DT/tclh 140 won't Idle

[bartow buddy]

I have a 1987 DT/tclh 140 140002 s/n 710141 It cranks and runs at high idle for 10 to 15 seconds then starts to skip but if you throttle up some it will run good untill you start to stop or you pull it back to neutral then it dies. Just won't run less than 4 mph.. Carbs. have been vatted and blown out. The oil pump has been removed and gas is mixed at 50 to 1 ratio. has new plugs. I have noticed that sometimes the tach. stops and sometimes it jumps un and down 2 or 3 hundred rps. where do I look first? Is there a possibility that a low oil sensor or an oil flow sensor could caues this? the pump tank and lines and drive gears have been removed but I'm not sure if there is something that was missed.

[BillCon]

That can have a lot of causes, for the beginning lets check the trolling speed switch to see if its not stuck on the lowest setting use the manual to ohm check its settings, sounds like when its dropping off the warm up circuit down to the trolling switch its dropping it to far, also try bumping up the idle speed screw to see it that has an effect, one more thing the carbs are running on the fuel idle screw settings find out where they are set and if off reset them to the correct start up turns in the manual, let us know what you find out and we can take you from there to check the next things such as gear counting coil and ignition system, you are our eyes and ears.

[bartow buddy]

That can have a lot of causes, for the beginning lets check the trolling speed switch to see if its not stuck on the lowest setting use the manual to ohm check its settings, sounds like when its dropping off the warm up circuit down to the trolling switch its dropping it to far, also try bumping up the idle speed screw to see it that has an effect, one more thing the carbs are running on the fuel idle screw settings find out where they are set and if off reset them to the correct start up turns in the manual, let us know what you find out and we can take you from there to check the next things such as gear counting coil and ignition system, you are our eyes and ears.

#1 I have tried the trolling speed switch to all the positions and no change. #2 The idle screw only helps if it is set to high and it idles at 4 mph. #3 by idle screw are you talking about the air adjustment screw if so I have tried from3/4 turn to 2and 1/2 turns. I have a Seloc manual now but should have the suzuki manual here today and will let you know what i see. #4 would the oil system being removed cause this problem? Thanks

[BillCon]

Ok, lets go back to the trolling speed switch for a minute it should be changing you rpms by about 50 even at 4mph, there is a checking procedure in the manual for that, pretty simple, also low float levels can cause the problem at idle speeds,and fuel pumps that may need looking into, but I'm sure that was checked when the carbs were cleaned up and reset hopefully, now go into the electrical section of the manual and follow it step by step in checking all the coils under the flywheel, you will find the culprit its just going to take a little time to hunt in down, you have to find out which system is causing the fault, most likely is a simple fix, I, always suspect the fuel systems first then work your way thru the electrical systems, let us know what you find in testing the coils

[BillCon]

Also I, doubt the dissconected oil system sensors could cause that at idle, your either loosing fuel supply or spark control, be carefull running the premix fuel as you can run slightly lean, the oil injection system is calibrated to change the oil ratio up and down as the motor demands

[bartow buddy]

The suzuki manual didn't come today so I'll have to wait and check the coils tomorrow. I have noticed that the last 3 or four times I tool it out that when I get it back home I take the plugs out and check to see if they are fouled but they are clean but very wet even to the point of dripping gas off them. and the plug wires are stiff and the second down from top has sparks jumping from the wire at times not sure at higher speeds but on the muffs at fast idle after the stepdown period and that is when it sounds like it is missing and dies. Thanks again for your help. Ellis

[Moonlighter]

Sparks jumping from the plug leads = bad.

First job: put a new set of leads on. That will deal with one clearly known problem.

Then move onto next issue, which seems to be fuel/carb related.

But replace the plug leads first!

[Solarman]

dt140, running problems

Fix the plug wires first. It might not sound like it's missing at higher RPMs, but most probably is dropping cylinder completely. The higher RPMs at start is normal for 10 - 15 seconds.
The oil system is an integrated part of the ecm, and yes, it can affect running of system detects problems.
Keep us posted on what's happening.

[bartow buddy]

I will fix the plug wires tomorrow and report back. Got the suzuki manual today and it look like it has more detail and don't have all the other size engines to confuse an old man. I sure thank all of you for your help and support. had to take the wife on a leaf tour today it is still beautiful here in north Ga. Again thanks for all your help and Input. Ellis

[bartow buddy]

Took the coils off today and can't get the plug wires out of them are they supposed to come out or do I have to replace the coils as well. Thanks

[Solarman]

dt140EFI, running problems

You only need to replace the coil(s) if wire is sparking, or shorting out, or dry rotted. As far as I know, the coil wires are part of the coil. I don't believe you can replace just the wire(s).

[bartow buddy]

The new suzuki manual doesn't say but the wires come out on merc. and omc. engines I'm wondering if these were installed with silicone or super glue the rubber was stiff and cracked on that one wire. so I tried to pull it out and broke it off but I got the rest out and it looks as if it is replaceable will let you know. Thank all 0f you very much for you patience and time.

[Solarman]

dt140EFI, running issues

Glad to hear. I have twin dt140's, and if ever have a problem with my plug wires, ill try the same.
Good luck and keep us posted on how it runs after the repair.

[bartow buddy]

The weather was so cold here yesterday and today that I didn't get to work on my problem but I plan to get back on it tomorrow if The Lord is willing. other than the #2 coil I'm going to check the wiring for the Tach. and inside the elec. box and hope to get the flywheel pulled off and inspect the coils and wires there. sure hope to have a good report for all you folks that have helped.

[Solarman]

Ellis, my thinking is, fix the coil wire and fire back up to see if running well. If that was all that was wrong, possibly going farther might create other problems. Not saying you will cause another problem, but checking to see how much this fix cures, we may find if you have a secondary problem. If so, then we focus on those signs.
Good luck, it has been cold here in the south easy also. Looking forward to the 70's ths next week. Let us know how it runs.