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Need some help with this one..I have a 2008 90hp 4 stroke..and cant run it full throttle..when I try it will run normal for sometimes not often 20 minutes...then it sounds like it's almost running out of gas or running on two cylinders and motor starts jumping...changed the plugs used sea foam changed oil and filter..I have a video of the motor acting up but cant seem to post it...any help would be greatly appreciated
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Wondering if your fuel tank vent is plugged or partially blocked? Would cause a fuel starvation issue over time. Did you give the fuel bulb a squeeze? As for the video some people include a link to YouTube or other platforms. -
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Thank you for the information...and was able to post the videoComment
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***, I have never seen an outboard do that with a fuel starvation issue! Once the engine starts to wobble is that you pulling back the throttle reducing RPMs or is the engine loosing revs on its own? Almost looks like something isn’t balanced anymore. Kind of reminds me of an unbalanced wheel that starts wobbling at a certain speed. Did this issue start out of the blue or has it been slowly getting worse? Any reason to suspect a faulty propeller? Does the issue occur at the same RPM? I’d be interested is hearing if an other members have experienced the same issue.Comment
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It sounds like you are losing a coil and dropping down to two cyls, the system runs a waste spark ignition, one coil for one and four, the other for two and thee.
Pull the plugs and you might see that one and four are darker than two or three or vise versa giving you an indication of which coil is faulty.Comment
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It does slow down when it happens but I half to throttle down because of shacking and skipping.its been happening for a while now , getting worse. It starts doing now at about 12 miles hour.Comment
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Hmmmm a 2008 DF90…..
Have you checked for the corrosion in the engine holder? When the corrosion breaks through it lets exhaust gas escape under the cowl which gets trapped, and eventually the gas chokes the engine???
You should check this ASAP as its a known issue on engines up to about 2008 MY.
The spot to look is on the port side, directly below where the fresh water flushing attachment is located. You will need to take the top and side cowls off to see it. It looks like a welsh plug. If its corroded thru, you will see the damage quite clearly.
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'''''''''' By reducing the throttle will put less load on the ignition system and allow the spark to jump the plugs again instead of sparking internally inside the coil.Originally posted by Ellen Devine View Post
This problem would have started randomly and just got worse over time. Looking at the video it sounds like you abruptly loose two cyls, that don't happen when you are running out of fuel, all four cyls will be effected at the same time.
If the internal driver inside the ecu that is switching the injectors on and off was failing would produce something similar but I doubt it. Pull the plugs and look at the color of the porcelain and see if there is a difference between one and four and two and three.Comment
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2008 has no plug, if CO was escaping under the cowl all four cyls would be effected and the engine would loose power evenly, same thing as a blocked exhaust all the gas going back into the combustion chamber, I think the spark is tracking taking one coil out and loosing two cyls. These coils fire two plugs at the same time one cyl on compression and its companion on exhaust.Originally posted by Moonlighter View PostComment
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I will look at the spark plugs and check for corrosion when I get back to camp...thank you for the information...any more input on this issue is great appreciatedComment
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