Force 150 - Trim/Tilt almost started a fire!

[arriva2001]

This weekend, I had my boat out, and all was working well until I had engine tilted all the way up to install the trailer bracket. When I went to lower it down, I heard a hiss, the motor didn't do anything...and then all of a sudden, smoke was pouring out of the engine cowling. I opened it up with fire extinguisher at the ready, and what has happened is most of the insulation off the wire leading to the trim/tilt motor has melted, along with insulation on red, blue, and green wires on the Trim/Tilt relays. Thankfully I didn't need the fire extinguisher--all this wiring is SO close to the carburetors and fuel!!

I closely inspected the wiring leading to the pump that still had some insulation left, and from what I can tell, the insulation looks like it was dry rotted/cracked, and it shorted out--and the melting started right where the short started.

I have ordered a new wiring harness and will replace the wire leading to the pump with 100% new wires and heat shrink tubing.

My questions are:

1) do I need to look beyond this area under the motor compartment for melted wiring? Where do I need to trace back to to make sure there is not an issue? Could it go all the way up to the gear shift handle and switch? A lot of that wiring is going to be very difficult to get to, so I"m wondering if there are any tests I can perform or things to look for to see that it stopped at a certain point. I was hoping a fuse or something would isolate this problem. (Next question)

2) Is there any sort of a fuse or circuit breaker in this system that should have tripped? I am not all that familiar with electronics, but I thought the whole point of the circuit breaker/fuses was to prevent things like this from happening. If there is a fuse or circuit breaker, any idea where this is located in the engine compartment? I didn't try ANYTHING and unhooked the battery after this had happened, so no idea if anything else is toasted like starter or ignition, etc.

When I'm replacing things, is there an additional fuse I should put into place to prevent this from ever happening again?

For reference, my motor is a 1994 Force 150, model number H150412PE (I'm the original owner and no modifications have been made to this engine).

Thanks in advance for any help!

 

[The Force power]

there are two 30 amp breakers in the wiring set-up, look in the trim tilt section on these forum; there's some schemat

 

[Jiggz]

There's supposed to be a trim motor circuit breaker. If you follow the red/purple wire from one of the relays it will lead you to the ckt bkr and it is actually located inside the engine cowling. Unless, it malfunction or was by-passed it should have tripped before melting wire insulations.

No, you do not need to check under compartment wiring, unless you wanted to. This is because this system actually has two separate wire system. The control wiring and the so called power/load wiring. The control wiring usually uses small gauge wire and it only controls the two relays which uses very small amount of current. This circuit is protected by the fuse for the under the dash wirings.

The power or load circuit is on the other side of the relays, which connects the trim motor to the battery and it's protected by the circuit breaker. Check to make sure the relays' power contacts (red wire and blue or green wire depending on the relay) are not welded together and also the ckt bkr should be tripped unless you already reset it.

Personally, instead of shrink tubes, replace the entire cable from the tilt motor to the two relays. You can use that round two wire cable . . . not sure about the wire gauge but should either be 12 or 10 gauge. (usually used as power cord for small appliances) from the big box stores. Just make sure you get the one that is oil/fuel resistant and for marine use.

 

[arriva2001]

Thank you for your help, and thank you for the suggestion on the small appliance cable. that's basically what the OEM cord looked like, so I'll do some searching to see if i can find a marine grade cord like that--that would work great.

A couple more questions about the circuit breaker you mention. I can't seem to figure out where they are, or even what they look like. This is a picture of my melty wires...I don't see a red/purple one unless it's the melted one. What does a circuit breaker look like compared to what one looks like in a home fuse panel? I found this one on amazon..is it something similar to this? https://www.amazon.com/Circuit-Brea...ocphy=9024746&hvtargid=pla-568771229162&psc=1

One more question...I pulled out the trim pump motor to get to the wiring. Do I need to bleed and service the system now that I've done that? or is it somewhat isolated from the hydraulic fluid and pump?

Thanks again for your help.

 

[jerryjerry05]

Your getting instructions for the old Prestolite system
You 94 has the Mercury system, no circuit breakers.
That's why they pop!!!

You can install the breakers you have pictured, but get the ones that have the manual reset .

These systems are self bleed. Just make sure the oils full and cycle a few times and check the oil again.

 

[arriva2001]

Thanks. Do the instructions above of the 30 amp breakers hold true for the thunderbolt system? I do want to install an in-line breaker or fuse to prevent this from happening again since it doesn’t have one currently.

I guess my two questions are 1) do I install the breaker/fuse on the positive lead coming from starter relay (attached photo) and 2) is 30 amps correct for this 10 gauge wire (I believe—it’s still on order arriving tmrw-so not sure how thick the wire will be)?

 

[Jiggz]

That'll be a pissed poor design not to have a ckt bkr on the power circuit of the T&T especially with a motor designed to work under water. Here's a 91-94 150 HP diagram with T-bolt ignition system showing with the ckt bkr in between the relays and the starter relay terminal. However, if there's none in yours you can always install one and follow this diagram.

As for wire gauge, a 10 gauge will be safer and should fit the relays. However, this is not always true with the motor. So check the motor wiring making sure a 10 gauge wire will fit otherwise, 12 gauge will also suffice for 30 amps. The relays I believe are rated at 30 amps. Meaning even 12 gauge wire throughout, i.e. relays and motor should work.

Yes, the pic you attached is the correct ckt bkr. On one end there should be a small black tab which is used for resetting it.

 

[Jiggz]

After further review of the ckt bkr you attached it is an auto reset type which is also OK although preferred is one with a manual reset as mentioned by Jerry.

 

[arriva2001]

thank you for your help! I'll wait for the new wiring harness to arrive to figure out the wire gauge. But in the meantime, I'll find and order a manual reset 30 amp circuit breaker--that seems like a no-brainer to add one since there wasn't one, and since it seems other motors and configurations have it. If the book shows that it should have one, it has me stumped why there isn't one in there. Unless they changed configurations at some midpoint in 1994, maybe? Jerry mentioned that 1994 models don't have one, so maybe the model changed?

The only thing "different" about my motor is that it is a pacemaker factory edition. I'm not exactly sure what all this means, but when I bought it from the Mercury/Force dealer back in the 90s, he assured me it had a full warranty and these models were priced slightly lower than others because they had been used in "Force Mechanic School" as classroom examples. It was still sold as a new engine which required break-in. And I've only done routine maintenance on the electronics...no replacements or repairs up to now.

Thanks again for your help. I may have some more questions once I get all the parts in and begin re-assembling things.

One more quick question...since I have the trim pump motor out, is there anything serviceable in there I should concern myself with? or better left alone if it was working fine?

 

[Jiggz]

If the trim motor is working then just leave it alone. If you decide to break seals on the motor, make sure you re-seal properly. Even with the o-ring replaced, it's always recommended to re-seal it, i.e flex seal or some silicone sealant on the joint seams.

 

[jerryjerry05]

The difference is Mercury used their parts starting in 94.
There were 7 different models sold in 94.
3-4 different trim@tilt units used.
The difference from the first models of 94 to the last of 94 is quite a few different parts used.
They have model and serial#s and since you got it new? you should never have trouble getting the right parts.

 

[arriva2001]

Thank you. Interesting that so much changed that year...but it Makes sense with new mercury ownership. Yes I have the little cardboard card with model and serial number from when it was new, so that definitely helps when searching for a part.

 

[arriva2001]

I just wanted to close out the thread to let everyone know that i replaced the wiring harness and relays to the trim and tilt pump, and i added inline circuit protection, because my 1994 model did not have any ( I ended up using a 30 amp inline fuse rather than circuit breaker because there was not a great location to physically mount a circuit breaker.) I will say that I wasn't very confident that i could fix it after I saw all those melted wires and smelled that burnt electronic smell....but I took my time and put everything (the new parts) back exactly the same (or better) as I found them . I used heat shrink terminals and heat shrink tubing on everything.

After replacing all of the parts and wiring, and I had buttoned everything up and tested it out--I had no power to the pump motor. It still didn't work after ALL that... UGH. What a letdown. But, turns out I forgot to put the fuse into the holder, DUH!! After that, everything worked out great!

I ended upgetting the opportunity to take the boat out on Saturday for about four hours, and put the trim and tilt through a full battery of tests. And now that i have the inline fuse protection, I feel a lot better about it.

Everything worked just great, and it felt good to fix it myself.

Thanks all for your help. That's the most extensively I've ever torn into anything electrical, and I appreciate the help from the forum members.

 

[jerryjerry05]

That fuse will get ya everytime.
Glad it's working.