1986 DT 115 Suzuki power problems

[clamdigger1]

so close, yet so far...
After following all of the great advice from all of you, we finally got our engine running nicely.
We launched the other day, started up easily and headed out of the harbor.
At very slow idle, the engine would stall, but start up with no problem.
Once out in open water we put the throttle at 1/4 so far so good., then to 1/2, A-OK. Then went to hit it, she jumped up with amazing power and took off smoothly. Then lost 1/2 of her power, but kept running smoothly. We had the throttle open almost all the way, but only got 1/2 the speed. It wanted to pick up speed, for a second, then bogged down. Got back to port, wen tot dock, and at very slow idle, engine would quit. Starting up again with no problem. We thought we lost a cylinder, but all checked out OK. Tested plug temp., all the same.
Our feeling is maybe because our tilt doesn't keep the engine at at least level,
that maybe we were dumping too much oil into the gas?
Or we were getting air somewhere, possibly the lines from the tank to the separator to the engine in the quick connects.
Or the fuel pump.
How do you by-pass either temporarily, or permanently. I guess temporarily. I read in this forum that Suzuki's oil injection system was really good so I should keep it, and fix it rather than eliminating it.
How do I test the fuel pump?
How would you suggest I remedy the quick connect situation?
Do I eliminate that? or do I just replace the quick connects?
Are these engines nototrious for burning alot of fuel? My friend insisted he filled the tank, (12 gallons) we were out only for about 20 minutes and were almost out of gas. Does that sound right? If that's the case, it's back to sailing!!
While I'm at it, any suggestions on how to repair the tilt? I have a small leak somewhere. It goes up and down with no problem, but if you leave it in the up position say for transport and launch, the engine will stay up for anywhere from 2 to 20 minutes and will be totally down, no matter what.
Thank you in advance.
Clamdigger

 

[James R]

Re: 1986 DT 115 Suzuki power problems

You have asked so much. What do you want to address first?

 

[hankll]

Re: 1986 DT 115 Suzuki power problems

This may not help you but my 87 DT150 SS was not idling well and I thought fuel mix was to rich. I discovered by accident that one of my coils was breaking down under a load. When on muffs it seemed as though all cyl were firing. Checked this by pulling off plug wires one at a time to verify spark while it was idling on the muffs. Then on the lake, bad idling with frequent stops, but easy restarts. When I pulled plugs after one of these episodes, I discovered that on one of the cyl the spark plug was as clean and bright as if it was new. I was able to find some "new" used coils for the motor to try, and that solved my issues of bad idling. My mechanic told me when I told him what had happened that the raw fuel in that dead cyl would cause extra rich conditions in the other cyls. I don't know about that, but I also don't know much about 2 cycle fuel systems where fuel is inside the crankcase area. It made sense, but then he could have been all wet for what I know about 2 cycle. This may not help but it might be as simple in your case.

 

[James R]

Re: 1986 DT 115 Suzuki power problems

One cylinder not firing should not affect the mixture of the others.

 

[hankll]

Re: 1986 DT 115 Suzuki power problems

yes well, as I said what he said made sense, but I really didn't know for sure. Only that once I had a good coil on that cyl, all was fine, good idling and good WOT.

 

[clamdigger1]

Re: 1986 DT 115 Suzuki power problems

thanks to you for your advice.
Nothing is simple is it? I guess the more problems I have, the more I'll learn about this engine which in the long run is a good thing.
To somewhat eliminate the possibility of air in the fuel lines due to faulty quick connects, we hooked up a tank of pre-mixed gas directly to the engine.
We also disconnected the oil reservoir and pump to make sure we were not dumping too much oil into the gas. To do this, we disconnected the electrical connection to it, disconnected the 3 hoses that came from the small pump at the bottom, capped off the 4 hose connections that go to (correct me if I'm wrong), the reed valves. We also disconnected the linkage.
I took your advice about the coils, as we were intermitantly losing #3 cylinder. We switched them around and found the same problems. Then we lost #2 cylinder intermitantly. Switched coils around again, same problems.
#1 and #4 OK no matter which coil was where. We checked the readings coming out of the "flywheel" area into the power pack, all the same. Checked compression, (all 130) My mechanic came to the conclusion (after 2 good hours of diagnostics, of which I am being very general) that the power pack is bad. What we thought might be a fuel problem, turned out to possibly be an electrical one. Do you guys have any suggestions on the definative test of the power pack? Would you know where to get a good used one?
Thanks again for all your help,
clamdigger1

 

[James R]

Re: 1986 DT 115 Suzuki power problems

I figured we were headed there. I have no tests available but Ebay is my source for replacements of this type. These units are the same for 1986 thru 1994.

 

[James R]

Re: 1986 DT 115 Suzuki power problems

Made slight error in my previous post. The power packs are the same 1986 thru 1997.. There is a small diference. The later models do not have the idle switch. They have a fixed resistor. Makes no difference.

 

[waffles1]

Re: 1986 DT 115 Suzuki power problems

Looks like Mr. Suzuki himself posted a repy. lol

 

[clamdigger1]

Re: 1986 DT 115 Suzuki power problems

Thanks for the info. We're going to try a couple of more tests. Maybe we missed a nick in a wire somewhere.(wishful thinking)
Am I mistaken, or does the power pack for a 140HP also fit a 115HP? I guess now is the time to get a shop manual. I found a great guy in Ill. Really helpful and great prices on new and used stuff. No used power packs though. Did find a used 115 on craigslist with a cracked lower unit outer case for $750.00 Maybe too much. Gonna try e-bay.
Thanks again and will report our "progress".

 

[clamdigger1]

Re: 1986 DT 115 Suzuki power problems

Just thought I'd pass along what I learned from a Suzuki parts and outboard dealer in Illinois. He said that the power packs for a DT 115 are only interchangable for 1986, 1987, 1988. Other parts, i.e. gear casing, lower units, etc., are interchangable for a wider spectrum of years. I may have found an 87 DT 115. Let you know what else I find out.