# 90hp Mariner Help



## CodyW (Jan 26, 2016)

I got 90Hp Mariner that has no power until 3/4 throttle or around 2000 to 2500 RPM. When it kicks in it is sudden and will snatch you back. It also will not reach its max RPM, only got to around 4000RPM. Carbs have been rebuilt and tuned, spark plugs replaced and has spark on all cylinders, fuel check and lines replaced. What are some ideas to check?


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## Vertigo (Jun 3, 2012)

Check the prop first. Sounds like you're way over-pitched.


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## CodyW (Jan 26, 2016)

I don't believe the prop would cause the lower rpm issues. I would get no response from the engine until it gets to around 2000 rpm. Also I can throttle up immediately and get nothing from the engine. It is like it has a delayed effect.


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## Plantation (Nov 24, 2015)

Power pack? Ignition coils? Not sure. Ive been told that those two things can cause spark to be fine at one rpm but not work at others. Just a thought, no clue really


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## Jim Lenfest (Jul 20, 2016)

If the speed increase is instantaneous, like flicking a light switch, then I would assume it to be electrical. If the power comes on slowly, then consider fuel maybe. I just went through a similar issue. Mine would run fine then lose power on 3 of 6 cylinders instantaneously at an idle. But if I revved her up in neutral, she would grab it again and take off. I ended up changing the stater first and it helped a few days then the problem returned. (hard to diagnose a problem that is working sometimes and not working other times) I then changed the trigger and still no better. Finally I changed the lower switch box and for now I think I have cured it. I did not change the switch box initially because it had been recently changed and guessed it not to be the issue. But you never know. 

Lastly as a side note: In a two stroke, If no fuel is reaching a particular cylinder, and the engine is not oil injected, then you are getting no oil to that cylinder and it's crank area. An oil dry cylinder or two will lead to serious problems very quickly. If a cylinder is not getting fire, but still getting it's oil, then it can be run to return home. If in doubt, get a tow. Two strokes do not share a common crank area. Each piston is isolated from each other. So that section of the crankshaft is not getting oil either. Which means not only could a piston seize, but it could also cause connecting rod failure on that cylinder as well. In my case, it was obvious fuel and oil were still reaching the cylinder, therefore I crippled home on several occasions.


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## Smackdaddy53 (Dec 31, 2012)

If you have not replaced plug wires in a while replace them and the boots then connect with dielectric grease. If you jump spark you will lose power. You may also check the timing. I have the same motor.


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## Jim Lenfest (Jul 20, 2016)

CodyW said:


> I got 90Hp Mariner that has no power until 3/4 throttle or around 2000 to 2500 RPM. When it kicks in it is sudden and will snatch you back. It also will not reach its max RPM, only got to around 4000RPM. Carbs have been rebuilt and tuned, spark plugs replaced and has spark on all cylinders, fuel check and lines replaced. What are some ideas to check?


Not sure which engine you have, maybe the 6 cylinder Tower of Power in the grey version? In any event try disconnecting the lead from the ignition switch that kills the engine. You will have to choke it to stop it temporarily. Sometimes they develop a short in the harness that kicks in and out or changes with RPM like a variable resistor. If that cures it, get a new set of controls and harness or change out the harness, or do like me and leave it disconnected and turn the motor off with the choke. Secondly check the coils one at a time by grounding the positive lead with a jumper wire to ground. Each coil grounded should show a drop in RPM's. If one or two do not, then check for voltage similar in volts to a working coil. I am thinking but not sure, that they should be about 30 volts there. Try swapping out a coil to see if it corrects the problem. If not, then look to the switch boxes or stator for issues there. It could also be the trigger. (You can also check for fire with a spark tester that goes in the ignition wire circuit) These testers are available on Amazon. you can buy just one and take turns doing each coil, or one like this is what we use, tests them all at the same time. https://www.amazon.com/Cdi-Electron...7005&sr=8-19&keywords=6+cylinder+spark+tester


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## Smackdaddy53 (Dec 31, 2012)

Jim Lenfest said:


> Not sure which engine you have, maybe the 6 cylinder Tower of Power in the grey version? In any event try disconnecting the lead from the ignition switch that kills the engine. You will have to choke it to stop it temporarily. Sometimes they develop a short in the harness that kicks in and out or changes with RPM like a variable resistor. If that cures it, get a new set of controls and harness or change out the harness, or do like me and leave it disconnected and turn the motor off with the choke. Secondly check the coils one at a time by grounding the positive lead with a jumper wire to ground. Each coil grounded should show a drop in RPM's. If one or two do not, then check for voltage similar in volts to a working coil. I am thinking but not sure, that they should be about 30 volts there. Try swapping out a coil to see if it corrects the problem. If not, then look to the switch boxes or stator for issues there. It could also be the trigger. (You can also check for fire with a spark tester that goes in the ignition wire circuit) These testers are available on Amazon. you can buy just one and take turns doing each coil, or one like this is what we use, tests them all at the same time. https://www.amazon.com/Cdi-Electron...7005&sr=8-19&keywords=6+cylinder+spark+tester


It's been a year since he post this, I hope he resolved the issue!


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## CodyW (Jan 26, 2016)

Man time flies. I did resolve the issue, turned out that one of the jets was not matching with the other two jets. I've moved on from this motor and currently installing a etec now.


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## Smackdaddy53 (Dec 31, 2012)

CodyW said:


> Man time flies. I did resolve the issue, turned out that one of the jets was not matching with the other two jets. I've moved on from this motor and currently installing a etec now.


That is a good choice. I have the same motor on my old boat and it's junk. Nothing but issues.


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## CodyW (Jan 26, 2016)

Smackdaddy53 said:


> That is a good choice. I have the same motor on my old boat and it's junk. Nothing but issues.


Reason I went to the e tec. Every time I took it out it had some kind of issue. I would address the issue then another one pops up.


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## Jim Lenfest (Jul 20, 2016)

Missed that date, but certainly good info to have up for others to consider. I love those old inline sixes, but agree, they can be a pain. I am thinking the replacement parts are usually used or maybe not of original OEM quality. I had one just last summer, that it turned out to be a switch box and one coil, ran great after. Another I changed everything, one piece at a time, and it was the trigger, the last thing on the list. What is aggravating is that it was running fine when I put it away for storage prior to using it. Just goes to show that things do let go from sitting.


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