1987 dt175 permissive question

[skidplate]

Does this motor have a limp mode and if so what sensor would need to be bypassed to check. The motor seems to be randomly firing an 3 cylinders

 

[rodbolt]

Re: 1987 dt175 permissive question

yes and yes.<br /> however if its an overheat or oil alarm you will finnish off the motor.<br />do you have the monitor gauge?<br /> do you have a service manual?<br /> do you have any test equipment?

 

[skidplate]

Re: 1987 dt175 permissive question

Thanks Rodbolt for responding.<br />yes yes and yes.<br />The engine monitoring gauges all show no faults, I do have a clymer shop manual and I have a Fluke digital ohm meter. The problem I'm having is that I can't find any gremlins in the electronics when testing per the book unless I'm just missing something.Also the carbs were cleaned (soaked in B-12 and air blown clean)<br />skidplate

 

[rodbolt]

Re: 1987 dt175 permissive question

what method are you using to determine spark is random ?

 

[skidplate]

Re: 1987 dt175 permissive question

Well..... about the best I can answer that is by spark plug examination. but now that you mention it I'm not sure. It seems that 3 cylinders were firing after examining new plugs, after a short run on muffs. It was obvious that only 3 were firing , the other 3 were just wet. I set the motor aside last year after becoming frustrated and am now determined to either fix or bring to the shop.I have done compression test ( all even) , rebuilt carbs, tested pulse coil, and associated. I'm not sure of my cdi results and plan to test again tomorrrow. The ignition coils were tested by my local dealer and all tested fine.<br />Rodbolt if I had confidence in my local dealer I would have brought it in a long time ago butI don't due to previous visits. The problem here is only 2 dealers within 100 miles. Anyway I degress; Your assumption is right I don't know for sure its randomly firing.

 

[R_Andersen]

Re: 1987 dt175 permissive question

I had the exact same problem in both my motors (1988 DT 200's). It turned out to be the "low oil warning module". I unplugged the connections to the module and my motor has ran fine since.<br /><br />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.<br /><br />Let me know if this works for you. It should only take about 15 minutes to unplug the module and see what happens.<br /><br />-Rob A.

 

[skidplate]

Re: 1987 dt175 permissive question

Well I disconnected the low oil module with no good results. The one thing I did notice is the idle adjustment switch ( 4 position idle contol swich ) does not work. It maintains the same rpm regardless of position. Could this switch be part of the problem ? Lots of unburned fuel exiting out of the exaust.

 

[rodbolt]

Re: 1987 dt175 permissive question

buy the DVA adapter for your fluke, test the CDI output to each coil primary. the voltage should stay steady on all primaries. you can also test the pulser coil outputs with the same meter.<br /> there is a test harness avalible to clip into the pulser harness.<br /> the idle switch is just a set of resistors, changing the switch changes the bias in the CDI and alters the timing to increase or decrease the idle speed.<br />with the DVA adapter you can also test the stator charge coil outputs.<br /> its a must have for testing altenator driven CDI ign systems.

 

[skidplate]

Re: 1987 dt175 permissive question

Thanks rodbolt I'll give it a try .

 

[spego]

Re: 1987 dt175 permissive question

I have a DT175 (1988) and mine recently started acting a little strange as well. The buzzer goes off at idle and the water pressure light comes on on the monitor gauge but I have a pressure gauge and the pressure is fine for idle....so every once and a while it will act as though it is running on 3 cylinders until I back off and get on it again. It seems like the sensor for the pressure is going on mine and may be causing it to happen. Just a thought for you to look at as well.....I do believe they have the same "feature" for the water pressure as well as the oil.

 

[skidplate]

Re: 1987 dt175 permissive question

Thanks rodbolt I'll give it a try .

 

[skidplate]

Re: 1987 dt175 permissive question

[quote time1147700940= userskidplate= uid53862= fid30= tid= rid8= Thanks rodbolt I'll give it a try .[/quote]

Well I finally got the problem resolved 87 175 87 175. I was lucky enough to find a friend of mine who suzy a suzy rep. when they first came to Louisiana in 80s early 80's. He now owns a Mercury dealership? Anyway he found solenoid choke soilenoid assembly needle valve was bad and dumping fuel carbs the carbs. He replaced it with a mercury assembly and runs great. He even felt sorry for me and only 100 me $100. I still 200 him $200 for his troubles and my piece of mind. I appreciate all the help from the forum and enjoy reading the posts.

 

[skidplate]

Re: 1987 dt175 permissive question

Thanks rodbolt I'll give it a try .

Well I finally got the problem resolved on the 87 175. I was lucky enough to find a friend of mine who was a suzy rep. when they first came to Louisiana in the early 80's. He now owns a Mercury dealership? Anyway he found the choke solenoid assembly needle valve was bad and dumping fuel into the carbs. He replaced it with a mercury assembly and runs great. He even felt sorry for me and only charged me $100. I still gave him $200 for his troubles and my piece of mind. I appreciate all the help from the forum and enjoy reading the posts.