1990 115 Merc 2+2 hole shot questions

[borderboat]

Re: 1990 115 Merc 2+2 hole shot questions

Meaning that all (4) carbs need to start to work when throttle is applied, if they are out of sync they won't all deliver the correct amount fuel per cylinder. When you look at the procedure, you loosen off the (6) screws on the bar that links the carbs together, pull the bar down lightly till all the carbs are all shut, then tighten the screws. If they are not working together, and sync'd, some cylinders are either gonna run rich or lean (depending on how they are out of adjustment). Its just like the old 6 pack mopars back in the day.

 

[MercGuy]

Re: 1990 115 Merc 2+2 hole shot questions

^^^ Additionally, the accelerator pump has to kick in at the right time and the timing must be advanced properly.

So a link and sync adjusts and times the throttle plates, accelerator pump and timing.

Very important on these 2+2 engines.

However, when adjusted properly they run very well.

 

[borderboat]

Re: 1990 115 Merc 2+2 hole shot questions

I totally agree MercGuy.

It is a little bit overwhelming the first time, the best thing to do is to print off the instructions and have them there with you while you are doing it. The diagrams are great in the manual, take you time and make sure you got a set of feeler gauges (thickest one you need is a 0.030"), you have to set a gap in a few places as per the instructions...

 

[filo_bedo]

Re: 1990 115 Merc 2+2 hole shot questions

Do you think the timing and carb sync could be the issue to dropping cylinders while the engine is running? I mean its like cylinders kick in and out all the time regardless of how many RPM's the engine is running at? The engine does always run though.
I am going to do as you guys have suggested regardless. I am just trying to find out where else to start.
Thanks again for all the help though!

 

[achris]

Re: 1990 115 Merc 2+2 hole shot questions

Do you think the timing and carb sync could be the issue to dropping cylinders while the engine is running? I mean its like cylinders kick in and out all the time regardless of how many RPM's the engine is running at? The engine does always run though.
I am going to do as you guys have suggested regardless. I am just trying to find out where else to start.
Thanks again for all the help though!

This si the best place to start. Once you have verified compression and healthy spark on each cylinder, go through the timing and synch. Only when all those things are right can you troubleshoot a problem, if it wasn't the timing and synch....

If you still have the problem, remove, strip, clean and rebuild carbs, fuel pump and accelerator pump...

Chris..........

 

[MercGuy]

Re: 1990 115 Merc 2+2 hole shot questions

I'm still a strong advocate of re-torquing the exhast cover plate bolts. This could possibly be the problem, and doesn't cost anything to try.

A leaking exhaust cover plate could cause random mis-fires at speed.

So my advice (which concurs with others here) is:

1) Change plugs if you haven't already

2) Link N Sync

3) New internal fuel filters (if you haven't already)

4) Check torque on exhaust cover plate

5) Take it for a ride (especially if you feel that you found something amiss)

If you still have the problem

6) Compression check

7) Rebuild and clean carbs

Best of luck to you.

 

[filo_bedo]

Re: 1990 115 Merc 2+2 hole shot questions

Thanks for all the advice and help. I will let you know if I have any sucess!

 

[pokman]

Re: 1990 115 Merc 2+2 hole shot questions

I'll be waitin to see what you find, my 94 125 runs great but sometimes it idles great and sometime it idles rough and dies also.