Dt85 dies off idle.

[Jim13]

I have a 1988 DT85 that dies just above idle.
It starts OK, idles great, and runs good everywhere else but you have to "goose" it a little to take off. When easing off the throttle, it will die also when that one spot is hit.

I just bought the boat so I don't know much about it yet. Can anyone give me some guidance and point me in the right direction?

 

[Yamajoe]

Re: Dt85 dies off idle.

Set your air/fuel mixture screws (side of the carbs) to the correct specs. If the settings are say 1.5 turns out from lightly seated, then carefully turn screw until it is seated ( not tight), and then turn the number of turns. do this on each carb. turn motor over, allow to warm up and fine tune settings as per your manual.

 

[bowhuntrrl]

Re: Dt85 dies off idle.

Could also be that carbs need cleaning/adjustment. I don't mean squirting stuff into them or running fuel conditioner through them either ! I mean take apart and clean properly, adjust the float and check carb synch. The new E15 gas is crapping up carbs everywhere !!!

 

[Jim13]

Re: Dt85 dies off idle.

Thanks fellas. I am off this weekend and will give your suggestions a try.
The carbs were just gone through according to the PO so I will try the mixture screws first and let you know how it turned out.

 

[Jim13]

Re: Dt85 dies off idle.

I checked the screws today and I found that the cover plate was missing 2 bolts on the bottom (vac leak?), top carb had the screw head broken off (no telling where it is set) middle one was at 1 1/2 turns and the bottom one was at 3 turns. My book says inbetween 1 3/4 and 2 1/4 is correct. I ran some seafoam through it, set them both at 2 turns out and called my dealer to get a new screw.

My problem is going to be getting this air-bleed screw out without damaging anything. It is broken off flush with the carb. Anyone have any ideas?

 

[JUSTINTIME]

Re: Dt85 dies off idle.

reverse drill

 

[Crapduster]

Re: Dt85 dies off idle.

I have a 1987 dt85 and you pretty much summed up the last little nagging problem I have with my motor. I have that baby purring at all speeds except exactly what you just described and it is driving me crazy insane! So I am going to also follow the suggestions here. I checked my shop manual and indeed it says 1.75 to 2.25 screws out... I have mine at 1.5 now. I am going to set them to 2 out and I will be in the lake in the morning for a tuning/fishing day. I will also be going through a seafoam de-carbon run and after smoke bombing the place I have 3 new plugs I am going to pop in. I will post back and share my experience and results. For the sake of this thread I will test first with just the air-idle screws and see what difference it makes for me.

Things done to the engine over the last few months... was running like a dog when I got her:

Reed valves replaced (originals in GREAT shape but did it anyway). Carbs rebuilt (again, needle and all parts in great shape but replaced anyway), new gaskets, replaced all the missing odds and end nuts/bolts and checked/tightened the rest. Rebuilt fuel pump (was in good shaped, but replaced spring/diaphragms anyway). Had a shop replace every last millimeter of fuel line on the engine and do a compression check for me and it was flawless. Everything OEM Suzuki parts from Brownspoint. Amazing what a bit of DIY and patience can accomplish!

One thing I did find when I rebuilt the carbs... it was amazing... I get the first carb off and the gasket between the carb and the engine is on backwards... the holes will line up either way, but there is only one way that the gaskets fits. So yeah, first cylinder about 1/4 of intake blocked by gasket... 2nd carb, same deal... 3rd carb, it's a miracle!! I was actually pretty happy at that point because I knew I had just found the easy fix for the majority of my problems. Lesson... I'm not sure, but I saved a ton of $$$ figuring out that one by myself vs. $95/hr labor.

My handle is pronounced cropduster... I was trying to be cute and make a play off crappie... most people don't get it and just think my handle is crude

 

[Crapduster]

Re: Dt85 dies off idle.

Definitely more tuning than fishing today. Ran terrible at 2 out on the idle/air screws. would not stay running and way too hard to start. Back to 1.5 and and much better, but since I already had everything there I decided to slowly adjust each one down to 1.25. This made a difference at at 650-700rpm in gear; motor ran smooth and didn't die . Motor idles at 1100 in neutral now though... think the spec is 1000rpm after warm. I think this means I should adjust the idle bolt that is attached to the timing advance mechanism to bring the rpm's down to 1000 again.

So I guess sometimes you can't go by the book, or I am wrong about my year model.

 

[Jim13]

Re: Dt85 dies off idle.

I tried drill a small hole in the screw and us an easyout on it but the brass screw just isn't strong enough.

It seemed to run ok in the driveway so I took it to the lake last night to do some night fishing, and it ran like a dream.

As a bonus I got a few small catfish and a 34" Red drum.

Thanks for the input and suggestions!

 

[Yamajoe]

Re: Dt85 dies off idle.

getting there, the idle adjustment screw is on the bottom carb, screwing down, next to the throttle rod assembley, turn this screw to adjust idle to recmmended rpm.