Suzuki DT55 limp mode? Low RPM's

[Big_worm81]

Hello I have a 1995 Suzuki DT55 outboard motor bought used strapped to a 15' RHIB. I've been using it a lot and its been running wonderfully ... Moves like a stung bear! Always premium fuel, never runs out of oil ... I was playing in some waves and came down hard on a few. Now it's running poorly. Running only on bottom cylinder. Can't get up on plane with more than 1 person on board. Tried swapping plugs around to no avail. Tried dumping fuel into my big boat and refilling RHIB with fresh fuel. No "Suzuki alarms" from gauge cluster ... Lots of water from exhaust ... It's being limited by something I'm sure. I just bought a tube and skis and have friends arriving tomorrow. Any ideas? Let me know if I left out any details.

 

[mphelle8vld]

Re: Suzuki DT55 limp mode? Low RPM's

You may have stirred up some debris in the fuel bowls and have clogged jets, if so, you risk damaging the motor by running lean. Not sure how you determined it was running on one cylinder but don't pull plug wires while running, it can damage the CDI. Do you have a tach?

 

[Big_worm81]

Re: Suzuki DT55 limp mode? Low RPM's

I do have a a tach installed in the boat. I determined that it was running on one cylinder by pulling the plug wires off the top spark plugs and starting the engine. There is only a difference when I attempt to start with the bottom wire pulled .. It won't start. If I am in the boat by myself I can get on plane ..... When I cross someone's wake it seems like the other two cylinders come online in rhythm with the waves .... The fuel tank is external and clean with fresh fuel ... Even before this issue. Thank you for any help you can offer.

 

[mphelle8vld]

Re: Suzuki DT55 limp mode? Low RPM's

Have you ever cleaned the carbs? I would pull the plugs and see if any cylinders are running lean. What rpm are you turning at WOT?

 

[Big_worm81]

Re: Suzuki DT55 limp mode? Low RPM's

I haven't cleaned the carbs, and unfortunately I'm not in a situation to clean them at the moment, the boat is in the water moored along side my 33 footer in the middle of my holidays.. When the boat was running good I would get about 5300 RPM with 4 big guys on board ... And just hauling a s s ... It was awesome. Now with just me on board I'm lucky to break 5k if I can even get on plane. I'm curious what people think about the engine trying to power up when I cross other people's waves ... Is there a fuel or water float switch is these engines or anything?

By pulling the plungs to check if any cylinders are running lean ... I should check for plugs fouled with oil?

 

[mphelle8vld]

Re: Suzuki DT55 limp mode? Low RPM's

If you can get on plane at 5k, you are running on all 3 cylinders, I just think that one or more aren't getting enough fuel.

 

[mphelle8vld]

Re: Suzuki DT55 limp mode? Low RPM's

Just saw your edit, if the cylinder is running lean, the plug will be white and dry. It should be medium brown and oily.

 

[Big_worm81]

Re: Suzuki DT55 limp mode? Low RPM's

Okay so I did check the plugs earlier today when I was swapping them around. All three were brown.

 

[Big_worm81]

Re: Suzuki DT55 limp mode? Low RPM's

Okay so I should clean the carbs before I get too excited. That seems like quite the task with all those linkages in there connecting everything together. What a mess.

 

[mphelle8vld]

Re: Suzuki DT55 limp mode? Low RPM's

Good to hear,

All safeguards on that motor would limit the rpms to 3000, since it is running at 5k but with reduced power, I have to think it is not getting enough fuel. As you said it would be hard to address the carbs now.

 

[Big_worm81]

Re: Suzuki DT55 limp mode? Low RPM's

I will go back out tomorrow and take her for a run by myself to be sure it ill do more than 3k RPM's ... With the wife/kids/beer/food on board today it wouldn't exceed 2800-3000 RPM's

 

[mphelle8vld]

Re: Suzuki DT55 limp mode? Low RPM's

If you find yourself at 3k check the monitor gauge.

 

[Big_worm81]

Re: Suzuki DT55 limp mode? Low RPM's

I was out this morning and managed to get it over 4,000 RPM ... Just out of curiosity, where is the monitor gauge?

 

[mphelle8vld]

Re: Suzuki DT55 limp mode? Low RPM's

Should be mounted near your controls, don't have a picture but you can google DT55 monitor gauge. It's not in limp mode if you're over 3k.

Would look like this http://www.ebay.com/itm/TRACKER-347...ar&hash=item2ec2ac4efc&vxp=mtr#ht_3233wt_1189

 

[Big_worm81]

Re: Suzuki DT55 limp mode? Low RPM's

Ah, yes ... Duh ... The gauge. Haha, okay I can check that. Well the boats out of the water now and at home. On the way back to the dock I had 3 guys in it and we got on plane by walking to the bow, achieved about 4,000+ RPM, then after about 5-6 minutes it died out, dropped off plane and wouldn't go above 2,400 RPM. I changed plugs with no improvement. A friend who has a ton of snow mobile experience says I should switch to synthetic injection oil and it will solve my problems. I'm using the same oil the previous owner used for 18 years ... So I doubt that is the issue.

 

[mphelle8vld]

Re: Suzuki DT55 limp mode? Low RPM's

I would do a compression test first, should have around 120psi in each cylinder, and then rebuild the carbs.

 

[deejaycee_2000]

Re: Suzuki DT55 limp mode? Low RPM's

Changing your oil won't make a difference, do a compression test and let us know the results ...

 

[Big_worm81]

Re: Suzuki DT55 limp mode? Low RPM's

Hi folks,

I finally got around to doing a compression test. 116 PSI in top and bottom cylinders, 15 PSI in middle cylinder. I'm thinking broken ring. If it was a hole in the piston there would be 0 PSI, no? Thanks for your insight, no water skiing for me this weekend.

 

[jackd1023]

Re: Suzuki DT55 limp mode? Low RPM's

sounds like you ran middle lean, time for a rebuild or find a powerhead . before you reinstall the carbs rebuild them!!!! chances are the center carb is clogged letting it run on 2 instead of 3. center piston got hot due to no lube and kaaapow.

 

[mphelle8vld]

Re: Suzuki DT55 limp mode? Low RPM's

Bummer.. At least it died honorably, toasting a piston while jumping waves. If you pull it apart you will most likely find aluminum smeared across the rings near the exhaust port. You have provided a cautionary tale regarding maintainance, I clean the carbs and inspect the reeds each winter, only takes a couple hours. Let us know what you end up doing with it.