Yamaha 40 power lift/lower problem

[Whitelighter]

The Yam 40 on my tender has continued where it left off last year generating issue after issue.
Having sorted the non runing/running rough/ no idle issues it decided to throw another one at me today.

Was working well yesterday, loaded it on the back and went about 45 miles.

Launched it at lunchtime and now the power tilt only drops about 1/3 the way then stops. The motor is still spinning and I cannot see any physical obstruction.

Any one got any ideas? We were med moored last night in a folly harbour but I can’t see how that would have affected the trim of the motor. Does it on the throttle switch and the switch on the side of the motor, so not the switches. Something up in the ram. It’s like it thinks it’s down but isn’t.

 

[GSL]

When you lower the motor down, when it normally reaches the "fully down" position, does the pump motor keep running, or is there a switch that stops the pump motor totally, even if you are still holding the up / down control in the down position.

If the pump motor normally keeps running even when the motor is in the fully down position, maybe there is a bypass type switch that cuts the oil flow to the ram. If so that switch may be coming in early and stopping the oil flow to the ram, therefore not letting the engine go all the way down.

 

[jfm]

Is it still on the tilt ram when is stops Jez? Or is it stopping precisely at the point where the tilt ram stops doing its thing and the trim ram takes over? In which case problem is with the trim ram (seized?).
Feels like a mechanical obstruction, because the pump keeps running (and dumping through the pressure relief valve)

 

[jfm]

When you lower the motor down, when it normally reaches the "fully down" position, does the pump motor keep running, or is there a switch that stops the pump motor totally, even if you are still holding the up / down control in the down position.

If the pump motor normally keeps running even when the motor is in the fully down position, maybe there is a bypass type switch that cuts the oil flow to the ram. If so that switch may be coming in early and stopping the oil flow to the ram, therefore not letting the engine go all the way down.

No there is no switch. The motor keeps running. Like all hydraulics there is simply a pressure relief valve that dumps the high pressure oil into the return circuit. It is 100% implausible for that valve to open consistently at the same trim/tilt angle because of the angle- it cannot know the angle and it only knows pressure. It is not opening randomly. So there must be a physical obstruction at the stopping point, which is what makes the valve open consistently at the stopping point. The valve therefore isn’t the culprit. Hence my suggestion of a jammed trim ram with a fully functioning tilt ram. Obvs I’m kinda guessing because I haven’t seen it. I used to own the same engine/year 2008/9 but forget the details!

 

[Whitelighter]

Is it still on the tilt ram when is stops Jez? Or is it stopping precisely at the point where the tilt ram stops doing its thing and the trim ram takes over? In which case problem is with the trim ram (seized?).
Feels like a mechanical obstruction, because the pump keeps running (and dumping through the pressure relief valve)

I’m not sure. I think I only have one ram but I might be wrong.
It’s consistent and stops in the same place every time.

I’ll take a picture later

 

[jfm]

Ithe 40 is one ram unlike the 50 upwards. https://www.boats.net/catalog/yamaha/outboard-by-hp/40hp/f40btlr-0408/power-trim-tilt-assy. But it has a trim and a tilt separate actions. This is your fault I bet. Parts not dear. Sorry can’t type more- taking off (and you are ATC!)

 

[TheOrs]

Is there a manual bypass screw that you can undo so that you can manually lift and lower the outboard? My Merc 75 has such a feature. On the Merc it's on the starboard side of the single ram unit. This would
a) Help you fault find as per JFM suggestions and
b) Allow you to continue to use the tender until you can arrange a fix.

 

[Whitelighter]

Good suggestion ors- I’ll take a look

 

[jfm]

It’s on the starboard side.

 

[Whitelighter]

Right.

Found that the manual lift screw isn’t there.
Found the hole - nothing in it.

However have solved the problem, the locking pin had slid into position with the engine up.
I never use the locking pin so hadn’t thought of it

 

[djefabs]

Nut behind the wheel then Jezz