80 hp jet (115) year 2000 carbed bogs

[Smokin Sam]

I am new to this forum so let me introduce myself. I am from central BC Canada. We fish the Bulkley River and a ton of lakes such as the Babine and Rainbow Alley. We are running a Merc 80 hp jet (115) . It used to run fine but it is giving us some trouble lately. Seconds after it comes up on plane it bogs and drops off. I've cleaned the carbs and rebuilt the fuel pump. I'm open to suggestions. I've heard talk about "high speed coils" on the stator going. Is there a way to check these (before buying one) with simple tools (VOM) or do you just replace them and hope for the best? Thanks for any help, Sam.

 

[Charlie61]

Re: 80 hp jet (115) year 2000 carbed bogs

mercury 80 hp jet , what is the (115) and what is a 80hp jet think a picture may help. is it make in the year 2000. there are a number of thing other an fuel . need to know little more how about a ser,number?

 

[Mi duckdown]

Re: 80 hp jet (115) year 2000 carbed bogs

Sam changing parts is costly. Need to find whats going on. Serial number would help.
Need DVA adapter to figure out that.
There is a sticky somewhere on this site to check that.

 

[Smokin Sam]

Re: 80 hp jet (115) year 2000 carbed bogs

OT732508 is the serial #. More research makes it an "03" not a 2000.

I have now tested the charging system and unplugged the rev limiter just for a try as well. No change.

 

[Smokin Sam]

Re: 80 hp jet (115) year 2000 carbed bogs

I found two stator wires that melted thru the plastic where they plug in. I replaced the stator. No change. It still revs then bogs hard. :facepalm:

 

[Smokin Sam]

Re: 80 hp jet (115) year 2000 carbed bogs

So we are not out of the water yet. Here is what I've found. There is NO switch box. Power goes directly to the coils from the stator. The compression is 125 per hole on my meter. The timing was at 28 degrees for wot and has been set to 25. 2 at idle setting. I got a little bit on the throttle stop adjustment but not much. Reeds look good. The spark jumps the tester gap on all cyls. All of the plugs look the same, a little oily. :facepalm:

This must be a newer series of motor, (2003) than my manual. The continuity checks on the trigger showed open between brown and black or white and violet, but it runs.
There are five wires from the triggers. violet, white, black, brown and blue, not four like my book says.

The stator is brand new.

What am I to test with a DVA and where? I bought one from Snap On for 40 bucks.

What else can I check before we take this back to the water? It's Oct and starting to freeze.

 

[wired247]

Re: 80 hp jet (115) year 2000 carbed bogs

mercury 80 hp jet , what is the (115) and what is a 80hp jet think a picture may help. is it make in the year 2000. there are a number of thing other an fuel . need to know little more how about a ser,number?

A 80 HP jet is a 115 HP powerhead with a jet lower unit. Jets are inefficient in the extreme and HP out the jet is 80 HP instead of the 115 HP you'd have with a prop. The 80 jet powerhead is not absolutely identical to a regular 115 HP powerhead and the ports on the jet motors tend to be a little higher as jets live in the upper rpm range and he probably has a 5800 rev limiter. 115 lbs compression is very good for one of those as they tend to be down on compression a bit because of the higher ports.

 

[wired247]

Re: 80 hp jet (115) year 2000 carbed bogs

On that motor I'd be looking at the trigger linkage and making sure it isnt binding and that you are getting full advance. The stator does fire the coil directly but the trigger controls timing.

 

[Smokin Sam]

Re: 80 hp jet (115) year 2000 carbed bogs

It seems to move OK, and it moves to full advance when I check the timing.

Can someone help me with trigger testing? My manual is a little older than my buddies motor. lol I wonder about the trigger output and continuity tests. Do I disconnect all of the leads to check? What wire colors do I test? There is no switch box on this unit. Specs?

Can the trigger output affect motor performance at wot? It seems to me that it could. All the plugs look equal, oily.

Aw sh!t, it just started to snow! lol

 

[Dave1027]

Re: 80 hp jet (115) year 2000 carbed bogs

So we are not out of the water yet. Here is what I've found. There is NO switch box. Power goes directly to the coils from the stator.

No switch box?

 

[wired247]

Re: 80 hp jet (115) year 2000 carbed bogs

Theyre kind of like a 70's and 80's OMC in that there is no "switch box". The CD unit and the coil are integral. The trigger acts as the switch box . The current doesnt really go directly from the stator to the coil. It does but its timed by the trigger that rotates as the throttle is opened. If the trigger is held up the spark advance wont progress fully.

I hate the term switch box. Its a transistor that signals the capacitive discharge unit to fire the couil. The motor he has uses the trigger ring which is a proximity switch to do the same thing.

 

[Smokin Sam]

Re: 80 hp jet (115) year 2000 carbed bogs

So what is the test sequence for this? Can anyone help a guy out?

 

[CharlieB]

Re: 80 hp jet (115) year 2000 carbed bogs

The fact that it pulls up to speed THEN starts slowing down is suspicious of a weak fuel system. The fuel pump output is limited and once full demand is there, the carbs start to run low and the motor looses power and slows down.

Check the fuel system for air sucking in somewhere before the fuel pump by TEMPORARILY installing a clear hose as one of the fuel hoses immediately after the fuel pump. Run the motor and look for air bubbles passing thru that hose, proving the air leak. Finding the leak is the problem, it could be anything from a looses hose clamp, old cracked hose, loose fitting, to a cracked dip tube in the fuel tank pick-up.

Just REMEMBER to remove that clear hose once finished with your repairs, it is NOT APPROVED nor safe for fuel use, it will crack and leak and can quickly become a serious problem.

 

[Smokin Sam]

Re: 80 hp jet (115) year 2000 carbed bogs

I'll give it a try. Thanks for all the help with this!

Yikes it might be next season now, suddenly it's freezing and snowing out!

Dam I still have a virgin DVA adapter lol.