Starter

[Therman]

I have a brand new battery, and starter but it dosent turn the flywheel quick enough to turn the engine over. I've jumped negative battery termainal to block and positive battery termainal staright to post on starter with same results. Anyone have any ideas.

 

[F_R]

Re: Starter

First, make sure the engine isn't hard to spin by hand with the plugs out. Then further check the general health with a compression test if it will crank fast enough to do it. Otherwise, rope it over. If it passes all the above, it is time to do voltage drop tests on the starting system. Do you know what a voltage drop test is?

Jumper cables often fail to crank because of the tiny contact area at the clamps. And the el-cheapo ones just aren't heavy enough to carry the current.

 

[Therman]

Re: Starter

Ok. The engine turns over by hand like normal with the plugs in and plugs out. I dont think it turns fast enough to do a good compression test. When you say rope it over is that to try and start it or for a compression test? Would low compression cause the starter to not turn the flywheel quick? Just so you know every once in a while the starter works perfect and the engine turns right over. I dont know what a voltage drop test is but i have a voltmeter. Thanks.

 

[F_R]

Re: Starter

The compression test is simply to see if the engine is in good health. No point in beating a dead horse. Yes, I meant rope it over to test the compression if you have to.

Ok, lets say the general health is ok. A voltage drop test will isolate a high resistance in the individual part or connection being tested. Let's take the positive battery cable for instance. You would put your voltmeter leads on each end on the cable and have somebody turn the key to crank it. The voltage reading in a perfect world would be zero, but the world isn't perfect, so you are looking for something significant. A couple of volts would be quite significant, indicating somethng is amiss with that cable. You can do the same thing with each cable, connection, solenoid, etc. Just put your leads on each side of the item. Most would be zero, like battery post to battery cable lug should be zero. Remember--red meter lead always go to the side closest to the battery + post.

Across the starter motor reading would be about 12V in a perfect world. At least about 11V. That is, red lead to the cable stud, black lead to starter mount.

 

[Therman]

Re: Starter

Ok, I got .7 volts in the positive cable but I dont think thats enough to stop the engine from turning over. But with a battery that reads 12.8 volts when I crank the engine it reads 10.4 volts. This is a brand new battery with 500 cranking amps. Also, the negative cable gets pretty hot could someone explain how to do a voltage drop on the negative battery cable. Im really stuck now any help would be appreciated, thanks.

 

[JB]

Re: Starter

Go to the Top Secret File and do the starter circuit troubleshooting in "Outboard won't start".

You could have faulty electrical connection from the starter to the engine block. See what happens if you ground the negative jumper directly to the starter case.

 

[Therman]

Re: Starter

I tried but with the same result. I have the voltmeter directly on the battery post would a bad ground affect the voltage coming out of the battery.

 

[JB]

Re: Starter

I tried but with the same result. I have the voltmeter directly on the battery post would a bad ground affect the voltage coming out of the battery.

Yes. A bad ground would limit the current coming out of the battery and its measured voltage with the starter engaged would be higher than normal (above +10 to +11V)

 

[boobie]

Re: Starter

Is this mtr used in a salt water area ??

 

[metriccrescentwrench]

Re: Starter

Ok, I got .7 volts in the positive cable but I dont think thats enough to stop the engine from turning over..

According to my OMC manual the voltage drop on each battery lead should be 0.3 volts maximum, so you're drop is over double what's allowed there.

Going through the starter circuit, you're allowed a voltage drop of 0.3 volts between + battery terminal and the solenoid, 0.2 volts across the solenoid, 0.2 volts on the cable between the solenoid and starter, and 0.3 volts between the engine block and - battery terminal.

Also, the negative cable gets pretty hot...

That's another important clue. I'd bet you're seeing well over the 0.3 volts allowed between the engine block and - battery post as well. I'd guess either your battery cables are too small or else they're getting corroded.


(By the way, the thread police here on iboats frown on starting multiple threads for the same issue. It's just much easier to follow if you put all the information into one thread, plus someone else with a similar problem can better gain knowledge also.)

 

[Therman]

Re: Starter

Ok, I'll keep all information in one thread next time. Im going to continue with voltage drop tests and see what happens. Thanks for all the help. Also, when testing the negative cable does the positive voltmeter lead go to the block or the - battery post.

 

[Therman]

Re: Starter

Also, does anyone know the proper gauage for the postive and negative battery cables for a 1988 evinrude 70 hp vro.

 

[HighTrim]

Re: Starter

It is likely 6 gauge from the factory, I personally use 4 gauge where I can when I do a rewire on my motors.

As Frank stated, jumper cables are usually of no help, I made a set out of heavy 4 gauge wire with proper connections so that I do no lose current through poor contact surface area.

 

[metriccrescentwrench]

Re: Starter

Also, when testing the negative cable does the positive voltmeter lead go to the block or the - battery post.

If you have an older analog voltmeter with a needle (I haven't even seen one in years, do they even exist anymore?) you'd want to put the positive lead at the block and the negative lead to the - battery post. With a digital voltmeter it honestly doesn't matter, you'll just see a negative reading one way and a positive reading the other way.

By the way, if you do end up replacing your battery cables here's where I got mine for the Checkmate rebuild. They'll do all the assembly for you and make them to any length you specify.

http://shop.genuinedealz.com/Marine Grade Wire/

 

[Therman]

Re: Starter

Ok, both battery cables showed high resistance so I repalced both with 6 gauge marine wire. The engine turned right over then started doing the same thing. So i checked battery cable connections they were loose so I fixed those it started to work again then went back to the same problem. Battery shows 12.6 volts and 10.6 volts when cranked. I used connections made for 8 gauge wire for the 6 gauge because thats all they had but its a strong connection. I also went through a voltage drop test again and all wires were to spec but with the key in the off positon all 12.6 volts were reading through the soleniod posts. Is the supost to happen or just when the engine is cranked? Any help is appriciated. Thanks.

 

[metriccrescentwrench]

Re: Starter

but with the key in the off positon all 12.6 volts were reading through the soleniod posts.

Yes, that's normal.

12.6 volts sounds a little low, try putting a charger on the battery and get it fully charged first and then see what happens.

 

[HighTrim]

Re: Starter

Yes, that's normal.

12.6 volts sounds a little low, try putting a charger on the battery and get it fully charged first and then see what happens.

Im confused, am I reading this wrong? 12.6 is fully charged, well 12.65, but should be tons. Voltage flow through the solenoid is normal when shut off? Starter will stay engaged if this is the case.

What motor are we talking about here anyways?

 

[Therman]

Re: Starter

Its a 1988 evinrude 70 hp vro. So if the battery is at 12.6 volts and the volt drop test checks out ok, then what else could be the problem. It fires half the time so I feel its something small.

 

[Faztbullet]

Re: Starter

Uhhh what size battery you using? What the CCA rating?

 

[Therman]

Re: Starter

500 cca. Marine battery from walmart.