Twin 91 merc 135 issue

Alterego

Recruit
Joined
Aug 20, 2012
Messages
2
Hello,
I am new to this forum, but have used the advice on here a lot so hopefully I will get some good advice this time. I've got a 91 searay laguna FDC with twin merc 135's mdl# 0C290*** and 0C291*** compression on both engines is 124-125 psi which from what I understand is good bore scoped cylinders there is no scaring and cross hatch is still visible. reeds are all good carbs are cleaned and rebuilt jets are correct for the area I am in. new fuel lines 3/8in new fuel pumps, water separators, fuel filters, and premium gas. Now that I got all that out, took the boat to my local Intercostal waterway with my wife and kids to have some fun. The boat will idle fine, but will not get out of the water at all. I noticed the volt gauges were hanging around 11volts which I know is not correct and the port engine was running rough under a load. The boat has 19 pitch stainless props. now I did do some checking when we got it home port engine has 16 amp stator that is putting out around 14 volts AC at 1500 rpms and doesn't change as rpms increase with very little output around 6 volts dc also the #4 coil is not firing but ohms out good according to merc manual, could be switch box?? The Starboard engine all coils fire, it has 40 amp stator getting around 16 volts ac out of stator but only about 4 volts DC out of regulator and tach is dead so I know that regulator is bad.

So with all that being said is there a way to change the water cooled regulator to a different version with out changing the stator? Will the low voltage cause the engines to not function properly even on full charged batteries?? And finally I need more power to run electrical and was going to do a 40 amp conversion on port engine, any suggestions on this??

I am running 4 optima blue top batteries 2 for each engine with isolators, 2 lowrance HDS10's, Furuno radar, 4 35watt HID spreader lights (Light Force), 2 50watt HID driving lights (Light Force), LED deck and Cabin lighting, 2 washdown pumps, 4 fish box pumps and 2 live well pumps, and all the other regular boat required stuff. The lights I have converted to all LED or HID to keep the current draw low.

Sorry for the length just wanted to explain what I have done. I am an aircraft mechanic where you have to be through. Thanks in advance for help!!
 

Alterego

Recruit
Joined
Aug 20, 2012
Messages
2
Re: Twin 91 merc 135 issue

Well I think I have figured out what I am going to do. Port engine R2 coil it's bad and do 40 amp conversion with CDI kit and 40 amp flywheel then re-time. Starboard engine is 40 amp so getting CDI kit for it also to change 2 wire stator to 4 wire. I did a quick ck on my system draw with everything on and it's pulling 57 amps total. that's running everything radar at max power both electric down riggers and 4 electric reels with 100lb weights hanging on them. planning on adding a 6k genset this winter. trying to build my perfect offshore boat lol!!! still any advice would help before I go drop 2 grand on parts! :facepalm:
 
Top