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BF20D starter motor struggles to turn over.

C

ChrisHarding

Contributing Member
Hi Guys
My BF20 is struggling to turn the motor over for some reason. Battery is fully charged and the tilt up and down seems strong with no issues. If I hand pull the motor it starts very easily and runs fine. Where to look next please??? Now and again it will half turnover and die and if I repeat the process it will sometimes turn over just enough to start ..once running it's perfect

Many Thanks
 
Check your cable connection at the starter by first disconnecting the battery to prevent accidentally grounding. Take it completely off and clean all contact area. Then reinstall and carefully tighten it.

Clean the battery posts and inside the clamps before reinstalling them.

The starter will be the biggest ampeeagr draw....even higher than the tilt motor.... so good connections and sound cables are important.

If cleaning and tightening the positive cable doesn't make a difference then do the same for the negative cable. It's a little harder to do but you won't need to disconnect the battery and it is just as important to have a good ground connection and a cable that isn't rotten.

When you are confident the connections are clean then, if things haven't gotten better, you are at least in a position to do some voltage drop testing to see if one or both cables are bad.

Worst case scenario, financially, is that the starter is failing. It's expensive so that's why I would clean, tighten and test before considering a rebuild or replacement.

Good luck.
 
Hi JGMO
Thanks again ..prior to today's issue you gave me huge amounts of help on this motor and the carb issues so always appreciate advice from the expert here!! All very sound advice and when I bought the boat and motor the cables had been "soaking" under dirty water for probably a year or more ..I did dry them out over Summer (we are opposite to you guys) but that doesn't mean that either a positive or negative cable has an issue that doesn't show up when you tilt the motor up or down but once the starter kicks in there is a problem. Between the battery and the motor I also have an isolator which also could be an issue so I'll bypass that once I have checked connections at the starter.
Replacing the two cables if needed is no problem either!!

Will do all your suggestions and post back to help others with a similar problem!
 
It may well be the actual cable.
My 1972 John Deere tractor was exhibiting the same thing as your motor. Clean, tight connections didn’t help. I noticed a bit of “green stuff”, probably a product of copper corrosion on the battery end of the + cable.
Cutting back the insulation showed about 3” of the copper strands looked bad. Replaced the cable, & it turns over like new.
 
Hi Chris,

Yes, "isolating the isolator" is a GREAT idea:)

And....here's where I climb atop my soap box to preach about learning and using
VOLTAGE DROP TESTING. The "magical" method for "seeing" wiring and cables underneath the installation.

Actually, it's a test to observe the drain a faulty wire or even one, single connection point puts on a circuit WHILE THE CIRCUIT IS ON. All it takes is a digital voltage meter or multimeter.

I put "while the circuit is on" (working) because that is the part that trips people up the most it seems.

Anyway, whether you find this quickly or need to keep trying to find the issue, I urge you to Google it and read up on how it's done. It can save you a TON of time and money.

Since auto and boat electrical systems are so alike, I've attached a file from All data for you. It's simple and easy but there are SO MANY good tutorials written and on video you might want to check a couple out.

Good luck.
 

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jgmo said:
Hi Chris,

Yes, "isolating the isolator" is a GREAT idea:)

And....here's where I climb atop my soap box to preach about learning and using
VOLTAGE DROP TESTING. The "magical" method for "seeing" wiring and cables underneath the installation.

Actually, it's a test to observe the drain a faulty wire or even one, single connection point puts on a circuit WHILE THE CIRCUIT IS ON. All it takes is a digital voltage meter or multimeter.

I put "while the circuit is on" (working) because that is the part that trips people up the most it seems.

Anyway, whether you find this quickly or need to keep trying to find the issue, I urge you to Google it and read up on how it's done. It can save you a TON of time and money.

Since auto and boat electrical systems are so alike, I've attached a file from All data for you. It's simple and easy but there are SO MANY good tutorials written and on video you might want to check a couple out.

Good luck.
Click to expand...
 
I'm pretty sure it's the cable ..I rewired the positive lead and eliminated the isolator and connected directly to the battery terminal and made sure the bolt was tight and the terminals were clean! (The battery has spade terminals not the standard vehicle style round posts) The boat is a 3.7m PVC with a centre console (where the battery is) so I gave it a try and no load voltage was 12.7v and when you try to start it falls to 10.38v and of course fails ..I did that a few times and then felt the cable that runs out the console and then has a joint spliced into a twin 50a cable so it runs the negative too. The positive cable was pretty warm after just a few start attempt so I'm pretty sure that's where the problem is! I'll visit the hardware store tomorrow and grab some decent cable and some crimp terminals!! One quick question ..where does the negative line connect inside the motor ..positive is easy to trace to the solenoid but the negative seems to disappear under the starter motor. The negative cable looks in good condition and has no joints so could I ignore replacing that for now ... I was thinking about also putting a crimp connector on the positive cable either side or is it better to go one direct line direct to the solenoid? I do have plenty of 100amp cable which has a 10mm diameter but the Honda cable at the solenoid seems to be a little lighter so maybe better to use 50amp cable with 8mm diameter to it fits the existing one more accurately! What is the standard cable diameter that Honda would use??

Thanks again

Chris
 
Well....

Are you positive that the battery is good and will pass a load test? Because this does sound like a marginal battery to me. And, the fact that it has blade connectors says it's a very light duty one to begin with.

You might be right about the cable being bad but you could PROVE it without removing or replacing anything by using VOLTAGE DROP.

Ok, that's all I'll say about that.

Use the largest cable that you can. Because, in an electrical sense, it's just "better" due to the fact it will have the least resistance to current flow.

Looking forward to what you come up with.
 
Hi JGMO

Problem solved thank you ..I replaced the positive cable and turned the key and the solenoid went "click" ..nothing more .. Based on the condition and corrosion of the positive cable I rigged a jumper from the battery negative to the bolt under the starter motor and started first touch!! It also had a hidden joint that was corroded! I just need to get a few more crimp terminals and the job is done ...All the fancy hardware store had in cable was some red 100amp and it looks a little light so I'll replace it with something decent and correct colour coded tomorrow!!

Thanks for all your help ..the 20D starts easily on the battery I have which is supposed to be for a ride on mower but it has no issues cranking the starter motor and fits neatly in the centre consol!!

Chris
 
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