Sometimes Motor Cranks, Sometimes it doesn't - Runs great when it gets started - Why?

[oldboat1]

posted a pic of one of my project motors on an earlier thread, but has a solenoid setup that might be of interest. Pos from battery to left large post, pos to starter at right large post . This solenoid is grounded from a small post to the battery (neg). The negative wire from the motor ground also goes to the battery neg post.

 

[jhouser]

bwkre, yes it looks very similar but is black in color. Thank you for the test. i will try that.

Silvertip, I will try that as well.

Fed, I am thinking it may be an electrical connection as well, but it could be the solenoid. Still holding off on ordering a solenoid until I make sure that is definitely the problem. Some of these new tests given above will help me determine that. Here is the latest on the situation.

I pulled off the motor cover last Friday. As suggested, I cleaned every connection possible to bright metal. Then I put it all back together. It was doing the same click again, but then suddenly it started cranking every single time I turned the key in my driveway, about 20 or 30 times straight, over two days. GREAT I thought, it is fixed. I told my family "let's go boating on Labor day."

Then we got out to the Potomac river. Same. Problem. Happened. So frustrating. Took 10 minutes to get running at the dock. But once it got going, it ran great all day. Whenever I shut it off I was nervous that I would get stranded (I have towing coverage just in case), but luckily it started right back up every time. We had a great time tubing on Labor day.

I am thinking the only connections I can clean up now are the ones to the key in the unit up by the driver. Could that be where the connection problem is, at the Key? Is it OK to take that box apart? Would hate to break it somehow!

Thank you all for your help. In the mean time I will test things with the recommendations you all provided above. Thanks, again.

 

[Fed]

If the solenoid is clicking then the problem will not be the key switch so don't waste your time pulling the controller apart.

Getting low readings at both the solenoid coil small terminals & the starter motor strongly suggests there is a high resistance connection between the battery & the motor.
Did you remove & clean the main battery ground at the block?
The problem could also be inside one of the two main cables to the motor, do they appear to be in good condition with no cuts in the insulation that would allow water to get in & corrode the cable?

 

[jhouser]

Thank you for the insight, Fed. I will not waste my time doing that then. I did do the main block ground, it actually was in very good condition, I believe, because it was thoroughly covered in dielectric grease, very thoroughly and when I pulled the bolt out, it looked new. The cables all look good as well, no cuts I can see. What is weird about this, is that when I bought it from the guy, it did not have this problem at all, after having the boat for two months it came on suddenly and has gotten progressively worse, which is why I felt it was the solenoid going bad. I even called the guy, who said that he never had this problem with it at all. He has been very honest and up front with me, he showed me everything wrong with the boat before I bought it, stuff he did not have to show me, mostly cosmetic stuff.

I will be doing the rest of the tests people gave me above this weekend, just to make sure I do my due diligence before wasting any money on the solenoid for no reason.

 

[oldboat1]

continuity testing of ground circuitry might find an issue. Test out that ground wire first, and consider a jumper to ground the block.

 

[Fed]

Just get someone to turn the key to the start position and when the solenoid clicks but the starter motor doesn't spin use your meter to find out where you're losing the Voltage. Once it fails it will only take a minute to zero in on the problem.

 

[jhouser]

Oldboat1, what is a jumper block?

Fed would the person who is helping me keep the key turned all the way on the the start position while I am testing, or would they release it to the run position while I am testing?

Thank you for your help.

 

[oldboat1]

substitute a ground wire from the battery negative post to the engine block -- replace/bypass the existing ground. Get a continuity tester if you don't have one, and use it to test grounds.

edit. could use an automobile jumper cable for a bypass -- connect the ground while a helper is trying to crank. Most instructive would be to use the jumper while the key start is failing. If the starter kicks in, you found the problem. The old models ('50s) have a plug from the transom box (solenoid) to motor, and I've found the ground can be a problem inside the plug.

 

[Fed]

Keep it turned but you will have to get it to fail first so you can find out where you're losing power.
If you start with 12 Volts at the battery but zero or very low Volts at the starter motor then there's only 3 bits of wire & a solenoid to test at.
Should take you 30 seconds.

 

[emdsapmgr]

It's very common for solenoids to crap out after many years. The internal contacts get burned with long-term use. Once the tips get burned, they won't transfer proper current to activate the starter. Sounds like that's what's going on with your engine. They are cheap, like $25. Replace it. Marine solenoids are different from car solenoids. They have an extra terminal that detects if the control box is in neutral or not. That prevents the engine from starting in gear. Get a factory marine solenoid.

 

[interalian]

It's very common for solenoids to crap out after many years. The internal contacts get burned with long-term use. Once the tips get burned, they won't transfer proper current to activate the starter. Sounds like that's what's going on with your engine. They are cheap, like $25. Replace it. Marine solenoids are different from car solenoids. They have an extra terminal that detects if the control box is in neutral or not. That prevents the engine from starting in gear. Get a factory marine solenoid.

Curious. Mine (original 1982) has 4 terminals exactly: 2 large, 2 small. One large goes right to the battery, the other jumps to the starter. One small goes straight to ground (solenoid coil ground), the other to the key (solenoid coil hot). There's a neutral start switch in series with the hot side (in the control box) that provides the 'start in neutral only' function.

Automotive (Ford...) solenoids get their energizer grounding through the solenoid frame to chassis, and some have an extra terminal that provides a 'hot on crank' function.

 

[oldboat1]

motor ground to bat. ain't nothin going to work if the motor ground is bad, weak, cutting in and out, or otherwise mucking things up....

 

[jhouser]

Thank you all for your advice. Wanted to provide a quick update since I have finally had a chance to get the boat back out on the water a few times - I wanted to thoroughly determine whether or not cleaning the connections had any impact - the short of it is - cleaning the connections definitely helped!!

What I did first was take of the motor hood, take apart each connection one by one and use a vibrator sander on all flat pieces (such as wire end blade connectors and the nuts that hold them down), and I use a wire brush and steel wool on all bolt shafts. I put everything back together and the 'click only when turning the key' issue went from happening 9 out of 10 times to happening 3 out of 10 times. Still not satisfied (and not wanting to be stranded on the water), I took apart all connections again, cleaned them and this time used dielectric grease on every connection before I put it back together. Now the issue happens less than 1 out of 20 times. So that is a HUGE improvement.

In the spring I will probably replace the solenoid, they are only about $20 and it will just be one less thing that can go wrong in the future.

Again, thank you all for your help!

 

[racerone]

The starters are elegantly easy to take apart and to install new brushes.--------Take the time to learn how to take it apart / test and reassemble.--------Never did this kind of work ?-----Just ask after you have it apart.------I install brushes at $5 a set all the time !

 

[Fed]

First I checked the battery to make sure I had juice, the battery had 13.2 volts. Then I checked to make sure the solenoid was getting proper voltage. It read at about 12.5 volts. Then I moved the test leads to the starter, it was at zero volts with the ignition off.

Then I had my friend turn the ignition all the way - the solenoid clicked like it likes to do, and I only got about 0.02 volts at the starter, it was barely anything. I did this test many different times, testing the leads to different places on the wires, and it was always the same, 0.01 or 0.02 volts with the key turned all the way. Does this mean my solenoid is bad?

All you had to do at this point was to test all the points between the battery & the starter to see where you were losing the 12 Volts, missed opportunity.

Does the boat have a battery isolating switch?

 

[oldboat1]

really think it's time to get after that starter. Try a new set of brushes, and if it's not your thing or doesn't fix the problem, take it in to a shop and have it tested and possibly rebuilt. Would set aside the multi tester. Grab a pair of jumper cables and see if the starter will crank with a jump from the battery. Use one of the cables to connect one of the small solenoid posts to the battery (negative), then try to crank.

But if a betting man, bet on the starter brushes.

 

[racerone]

Do not use any small posts on the solenoid when using booster cables !!

 

[oldboat1]

suspect a ground/common ground issue, until ruled out. (but bet on starter brushes).

 

[Fed]

It's hard for a stater motor to work if you only put Zero Volts to it.