DT55 Low RPM

[biffwillingham]

I have a mid 80's DT55 on a pontoon. The engine revs to limit out of gear. Put in gear and at full throttle RPM only goes to 2000 and runs smooth.
There are no alarms/buzzers, oil tank is full, water fine out of tell-tale hole. Carbs rebuilt along with fuel pump. New spark plugs. Any ideas?

[mphelle8vld]

What's the model/serial number? Put an inductive timing light on one plug wire at a time to make sure you have spark to all cylinders.

[biffwillingham]

It is a 86 model VG DT55

[mphelle8vld]

While you have the timing light out, make sure the timing is advancing with engine speed on number one. You should have max timing of 25BTDC at around 2800rpm.

[biffwillingham]

Dt55

Timing light shows on all cylinders. Timing advancing. Something noted today was in neutral and reverse engine revs freely to 4000+ rpm. Put it in forward and goes to 2000 rpm only. What gives?

[mphelle8vld]

Timing light shows on all cylinders. Timing advancing. Something noted today was in neutral and reverse engine revs freely to 4000+ rpm. Put it in forward and goes to 2000 rpm only. What gives?

Is this in the water under load, or muffs? What was the timing at 2000? With the motor off, pull the intake cover and make sure the throttle butterflys are fully opening with the controls.

[biffwillingham]

DT55 low rpm

In water under load. Timing around 20. Butterflys fully open.

[mphelle8vld]

Strange that it is able to spin reverse under load but only 2k in forward. Is it shifting normally, smacked anything recently? What was going on when the problem first started?

[biffwillingham]

DT55 low rpm

Have not smacked anything. Problem started as alarm for low water due to failed water flow switch. Replaced switch and impeller. Now have good stream and switch works as designed. No alarms and low rpm. Frustrating...............

[mphelle8vld]

When you got the water alarm, was the rpm limited to 2k?

[biffwillingham]

DT55 low rpm

Yes. RPM limited at alarm episode. Cannot find out from service manual or persons how to reset or repair. Only reset I can find is low oil alarm and it does not clear the low RPM issue.

[mphelle8vld]

While it's called the "low oil warning reset unit", it actually handles all three warning systems, low water flow, low oil, and overspeed. If you are confident that the cooling system is functioning correctly and you have plenty of oil in the tank, temporarily disconnect the four wire connector from the reset unit to the CDI. If the motor now revs normally the reset unit has failed and needs to be replaced. Let me know what you find.

http://www.ebay.com/itm/86-SUZUKI-DT...r#ht_288wt_789

[biffwillingham]

DT55 low rpm

The reset button on my motor is only 2 wire and it is located on the left side facing forward and just below the upper cowl lower edge. I have check it with a OHM meter and it is functioning normally. I have tried depressing it static and while the engine is running.

[mphelle8vld]

My last post had nothing to do with the reset button.