1989 DT200 - I'm running out of options?!

[chackett]

Hi All-

I'm about at my wits end chasing this down .. I sure could use some hits or ideas ...

There are multiple symptoms that feel to me like they may be caused by the same problem. The most obvious symptom is the tachometer giving a reading that seems to be ~ 2x the actual motor RPM. The engine cranks right up and idles very nicely. My handheld tach reads about 650 RPM at idle, but tach gauge reads about 1,00 - 1200. As throttle increases, tach seems to maintain the x2 pattern and quickly the gauge is getting close to 4k - 5k rpm. I am VERY certain the motor is not actually turning this fast. I've really only done this once or twice, as I know it's quite bad to rev the motor while not under load. This RPM issue is present whether the prop is engaged or disengaged.

The second symptom is that when engaged and running, it really stumbles and maybe misfires or something and it just can't get much past 1500 RPM (tach reads closer to 3k rpm). I know it's not turning at 3k RPM, because when the motor was running correctly, 3k RPM was quite a bit faster.

So here's what I've tested or done so far:

1. Check for spun HUB - marked prop, ran boat, checked marks .. all still lined up. Of course since RPM issue is present when not engaged, this was probably not productive.

2. Clean the oil flow sensor and filter screen. It did have stuff in it, but didn't seem like enough to put it into limp mode.

3. Bleed the oil pump multiple times, ensure proper oil in the oil tank, use syringe to fill oil pump and oil lines.

4. Check all in-line oil check valves.

5. Finally I removed the oil pump all together and disassembled it and cleaned all the obvious passages. Re-install, bleed the pump, no change in behavior.

6. Check spark on all cylinders (did with an in-line light type tester). Did not check strength of spark or ability to jump particular gap. Definitely have some spark at all cylinders.

7. Compression check .. very consistent 90 psi on all 6 cylinders. Seems like a low number to me, but it's very consistent.

8. Disconnected oil level indicator and disconnected oil flow sensor .. ran motor with no change.

9. About 8 months ago I had the carbs professionally cleaned and I installed rebuild kits on them. At the same time I removed the oil pump, I removed the carbs and gave them a good cleaning, even though they all still looked very clean.

I'm really at a loss now. Someone has suggested to me to check the coil counter at the flywheel. I am wondering if I should also check my throttle position sensor. I don't know the correct procedure for that, but did measure a consistent resistance on it. The shop manual has a set of calculations to conduct on it, but it required the TPS to be on the motor with power supplied, and maybe even wanted some expensive testing harness. There were some voltage / ohm calcs it wanted me to perform, but since I didn't have the TPS installed at the time, I couldn't take the readings. I did however measure resistance with the TPS off. I don't know it it's meaningful or not, but I got a reading of 9.7 kohm fully closed and 4.1 fully opened, with a smooth transitions between the two. Based on other threads about TPS, i'm guessing I didn't have my tester set correctly, cause these numbers don't seem to be anything like others I have seen.

So that's about it .. I'm not sure where to go from here. Someone has suggested I look at the coil counter and see if that's reading correctly.

Anyone else got any ideas? I'm running out of stuff I know how to look at!

Chris

[BillCon]

I, have the DT150 and had a similar problem it turned out to be the tachometer control unit behind the side cover where the trolling speed switch is, it went bad,but dont replace it until you check out the wires and the tach itself first, I'm not sure that has anything to do with the missing or stumbling problem though, one of the experts here may weigh in on that.

[chackett]

I, have the DT150 and had a similar problem it turned out to be the tachometer control unit behind the side cover where the trolling speed switch is, it went bad,but dont replace it until you check out the wires and the tach itself first, I'm not sure that has anything to do with the missing or stumbling problem though, one of the experts here may weigh in on that.

Hey Bill,

Thanks so much for that super helpful response. I will absolutely look into that as soon as I can. Can you tell me anything more about this part? What does it look like and is there a test procedure for it? Or can I find it on a parts diagram?

Looks like I found it here - http://www.brownspoint.com/store/pc/...200%20(86).pdf Figure 15 part 23 I believe...

Feels like a very good lead to follow ... thanks again.

Thanks Bill,
Chris

[Solarman]

tach error

Some tachs had a switch/lever on back that changed the tach for the #polls it read, if you have that lever on yours, leave key off, and change it back and forth, putting it back in same place it was. Then try to see if reading correctly. It may have gotten dirty, or moved.
Let us know if works for you.

[Solarman]

dt 200, running issues.

Since carbs rebuilt, has it run good, like supposed to? Or, had this problem existed that long? You mention oil system completely, why did you focus on that system?
Let us know

[chackett]

Since carbs rebuilt, has it run good, like supposed to? Or, had this problem existed that long? You mention oil system completely, why did you focus on that system?
Let us know

Hey Solarman,

Thanks for the responses, I appreciate it. Back when I fist got the boat I went through the carbs about 6 times .. eventually bringing them to a local mechanic and having him soak them in his ultrasonic hot bath cleaner, and I bought rebuild kits and installed them. After that the motor ran like a top for most of the season without any difficulty at all. Even now, the motor idles very very nicely and smooth without any hiccup or trouble.

As for the oil system. I don't remember how I got in touch with them, but somehow I've been talking with a team in Europe that used to race these Suzuki's, and one of their techs suggested that my problem could have been caused by the fact that after I had removed the oil tank and worked on the motor, I didn't bleed the oil pump. He said I needed to do that before we investigated further.

In the process of bleeding the oil pump (which by the way is a serious pain on this motor, unless there is a secret I don't know about), I just decided I really needed to do a thorough job. I'm not sure how that oil pump works but it seems impossible to "push" oil through the pump. Meaning I can not push oil into the oil lines, through the flow sensor and through the pumps and eventually have it seep into the throttle body. After having taken apart the entire oil injection system, including the pump, I'm guessing that's normal operation. Not knowing that, I thought it was possible the pump was clogged since I couldn't push so much as a drop of oil through it.

I suppose my original thinking was that the oil flow sensor may have been tripped putting the motor in limp mode and that's what was causing my trouble.

And when I say I took the oil injection system apart, I took every piece of it apart. All the oil lines, the oil flow sensor .. all the in-line check-valves. I also removed and disassembled the actual pump. Cleaned and sprayed all parts to ensure smooth action within the pump. I still don't understand exactly how the pump works, but it was pretty simple to take apart and put back together.

Diagnosing and testing electrical systems is probably what I'm least comfortable / experienced with, so I'm probably avoiding it by eliminating all other systems first I've eliminated the carbs, the fuel system, and now the oil system. I'm not sure where to go from here.

Thanks!
Chris

PS - Sorry for being so long winded.

[Solarman]

Ok so check tach, see if has switch or bad connections in back. If running right RPMs. then see if still stumbles, misfires, and at what rpm it does that; also, check for any buzzers, indicators that might pop up?
And let us know.

[chackett]

I'm going to try and take it out and shoot some video of it tomorrow. I'll post that up and maybe it will help get to the bottom of it.

Couple other things that have been suggested to me to check / test / replace:

1. The gear counting coil Found one on ebay, it's on the way. Not sure how to test the old one, so not sure if it's bad or not. It's inexpensive though, so I guess no harm ni swapping it out to see if it makes a difference.

2. The voltage regulator/rectifier assembly. Also seems relatively inexpensive to find on ebay (even new from brownspoint it's only about $100).

3. The tachometer control unit - don't know much about this part or what it does exactly. Haven't looked for it, but I'll take it one step at a time.

Thanks Solarman .. I appreciate you sticking with me!

Chris

[Solarman]

A simple ohms test is what you test gear counting coil, and timing coils.
A volt ohm meter, set on the 20k ohms scale. Touch both wires of each coil and post you're reading.
The gear counting coil should be close to flywheel to read each tooth. If not it will misfire on all plugs.

[BillCon]

Hey Chackett sorry was busy at work yours is on page 63 at brownspoint diagrams, number 23 its a small black rectangle box inside the side cover you will see it on the diagram but always rule out the wiring and the tach itself as solarman suggest first it could be just that simple as a bad connection.

[Solarman]

dt200, running issues

The reason I suggest the tach fix first, there are indicators that describe where an error might be, but it's related to RPMs.
You can also read (do a search here) for ” missing at speed” by seaox230c,.it might help to understand how intricate these systems are.
But, never give up. We here would like you to succeed, and be back on the water, without throwing excess dollars out for no reason. In other words, don't just keep buying misc parts to try. Many parts will last a good long time, but there is a chance that somethings will need to be replaced. Save your money for the part (s) that will fix the problem.
Good luck.

[chackett]

Good Morning All!

So I was able to get up to the boat and do some more troubleshooting. No resolution yet, but I do have more information to share.

First, the resistance readings on the gear counting coil. I read .20 on my multi-meter while set on 20k ohm as suggested by Solarman. I didn't have time to check all the iming coils, because (a), I don't know exactly where they are, and (b) it started raining on me and I had to pack it up in a hurry.

While inspecting all the connection in and around the motor, I discovered one of the fuses in the housing where the low oil warning reset button is was blown. I was really optimistic that might have been my problem, but it ran the same as before. I'll check my books and see what that fuse was for.

I also removed the tachometer from the dash and inspected it. I wasn't able to find any switches or dials that looked like they could be used to adjust the readings. I'll look again since I got rained on, and maybe missed it, but initial inspection looked like the connection and tach are in good condition with no corrosion.

I took a handful of videos of the motor running, with the cowling on and with the cowling off.

Here is the first video. At 1:28 is when you can hear the rev limiter kick in. Shortly after that I throttle forward to show the actual rev limiter indicator flashing as the limiter is kicked in.

Here is the second video. This one is with the cowling off so you can hear the motor better. In this video with the cowling off, you can hear the motor better .. and being able to hear it better, I think I can tell it's not running smoothly at idle either .. it's just much less pronounced.

Is there anything special I need to do to test the resistance of the timing coils? Just do the same as before, find the leads, multimeter on 20k ohms and take the reading?

Also, I noticed a new symptom. I don't know if it's really new or if I only just now noticed it. But every time I depress one of the trim buttons on the throttle lever, an alarm sounds, and the port water light is illuminated on the gauge. I have removed and inspected the water flow valve that's in the cylinder head, and it seems fine. I didn't do the hot / boiling water test on it, but visually it appears fine with no stuck components.

So Frustrating!!

Thanks for sticking it out with me .. I'm determined to get to the bottom of this!

Thanks again all,
Chris

[Solarman]

dt200, running issues

Hey Chris,
The reading your getting on the gear counting coil is not what I expected. Please check that reading again. What does the manual say it should read, and how to test it?
Get back to us. And the timing coils are all under the flywheel. If you have the wiring diagram you can check the leads for those wires that come from under the flywheel.
Let is know.
And if no switch, or lever to change the tach, then just clean the connections, and replace. If that doesn't fix that problem then it will probably be the box under the cover for the tach, or those connections.

[chackett]

Hey Chris,
The reading your getting on the gear counting coil is not what I expected. Please check that reading again. What does the manual say it should read, and how to test it?
Get back to us. And the timing coils are all under the flywheel. If you have the wiring diagram you can check the leads for those wires that come from under the flywheel.
Let is know.
And if no switch, or lever to change the tach, then just clean the connections, and replace. If that doesn't fix that problem then it will probably be three box under the cover for the tach.

Thanks for the quick response. I will search through the manual and see if I can find anything that would suggest what the reading should be.

I checked that number three or 4 times to be sure. With the multi-meter on the 20k Ohms range as you suggested the reading is .20. Since it's resistance, I imagine it doesn't matter the direction, but the reading is the same switching the leads. I also took a reading with the coil installed and near a tooth, and I took a reading uninstalled and not near anything. Always the same .20

I ordered a replacement gear counting coil and I think it may be delivered today. If it is delivered, I'll be very curious to take a reading on it when I get home this afternoon.

Chris

[Solarman]

Thnx Chris. Think you should have a different reading, and when gear goes by it should change readings.