DT175 Problems

skidplate · Jul 2, 2005

Seems to be running on 2 to 4 cylinders. I have checked compression (110 all) cleaned carbs and using fresh gas/oil. I tested for spark by grounding each ( new ) plug and all are firing although they do seem weak. What is the next logical step in troubleshooting ?

JB · Jul 2, 2005

Re: DT175 Problems

Could be spark, could be carburetion. With engine at idle (on muffs) disable each spark plug, one at a time. If the engine rpm does not change, that cylinder is not making power. If rpm drops, that cylinder is okay. If side by side cylinders are not making power you have a carb/fuel problem. "Cleaned" carbs are as often a problem as not. Let us know what you find, and welcome aboard.

jim dozier · Jul 5, 2005

Re: DT175 Problems

What JB said and you can buy an inexpensive spark tester at an auto parts store to verify the quality of your spark. Also pull off the airbox and squirt some premix into the carb throats 1 at a time. If it picks up check your fuel system (probably the carbs).

skidplate · Jul 9, 2005

Re: DT175 Problems

Ok sorry for the long delay but I've been working nights. Well I removed carbs again and cleaned again. (no problem found) Bought and replace both fuel pump diaphrams and used separate tank with clean fuel oil mix. Engine starts but runs very weak. I systematically pulled each wire and found #1 and #2 cyllinder to be the only one firing. ( the others had no effect to engine rpm. While engine was running I sprayed premix into cyllinders with no success. Next I disconnected all of the ignition coils and checked per the clymers manual. All primary sides of all coils read .8 ( spec = .3-1.0) But the secondaries read as follows #1= 27300 , #2= no reading #3= 21300 #4= 216000, #5 no reading , #6 no reading. Can this be right and what does it mean? I would think if the readings were real #2 cyllinder would not be firing.

skidplate · Jul 9, 2005

Re: DT175 Problems

Sorry this info was left out: 1987 dt175 power head recently rebuilt. I would be willing to replace the coils but need some expert advice on the readings I have gotten from the coils before throwing good money at the wrong problem.

skidplate · Jul 10, 2005

Re: DT175 Problems

OK I feel like I'm talking to myself: But anyway I checked the coils at different points during the day and they read the same until dusk when the air was cooler. Now most of them read 31K to 39K. Can these coils coils change by the temp. of the day are, are they shorted. Please advise.

ianyoung77 · Jul 10, 2005

Re: DT175 Problems

skidplate, Have you done the spark test? Did you get more than 1/2". If you did it is probably time to look elsewhere. Ian

jafa · Jul 12, 2005

Re: DT175 Problems

Hi Skidplate. I dont know that motor but if 1&2 are running the engine then swap the coils with another pair , say 5 &6 and repeat the tests to see if the problem moves or stays in the same place. 4 coils gone out seems a bit unlikely. Were you testing the secondary from plug cap to ground ?

jay dezman · Jul 12, 2005

Re: DT175 Problems

have you checked the pulser coils?

skidplate · Jul 16, 2005

Re: DT175 Problems

Well here's the update. Had coils checked at suzy dealer and all checked out good.( cool tester) # 2 coil was a little irratic but would not cause my problems. I was able to test the pulser coils per my clymer manual and resistance was within book specs. The next thing I will try is to pull the flywheel for an inspection below. ( I don't think I will find anything but I've got to look!)Also the TPS is adjusted to 220 ohms ( 200-250 specs) Any other ideas would be greatly appriciated

jim dozier · Jul 16, 2005

Re: DT175 Problems

Pull off the airbox and squirt some premix in the carb throats. If it picks up you have fuel issues, either supply- tank, hoses, and fuel pump; or mixture- back into the carbs again.

aabfeh · Jul 16, 2005

Re: DT175 Problems

I just experienced a similar problem with a 150. No power and mine only ran on 3 cyl. Took it to a mechanic who replaced an exhaust plate and now it runs great. He said that the faulty exhaust plate allowed water into the cylinders.

jay dezman · Jul 18, 2005

Re: DT175 Problems

fishing1- what was the cue/clue the mechanic used to diagnose the exhaust plate and which one needed the attention?

aabfeh · Jul 19, 2005

Re: DT175 Problems

Jay- I wish I knew exactly what his diagnotic procedure was. I think he could tell there was water intrusion from the plugs or possibly removing the head. My engine is an 89 model and he said this was a faily common problem. Something about this being a two piece plate and newer ones being one piece. This was a tough piece to replace because of broken studs etc. He replaced both of them while he was at it. Like you, I was shure I had an electrical or fuel problem. The entier bank on the right side would not fire at all. If I struggled to keep it running for 10-15min it would sometimes clear out and run well. Kept getting worse however. It possible sounded a little louder.

skidplate · Jul 19, 2005

Re: DT175 Problems

I'm pretty sure I don't have a n exhaust plate problem due to the fact it shows none of the signs of water intrution on the plugs are cylinders. The one thing I did'nt mention is while the engine is idling and I adjust the idle adjustmet switch ( 4 position : slow to fast) the engine runs worse at the high idle position. From what I can tell this switch increases the idle by adjusting ignition timing. So I don't know if it runs worse as the timing is increased or if it runs worse at increased timing due to the lack of plugs firing.( wow that sentence confuses me LOL) Anyway it off to the suzy dealer next week if I dont find the problem.Thanks for the input.

aabfeh · Jul 19, 2005

Re: DT175 Problems

Skid- Whatever you do, don't tear into the exhaust plates unless you're 100% sure that's the problem. The mechanic had a terrible time with frozen and then broken bolts. Lots of soaking with penetrating oil and still broken bolts.

skidplate · Jul 19, 2005

Re: DT175 Problems

fishin1 , been there done that! I completely disassembled and replaced many broke bolts after removing with ease-out. Was'nt to bad of a job but then again I have a machine shop at the house. Thanks for the reply.

R_Andersen · Jul 19, 2005

Re: DT175 Problems

I had a very similar problem on a 1988 DT200. It turned out to be the "low oil warning module". I unplugged the connections to the module and my motor has ran fine since. What happens is when you run low on oil, the module kills spark to 3 cylinders to protect the engine. For some reason my module went bad and the motor only had spark to 3 cylinders and pressing the low oil reset switch had no effect. The module was located behind the ignition coils, but I just looked at a wiring diagram to see what wires to unplug. Hope that helps, Rob A.

skidplate · Jul 19, 2005

Re: DT175 Problems

Thanks I'll check it out. This problem is driving me crazy and my pride has prevented me from bringing it to the dealer. I have rebuilt 5 outboard motors and many pumps, turbines, and 4 stroke motors but I am a novice on the CDI unit even using the manual. I just hate to admit defeat! Thanks again.

skidplate · Jul 25, 2005

Re: DT175 Problems

OK Rob I found the low flow module but it has many wires coming from it including the brown and white which the book says is the alarm. No way to diconnect directly from the module. Can I disconnect at the reset button and tie those two wires together to eliminate the trip. ( only for troubleshooting purposes.) are do you know a simpler disconnect. Thanks Skid

DT175 Problems

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