Force 120 Hp won't start

[lifan]

Hi, for the sake of the reader, I will try to make this Long Story as short as possible. Any Help would be greatly appreciated.

My Force 120 hp 1994 overheated on the way back in.
Tried to start the boat and it seemed as though the battery was weak, I say this because the starter just would not go fast or spin completely.
So, Did the following with no real positive results:

First, tested battery had 11.9 amps
cleaned all terminals and ran continuity from cable to cable. Checked Fine
Checked all starter related connections, checked fine
Replaced starter cables anyway (Because I just love wasting my time and money)
Replaced Starter Relay (Same as Above)
Pulled starter brought it to rebuilder and he said "It's Fine" Not the starter.
Pulled all plugs and starter spins like it should
Flywheel spins great with no friction at top dead center when plugs are out.
Dropped lower unit to change water pump and left it off, just in case it was somehow binding (I Know I'm Reaching)
Disconnected battery cables from starter, attempted to run starter with fully charged power pack, same results
Ran positive cable direct to starter, just tapping to engage, bypassing relays, Same Results

Am now completely baffled. Please Help!

P.S. I posted this in another forum and could not find it, so If you saw it there and answered with some advice, forgive me and post it here again.

Thanks for your help!

P.S. When we pulled the head gasket found a tiny scratch in cyl #3 Had compression on all 3 Cyls, three being slightly lower.

 

[pnwboat]

Re: Force 120 Hp won't start

Have you load tested the battery? From what it sounds like you've done, it's most likely the starter itself, or the battery. You can take the end cap off of the starter and inspect the brushes. Clean them up if necessary.

 

[JB]

Re: Force 120 Hp won't start

To check starter, run + and - cables from battery direct to starter. Continuity check won't find resistance in the milli-ohms necessary to cause starter to slow down. Load test battery.

 

[lifan]

Re: Force 120 Hp won't start

Have you load tested the battery? From what it sounds like you've done, it's most likely the starter itself, or the battery. You can take the end cap off of the starter and inspect the brushes. Clean them up if necessary.

Load test on battery checks okay. Ran + cable battery to starter and no negative terminal on starter so it's on the block. Same issue.
Starter Looks clean and was tested, but I think the starter may just not be good enough, it's an aftermarket rebuild. Leaning towards buying a new one but since you can't return them, I just thought it could be something else. Thanks for the replies and suggestions.

 

[Jiggz]

Re: Force 120 Hp won't start

Unfortunately in your case, the only fool proof diagnosis is to test it with a known working starter unit. If you know someone or a repair shop that has one you might want to talk to them. or you can get an aftermarket for less than $100 on ebay or amazon. I'm thinking the starter armature could be riding or rubbing the stator already due to worn out bearings. You can test this by trying to test for movement on the starter shaft horizontally and vertically and there should not be any play.

 

[lifan]

Re: Force 120 Hp won't start

Have you load tested the battery? From what it sounds like you've done, it's most likely the starter itself, or the battery. You can take the end cap off of the starter and inspect the brushes. Clean them up if necessary.

Brushes look great, windings do to. But thanks for the Tip

 

[lifan]

Re: Force 120 Hp won't start

To check starter, run + and - cables from battery direct to starter. Continuity check won't find resistance in the milli-ohms necessary to cause starter to slow down. Load test battery.

Tried that, still not working, but Thanks for the Tip

 

[jerryjerry05]

Re: Force 120 Hp won't start

IF???? You've take the starter apart and it's all good.
You've load tested the battery.
The cables are good.
The connections are good.
I think you've already touched on the problem?
The compression,what were the #s??
Low compression can cause the symptoms your describing.
These motors need even comp or it can be a bugger to turn over.
The comp needs to be within 5-10 # of each other.
If one of my motors had a difference of 10# in 1 cylinder, I'd FREAK and start looking for a fix.

 

[procraftguy]

Re: Force 120 Hp won't start

If its a ground to block starter on bottom . Run jumper cable to battery ground to rule out ground it effectively rules out ground issue witch it sounds like to me