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Author Topic:   Starter Slow to Crank
Phillips posted 05-25-2006 11:58 AM ET (US)   Profile for Phillips   Send Email to Phillips  
Hi, group. I’m having problems staring my motor. When I engage the starter it cranks slow. Way too slow to start the motor. Before I take it into the shop I’d like to get your comments, thoughts, or suggestions.

My ’89 Montauk is powered by an ’89 100hp Mercury. When I put it away in the fall it ran like a top. I’ve just taken it out of inside winter storage, and when I crank the engine it turns over very slowly. I got a new battery and charged it up, but the engine still cranks slowly. Now what?

Before putting the boat away for the winter I fogged the engine, removed the spark plugs, sprayed the cylinders with fogging fluid, and replaced the plugs. After I brought it out of storage I removed the plugs, cranked the engine to expel the fluid remaining in the cylinders, and installed a set of new plugs. I cranked the engine again, but it turned over slow. Real slow. This isn’t unusual after the motor has sat unused for a while, so I turned off the key and tried it again. Same thing. This IS unusual. Thinking that it was a bad battery, I got a new one and charged it up. Again, I cranked the motor, but it cranked slowly. I let it sit for a while as I scratched my head, and then tried it again. It began to crank slowly, then briefly sped up to normal, but then went back to cranking slowly. Any recommendations, before I take it to the mechanic?


Al Phillips

Casco Bay Outrage posted 05-25-2006 12:22 PM ET (US)     Profile for Casco Bay Outrage  Send Email to Casco Bay Outrage     
Sounds like a loose connection.

Is the battery in the stern or in the console?

I would check positive and negative connections at the battery then back to the engine and then to the starter. Check the connectors too.

JBCornwell posted 05-25-2006 01:49 PM ET (US)     Profile for JBCornwell  Send Email to JBCornwell     
A more common problem than you might think, Phillips.

The most common, and easiest to fix, cause is loose or corroded connections in the high current circuit. The most common bad connection is where the battery ground cable bolts to the engine block.

Other possibles are a cable that is corroded inside the insulation, bad connection to the battery post(s), poor electrical connection where the starter motor is bolted to the block.

More expensive would be a failing solenoid and most expensive would be a starter motor in need of rebuild.

Good luck, and let us know what you find.

Red sky at night. . .

bsmotril posted 05-25-2006 01:50 PM ET (US)     Profile for bsmotril  Send Email to bsmotril     
There's a thread on this same topic in the Electrical forum at this site. BillS
Link posted 05-25-2006 02:31 PM ET (US)     Profile for Link  Send Email to Link     
I had a problem last year where my starter drive started sliping. We couldn't get the motor started as it was turning too slow. While checking out the motor someone touched the drive and burnt their hand. We pulled the drive of and it was slipping inside, so we replaced it and everything has worked fine since.
BBS posted 05-25-2006 02:52 PM ET (US)     Profile for BBS  Send Email to BBS     
I recently had the same problem. It cranked and cranked (slowly). I glanced down toward the stern and the battery cables were smoking and melting - apparently they failed where they came in contact with the splashwell.
flawton posted 05-25-2006 04:55 PM ET (US)     Profile for flawton  Send Email to flawton     
I had this problem on my 90 hp yamaha last year. It ended up being one of the short fat scews that held the brushes in place on the starter. There are four of them on the starter and the one on the back side had worked its way out causing the starter to turn over slowly, even with a new battery. I found the screw cause I could hear it tumbling to the front of the engine compartment when I tilted the motor out of the water. pulled the starter, reinstalled the screw with a little locktite and it works like new.

A longshot.

pglein posted 05-25-2006 06:05 PM ET (US)     Profile for pglein  Send Email to pglein     
This is a common problem with outboards. Most common is just a loose or dirty connection to the battery. Also common is a bad starter. Take your starter to a qualified rebuild shop and save yourself some money over buying a new one.
kamie posted 05-25-2006 08:28 PM ET (US)     Profile for kamie  Send Email to kamie     
Looks like I am in the same situation.
marshmstr1 posted 05-26-2006 12:29 PM ET (US)     Profile for marshmstr1  Send Email to marshmstr1     
Sounds like batt problems, if you check all connections and charge batt it should work fine!! If not your batt may have enough volts but not enough amps!!!!!Batts don't last forever, i wish they would!!
jimh posted 05-26-2006 12:58 PM ET (US)     Profile for jimh  Send Email to jimh     
jimh posted 05-26-2006 01:12 PM ET (US)     Profile for jimh  Send Email to jimh     
Also see:

There are many components in the starter motor current path:


--battery terminal
--battery cable to master switch
--master switch terminal (in)
--master switch
--master swtich terminal (out)
--battery cable to engine
--starter solenoid terminal (in)
--starter solenoid
--starter solenoid terminal (out)
--battery cable to starter motor
--starter motor terminal (+)
--starter motor
--starter motor terminal (-) (often the case itself)
--connecting bolts
--engine block


--battery terminal
--battery cable engine
--engine block

You should carefully check all of these connections. Even a very small resistance will cause a substantial voltage drop due to the high current drawn by the starter motor.

The starter motor current will be on the order of 100-amperes. In order to limit the voltage drop between the battery and the starter motor to only 1-volt, the resistance in the circuit has to be less than 1/100-th of an ohm.

In my experience it is quite common for low-voltage, high-current connections to develop some resistance due to oxidation or corrosion, particularly if subjected to wide temperature ranges and moisture. It is difficult to assess the condition of a connection visually. You have to check each one with an ohmmeter.

If there is a large voltage drop between the battery and the starting motor when cranking, you can locate the problem by measuring the voltage drop across each connection. This should locate the segment of the circuit with the high resistance.

Phillips posted 05-26-2006 09:25 PM ET (US)     Profile for Phillips  Send Email to Phillips     
Thanks for all the replies, group. This morning I spent some time looking for bad connections, but struck out. I would have liked to have tackled the starter, but since I didn’t have the time to do the necessary homework I took the easy way out. I dropped the boat off at the local dealership this afternoon. When I get it back I’ll let you know how it turned out.

Al Phillips

jimh posted 05-27-2006 09:53 AM ET (US)     Profile for jimh  Send Email to jimh     
Al--Yes, please let us know what fixed your problem. We always like to hear "the rest of the story."
Phillips posted 06-22-2006 11:55 PM ET (US)     Profile for Phillips  Send Email to Phillips     
Hi, Group. Well, it took a while, but I picked up my boat today, so I can finally tell you how it turned out. My “slow to crank” problem turned out to be a worn out starter. The mechanic began by cleaning all the connections, which did improve the cranking speed somewhat, but not enough to pronounce it fixed. He recommended a new starter, which I approved. It now works great. The breakdown on the repair bill is: Brand new starter from Mercury $291. Labor $89. Miscellaneous shop supplies / parts $25. New Jersey sales tax $23.

As I said previously, I would have liked to have tackled the starter my self, since it’s easily accessible. Unfortunately, I just didn’t have the time to learn while doing. (Not that I’m a slow learner, mind you. I just have a lot on my plate these days.)

Thank you for your inputs and interest.

Al Phillips

Phillips posted 06-23-2006 08:46 PM ET (US)     Profile for Phillips  Send Email to Phillips     
Another observation:

Today I put the boat in the water and actually turned the key with intent to start. Wow, does that starter spin fast!! I bought the rig new in ’89, and had forgotten how fast the motor cranked when new. It hasn’t turned over this fast in years!

Happily boating,

Al Phillips

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