1989 Yamaha Starting Problem - Weak Cranking Power

[GradyWhiteJohn]

I hope someone can help me figure out a solution for a starting problem I'm having with my 1989 150HP Yamaha engine. The engine will not start because of low cranking power. It starts to crank very weakly and then dies after a few seconds. My boat is set up with twin 150s and the other engine cranks very strongly and starts without a problem. I have two batteries and both are new and fully charged. All terminals have been meticulously cleaned. This problem just started to happen after the boat sat for 1 month and the weather got colder (55 degrees). Any suggestions on how to go about solving this problem?

 

[bgbass.1]

Re: 1989 Yamaha Starting Problem - Weak Cranking Power

could be one of your battery cables they corrode from inside out so look very closly at cables for nicks a bump in one that should help you

 

[GradyWhiteJohn]

Re: 1989 Yamaha Starting Problem - Weak Cranking Power

Thanks for the reply. I checked the cables and didn't find any problems. Any other suggestions?

 

[bgbass.1]

Re: 1989 Yamaha Starting Problem - Weak Cranking Power

get a jumper cable hook to positive stud on starter and other end to fully charged battery see if starter works ok then.

 

[JB]

Re: 1989 Yamaha Starting Problem - Weak Cranking Power

Get a voltmeter and measure the voltage from the hot terminal on that starter to the starter frame while power is applied. If it is above about 9volts you have a failing starter. Alternately, apply 12volts directly from a battery to the starter with good jumper cables. If it is still weak you have a failing starter.

If the starter voltage is below about 9 volts you have resistance in the circuit. Measure the voltage from the input to the output of the solenoid while energized. It should be less than 1 volt.

Finally an often overlooked part of the starter circuit is the electrical connection from the starter frame to the engine block. You might try loosening, moving about and retightening the starter mount.

There are step by step instructions for troubleshooting the starter circuit in "Outboard won't start", Engine FAQs.

 

[GradyWhiteJohn]

Re: 1989 Yamaha Starting Problem - Weak Cranking Power

I'm still having trouble starting my 150 Yamaha. I tried what everyone suggested to help diagnose the problem and then went on to swapping parts from my good engine (starboard) to the bad engine.

1) Swapped power cables from good engine to bad engine. This was done to eliminate a problem with the cables.
2) Swapped starter.
3) Swapped relay switch.

I'm stumped... Please reply with any suggestions you may have.

 

[BruceAML]

Re: 1989 Yamaha Starting Problem - Weak Cranking Power

Does each engine have it's own battery? Have they been load tested? Are they batteries that are not sealed? Have you checked the electrolyte level and the specific gravity of each cell?

 

[GradyWhiteJohn]

Re: 1989 Yamaha Starting Problem - Weak Cranking Power

Thanks for the reply.

I have a single battery switch for my two batteries. The hot cables from the engine go to the switch and one ground goes to one battery and the other ground goes to the second battery. To ensure the switch wasn't broken, I moved the hot cables to one battery. This battery started the good/starboard engine and didn't start the bad/port engine.

I haven't load tested the batteries or checked the battery cells. But, one battery is new and the other is 1 year old. I'm thinking the batteries are good because the good/starboard engine has strong cranking power. I also took the batteries out of the cold (approx. 32 Fahrenheit) and put a fresh charge on the batteries.

 

[jim daigle]

Re: 1989 Yamaha Starting Problem - Weak Cranking Power

If you changed out the cables,starter, and switch, then you might have a problem internally something is binding and creating an abnormal amount of friction somewhere. Can you turn the engine by hand freely? Your impeller may be binding?

 

[rodbolt]

Re: 1989 Yamaha Starting Problem - Weak Cranking Power

do you have a volt meter?
post the complete engine model number.

 

[GradyWhiteJohn]

Re: 1989 Yamaha Starting Problem - Weak Cranking Power

The model number for the engine is L150H. I do have a volt meter, but I don't have much experience using it. I've only used it to check the battery charge.

Also, I didn't get a chance to manually crank the engine to see if anything is binding up and causing friction.

 

[rodbolt]

Re: 1989 Yamaha Starting Problem - Weak Cranking Power

ok, place the meter leads on the battery posts, remove the E stop lanyard, crank the motor, it battery voltage remains above 11 v its ok.
next leave the - meter lead on the - batt terminal and the positive meter lead on a good engine ground, crank the engine. meter should show less than .6 V, anymore and ya gotta find and fix the ground cable.
next move the + meter lead to the + battery terminal, place the - meter lead on the battery lead at the starter solinoid and crank, should show less than .4 V. next go to the starter cable side of the solinoid and crank, should show less than .6v. then at the starter terminal, still should read less than .6v.
if this is a 25" model it can also be the steady bushing in the midsection clamping the driveshaft

 

[jim daigle]

Re: 1989 Yamaha Starting Problem - Weak Cranking Power

So out of curiosity what did you ever find was wrong with your motor?

 

[GradyWhiteJohn]

Re: 1989 Yamaha Starting Problem - Weak Cranking Power

Thanks for the great suggestions... I haven't gotten a chance to try any of them since November 26th. I plan on trying them this weekend. I'll keep you posted.

 

[GradyWhiteJohn]

Re: 1989 Yamaha Starting Problem - Weak Cranking Power

I tried to turn the bad engine by hand and it is much harder to turn than the good engine (Note: I did this with the spark plugs removed in the bad engine). Based on replies for my problem, I started to remove the lower unit to see what might be causing the drive shaft to bind. I didn't get very far because the lower unit is stuck on.

Any suggestions on getting the lower unit off?

 

[dhawk]

Re: 1989 Yamaha Starting Problem - Weak Cranking Power

GW John: had a similar problem on an '86 200hp. As noted by Rodbolt it turned out to be a rubber bushing inside the bottom part of the mid section binding on the drive shaft. If I remember correctly, my lower unit was held in by six bolts under the cavitation plate, one under a rubber plug above the trim tab, and one under the zinc tab.