115 hp mercury Starting/Electrical Problem

[Tripp Halbert]

ID # is faded out but i believe this motor to be a 1995 model. It will crank and turn over but very slow crank speed and then dies very quickly after turning over. I ran a compression test on all cylinders, 1-3 are 135psi. Last cylinder gets to about 132 or so and then the coil arcs and the starter stops.I havent gotten to doing a spark test yet. How do i test the coils to see if there any good or is this coil grounding somehow? never seen this happen during a compression test before...

 

[racerone]

Remove starter and take it apart.----Very easy to check these starters.--Take ohm reading from shaft to the commutator .--Should read infinity.----Perhaps install new brushes if ohms test ok.--I install new brushes all the time at $5.00 a set.

 

[Tripp Halbert]

thanks for the info racer. The starter has been starting the motor no problem though. just when i did the compression test on that particular cylinder is when i see the coil spark and the starter just stops.

 

[racerone]

Coil or solenoid ?-----Any loose cables ?

 

[Tripp Halbert]

It's the mechanism that sends spark threw spark plug wire to spark plug, coil right? I check cables nothing obvious. Note: Bolt on head where all the coils ground is pretty corroded.

My phone pics are to large to upload so please visit my Facebook page through the URL I provided to see what I'm talking about as well as some other issues I've noticed

https://m.facebook.com/larry.halbert/albums/10206074845813706/?ref=bookmark

 

[Tripp Halbert]

Bumppp....Anyone??

 

[enginepower]

That ground is badly corroded. Clean that up and see if you get a better spin. Now you say, when I test that cylinder, you should be doing a compression test with all spark plugs removed.

 

[Tripp Halbert]

Yes I did the test with all of them out. Could not warm the engine up tho as it won't run long enough. And for cleaning the ground, sandpaper and pb blaster good? What would u suggest using?

 

[Tripp Halbert]

Update:
I conducted a spark test and all were blue. So I was curious to try another compression test. Needle ran up to 120-122 PS I And Then Would Shut off. I held the pressure switch on the tester to let the cylinder pressure run threw, cranked it, and it kept cranking

Now what does this mean guys, when getting up to a certain pressure, the cranking stops? Maybe a switch? Bad ground?

 

[racerone]

The pressure has nothing to do with stopping the starter.---------------Inspect the starter as there might be an issue with the starter or solenoid.---As per post # 2

 

[Tripp Halbert]

thx

 

[Tripp Halbert]

check out this wire that's been cut on the starter. Which wire is this?

 

[Tripp Halbert]

Racerone. You sir are a genius. Starter brushes were destroyed down to the wires!!!

 

[Tripp Halbert]

Okay racerone. I rebuilt the starter with a brush kit
existing brushes were fried. Got motor to fire a couple times with a strong crank. Then starter got stuck engaged and on. I had to disconnect battery and almost got shocked. disassemble the starter. Reinstalled.

Weak power, wouldn't turn flywheel. Listen for a click in starter solenoid but there wasn't so I replaced the solenoid. Now I hear the solenoid clicking but still won't turn flywheel unless All sparkplugs are removed. Now trim and tilt is very weak sounding as welll. Charging battery as we speak and will try again.

Battery fully charged. changed battery terminal positive wire fitting that was pretty messed up. Tilt-trim is strong again. Turned key and had it fire up about 5-10 times. But then the ability to make the starter engage and turn got shorter and shorter. Now when i turn the key all that happens is a sound comes from the starter solenoid, the whole time i hold the key to start position, the solenoid clicks. not just one click, it goes click-click-click-click, etc.

I have no idea where to go from here people....:grumpy:

Also, Please visit my fb page link below for a video of the starter hooked directly to a 12v battery to show how strong it runs. I believe this rules out the starter as being any problem at all to a lack of engagement or power to start, correct?

https://www.facebook.com/video.php?v...02996036927923

 

[Bigreddon]

You have a bad battery. As you crank, keep a voltmeter on battery. Voltage should start at 12.5 , and as you crank for ten seconds should not drop below 10.5 v. And after cranking, battery should recover to over 12v .

 

[Bigreddon]

This will be hard to explain..use a VOLTMETER to measure ohms. First, place the positive lead on the battery TERMINAL. Second, place the negative lead on the starter STUD. Crank engine and read DC voltage. Should be less than .5 volts. This is the amount of voltage going through your meter, and not the starter cable. Use this method to find voltage drop (ohms) on every connection. Battery post to starter, battery connection to starter connection, starter positive to starter negative, etc, etc....using voltage drops is the correct way to test connections .

 

[Bigreddon]

Your video shows the gear not kicking out. That hear should kick out to the top under full starter speed. I think your battery is flat. Do a voltage drop test across cables to measure for voltage loss across cables and connections. (Voltmeter plus and minus at each end of cable to measure voltage lost while cranking)

 

[Tripp Halbert]

yes i believe you are somewhat correct. I noticed the battery would crank no problem for a bit, only for about 10 cranks. After that it got weaker and weaker to where the solenoid would just click. This battery has no problem cranking my 70hp motor over and over. I guess maybe the cranking amps are not high enough for this 115 battery? What battery do people usually use for a 115hp motor?

 

[racerone]

Did you take an ohm reading on the armature when it was apart.---Take a reading from the commutator to the shaft.-Should read infinity.

 

[Tripp Halbert]

it was a combo of the starter brushes being fried and my battery dying pretty quickly after a couple of cranks. all is well now, thanks guys.