Poor Performance from Suzuki 115

walleyehed · Dec 17, 2004

Re: Poor Performance from Suzuki 115

You've definately got a problem there (picture of plugs)I see only 1 plug that is firing all the time. The first 3 are all intermittant. A carb-job is a must here...they show a lack of fuel/oil present. It only takes about 2 seconds to melt a piston if conditions are right.

Paul Moir · Dec 17, 2004

Re: Poor Performance from Suzuki 115

If you want to avoid going to your dealer everytime you want to look up a part, you can download the parts catalog: EDIT: I can't post the link since Iboats' BBS software is so lousy. Copy and paste this into your browser, and remove the space between 'biz' and '/pdf/': www.brownspoint.biz /pdf/DT115_140(86-01).pdf (Warning - that's 8.3MB) I noticed they have a carb kit marked as PN 13910-94400. Sounds like your local service people are real champions.

badbass · Dec 20, 2004

Re: Poor Performance from Suzuki 115

So I decided to pull the carbs this weekend and made quite a shocking discovery. First of all Jimd the pump seems to be connected to cylinder 3. After checking out the parts list that you gave me Paul I noticed that the jetting might be wrong. My Motor. ( But the list gives this as jets for the 86-88 Model DT115) 82.5 Pilot Jet 132.5 Main Jet ( I found a 048 jet installed in the bottom carb with the sensor on it .... I dont think this is right) It realy looks like they are champions

According to the list I should have a 65 pilot jet and a 137.5 Main jet for the 89-97 motor. Please give me advice on what jets to put in ( I am 1700m above sea level). Should I check the reed plates while the carbs are off and will Boyesen reeds make any difference Much Appreciated Rudie

jim dozier · Dec 20, 2004

Re: Poor Performance from Suzuki 115

The 132.5 main and the 82.5 pilot jets may be OK for your altitude. The main is one jet size leaner which is appropriate for the rise in altitude. You are at about 5500 feet (1700 meters). There are other leaner main jets available so you aren't the leanest. The pilot jets meter air to the idle circuit so a larger pilot jet is leaner. I don't know what the 048 jet is you mentioned are you sure you got that right? Clean those carbs thoroughly with solvent and compressed air and install new float valves and gaskets and then see what happens when you run it.

badbass · Dec 21, 2004

Re: Poor Performance from Suzuki 115

Ok so i soaked the carbs in carb cleaner replaced the float valves and gaskets( For a change they has something in stock

) Carbs seemed clean when I soaked them, i cleaned them with compressed air after soaking them also replaced the bottom jet just in case and had the boat out this afternoon...... Still no luck. I noticed a throttle sensor on the lower carb and took a ohm reading on it( 2ohm ) is there any other means of testing the sensor at WOT and at FCT. I read on another post that he disconnected the sensor and shorted out the wires to test the unit, is this safe and should I try this. Rudie

jim dozier · Dec 21, 2004

Re: Poor Performance from Suzuki 115

I believe the throttle position sensor won't have much effect on full throttle though I could be wrong. Is the engine running smoothly and just not reaching proper rpm or is it running poorly? If its running smoothly but at too low an rpm it may be time to look at your prop selection. I recall that you went the wrong direction on your first prop change. Maybe you need to borrow a smaller pitch prop for a test.

badbass · Dec 21, 2004

Re: Poor Performance from Suzuki 115

We did try a 15 pitch prop at the shop I bought the motor from and it just touched 5000 rpm with that prop, I do believe that the motor should have no problem reaching full rpms with a 15 pitch prop. The Motor is running fine up to about 4300 rpm then simply bogs down and loses all power. I know that I should go smaller on the pitch to increase revs, I was just giving a example on the first post .

jim dozier · Dec 21, 2004

Re: Poor Performance from Suzuki 115

Oh. Perhaps there is a problem with the ignition at full throttle. Have you checked the linkage. Does this engine have electronically advanced ignition or mechanically advanced? If its mechanical advance, check to see it is up against the stop at full throttle. Either way put a timing light on it and see if its receiving full advance at full throttle. Are the throttle plates open all the way at full throttle? I believe this engine had an rpm limiter that can be triggered by low oil flow from a clogged oil filter beneath the oil tank. Verify that its not limiting the rpm. If you have compression, correct mixture, and properly timed spark its gotta go. That's a good engine if its running right. Usually if an engine is running fine to a certain rpm and then bogs down its either a lack of fuel caused by a clogged main jet, bad fuel pump or kinked hose or air leak, or your ignition is going soft at high rpm for some reason. Try pumping the fuel bulb when it starts to bog down. Also try choking it (manually part way) or squirting some premix into the carb throats and see if it picks up any. If either of these work you are running out of fuel for one reason or another. Have you checked the status of your fuel filter? Perhaps its clogged.

badbass · Dec 21, 2004

Re: Poor Performance from Suzuki 115

Ok now I have quite a few things to check. The fuel filter is fine I checked that first.... I checked the linkages and all the carbs seem to be opening all the way. This engine has electronic advance timing, what do you mean by checking if it is recieving full advance at WOT, I will check the filter on the bottom of the oil tank . Please explain what I should check for with the timing light. Thanks Rudie

jim dozier · Dec 21, 2004

Re: Poor Performance from Suzuki 115

On the earlier models the ignition was advanced mechanically and you could see the arm come up against a stop (which was adjustable). If its electronically advanced you can't see it unless you put a timing light on it. Either way you should verify that it is getting full advance with the timing light (whatever the manual says it should be. There are degrees marked on the flywheel with a pointer) at full throttle. If its not getting full advance the engine will fall on its face even if the throttle plates are wide open. Most of the initial change in power comes from the ignition advancement, its only the last 1/4 that comes from opnening the throttle plates. This is where a manual is a necessity because each engine model is a bit different and the synchronization between throttle and ignition advancement is critical. You also have to check out the throttle position sensor but somebody else will have to help you there. It may be that whoever put this engine back together during the rebuild didn't get something in the linkage right.

DJ · Dec 21, 2004

Re: Poor Performance from Suzuki 115

The problem is definetely not the prop. A 15" wheel on a 15' bass boat should hit the rev. limiter every time.

R_Andersen · Dec 22, 2004

Re: Poor Performance from Suzuki 115

I vote for a misadjusted or non functioning TPS. I have an older DT200 that would only reach 4800 rpm at WOT with the TPS unplugged and when it was plugged back in it reached 5400 rpm, so the TPS definately affects WOT power. If your's is set completely wrong that could be the problem.... -Rob

walleyehed · Dec 22, 2004

Re: Poor Performance from Suzuki 115

DJ, Please take into account the altittude...most over-look this. If I hadn't grown up at 4000ft., going to lakes above 5000ft-as high as 9000ft., with my dad being part of a pit crew for OMC, we got some (He then me)great training on high alt. operations. It figures out to about 1 to 1-1/2" pitch drop for every 2000ft above sea-level. One of our SSV-176 Glastrons required an 11 pitch prop on a 115 @ Dillon in Colorado (9000ft) to even get close to 5500!!!! We even had to advance timing around 8 degs at this altittude. BTW, that same boat would turn close to 6K with a 17 at home...

badbass · Dec 22, 2004

Re: Poor Performance from Suzuki 115

I am getting my manual today and will check the tps setting. I have tried setting it back and forth with absolutely no difference at all. Maybe there is just a specific voltage setting for the TPS to work properly. I know my SR20DE Motor would lose at least 10hp with incorrect TPS voltage setting, the timing would actually retard at WOT due to incorrect voltages supplied to unit.

DJ · Dec 22, 2004

Re: Poor Performance from Suzuki 115

walleyhed, You're right. Altitude plays havoc on outboards. The altitude info. came late in the thread. VERY IMPORTANT.

badbass · Dec 23, 2004

Re: Poor Performance from Suzuki 115

Ok got the manual today but it simply confuses me more, the manual says that on those models the timing can not be adjusted and is only controlled by the gear counting sensor and the TP Sensor, both seem to test fine with multimeter. There is only documentation on adjusting the TPS sensor for fuel injected models and not for carbed motors, will the voltage setting be the same for both..... I guess so since there is nothing else about it the book. The book says at the end of this chapter that the timing should be between 22-26 degrees BTDC @ 5000 rpm. How can they give you timing if you cant adjust it . Do you guys think that altitude could kill my motor this much. I can understand at 9000 ft but I am at about 5000 ft where other guys are running close to 6k. I know I would be pushing my luck running a 19 pitch prop but a 17 should be fine. By the ways may you guys have a Merry Christmas and a Blessed New Year. Rudie

badbass · Dec 24, 2004

Re: Poor Performance from Suzuki 115

I had the boat in the water this morning and no improvement at all. I took the wires from the TPS sender and bridged them out to simulate a timing advance and retart, this only seems to be a relay switching two wires. Even without any load on the motor it has trouble reaching 5800 rpm, it revs clean all the way to 4900 and then takes quite a while to reach 5800. One more thing I noticed was that if I disconnect the linkage on the carbs and rev the motor with each individual carb the motor only picks up revs cleanly with the bottom carb . I tried to check the timing andvance at 5000 rpms but he timing light seemed too dull for me to see anything on the flywheel, I will try to get a hold of another timing light to check the timing.

badbass · Dec 30, 2004

Re: Poor Performance from Suzuki 115

I have now completely thrown in the towel. The dealer is taking back the motor for the same price I bought it for so I am in the market for something bigger. I looked at a 200 merc offshore in very good nick but I think this is overkill on a 16.5 ft bass boat. The dealer is looking out for a 140 - 150Hp motor, do you guys have any suggestions as to model and type. Problem solved

Rudie

Poor Performance from Suzuki 115

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