87 suzuki 200hp questions

[jay dezman]

i have a pair of these and one is/has lost some performance.<br /><br />the torque on acceleration is way down (one engine will plane the boat and the "weak" one won't) and max rpm on the weak one is 800-900 lower.<br /><br />i have good compression (110+ in all cylinders with a range of +/- 5)<br /><br />all 6 plugs are firing.<br /><br />i've tried to adjust the throttle position sensor and find the procedure in the manual a little confusing (after a hard week at work i must be brain dead). at any rate, there is a pin that is used to align the gear with the internal pot and there is also mention of a particular voltage reading at idle. what i have done is put the pin in place to get everything installed, then pulled the pin and rotated the switch housing to try to get the voltage reading. <br /><br />is this the correct way or have I screwed it up.<br /><br />by the way the nearest suzuki dealer i know of is about 150-200 miles away so i have to figure this one out!<br /><br />thanks all for your help.

 

[JB]

Re: 87 suzuki 200hp questions

Hi, Jay.<br /><br />Welcome to iboats. <br /><br />I think the first thing I would do is a compression check. You don't seem to be down enough on power to indicate a dead cylinder, but it sure could be a weak one.<br /><br />If the compression checks out (less than 15% span on all 6) I would then proceed with checking out throttle plate opening and ignition advance linkage.<br /><br />Good luck.

 

[jay dezman]

Re: 87 suzuki 200hp questions

what will another compresion test do?<br /><br />suzuki does not have a linkage to the ignition system, the throttle position sensor tells the microprocessor when and how much throttle opening there is, hense the question regarding the proper setting of the switch.<br /><br />thanks for your response

 

[JB]

Re: 87 suzuki 200hp questions

My bad. I missed your report of compression results.<br /><br />Nothing more to offer.

 

[jay dezman]

Re: 87 suzuki 200hp questions

ttt

 

[ThomWV]

Re: 87 suzuki 200hp questions

The pin that you refer to is just used to initially set the gear in the proper place, it is removed for the actual calibration of the sensor. The sensor is set with the engine shut off and the sensor unplugged. What you measure is the resistance between the black and the (this is from memory) the green/red one. The reading should be 240 Ohms as I recall. It is a bit difficult to adjust to be quite honest about it but the problem is that the reading will change as you tighten down the three screws that hold the sensor in place.<br /><br />Having said that I sort of doubt that the problem is with the throtle position sensor. The thing about them is that if they are way off, or even off a little bit to tell the truth, the first noticable effect is not in how the engine runs at speed, its how it idles. The idle will be way high or the engine will be unable to idle at all if the sensor's setting is way off.<br /><br />Thom

 

[R_Andersen]

Re: 87 suzuki 200hp questions

Hmm, I'm actually having a similar problem with a pair of 88 DT200's I have. Last weekend the low oil warning module died on one of my motors which caused it to run on only 3 cyliders. I just disconnected the module and now the motor runs fine again, but it runs about 600 rpm less than the other motor at WOT and I need to have the throttle farther forward on the one motor to keep them in sync. I ran it this way all day fishing last weekend and had no problems other than the difference in power. <br /><br />I'm hoping it's just a fouled plug (though I have 2 plugs per cylinder) but I haven't really had a chance to look it over yet.<br /><br />-Rob

 

[jay dezman]

Re: 87 suzuki 200hp questions

R_Anderson, that is how i've been operating since the inception of this problem.<br /><br />i guess i'm confused then as to why there is such a "fine" adjustment necessaary. i recognize that the tps has another set of contacts which have to do with the idle speed issues mentioned above....<br /><br />lets take this a step further. i have not noticed any "adjustment" built into the "base" ignition timing but there is a pointer/reference mark on the flywheel. is there a base timing that needs to be set/checked from time to time? i guess this could affect overall performance also, but as i said it looks like all the sensors up under the flywheel have a fixed radial location, but can be adjusted for proximity to the flywheel teeth. is the proximity (gap) of any significance to operation (my gut tells me it would be "go" or "no go")

 

[jay dezman]

Re: 87 suzuki 200hp questions

have you ever replaced the head gaskets?

 

[R_Andersen]

Re: 87 suzuki 200hp questions

I have never replaced head gaskets. As far as I can tell my motors are all orginal and have never been apart. I'm going to replace all the plugs this weekend (they are at least a few seasons old) and hopefully it's just a fouled plug. If it's a bad head gasket or other problem, I should be able to tell by looking at the old plugs....<br /><br />-Rob

 

[ThomWV]

Re: 87 suzuki 200hp questions

If you have a blown head gasket it will be leaking water into that cylinder and the effect of that would be one cylinder that has plugs that are shockingly clean compared to the others. You should probably be changing plugs annually. I have never heard of a V-6 Suzuki having a head gasket let go, but I guess it happens.<br /><br />The sensitivity of the setting for the throtle position sensor only shows at low speed. It has absolutly no effect on high speed operation, none what so ever.

 

[jay dezman]

Re: 87 suzuki 200hp questions

likewise, mine appear to be all original (i'm not the original owner).<br /><br />prior to this thread/phone call i had never heard of such a thing! i don't understand the physics of this situation. how could a high pressure gas be sealed in, but a low/no pressure fluid pass thru the same seal? i'm confused. in the past i thaught it was either good or bad not good enough for gases but not for fluids.<br /><br />my assumption on the tps was that i thaught the resistance reading the rest of the ignition saw had an effect on the advance curve the engine "sees" thus if the advance pulled in earlier it would increase the torq on acceleration. that works on performance car engines (i know their 4 cycle) but 2 cycles also have an advance curve.

 

[jay dezman]

Re: 87 suzuki 200hp questions

with the explanation of the clean plug if there is a leak, a clean piston top would likewise be visible thru the spark plug hole when changing the plug (assuming the piston was near tdc)<br /><br />this should also show if the exhaust water cover is leaking, too

 

[jay dezman]

Re: 87 suzuki 200hp questions

ThomWV....<br />a blown head gasket would show on a compression test....

 

[R_Andersen]

Re: 87 suzuki 200hp questions

Jay,<br /><br />Just wanted to update you on my motors. I was having the same problem as you that I described above. It turns out, when I had disconnected the low oil warning module, I also unhooked the throttle position sensor plug that hooks to the CDI unit by accident. When I checked the wiring this weekend I found it dicsonnected so I plugged it back in. Both motors now run equally and both turn 5500 rpm at WOT as they used too. <br /><br />I know some people say the throttle position sensor has no effect on WOT, but in my case, with the throttle position sensor completly unplugged the motor idled perfectly and ran fine, it was just down on power at higher rpms. I think you should take a closer look at the position sensor and anything else related to it. I'm assuming by having mine unplugged I was not getting full timing advance at high rpms, so I'd also look into anything that is related to ignition timing advance.<br /><br />Hope this helps,<br />Rob

 

[jay dezman]

Re: 87 suzuki 200hp questions

glad to hear your problem is solved. with what i found on mine last weekend and your input, i'll be going over the wiring harness with a fine tooth comb.<br /><br />i found a coil that had unplugged itself-both bullet connectors had separated. unfortunately, i've pulled the boat for the season so its unlikely i'll be able to "test" anything i discover deficient.