1986 dt 140

[riverbarron]

the issue my dt140 has is this. when in the water the motor will not idle cleanly. it stalls when put in gear or when accelerating. when on the trailer the motor runs fine. i stuck it in a barrel of water to add backpressure, but still runs fine. i have adjusted the idle mixtues, still no change.the only thing i cant do is put the amount of angle the motor sits at in the water.i have a 16ft. checkmate predictor. any ideas??? also, it has 125psi compression on all cylinders.plugs burn evenly.

[Solarman]

Is this a recent problem?
You say you've adjusted mixtures? All the mixture screws should be set per the manual for each carb, and left alone. The idle stop screw adjust till you have about 700 rpms or even 800 rpms. You can adjust later if need to.
When was the last time you cleaned the carbs? When you clean them, do you soak them for a good couple hours? Do you use a good air compressor (after soaking) to blow out all the air, and fuel pas-sages (extremely important step)? Also blow all the small holes in the jets clear.

Do you use any fuel system cleaner/additive in every tank of fuel (especially needed if using ethanol fuel)?

When you clean carbs, make sure all parts stay with each carb, do not mix up jets between carbs (early models had different size jets in some carbs to balance their flow rates.). Your carbs do have different jets for each carb, according to parts list.

I'll look up what parts your motor ignition system has. After looking up your motor, your carbs are your most likely area of problems with idling, if the motor runs well at slightly higher rpms (smoothly).

Post back with this info above when able. Good luck.

[riverbarron]

1986 dt 140

the main issue i have with the motor is when its in the water. when running on the trailer it runs fine - starting, idle, throttle response is good. when sitting in the water idle is irratic,stalls when going into gear and when accelelrating sometimes. im wondering if the float levels are out.the boat has a fair amount of bow-up when sitting.i have trimmed the motor out to try to level it but doesnt seem to help.

[Solarman]

Yes, float levels are possible problem, this is also part of carb rebuilding/cleaning. As I said, there are just a few things that control your motor running and idling, most is related to carbs not flowing fuel, or air properly. The rest is electrical, and it doesn't sound like this is a problem.

It may be fuel pump related, if fuel pump is bad, but with you telling me that you adjusted mixture screws, I'm thinking carbs are your problem, either dirty, or not set properly.

If using different fuel source, when in the water, that could also cause problems, if not good?

Post back when able, and let us know how it's going.

[Thedude77]

I'm having the same exact issue with my 86 dt140, did you ever figure out what the problem was?

[Solarman]

Dude, it is always better to start your own thread, identify your motor, then give us a good history of your specific problem. Reading other owners problems is good, but don't need to post that motor's historic info. It can help, but may interfere with diagnosing your motors problems.

I would suggest a good carb cleaning for all your jets, fuel and air passages, including needle valve seat, and resetting float levels properly, then reinstall the idle air-fuel mixture screws per the service manual, all 4 should be set identically, the manual only gives one setting.

Be careful, some older carbs have different jets from factory to balance those older motor's running, with respect to position of carb. Don't mix up any parts between carbs.

Start your own thread, and copy this response to it.

Good luck, post back on what you find out.