Idle / Throttle problem

[Eddie Mullins]

Ok - new boater, with 1st boat, new to site, and have many questions so please bear with me.

Just got 197? , Bass Buster? boat with 50 hp motor. Console steer. Has lever for gear and for throttle.

Motor cranks right up, idles well. In neutral it can be throttled up and will run well.

Push lever out of neutral and gear engages, boat will move forward at an idle.

Problem - begin to move up the seperate throttle lever and it just dies. It will not throttle up in gear, forward or reverse.

Here is maybe the dumbest question I will hopefully ever ask on here, could I be operating the throttle and gear levers incorrectly some how or could the malfunction be there? SHould the throttle increase as the gear lever is moved forward? Or am I supposed to push the gear lever all the way forward and then bring up the throttle as desired?

I am hoping this is just a carb adjustment? I don't have any kind of manaual for this boat or motor. Any tips on locating a manual for at minimum the motor?

 

[Silvertip]

Re: Idle / Throttle problem

If you really have a two-lever control, the gearshift lever is F-N-R (forward, neutral, reverse) Push the lever all the way forward to go forward, all the way back for reverse, and in the center detent position for neutral. The other lever is the throttle. All the way back is idle. All the way forward is wide open. Anywhere in between produces whatever speed that setting provides. You shift first, then advance the throttle just like you would step on the gas in your car or truck. The more you push the faster you go. If the engine doesn't respond, it needs attention and the problem is very likely not in the controls. Gunked up carbs, bad fuel, water in fuel, bad plugs, low compression, stuck rings, bad fuel pump, and a host of other stuff can cause poor performance. Do not shot gun this problem. Diagnose it.

 

[Eddie Mullins]

Re: Idle / Throttle problem

Thanks for the response. I was using the controls as you described. I believe its probably time for a trip to a boat mechanic. Hopefully nothing major. I know it has been sitting for several months and am hopeful its maybe just a problem with the fuel or gunked up carbs..

 

[86RajunCajun]

Re: Idle / Throttle problem

If yu have a small flat lever that sounds to me like the high idle lever. This is used just to increase idle speed in neutral to warm up and ease cold starts.

If you do have this fast idle lever, it is suppose to lock out the main throttle/shift lever till the fast idle lever is pushed all the way down.

You may have a manfunction in your controls if you can shift out of Neutral with the fast idle lever up.

GL

RC

 

[Eddie Mullins]

Re: Idle / Throttle problem

86RajunCajun - the throttle lever is a small flat lever that seem to me to be designed for continual use. I can rev the motor up with it and then shift out of neutral (although I didn't rev much before doing this). One thing I noted was when I had the idle lever up slightly, then went into reverse, I think the the throttle lever moved as I moved the shift lever? Does that sound right?

Anyway, with no manual for the boat and my limited experience, I think I'll have to go ahead and take it in...

 

[CharlieB]

Re: Idle / Throttle problem

Eddie

If the shift lever was a clock hand it would be facing straight up at 12 o'clock.

Many Merc control boxes have a 'fast idle' lever that lies flat along the top of the box in the 3 o'clock position, used to start and warm up the motor.

This type of box should have an interlock that does not allow the main shift control lever to move until the fast idle lever is returned to its 'parked' position. This is to protect the gears from shifting into gear at high engine speeds.

The shift lever is also the throttle control lever. Moving the lever forward or back initially shifts the gears, this occurs in the first couple of inches of movement, about 10:30 and 1:30 of the clock face. As you shift into gear you feel the lever sort of come to a stop. At this point the lever begins to move the throttle cable, continued movement of the lever to almost horizontal opens the throttle wide open.

If the motor idles fine but then dies once it is shifted into gear, then there is a problem with the motor that needs to be checked out.

You can purchase a service manual, read it and ask questions here and we will help guide you through fixing your motor, or you can take it to a shop and have it done for you at some expense.

It's your call.

 

[Eddie Mullins]

Re: Idle / Throttle problem

CharlieB - You described my controls exactly. The throttle lever is just flat metal and lays amost flush with the housing when down. I thought it should operate as you described. Meant to say in my prior post it seemed NOT to be designed for continual use.. however, it will go into gear with the throttle lever raised.

I will do some surfing on where to by a manual - any tips on that would be appreciated. Is there any idenitifcation I will need fom the motor? a serial # or something?

Its apparent my interlock isn't working and that there may be an issue with the motor. Any ideas on where to start would be great, I'm certainly not opposed to trying myself and saving some $, just don't want to do anyy further harm.

We have muffs for it, and ran it breifly with them. Are these ok to run the motor while trying to diagnose and work on the engine? if not, what are my options other than only taking it to a lake?

 

[saumon]

Re: Idle / Throttle problem

We have muffs for it, and ran it breifly with them. Are these ok to run the motor while trying to diagnose and work on the engine? if not, what are my options other than only taking it to a lake?

I hope so, cause we all do that! There's some work that have to be done in the water, with a load on the prop when in gear, like final carbs and timing adjustment, but not much.

 

[Eddie Mullins]

Re: Idle / Throttle problem

Thanks. I had just seen a post somewhere about the muffs maybe not providing enough water , or not as much as the motor could pump? Didn't remember the specifics but didn't want to over heat it or cause some other damage.

 

[saumon]

Re: Idle / Throttle problem

They're ok as long as you don't go past 2000rpm.

 

[86RajunCajun]

Re: Idle / Throttle problem

the symptoms you are talking about on your engine are pretty much spot on to the problem i was having with my 150.

Your high idle lever as i said shouldnt play much into the problem you are having. It is nothing but a limited secondary throttle lever. It should be locked down when you go into any gear anyways.

My 150 would idle fine and cruise at idle fine but as soon as i would put it in forward and try to apply throttle it wouldt either go up to 1000 rpm and then fall on its face fast, or it wouldnt go anywhere and just die.

Problem was my stator. Got a new CDI stator and installed it and it had a strong hole shot every time.

You can think of the stator as the generator and alternator for the ignition system and battery charging system. It generates electricity using a magnetic field or resistance between the stator magnets and the flywheel magnets, which it then sends to the battery via the charging circuit, and the power packs via the low speed and high speed windings. If it is shorted, it wont send the spark to the power packs, and therefore the power packs wont send the spark to the coils and on to the plugs via the plug wires. If your high speed winging is shorted, you will get idle spark, and may even be able to rev on some cylinders while in neutral or light drive throttle, but when the RPM's go up, the high speed winding takes over to increase voltage and amps, and if shorted it will cause a cut in spark immediately.

These kind of running problems are heavily contributed to spark problems, as well as fuel problems, afterall all the engine needs is fuel, spark and air to run. As long as those componants are operational it should do as it is designed.

Test your stator with a voltmeter set to read Ohms. Some stators have different Ohms levels that equal a good reading for the unit. So be advised you will need to know what is considered a passing test score for the stator to determine if it is bad.



Typically you will read the Ohms resistance between the AC voltage charging leads <the 2 yellow wires usually> and the spark distributing wires from the windings <high speed winding and low speed winding>. The red and red/white wires are your high speed winding leads, and the blue and bluw/white are your low speed winding leads i believe.

The Ohms readings will be taken between the red/white and blue/white to ground, and the blue and red to ground. Also test between the two yellow charging leads. They should have no continuity.

This is what fixed my throttle up problems with a 156$ part and about an hour of install and troubleshooting time.

GL as always!

RC

 

[86RajunCajun]

Re: Idle / Throttle problem

To increase your engines water pump function while on muffs, and to create the exhaust back pressure your motor needs to run as it is designed, you should remove the muffs and put it in a deep container full of water. This will submerge the water intake port and the exhaust and you can safely increase the RPM past 2000 this way. Do not hold the RPM high for sustained periods. Do your test quickly and back her down.

A large trashcan usually works very well for this. Trashcan is what i use anyways.

Iv done this many times as suggested in repair manuals to test DVA <direct voltage> readings and check timing advance etc.

GL and keep us informed if you learn anything.

RC

 

[Eddie Mullins]

Re: Idle / Throttle problem

86RajunCajun - Wow! Thanks for the detailed responses. I am going to be ordering a manual and will give the stator a look once I do. Right now I am afraid I may not even be able to locate it LOL. The trash can is a good tip too. I had some old barrel here and I was thinking about cutting the top out of one of the, but I already have a large spare trash can in the barn that I can just grab and go. I just need to get the boat home so I can work on it.

 

[86RajunCajun]

Re: Idle / Throttle problem

No problem!

The stator is very easy to locate as it is in one place and one place only on pretty much every outboard i have ever worked on.

It is under the flywheer, bolted to the block. Look under your flywheel for a wiring harness that seems to come strait out of the flywheel. The harness should have red/white , blue/white , solid red , solid blue , 2 yellow wires and a black wire coming from it. This is your stator harness. To access the stator you will need to pull the flywheel.

Your manual will detail the removal process of the flywheel and you will need to get the correct puller for it. Some can be removed fairly easy with a automotive harmonic balancer puller or steering wheel puller but the correct puller makes the job 100% safe and easy.

Follow the harness from the stator down to the switch box(s) <also called power packs>. The switch boxes are labeled for each connection as to what wire goes where, and your manual will have a detailed wiring diagram to follow as well.

As always GL and post results when you learn something!

RC