Sluggish cranking Yanmar

[awaywego]

Why won't my Yanmar 3JH2e crank instantaneously and reliably? I have a new cranking-specific battery at highest MCAs that West Marine sells (1050). I have a new starter. I have good voltage at the batteries, at the battery selector switch, and at the engine. I have cleaned up and retightened connections at all three places.

Yet, I get engine cranks that are sluggish or sometimes no response at all when key is turned to crank. I always get a good strong tone from the key switch when turned one notch over before cranking. Any chance the ignition switch itself is the problem? I think it may be the original panel and ignition key switch (1994?). What ideas do you have?

[Wotname]

Originally Posted by awaywego

Why won't my Yanmar 3JH2e crank instantaneously and reliably? I have a new cranking-specific battery at highest MCAs that West Marine sells (1050). I have a new starter. I have good voltage at the batteries, at the battery selector switch, and at the engine. I have cleaned up and retightened connections at all three places.

Yet, I get engine cranks that are sluggish or sometimes no response at all when key is turned to crank. I always get a good strong tone from the key switch when turned one notch over before cranking. Any chance the ignition switch itself is the problem? I think it may be the original panel and ignition key switch (1994?). What ideas do you have?

You have an electrical problem (or the engine is seized ). Clearly the engine isn't seized so it's an electrical problem and given what you have stated, probably with the starter solenoid and / or ignition key switch or it's wiring.

When you say you have "good voltage at the batteries, at the battery selector switch, and at the engine"; is this measured under load i.e. when trying to crank the engine. Unless you are measuring voltages under load, it is meaningless as a method of fault analysis.

In particular, you need to measure the voltage at the solenoid and starter motor while cranking it over (with the starter motor).

Likewise you need to measure the voltage at the coil of the solenoid (the small wire) to know if your ignition key switch and wiring is OK (again while the key is operated).

These voltage reading will point you to the problem. Of course there are other ways to determine what is wrong but voltage readings are a good start (no pun ).

[dlymn]

Shift your battery next to the motor and use heavy cables (12mm)to connect the positive to the starter motor terminal and the negative to a bolt on the engine. Use a heavy object (a big screwdriver) to short from the positive across to the solenoid terminal. If she spins over easily, it's your heavy lead from the battery to the starter, most likely corrosion in a terminal. This is the easiest guess,
When the engine is out of gear and the decompression lever pulled, can you turn the motor over by pulling on the alternator v belt? If so, then the engine and bearings are not a problem. Double check that the gearbox actually is in neutral when you start; you should be able to rotate the prop shaft by hand.

[awaywego]

If under load the voltage drops way down, would that indicate a bad battery or bad wire or something else?

[dlymn]

a drop in voltage indicates that the battery is under load. That's about it. it's what batteries do. It can be an indicator of a faulty or poorly charged battery. Are you sure that your battery is getting charged? Once the motor starts, does the voltage across the battery terminals increase to 13.6 volts over time? Do you charge with shore power? if so, get the charger going and don't stop until the voltage across the battery reads more than 14.4 volts with the charger going. Then try your starter.

[Stu Jackson]

You could read some of the previous "sluggish" Yanmar topics in this section of the forum. There are lots of them, lots.

Like this one:

http://www.cruisersforum.com/forums/...sh-137162.html

It's either:

wires
connections
starter
sometimes there's a fuse between the key and the solenoid
key (Usually the first to inspect and the very last to go wrong, easy to bypass to check)

[a64pilot]

One thing to check is voltage at battery Vs voltage at starter when cranking.
If battery drops to 10 but voltage at starter is 8, then of course you have a wiring / connection issue.
Unless you have a much larger than average sailboat motor, a lawnmower battery will start it easily

[Stu Jackson]

Here's another one

http://www.cruisersforum.com/forums/...ry-180728.html

They abound!!!

All the answers are identical, too.

[awaywego]

So I moved the cranking battery down next to the engine and connected the positive terminal to the starter solenoid with a new cable and connected the negative terminal to the engine block ground with a new cable. I almost teared up at the sound and feel of that beautiful, powerful, instantaneous start. I shut it down and did it again. Immediate crank. Wonderful!

So what does this mean? The original long positive cable from the battery is bad? The negative? Should I change out both?

[awaywego]

And to add to that previous post, my negative black wire feels stiff and crunchy while the positive red wire feels flexible.

[Uncle Bob]

Originally Posted by awaywego

And to add to that previous post, my negative black wire feels stiff and crunchy while the positive red wire feels flexible.

Stiff and crunchy not good, perhaps the changing of one lead at a time will be the most cost effective ! In this case the neg lead and if that doesn't do it then the pos lead.
Good luck.

[Stu Jackson]

Originally Posted by awaywego

.....

...................................

So what does this mean? The original long positive cable from the battery is bad? The negative? Should I change out both?

Good news! Congratulations for doing the work and reporting back.

What should you do next? Hmm, what did you learn from the last exercise? Really. Does "one at a time" come to mind?

[a64pilot]

You can fault isolate with jumper cables and disconnect one at a time to see which one is the problem.
I'd replace them both, it's like a cooling hose, if you just replace the one that busted, how much life is left in the other ones?

[awaywego]

I'll do that, starting with the black cable first.

Really what it comes down to though is over the last year I've replaced basically everything BUT the cables, so it's just about all that was left. New cranking battery in August. New cranking motor and solenoid in September. New battery selector switch in October. Just about the only thing left in the equation was the wires themselves. That's just about the approach that most shitty mechanics use, ain't it? Replace everything till it works?

[Terra Nova]

You might wind up having to install a relay at the engine so the solenoid power need not go through the ignition switch.