Suzuki 1988 dt30 running problems

shelbert

Cadet
Joined
Aug 26, 2003
Messages
28
Hi I have recently been given this motor from a guy down the road. <br /><br />From what I can tell it seems to have overheated at some point since the gold around the top cyl is discolored and some of the plastic parts are melted a bit.. He said it was that was when he got it and it ran for years that way. Im not so sure but hey it was free.<br /><br />I started it up and it ran , but was leaking water around the water jacket. I took this off and replaced the head gasket and water jacket gasket. While I had it apart I inspected the Cly walls and they are in perfect shape as are the pistons. Once I put it together i did a compression check and the cyl are 110 105 110. Then decarbed and soaked in sea foam to clean it out a bit. I cleaned the carbs as they were all gummed up badly and started it up again.<br /><br />It ran smoother but will not run in gear under a load at all and will barely run in water at idle. It also seems to rev weakly. I suspected that it was not running on all 3 cyl. I tested all 3 plugs for fire, they are all firing well. ( I just checked visually) <br /><br />I then proceeded to isolate plugs and it seem the bottom cyl has no effect on the engine running, the middle cyl has little effect on the idle and the top cyl has a noticable performamce hit when removed. I can run it on any 2 and the engine will still run though although badly if the top is not hooked up so they must be trying. <br /><br />Any help on how to troubleshoot this engine a bit more precise.<br /><br />One more thing I would like to ask, does anyone know the proper way to disable the oil injection system on this motor at least for the time being. I am running premixed and want to continue to do so untill I can verify this thing is working. As it is I cnat keep it going long enough to test the oil injection.
 

fish4970

Petty Officer 2nd Class
Joined
Mar 11, 2003
Messages
105
Re: Suzuki 1988 dt30 running problems

does the bottom plug look wet with fuel<br />did you soak the carbs in a bath type cleaner &<br />blow out all of the jets with an air gun
 

jim dozier

Lieutenant Commander
Joined
Jan 8, 2003
Messages
1,970
Re: Suzuki 1988 dt30 running problems

Try disconnecting the fuel hose at the engine connection and run the engine under load if it picks up a little before it quits you may be running rich in the bottom cylinder. If the bottom cylinder isn't firing and has spark I would check the fuel pump (which is attached to the bottom cylinder on that motor I think) diaphragms. A leaking inner fuel pump diaphragm will inject fuel directly into the intake port and cause that cylinder to run rich. A fuel pump rebuild is quick, easy, and inexpensive.<br /><br />On the oil injection, no need to disable it, just run pre-mix 50:1 until you see that the oil is going down in the tank. Probably would be a good idea to replace the oil filter which is a little puck in the oil line beneath the oil tank. They can get clogged if old oil gels in them. If you really want to check the oil injection, get a manual. You can measure the amount the engine uses in a measured time period with a large syringe feeding the oil line instead of the oil tank.
 

shelbert

Cadet
Joined
Aug 26, 2003
Messages
28
Re: Suzuki 1988 dt30 running problems

The plugs are all wet with fuel, I look oily but it could just be the carbon mixing with it from the burning oil. <br /><br />Although I am not convinced the carbs are as clean as I could get them, they are the mother of all evil to get off so i will try the fuel line and pump today and see if that helps. If not I will reclean them before posting back. <br /><br />As for the oil injection I do not believe it is working since there are no signs of oil in the oil lines going to the intake while it is running. But that problem, unless it could be causing my problems will have to wait untill it is running with premix well.<br /><br />I do have a manual, but it is severly lacking in this area. I did run all the electrical test it recommended though and the coils all seem to be fine. The CDI test was one test I could not test though.<br /><br />One more question if possible, with the top cyl having much more effect on the idle, and the bottom 2 having little. Should all 3 of the cyl effect the idle the same or not. I was told by a friend that some engines didnt run on all 3 cyl at idle. This seems odd to me but I dont know for sure.
 

shelbert

Cadet
Joined
Aug 26, 2003
Messages
28
Re: Suzuki 1988 dt30 running problems

Ok a update on my progress. I took the fuel pump apart, looks good from what I can tell, no breaks or tears in any of the gaskets. I also took it to the boat ramp to take the fuel line off, It ran good enough with the hose off to acually go in gear but would not rev or really do anything before dying.<br /><br />I decided what the hey I would check the Carbs again. Upon initial inspection they looked good, the channels are open and jets are clean. But when I was putting them back together I noticed that the top carb float jet pin is springy while the lower 2 are stuck in the extended position. I tried to free them with no luck so I am soaking them in cleaner overnight. Another thing I apear to have forgotten to hook up the throttle valve, what this does I hope you guys know because I dont.<br /><br />Could this cause the problem I am having. I am just not good with carbs and not sure what that springy action does (again). I did notice the carb float moves alot more on the free one.
 

jim dozier

Lieutenant Commander
Joined
Jan 8, 2003
Messages
1,970
Re: Suzuki 1988 dt30 running problems

If you go to the trouble of getting the carbs off and apart they should not be put back together without a rebuild kit. Especially since the float valves are now suspect. I hate to suggest you take them off 1 more time (you should be good at it by now) but I will, take them off buy the rebuild kits and relplace the float valves and gaskets.<br /><br />The same goes for the fuel pump. I am assuming that when you went in there you did so with a rebuild kit.
 

shelbert

Cadet
Joined
Aug 26, 2003
Messages
28
Re: Suzuki 1988 dt30 running problems

No need to take them back off again, they are still off soaking to free the pins (which are free now after soaking all night). Parts are a problem or me as I have to order them since there is nowhere to get them locally. <br /><br />Ill rebuild the carbs but will take a week or so to get the parts. In the meantime I will have to put the carbs back on just to keep the parts all together and prevent kids from getting into the parts.
 

snappernz

Seaman
Joined
May 3, 2002
Messages
57
Re: Suzuki 1988 dt30 running problems

you may find the pump is the same as a yamaha if that makes it any eaiser for you they r the same on a 93 dt30
 
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