1986 DT 65 Throttle Valve Switch Question

[MOPMan]

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as not been used much since new. I cleaned carbs because it would run, but when attempting to go more than about 6 mph, the engine would die. Same results with quickly or slowly advancing the throttle. While removing the carbs for cleaning, I noticed a weak/severed connection of the black wire to the 'Throttle Valve Switch'. Could that broken black wire (ground wire?) cause the engine to only run at slow speed? There was a little dirt in the bottom of each of the bowls (like pepper) but they weren't gummed up as I anticipated. Good compression, all 3 at about 120 psi.

[Solarman]

Yes, that wire helps advance the timing when you advance the throttle. Do you have a suzuki service manual for your motor? That manual will tell you how to test that throttle valve position sensor. Or, repair the wire and test to see if that was the problem.

Good luck. Post back when able to let us know.

[MOPMan]

Thanks so much for your quick response. Yes I have the Suzuki service manual as well as a Clymer Suzuki outboard shop manual.

Part of my problem is knowing what the instructions mean. Since a more knowledgeable person had cleaned the carbs a couple years ago and had it running well, I figure the Throttle Valve adjustment was probably set OK. I do plan to test it to see if that was the problem since I was able to repair the connection by replacing the male end. I hope to get it out this evening or tomorrow and will let you know.

If fixing that black wire and cleaning the carbs doesn't fix it, my thinking is a possible problem with oil injection system since page 10 or the Owners Manual says: "When ...the outboard motor after letting it alone for long time of period, be sure to perform the procedure (air bleeding)..."

[Solarman]

If you think a problem exists in the oil injection system, do not run motor unless you mix oil and gas, until you know oil system is working. You do not need to bleed oil pump, just mark oil level at container on motor, then run oil and gas mix for a few hours. Once level in container is going down normally you can stop adding oil to fuel.

Good luck.

[MOPMan]

I did use oil & gas mix since it had been setting a long time. 'Glad I'm doing some things right!!

[MOPMan]

Fixing that black wire and cleaning the carbs fixed it. Now I think it just needs some 'fine tuning' because it still doesn't like to idle perfectly and it bogs down and would occasionally die when coming off idle. I gave the air idle jets another 1/4 turn in (to make them richer) when I got out of the water and plan to do a carb sync and check the linkage to see if that will fix this issue. Thanks for the help so far.

[Solarman]

First off don't change the linkages!
Your problem may still be carbs have something off, but did you use compressed air to blow-out the small fuel & air pas-sages? All of your carb air mixture screws are set identically, by the book. Also, on some of the older motors the jets are carb specific, meaning there might be different size jets between the top, middle, and bottom carbs. When cleaning carbs, all jets have to be removed and replaced in the proper carb after blowing each pas-sage clean. You do not need to remove any linkages, or change any linkages when cleaning carbs.

Post back when able to let us know what you did.

[MOPMan]

Normally I would agree with not changing the linkage, however a week ago an interested DNR guy offered to help at the ramp and he changed the throttle lever rod which goes between the throttle control lever and #2 carb. I just want to do some checking after cleaning the carbs. Yes, I cleaned the fuel and air passages with carb cleaner and air.

[Solarman]

If they weren't soaked well, then blown out with good compressed air, they may still be partially blocked? Same with the small holes in the jets. But if you're sure all pas-sages and jets are cleaned thoroughly, then set all carb mixture screws exactly the same, to what the manual calls for. To sync all carbs butterflies, back the one idle stop screw out just till butterflies bottom out in carb throat, with no throttle. Makes sure all carbs butterflies are identical, at zero opening. Adjust linkages so all are at rest with same setting (zero opening.), then adjust idle stop screw back to its previous adjustment. Once motor warms up readjust idle stop to proper idle.

Good luck.

[MOPMan]

I have done several motorcycle carbs so I think I have everything cleared and I did put the jets back into the same carb. I have learned my lesson of doing just one at a time - learned the HARD way.

[MOPMan]

It runs much better, but is not perfect. It is a rough transition from low speed to high speed, and will occasionally stall, even with slowly or quickly advancing the throttle.

I find no mention of an 'idle screw'. It appears that the 'Throttle Valve Switch' located on the #2 carb or the 'Idle Speed Adjustment' or the individual pilot air screws are the only way to control the idle speed..

I don't see any accelerator pump in the carbs to squirt additional fuel into the carbs when accelerating and wonder how it is to receive the additional fuel upon acceleration.

[Solarman]

That leads me to think, you did not soak carbs thoroughly, or you didn't blow through all the pas-sages and jets with good compressed air after soaking to clean carbs.
Your carbs operate by stages, low speed/idle, mid range, and high speed. Low speed is controlled by air- fuel idle mixture screws, and pas-sages. Additional pas-sages, for fuel open up for mid range. Then the high speed jet adds more fuel-air mix for wot. But that throttle position switch/sensor varies/advances the timing for each range the throttle is in.
Or, you could have a problem with your throttle position switch/sensor, it may not be advancing the timing system as needed.
Read the manual on your motor for testing that throttle position sensor.

Good luck.

[MOPMan]

Thanks Solarman. I'll keep working at it.

[Solarman]

Another thing you might check, the fuel pump, and if the check-valves in the lower section are still intact, if not, fragments commonly block fuel going into the float bowls on the back-side of the needle valve seat. You can not buy those check valves, have to buy a new pump, as i recall.

Good luck.

[MOPMan]

https://photos.google.com/share/AF1Q...pLVlFfNUhyNjZn This is a test run this morning. I wish there was a way to increase the idle speed other than the (timing) idle speed adjusting switch. I have the pilot air crews all a little rich. That drastically reduces the stalling when going from slow to high speed. Because they are rich, it idles rough. The fuel pump was replaced about two years ago and made no change. It has had this issue off and on since it was new. First 'fix' was under warranty work, but it returns all too often.