1994 Merc OB 150 Power-Tilt + Ignition Problem

[jedwards6]

Hope someone can give me advice. My intermittent problem is that the starter motor will occasionally not turn over. The diagnostic beeps come on OK, the gauges light up, but turning the key to start produces nothing. Whenever this happens, the power tilt switch, both the one at the motor and the one on the throttle also stop working. I don't know if there is a relationship between the two, but neither problem seems to happen separately. Whenever the power trim isn't kicking on, the start won't turnover... as soon as one works the other begins working too. On one occasion, the power tilt stopped working while the motor was running, and when I was trying the tilt switches, the ignition power-on beeps went off. The motor did not stop running during all this.<br /><br />Whenever this happens, the rest of the electrical system (Pumps, lighting etc.) seems to work OK.<br /><br />The batteries have full power and there is no visible signs of corrosion or bad connections. Could the keyswitch be a problem?<br /><br />The serial# of my motor is 0G110515. <br /><br />Thanks!

 

[KCLOST]

Re: 1994 Merc OB 150 Power-Tilt + Ignition Problem

This could be just a grounded out connection somewhere, since it comes and goes...<br /><br />But it shouldn't be the key switch... If it is wired like mine, the tilt/trim is hooked directly to the battery so you can use it when the key is off or on....<br /><br />Why the starter is affected? That has me stumped..... However, the starter feeds directly from the battery also, it sounds like there is a bad connection at the starter battery or leads from it to the engine... But I could be wrong. Disconnect everything and check thoroughly, Then reconnect and retest....<br /><br />Take a look at your wiring diagram for your motor, and see if there is a common connection that could cause both problems....<br /><br />It's common knowledge that most electrical problems similar to yours come from a bad wiring harness. When you catch the motor when it won't fire, turn the motor (to move the wiring harness around) or move the wires around near the battery and see if that solves it. Sounds redneck, but a good place to start. If it refires, you most likely have a short in the harness somewhere...

 

[Chris1956]

Re: 1994 Merc OB 150 Power-Tilt + Ignition Problem

Oldscad, The two items that fail to operate (starter and Trim) are the ones that draw the most current (by far) of any other device. I would suspect a bad ground, either on the battery cable or at the battery connection, assuming the trim ground is a seperate cable to the battery. Also, resistance of a cable changes with heat. I had a battery cable that was 3/4 rotted out under the insulation. This allowed the starter to operate well for about 20 seconds before the heat raised the resistance of the cable and the started slowed until it did not turn at all.

 

[jedwards6]

Re: 1994 Merc OB 150 Power-Tilt + Ignition Problem

Thanks for the responses! I did spend last night poring over the boat's wiring diagram and it does appear that the remote power trim switch (at the throttle) does share the wire from the keyswitch to the engine, a red-purple wire referred to as "eng circ pwr" on the diagram. The remote power tilt has three wires. Two go directly back to the engine to control up and down on the power tilt. The other attaches to the wire that is connected to the keyswitch. This is actually consistent with the recommended diagram shown in the Mercury install guide. The "start" wire is a different wire also coming out of the keyswitch, which in my uneducated mind leads me to the keyswitch as a possible problem.<br /><br />I have inspected the battery terminals and wiring and it all appears clean. I have a dual battery system and the problem has occurred on both batteries. I've also inpected the battery switch which looks pretty good. <br /><br />So am I thinking I'll replace the keyswitch which has had 10 years of saltwater use and for thirty bucks is not going to break the bank, plus verify the integrity of the "eng circ pwr" and the "eng circ ground" wires.<br /><br />Do I sound like I'm on the right track?<br /><br />Thanks.

 

[KCLOST]

Re: 1994 Merc OB 150 Power-Tilt + Ignition Problem

Worth a try.<br /><br />How about the other tilt/trim switches do they all fail to work at the same time? <br /><br />But it sounds like your heading in the right direction as the ignition power-on beep is a good indication that is the cause.

 

[jedwards6]

Re: 1994 Merc OB 150 Power-Tilt + Ignition Problem

When the problem occurs, both the tilt switch at the throttle and the one on the cowl stop working. So I think I'm resigned to verifying all of wiring associated with the starter and trim along with replacing the keyswitch. What a way to spend the weekend!

 

[DHPMARINE]

Re: 1994 Merc OB 150 Power-Tilt + Ignition Problem

oldscad,There is a fuse,under the cowl,near the starter (usually).It controls voltage to the ignition switch,and in turn supplies voltage to the solenoids that control the TNT as well as the starter cranking.<br />This fuse gets power from the same solenoid where the battery cable (+) attaches.<br />Your problem is somewhere between the solenoid,fuse,wiring connections.

 

[jedwards6]

Re: 1994 Merc OB 150 Power-Tilt + Ignition Problem

Seems to be fixed! Went through all the wiring that is accessible without tearing into the boat. I think I found the fuse you're talking about. There is also an inline fuse in the main power wire to the battery switch which was not easy to see without poking my head into the bilge and moving stuff around, so I did not see it before. It was oxidized and felt loose. Basically, based on everyones feedback that it sounded like a classic wiring issue, I just went through all points of connection/contact, cleaned, reconnected, tightened.<br /><br />Took the boat for test drive and experienced no problems! It could be my imagination, but it even felt like its power improved a bit. The true test will come after a few all-day trips, but I think the problem is solved. <br /><br />Thanks again for the expertise!<br /><br />By the way, what is the typical lifespan of the two-way Perko battery switch? Mine's been in place about nine years, the boat is mainly used in saltwater.