2005 Mecrury 90 Won't Crank

[rmarcy]

Help- I've got a 2005 Mercury 90 4-stroke on a pontoon boat. Its been sitting about 5 months with the battery disconnected.

I reconnected the battery but the engine will not crank. It will not even try. I've tried a different battery and cleaned all the connections. The fuses are all good.

All of the other electrics work on the boat: horn, gauges, lights, stereo, etc. BUT the down trim switch will work from the throttle but the up will not. The trim switch on the motor works equally well up or down. It lifts the motor without any hesitation.

So I'm thinking I'm losing power somewhere between the battery and the boat unless its something on the motor. I'm considering replacing the ignition. Would that possibly be the cause of this type of problem? How about a bad kill switch? It seems that could stop the motor but wouldn't effect the trim.

Any ideas will be appreciated before I give in and send it to the shop. Thanks in advance for your help.

 

[MaggieRose]

Re: 2005 Mecrury 90 Won't Crank

Trace the wire that goes from the starter back to the solenoid (this is your hot (+12V) lead. The other lead on the starter is the ground. This should be a solid ground. With a DVM set for Ώ, put one lead on the starter ground and the other lead on the block (bare metal). The meter should indicate close to ZERO.

After you verify good ground, starter can be checked directly by running a jumper cable from the + side of the battery directly to the hot lead on the starter. This should cause the starter to kick over. If not starter is shot.

Put muffs with water on the LU or do this with the boat in the water.

Check circuit by putting the voltmeter (set for DC Volts) from this hot lead to any good ground on the engine. Have a friend try to turn the engine over. When the ignition switch is turned to START, you should have 12 volts on the voltmeter. If not, the solenoid could be bad, bad ignition switch or contact or bad fuse.

 

[Silvertip]

Re: 2005 Mecrury 90 Won't Crank

Did you perhaps put the battery cables on backwards - even momentarily? If so, check for a blown fuse on the engine. And then hope you didn't fry the voltage regulator.

 

[rmarcy]

Re: 2005 Mecrury 90 Won't Crank

Thanks for the posts. I'm on hold right now while I look into muskrat damage. Apparently several boats in the area were damaged by muskrats. I got that response unsolicited from several local shops when i explained the problem. Apparently they may have chewed the up wire but not the down which would explain that piece.


I'll post back and let you know-

Thanks!

 

[Bigjohn1]

Re: 2005 Mecrury 90 Won't Crank

Trace the wire that goes from the starter back to the solenoid (this is your hot (+12V) lead. The other lead on the starter is the ground. This should be a solid ground. With a DVM set for Ώ, put one lead on the starter ground and the other lead on the block (bare metal). The meter should indicate close to ZERO.

After you verify good ground, starter can be checked directly by running a jumper cable from the + side of the battery directly to the hot lead on the starter. This should cause the starter to kick over. If not starter is shot.

Put muffs with water on the LU or do this with the boat in the water.

Check circuit by putting the voltmeter (set for DC Volts) from this hot lead to any good ground on the engine. Have a friend try to turn the engine over. When the ignition switch is turned to START, you should have 12 volts on the voltmeter. If not, the solenoid could be bad, bad ignition switch or contact or bad fuse.

Excellent input and recommendation, this is precisely what I would try.

 

[rmarcy]

Re: 2005 Mecrury 90 Won't Crank

Thanks everyone for the input. Very good advice. The muskrats were in fact the culprit, however. They had chewed through several wires underneath the boat were they could not be seen. After a splice job today everything is back to normal.