dt75protection mode?

[lake erie fishrman]

My 1989 Suzuki motor will start no problem but will go above approximately 1800 rpm no matter how long it idles. I have been told there is a protection mode on these engines but I am not sure how to move beyond it. Any ideas.

[Solarman]

If you could give a little more than the year '89, dt75, and that it won't go over 1800 rpms, but idles ok. Then possibly those of us on this side of the computer screen, might have a better chance to help solve your problem.

A brief history on the motor (how long it's been acting like this, did anything happen at same time it stopped running at wot?). What has been tried in repairing this problem (parts repaired/ replaced, carbs cleaned properly, plugs, fuel pumps checked, etc.)?

Do you have a suzuki service manual for this motor? This manual has tests for items, sensors, coils, that need to be checked.

Post back when able, and let us know these things to help you get some answers.

[lake erie fishrman]

Dt 75

I bought engine last year. It was running fine with rpm. Took it to a local marina for tuneup and check over and when it reurned it would not go over 1800 r.p.m.. I was told that there are two inlets for water cooling and if they did not mask or submerses both it goes into a protection mode with the outcome of not letting it go over ths limit. The water pump is relatively new with very little use but another marina said they woul replace that first and then keep checking. Wanted to get ideas around this protection mode and if there is something we need to do to do to bring it back to normal operation.

[Solarman]

Is the motor overheating when it goes over 1800 rpms? Does overheat alarm turn on when you go to 1800 rpms?
What parts did the marina use in the tune up? Does the tell-tale stream start spitting and turn to steam at the higher rpms?

Post back, and let us know.

[lake erie fishrman]

DT 75 H.P Suzuki

Thanks for your help. no alarm, they replaced spark plugs and did tune up. There is a constant stream of water but not very strong, no steam. When it starts the red light comes on but after it warms up it goes off.

[Solarman]

If the alarm turns on when it starts (red light is an alarm), and the tell-tale is weak, there might be a problem with the impeller (water pump), temp or flow sensor (reading low flow, or too warm at start up? Model specific). Might be bad sensor? Might be time for thermostat to be replaced?
It is also possible the motor has restricted water pas-sages (may need to be flushed)?

There could be multiple problems. However, if a mechanic does a tune up on a boat, and all he does is replace plugs, then he really hasn't done anything?

A competent mech would inspect/clean/replace fuel filters, (fuel lines if old/ bad), replace impeller, gearcase oil, plugs, methodically/carefully disassemble carbs (if needed) for cleaning, then properly reassemble and set them. Plus if any alarms are still indicating a problem, start testing the appropriate sensors related to those problems.

Sorry, to me these things are all part of a tune-up, and not everyone (marina mechanics, incl.), follow these/ similar guide lines. I think you need a competent mechanic, if you plan to pay someone.

Good luck, post back when able to let us know how it's going.