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I have a 1999 Force 120 hp outboard that will periodically…

I have a 1999...

I have a 1999 Force 120 hp outboard that will periodically and slightly turn over on start attempt. I have fully charged battery and have cleaned posts and connections, removed and cleaned up starter motor, bench tested starter and solenoid and both are okay. After reinstalling starter and solenoid, motor started and ran maybe 30 seconds and died. Tried to restart and had same problem as before...very labored turnover or nothing. Starter motor got extremely hot in trying to crank. Also tested and found voltage drop from 12 volts at battery to about 8 volts at solenoid when trying to crank. Could the voltage drop be the slow/no crank and hot starter?

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Answered in 8 hours by:
3/12/2018
Jason
Jason, Marine Mechanic
Category: Boat
Satisfied Customers: 16,771
Experience: Degree in Marine Technology. Gas and diesel marine mechanic.
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G​ood morning, my name is ***** ***** am I speaking with? I read what you wrote. Have you ever heard of the term "voltage drop" when it comes to electrical measurments?

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Customer reply replied 1 month ago
This is Steve. Viewed some YouTube's on voltage drop and how to measure with multimeter. I have meter.

H​I Steve. What voltage drop is, is the difference between your source voltage (IE the battery) and wherever you are measuring voltage. A standing battery is roughly 12.7 volts. When you put a load on it, by energizing the starter, that voltage will start to drop down. A good battery needs to maintain at least 10.5V when loaded. Your voltage at the battery is not going to maintain 12V when you energize the starter, it is normal for it to drop. Now the difference between whatever the source voltage is, and wherever you are measuring voltage, is called voltage drop. For example, lets just say your battery is maintaining 10.5V when loaded, but the voltage at the solenoid is 8V. That means you are dropping 2.5V across the circuit, which is to much. There are 2 things that cause voltage drop. 1. Poor connections. 2. Corrosion. Both poor connections and corrosion will take voltage and turn it into heat. If you have not done so already you can try taking the battery cables off, sanding down the ends, cleaning up the battery terminals, and reattaching everything and see what happens. If you still get low voltage at the starter. You can next try cutting the cable ends off, stripping the wiring back, and see if the wiring looks good or not. What happens with all boat battery cables over time is moisture will get in behind the cable end connectors, and that moisture will wick it's way up the cabling, where it will sit forever, slowly rotting the cable out from the inside. You can have a battery cable that looks like it's brand new on the outside, and you can slice that cable right down the middle and the insides of it will be rotten. For example, click this link for a picture, the green you see in the cable is all corrosion. This cable is a goner and requires replacement - https://imgur.com/a/YeEut. The starter motor itself requires 9.5V or better to start and turn the engine over. When voltage is below that 9.5, what will happen is the starter will attempt to draw more amps than it needs because of the lack of proper voltage. If this goes on for long enough, the starter will burn itself up as well. Where you need to start is by cleaning up the cables and seeing if voltage comes back up or not. If it doesn't come back up, then you would need to replace the cables, and make sure you are getting at least 9.5V to the starter. If the starter still spins slow or will not spin the engine over with the 9.5V, then the starter itself is also going to be burnt out. When you do this, you would need to make sure you do both the positive and negative connections/cables. Voltage drop does not just occur in the positive cable, it happens in the negative cable as well. Finally, when you are doing your voltage tests, make sure that there isn't any kind of battery charger hooked up, as that will skew the readings, and whenever you take a reading you want to make sure that you are reading battery voltage only, and not battery charger voltage. Does that all make sense to you. I think that should do it. But I work for tips so I do want to make sure you are happy with my service before you go. If you had a further or more specific question on the issue by all means feel free to ask. If not, Just in case you do not understand the way the website works (and some folks do not). You do have to put forth a positive rating in order for it to credit me for helping you. When ratings are not done, the website simply keeps your deposit and they will not credit me. The ratings box is located at the top of the screen. To rate, you must select the star you wish and also confirm it. Please let me know if you run into any problems or errors when trying to do it. If you do have a problem, or if you can not see the ratings box which is at the top of the screen. Please reply back "I rate Jason's service _______" and fill in the blank.

Questions do not close out, so if you have to come back later on with follow up questions to the issue you still can even after doing a rating.

Thank you
Jason

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Customer reply replied 1 month ago
Thank you Jason. I checked voltage drop between battery and solenoid, with less than 8 volts at solenoid. I'll verify your suggestions today and let you know results. I'll definitely do the rating.

You need 9.5V at the starter itself, so 8V at the solenoid is way to low. Start with those cables first, clean them up or replace them, whatever it takes to get the voltage up. If you do get that voltage up to over 9.5V at the solenoid, but it's still low at the starter, the solenoid itself is going to be burnt up as well, causing another drop in voltage. Let me know how you make out.

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Customer reply replied 1 month ago
Jason, sorry about the delay in getting back to you. I cleaned up battery connections, checked continuity on cables, and have 12.4 V, no load at solenoid, but only 8 V under load. Battery no load is 12.68 and 9.8 on load. There is a new noise when the few times turnover and the engine starts momentarily. Can't tell if it is starter or something else.If I understand your previous response, I probably have a bad solenoid. If you confirm this, I'll order asap. Thanks.

Right now you have both a bad, weak, or undersized battery for the outboard, as well as bad battery cables. Remember that the battery must maintain at least 10.5V when loaded, yours is 9.8, so that is to low. Also, if you are getting 8V to the solenoid, that means you are dropping 1.8V between the battery and solenoid, which means you have rotten cables as well. You will need to get a new battery (Group 27 Marine is the most common size, and will work for that engine) and new battery cables.

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Customer reply replied 1 month ago
Now I have 11.0 V on battery under load and 12.4 V at positive on solenoid with no load. On cranking, solenoid drops to 8.0 V on the starter cable solenoid post.

O​kay that is a 3 volt difference, which is to much. Did you replace those battery cables yet?

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Customer reply replied 1 month ago
they are new.

I​s there any kind of battery switch installed on the boat, or does the battery connect directly to the outboard?

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Customer reply replied 1 month ago
Directly to the outboard.
Customer reply replied 1 month ago
No switch on battery.

O​n the solenoid, there is an input side and an output side. The input side is where the cable from the battery connects to. The output side is where the starter motor connects to. When you get this 8 volt reading, which side is the meter lead connected to?

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Customer reply replied 1 month ago
starter motor connection side.
Customer reply replied 1 month ago
Just to clarify, the 8 V reading is from the output side of the solenoid where the starter motor cable connects to solenoid.

Okay got that. Now what is the voltage on the input side of the solenoid with the key held to start? (You will read roughly 12.4 with the key off, but the voltage will drop when the key is held to start)

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Customer reply replied 1 month ago
9.98 V under start load.

Okay so if you are almost 10 on the input side, and 8 on the output side, the solenoid is going to be burnt out as well. A good solenoid will drop less than .5 of a volt, yours is dropping 2. That means it's internal contacts are burnt up.

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Customer reply replied 1 month ago
Great to know this. I'll go pick up a new solenoid this PM and install Wed AM. Will let you know how it goes. Thanks.

You are very welcome. Keep me posted.

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Customer reply replied 1 month ago
Put the new solenoid on this AM, but it is doing the same thing as before. The first 2 times I tried to start after replacing the solenoid, it turned over normal, started and ran for about 5-10 seconds each time and then died. On the 3rd attempt, it started with only a very short and slow turn of about 3 teeth on the flywheel. It did this as I periodically tried to start it. Finally, I started getting a clicking sound from the new solenoid and nothing else. I rechecked no-load and load voltage rates at the battery and solenoid input side and these were good. I was unable to get a solenoid output test due to engine turnover issues.Any suggestions?

Good morning. W​hat is the voltage reading at the starter itself when you are trying to crank the engine over. Is it over or under 9.5V

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Customer reply replied 1 month ago
If the engine will not turn over, is there an alternative method to test starter voltage? It will be several hours before I can do this.

I​t doesn't matter if the engine turns over or not, you just have to see what the voltage is at the starter with the starter engaged. It's either going to be above 9.5V or it is going to be below. If it's below, we have to figure out why voltage isn't making it from the battery to the starter. If it's above, the starter is either bad or there is still an issue with the ground cable. From here you would just get an automotive jumper cable, clip 1 end to engine ground, clip the other end to battery negative, and see if it makes a difference or not. If it does, there is an issue with the ground cable, if no difference, the starter is going to be bad.

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Customer reply replied 1 month ago
With ignition key on, jumped across the solenoid, and got 12.42 V at the starter post. I then hooked jumper cable negative from battery to engine ground and again got 12.4 V at the starter post. Was this procedure correct?

I​fi'm following you correctly then no. All you need to do is hook the volt meter up to the starter motor directly (where the cable connect) and then turn the key to start (or have a helper turn the key to start) and then take a reading.

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Customer reply replied 1 month ago
I am still getting 12.4 V at the starter.

That sounds kind of on the high side, I would expect a little less than that actually. Is the key turned to start, and the starter engaged, when you took this measurement?

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Customer reply replied 1 month ago
The starter has stopped engaging when key is turned to on nor does the engine try to over now. Prior to today, the starter bendix would occasionally pop up and engage the flywheel only to give a momentary engine turn over. On rare occasions the engine would actually start, run 5 seconds and die. Immediately thereafter, I turned the key to start and would get the extremely slow turn for a second or two or nothing at all.

O​kay so the starter is not drawing at all then. Just to confirm, you have 12.4V at the starter with the key held to start, but when you let go of that key the voltage drops down to 0, correct?

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Customer reply replied 1 month ago
When the ignition key is turned to start, there is 12.4 V at the starter. However, after letting go (to the run position), my meter jumps to 50-60 and slowly reduces down. For some reason, I am getting 12.4 V at the input side of the solenoid/positive cable connection post with the key in the "off" position.

I am getting 12.4 V at the input side of the solenoid/positive cable connection post with the key in the "off" position.

​That would be normal. Remember that the positive battery cable is connected to that input side of the solenoid. The other end of that cable goes right to the battery. The input side of the solenoid will read the same as the battery terminal itself. If you are also getting 12.4V to the starter itself, and the starter is not cranking the engine over, the starter is going to be bad as well.

I know you have replaced a lot of parts here, the cables, the solenoid, and now you will be replacing the starter. What was ultimately the root of the problem here were the cables. when the cables rot, that rot causes a drop in voltage. The starter motor wants to draw more current than it normally would because of that drop in voltage. That extra current (amps) causes the starter and the solenoid to burn up. The next thing you need to do is replace that starter.

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Customer reply replied 1 month ago
One last questiom, hopefully. When the problem first began, I took the starter off, cleaned it, and bench tested. It spun normally and bendix worked. After reinstalling, had same problem. Could starter bench test OK but not work under starting load?

Yes definitely. At some point please do not forget to select a rating for my service. You can still ask follow up questions afterwards if need be. Thanks again -Jason

Jason
Jason, Marine Mechanic
Category: Boat
Satisfied Customers: 16,771
Experience: Degree in Marine Technology. Gas and diesel marine mechanic.
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