a manual for your engine if you feel inclined to do your own repairs. Good luck.