2003 F115 Trim Problems

[akdeweyj]

I have a 2003 F115 with 420 hrs on it that has been cutting out all summer & I thought was a bad battery connection or some kind of electrical gremlin.

Whenever I would try to trim the motor while underway, it would start cutting out & dropping rpms like the rev limiter was kicking in. I have 1) checked my batteries, which are good 2) replaced all of the wiring from the battery selector switch to the batteries with 4 awg cables with sealed ends 3) checked all of the connections to the trim motor for corrosion 4) replaced the trim indicator sender which was broken & 5) verified that the charging system was functioning properly (+1.5v when motor runs).

Last weekend, I tried running the boat again & this is what I got: if I run the motor @ 5400 rpm(wot) it trims up & down just fine, but if I run it under 4200 rpm, the cutting out & rpm loss takes place trying to trim up or down.

Does anyone have any other suggestions on where to look for the source of this problem?

Thanks

[boats.net]

Sounds like a low voltage problem. Check battery cables between battery and engine, look at cable ends for corrosion, look for a bad ground on engine, loose or corroded connections, check for large current draw from trim motor and possible even shorted voltage regulator.

[akdeweyj]

Sounds like a low voltage problem. Check battery cables between battery and engine, look at cable ends for corrosion, look for a bad ground on engine, loose or corroded connections, check for large current draw from trim motor and possible even shorted voltage regulator.

I did all of the above with no improvement so I took it to the local Yamaha dealer to look at. He checked everything you mentioned & could not find a problem. The only thing he found that I missed was the plastic fuel filter housing that Yamaha uses on the back of the OB had a crack in it & it has been replaced. I have not had a chance to run my boat since then & freeze up is upon us here in Alaska so this may have to sit until next spring. I don't think that the cracked filter housing was my problem.

[akdeweyj]

As a followup, the problem has been resolved after another trip to the shop & two sea trials. It turned out that the laminated grounding straps on the ignition coils were corroded. They have been replaced & the O/B is running perfectly. Too bad it took so stinking long to figure out what was wrong with it.

[Tucker]

Thanks for the follow up ak. Ok with all the things you checked and replaced, how'd corroded ground straps fall throught the cracks? You mentioned that you check all grounds; are these covered or hidden? In my marina many of the electrical problems guys are having with the big 4-strokes are usually ground related.

[akdeweyj]

Thanks for the follow up ak. Ok with all the things you checked and replaced, how'd corroded ground straps fall throught the cracks? You mentioned that you check all grounds; are these covered or hidden? In my marina many of the electrical problems guys are having with the big 4-strokes are usually ground related.

Basic ignorance on my part - I was too focused on the tilt motor, solenoid, battery cables etc. My only prior exposure to ignition coils before was bad coils, no start. Since the out board started easily, I did not look too hard at them. Another lesson learned!

[Tucker]

Yea, hate the lessons learned the hard way. That's why I'm always sticking my nose in on this forum. Just seeing if I can learn from someone else's experiences.

[akdeweyj]

Yea, hate the lessons learned the hard way. That's why I'm always sticking my nose in on this forum. Just seeing if I can learn from someone else's experiences.

I find that the more expensive or painful the experience, the longer the memory of it lasts!

[rodbolt17]

and thats been part of the learning curve.
all the 4 stroke EFI engines use a 12V waste spark TCI ign similar to the HPDI setup.
totally different than the rest of the ADI cdi units that most techs are used to seeing.
its actually similar to some of the early attempts of OMC and chrysler to use a transistor ign .
some of the early attempts at electronic ign on automobiles were similar as well.
they just used either LED;s or points to trigger the transistor and the yamaha uses a pulser coil and crank position sensor to do it.
face it, an ign coil is a simple inductive transformer.
aint but ONE way to make it spark on the secondary side.