1990 Force 120hp Starter is/going bad?

bart98stang

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Greetings all. I have a 1990 Force 120hp and sometimes when I turn the engine over it cranks like the battery is going dead, even when I have my 50amp engine starter hooked up. The battery is a Marine deep cycle battery, 650 cold cranking amps, it was bought new in February and it's fully charged. Just a few minutes ago I hooked up my meter and the battery was 13.4 volts and when turning over it dropped to 10.6 volts which I know is normal. I disconnected my meter and started to walk back in the house but I turned around and wanted to try it again. Hooked the meter back up to the battery, cranked the engine and it spun fast like it supposed to and the engine started. The starter is Arco P/N 5393. Cylinder compression 1 through 4 is 120-115-115-120 psi respectively and all connections are tight.

Just not sure what is going on here..... I do appreciate your time. Thanks.

Edit: Now after I wrote this post I'm thinking I need to disconnect and clean all of the connections. Lastly, I was reading another post in a different forum and somebody mentioned that a deep cycle battery could cause slow cranking because the plates are thicker than a normal battery. Is this true? Thanks again.
 
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Jiggz

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Re: 1990 Force 120hp Starter is/going bad?

Let us discuss the myth first about starting and deep cycle batteries. The biggest difference between the two is the starting power provided by starting batteries but for only a short period of time. The deep cycle however is capable of sustaining average starting power for a longer period of time and able to survive a deep discharge. A deep discharged starting battery is basically a dead battery which will never recover its charging capacity anymore unlike a deep cycle battery. Will a deep cycle cause a slow cranking, not true unless the rated CCA is rated way too low for the starter. In your case with 650 CCA, the starter will crank over at its rated speed. Even if you use a 1000 CCA starting battery I doubt the starter will turn over any faster except maybe for a few rpms more.

If you want to verify if the starter is going bad is to directly connect it using heavy gauge jumper cables directly to the battery. If it cranks fast enough to start the engine then the starter is OK. Otherwise, if it would not turn over fast enough to start the engine and the battery is verified to be fully charged, then the starter could be going bad.
 

jerryjerry05

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Re: 1990 Force 120hp Starter is/going bad?

Picture 346.jpgPicture 004.jpgPicture 001.jpgPicture 008.jpgPicture 006.jpgClean ALL the contacts.
Even the ones on the solenoid.
Then check the cables and then remove the starter and take it apart.
A bad brush or weak springs and dirt can cause the problem.
It's a 23 year old motor.
Possible it's a 23 year old starter too.
One pic is the tool I made to re-assemble the starter.
The springs are the old and new set.
The others are from a working but weak starter.
 

I`mNotMe

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Sep 3, 2013
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Re: 1990 Force 120hp Starter is/going bad?

Agree with Jerry.

I too removed my Force's starter and disassembled (as advised by Jerry as well). Its actually easier than it looks. To my surprise, very little internal dust and all looked good. 3 of its 4 brushes looked great. It's one remaining brush caught my eye. It was worn down so bad, even its wire was worn 1/3 through. Its brush was almost hanging on by its wire threads. No wonder why my Force starter was sluggish at starting at times. To repair, I simply ordered brushes from my nearest boat store. Recommend removal, disassemble, clean (using engine cleaner Junk spray fluid) and fully inspect their internal brushes as well. When re-assembling, put small pea size amount of grease using Q-Tip on its brass bushing and its 9 tooth gear. Little lube but not too much on its "metal on metal" rub areas. I put NO lub on its brush / brass contact area. For my every spring de-winterize tasks, I plan to disassemble, clean, inspect and lube my boat's starter as well. Hope this helps.

If your starter insides looks great, suggest removing / replacing its head gasket. When head is off, do in-depth inspection of its cylinder walls / piston tops as well. And if still shinny plugs after head gasket replacement, do further investigate its exhaust plate gasket next. If water is within the cylinders (being sucked in by hot engine), it will dramatically increase its piston compression. And, give the impression of starter problems. If plugs are different color (re: black and others shinny clear looking), it might be a water entry problem (instead of a starter problem). Or, could be both problems.

Hope this helps.
 
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bart98stang

Petty Officer 2nd Class
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Re: 1990 Force 120hp Starter is/going bad?

Jiggz, thanks for the knowledge regarding starting and deep cycle batteries. I connected the battery directly to the starter with no change. Cranked very slowly.

Jerry, I cleaned every single connection from battery, to solenoid, to starter prior took connecting the starter directly to the battery. I also took apart the starter and it was fairly clean and the brushes didn't look pitted.

NotMe, I took the head off and the pictures with my finger tips is what cylinder is what. This is what I found.

IMG_20130913_185951_614.jpg IMG_20130913_190006_179.jpg IMG_20130913_190405_946.jpg IMG_20130913_190428_363.jpg IMG_20130913_190456_752.jpg
 
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I`mNotMe

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Re: 1990 Force 120hp Starter is/going bad?

IMO, piston tops look good. Within picture IMG_20130913_190006_179.jpg not too sure why 3 x piston areas look black carbon but the one piston looks too shinny. Like a water leak that is "steam cleaning" its piston top / head area. All piston tops in this picture should look the same. Do fully inspect its head gasket (top and bottom surfaces). Perhaps there's a pin hole in the head gasket?

Also. Slowly manually turn the flywheel by hand and do full visual inspection of its cylinder walls. While each piston at its bottom position, how does each of their intake ports appear? How does each of their exhaust ports appear? If using a dentist type mirror (re: quarter size mirror on a stick - LOL!), can you also see inside each exhaust port holes? Do each of their ports look the same?

Hope this helps...
 
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Jiggz

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Re: 1990 Force 120hp Starter is/going bad?

The head indicates improperly set carb on the bottom pistons or the fuel recovery system is clogged and not working. There is obviously too rich mixture of fuel on these bottom pistons. The tops pistons on the other hand shows a very lean mixture or water leaks. If used on fresh water only this is most likely a water leak but if used on sea water, there should be some salting in the head and exhaust.Definitely need to inspect ports and cylinders are mentioned earlier.
 

bart98stang

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Re: 1990 Force 120hp Starter is/going bad?

Replace gaskets it is!! Both intake and exhaust ports on all 4 pistons look good and the same. The cylinder walls look good also. It looks like it used to be a salt water motor because there are some salt deposits in the water jackets but not much. Jiggz, in regards to the head cylinders 1 & 2 are the one with carbon deposits and 3 & 4 are the shiny cylinders which match the spark plugs in another post I had written.

So I'm going to replace the head gasket and while I'm at it going to replace the exhaust gasket. Since I cleaned all connections and assuming the starter is good, going to replace these two gaskets and stop water from entering the combustion chambers which is increasing compression as stated by NotMe in post #4, is it possible that this could correct the slow cranking problem that I'm experiencing?
 

jerryjerry05

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Re: 1990 Force 120hp Starter is/going bad?

You'd have to get a TON of water in there to make it hard to turn over.
NEVER!!!! Assume the starters good.See my pics above.
That starter would work. Slow and tired was the best way to describe it.
Takes 10 min. to disassemble the starter.
 

Jiggz

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3,817
Re: 1990 Force 120hp Starter is/going bad?

After jumpering the starter directly to the batttery (both positive and negative cables) and still cranks slow it is most likely a starter problem assuming the battery is verified to be fully charged at the time. I'll still go with Jerry's recommendation to open and inspect and finally clean and assemble the starter, unless there is something seriously bad and needs replacement. In fact, it's not even a day or two ago with one member experiencing the same problem and when he opened the starter, one of the magnets is chipped and the broken price jamming the armature hence slowing the starter down.
 

bart98stang

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Re: 1990 Force 120hp Starter is/going bad?

Gentlemen, sorry I haven't responded. I was away on travel for work. I already took apart the starter as stated in post #5 and it looked real good. It wasn't dirty at all. Neither of the magnets were chipped, all four brushes were smooth with no chips and no pitting, armature was clean with no chips or pitting. All in all it looked no where like Jerry's post #3 pictures. I will take apart once more and maybe clean with a degreaser.
 

jerryjerry05

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Re: 1990 Force 120hp Starter is/going bad?

The reason I suggest a compression test when it's hard to turn over is that uneven pressure on the cylinders will cause it to be hard to turn over.
Replacing the gasket,you do that?
Do another comp test.
When it's hard to turn over the motors telling you somethings still wrong.
When I first got my boat 88 in 89. One engine started turning over slow.
Only a year old?? I did a comp test.Found the rings were carboned and had to rebuild.
 

bart98stang

Petty Officer 2nd Class
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Mar 6, 2011
Messages
104
Re: 1990 Force 120hp Starter is/going bad?

Thank you for your time gentlemen. I went to a local used boat dealer and they had a used starter. I replaced it and it turns over like a champ. I did do another compression test and I got the same results as in post #1 120-115-115-120 cylinders 1-4 respectively.

I have other questions regarding this motor so I'm going to start another thread. Thanks again.
 
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