Pontoon Boat & Deck Boat Forum

occasionally on my Yamaha 115 four stroke, when I use the power trim it will stall the engine when I first push the trim button. If I hold it down, or up, the trim works, but the low battery indicator on the fish finder comes on. the battery seems to be fine as the boat starts every time, but this has got to be killing my electronics. any one else had an issue like this. to me it seems like a short in the trim circuit somewhere, but it's an intermittent problem and I don't even know where to start looking.

Have the battery tested, I think it might have a bad cell or two.

I suggest you check all your cable connections for corrosion and tightness. Especially the motor grounds. Your starter pulls more amps than the trim motor, so if it starts fine, but the trim stalls the engine it's drawing way to many amps in my opinion!

Sounds like the switch to me. On the motor itself you should have another trim button. If that one doesn't exhibit the same problem, then you've narrowed it to the switch and wiring at the controller or between the controller and the motor. If both switches do the same, then I'd start looking for a bad ground or corrosion on connections.

Does it only do it when motor is trimmed to a certain position? Only with throttle at a certain position? That could suggest a loose connection or binding condition.

sounds like a bad connection or possibly a intermittent short?

it doesn't seem to do it at any particular trim or throttle setting. I will try the switch on the motor, and see if that does it too. good way to isolate the problem. thanks.

You may also want to check the fuse clamps on the fuse box. I had a similar problem and found that the clamp wasn't making a good contact to the fuse. Disconnect the battery, pull each fuse indivigually and squeeze the clamps with a pliers.

Hope that helps...

thanks for the input guys, i appreciate it.

Did you ever find out what caused the problem? I haven't had my boat in the water yet, it's a 2007 90hp 4 stroke mercury. Had muffs on it and test started it up. Tried the trim button on the throttle and it almost stalled the motor. The trim works, just seems like it's pulling juice away from the engine. I tried increasing the rpms just a tad and it still wanted to stall. Didn't matter to trim up or down. The battery is a year old, it starts right up. The trim works fine when the motor is off, doesn't sound weak or anything. Just sounds like it's pulling too much from the motor to stay running. I didn't try the trim switch on the motor while it was running to see if that made a difference. I'm not sure why it would make a difference.

[quote="taylorjm"]Did you ever find out what caused the problem? I haven't had my boat in the water yet, it's a 2007 90hp 4 stroke mercury. Had muffs on it and test started it up. Tried the trim button on the throttle and it almost stalled the motor. The trim works, just seems like it's pulling juice away from the engine. I tried increasing the rpms just a tad and it still wanted to stall. Didn't matter to trim up or down. The battery is a year old, it starts right up. The trim works fine when the motor is off, doesn't sound weak or anything. Just sounds like it's pulling too much from the motor to stay running. I didn't try the trim switch on the motor while it was running to see if that made a difference. I'm not sure why it would make a difference.[/quote]

After Eight Years, I'm guessing he either fixed it or traded off the boat.

Will be interesting to see if he answers back.

Just a point of info. Since our boat was new, the low voltage indicator on the Huminbird comes on and also the radio drops out whenever start the motor after killing it for some reason. All connections look good. Trimming does cause the a drop but not like starting the motor. Get a clamp on ammeter to check trim current. I have no idea what it is normally.

The only real way to determine where the issue lies is to put a meter across any and all connections while running the trim. You're looking for where the voltage drops. That would be the area of weak connection. If the problem is at the main, the motor would most likely have issues starting because I doubt that the trim pulls more current than the starter.

You can try the trim button on the motor, but it porbably pulls the same power trim relay(s) as the switch in the control. Most power trim motors are powered through a relay(s) since they pull so much current. Most of the ones I have seen have one relay for up and one for down. Measuring voltage across all connections should find the issue.

Yes, there's a single set of relays. One for trim up and one for down. What I don't get is that the trim works fine if the engine isn't running. So it's getting power from the battery fine. The engine starts fine. But when you use the trim when it's running, it's like it's draining everything from the engine causing it to stall. The volt meter does drop when trimming, but I can't believe it's enough to stall the engine. So in the picture. The power goes from the battery, to a positive stud. Then a cable from the stud up to the starter relay. The trim relays are the red wires connected to the power with the starter relay. The thick red wire on the positive stud comes from the alternator. All the connections and wires seem fine. The relays ground right by where the battery grounds. Those connections look fine too. I'm stumped!

The only thing....I think my trim motor is on the way out. I removed it and put new seals in the cylinder and replaced the fluid, but the motor just doesn't sound all that great. It's louder and just not as smooth sounding. It does try and stall more when trimming up. When going down, it's not quite as bad. Could a failing trim motor cause it to pull that much more power? The wires aren't that thick when compared to the starter. I'd think if it was pulling that much power I'd have melted wires. Now when I had the trim unit out and would test cycle it a few times, yes, the wires got warm. I don't really want to spend $800-$1000 on a new trim unit if I don't have to yet.

Well, I did some more testing. Didn't matter if you use the button on the remote or the motor. Disconnected the trim motor, tried the controls and nothing happened, motor kept running, so it's not a short in the switches. I reconnected everything and it seems when you hit the trim button, the engine hesitates for a second, but doesn't actually stall, it keeps running even if you keep on the button. So I guess it's ok.