Susuki DT55 Low water pressure

oaseeker · 17 July 2009, 11:35

Mt DT55 had low water pressure & a weak tell-tale. I replaced my water pump impeller. The clutch shaft jumped out of place so I had to pay to have the crank case opened and the shaft put back. The propeller shaft housing was frozen and had to be replaced. I just got the boat back and 300.00 later, I still have the same problem. What else can it be.
This all started when I last took her out and she couldn't get on a plane. I can't get up enough speed.

David G · 17 July 2009, 11:43

If you mean the engine is in rev-limit because of apparent low water pressure but idles ok then I would check the waterflow float switch.
I had a problem with one on a DT85 which actually made the whole multifunction display unit stop working for some reason!!!
Orve

Steve.N · 20 July 2009, 22:28

I have exactly the same motor and same problem.

The motor would be ok for a while then cut back to 4000rpm (some sort of guardian mode I assume!).
I replaced the impellor the other week and then found the Tell-tale pipe was completely blocked - I unblocked the pipe and cleaned though all the water passages I could access, I was sure the issue was fixed so took her out for a run - she worked fine at first with a strong tell-tale but after 1hr or so she did the usual and cut back to 4000rpm (tell tale dissapeared after 10mins or so).
In frustration I took her into a so called Marine Engineer, it cost €200 to be told that she's fine, they only found some gunge in the oil flow sensor.
I replaced this yesterday (just incase), but I'm convinced it's a water flow problem. Why is my tell tale clogging with crap all the time?

Good idea about the water float sensor - how easy is it to access and fix?

Any help would be much appreciated as it's now driving me mad!

David G · 22 July 2009, 15:46

Mine happened on a DT85 and the sensor is easily accessible on the top/back of the powerhead near the spark plugs.

What actual alarm sounds on the multifunction display? If the oil then it could well be a gunked up oil-flow sensor..........

Best of Luck anyway.

Orve.

Downhilldai · 22 July 2009, 23:22

Quote:

Originally Posted by Steve.N

....The motor would be ok for a while then cut back to 4000rpm...
...after 1hr or so she did the usual and cut back to 4000rpm (tell tale dissapeared after 10mins or so).
.... they only found some gunge in the oil flow sensor.
I replaced this yesterday (just incase), but I'm convinced it's a water flow problem.

It could be oil flow, oil level, water level, water temp, or exceeding max RPM

Quote:

Originally Posted by Steve.N

Why is my tell tale clogging with crap all the time?

Soozooks are notorious for blocking tell tales. It is only a tell tale though and won't in itself switch the motor into guardian mode if it's blocked. The float switch in the cylinder head does this.

Quote:

Originally Posted by Steve.N

Good idea about the water float sensor - how easy is it to access and fix?

Two screws and an electrical plug. When you take it out, check inside the water jacket for any salty deposits.

As Orville asked, which warning light(s) shows on the monitor gauge when it goes into guardian mode?

Steve.N · 23 July 2009, 17:12

I know oaseeker mentioned at the start of the thread that he had an alarm but I don't get any, the engine just cuts back to 4000rpm out of the blue - no warnings, buzzers or anything.

I'm very careful not to over-rev the motor - She's always kept between the 5000-5500rpm (peak power-band), the last twice she cut back to guardian mode was when I had been at displacement speed for a while before powering up to cruising speed - she would power-up then cut back after approx 30secs - Very strange I thought??

Salt deposits makes sense as the previous owner used her on saltwater only, but he assured me she was flushed after each use - going buy the condition of the rib and motor I'd say he wasn't lying. Would deposits still build up through time even if he was flushing it with the muffs??

Would salt deposits around the thermostat cause any of these problems?

Downhilldai · 23 July 2009, 18:05

Do your warning lights and buzzer come on when you first switch on the ignition, before starting the motor?

Steve.N · 24 July 2009, 08:43

The buzzer doesn't come on, but the warning lights do before the motor starts up - they go out as normal when the engine starts.

They all work though as I tested them a few weeks ago.

Downhilldai · 24 July 2009, 10:04

Sounds like your buzzer's defective, as this should come on when any of the warning lights are triggered.

If all the warning systems and lights are working ok, then something else must be causing it to go into guardian mode. It doesn't appear to be over-rev and you've already looked at the oil flow, so I'd be looking at the oil level and water temp/float switches. These should in any case trigger the warning light.

Has the motor always done this, or has it happened since something has been changed or altered?

ribdraft · 24 July 2009, 17:28

glad to know i'm not alone??

Steve.N · 25 July 2009, 11:01

I assume my buzzer seems ok as it went off the other week when I had the motor running on the muffs (was flushing it out and had it on for around a minute when the alarm went off - Switched it off immediately).

We bought the boat last year and we had a few trips out before this problem cropped up - I'm not too sure if this was an underlying issue when I bought it.

I'm going out now to check/clean the float sensor and remove the thermostat and check there's no build up of salt deposits etc.
I'm just hoping I find something - I'll keep you informed!

Steve.N · 28 July 2009, 00:17

I started by removing the thermostat - it was completely choked up with salt deposits. After removing and cleaning it I verified that it worked ok, which it did.
I removed and checked the overheat sensor - worked OK
I couldn't find the float switch (As my Suzuki Manual states it's a 'Start-Up Ignition Timing Sensor') but after checking on-line found that this was infact the Float Sensor. When removing it, I started to pull it out when it broke (I used a tiny amount of pressure but it just cracked).
It seemed to be very brittle (well I suppose after 9yrs of salt water passing around it what can you expect).
I ordered the part this afternoon.

I'lll keep you posted after the part arrives to whether or not this fixed the issue.

Thanks for the advice!
Steve.

Steve.N · 04 August 2009, 14:49

The new Water Float Switch arrived today - This raises another issue that I'm hoping that you can give me some advice on.
My old switch definitely was defective as a part of it was missing

. There's a fixed part of the sensor and a paddle bit that must detect the water flow - the paddle bit was missing when I took the old sensor from the engine.
Where could it be?? It's a fair chunk of plastic.
When I initially changed the impeller I did check for any obstructions in the water passages of the lower leg and could see nothing - so where could it be??
Surely the water passages around the engine are too small for a 1' x 0.5' piece of plastic to get lodged??????

Downhilldai · 05 August 2009, 23:42

Quote:

Originally Posted by Steve.N

Where could it be??

Hang on, I'll have a look.....

Steve.N · 06 August 2009, 16:25

This engine is now giving me a pain in the nuts!!!!

After checking all the water passages yesterday, I replaced the water flow senor and took the boat out today around Howth (Dublin).
She ran great, even in pretty choppy weather - cruising at 35kmph. We ran around for approx 2hrs - We went up the coast then back with no issues. UNTIL we went into Malahide Marina for a nosey at all the boats. We cruised around at between displacement speed to approx 2,500rpm. We came out and powered up to cruising speed - after 20-30secs the engine cut back to 4,500prm and would not rev anymore (there were no warning lights or buzzers).
I turned for Howth harbour and she cruised back at 4,500rpm doing approx 28kmph - it took 10mins to get back to the harbour.
The engine ran at this 4,500rpm for 10mins without missing a beat but wouldn't rev into it's power band of 5000-5500rpm.
When the throttle was pushed forward it did nothing.

To Date I've changed - Fuel filter, plugs, Oil flow sensor, Water flow sensor and Checked functionality of Thermostat and overheat sensor.
I've checked all wiring on motor, and added a water/fuel separator filter.

This is the same issue I've had since the start - Where do I go from now??? PLEASE HELP.

ribdraft · 06 August 2009, 18:29

i know., get 1 drum of petrol,pour it over the engine ,then add match standin well clear of course, watch your troubles melt away, needless to say im not having much luck either, thinkin of followin this procedure my self

Steve.N · 06 August 2009, 22:05

Quote:

Originally Posted by ribdraft

i know., get 1 drum of petrol,pour it over the engine ,then add match standin well clear of course, watch your troubles melt away, needless to say im not having much luck either, thinkin of followin this procedure my self

Yeah I know the feeling!! For something so simple it seems so hard to diagnose this problem.
Not sure what's going on with it!! Thinking of taking the carbs off and checking them - grasping at straws now!!

David G · 10 August 2009, 07:38

Not sure if it is the same on the DT55 but on the DT85 there is a rotating plastic throttle position sensor that links the physical, mechanical position of the throttle to the electronic timing of the ignition.

This can get stuck and could need cleaning out and worn burrs removed.

It may be that the period of time pootling allowed the area to warm up a bit and then become a little sticky when you went out again after.

On the DT85 this was positioned on the left side as you stood behind the boat looking in just before the carbs.

Failing that I've had quite a lot of good advice from here:
http://www.themarinedoctor.com/cgi-bin/YaBB.pl

Orve

Steve.N · 11 August 2009, 05:39

Quote:

Originally Posted by Orville

Not sure if it is the same on the DT55 but on the DT85 there is a rotating plastic throttle position sensor that links the physical, mechanical position of the throttle to the electronic timing of the ignition.

This can get stuck and could need cleaning out and worn burrs removed.

It may be that the period of time pootling allowed the area to warm up a bit and then become a little sticky when you went out again after.

On the DT85 this was positioned on the left side as you stood behind the boat looking in just before the carbs.

Failing that I've had quite a lot of good advice from here:
http://www.themarinedoctor.com/cgi-bin/YaBB.pl

Orve

I was reading the manual last-night (that's how obsessed I'm becoming reading a service manual in bed) and was planning on checking the Throttle Position sensor next. I've just asked the Marine Doctor for his advice - Fingers crossed that I can get closure on this!!
Oh, just incase anyone is following this saga to solve their own problem - I also hi-jacked another thread (Power loss... - Sorry Blackroady!!), there's more advice there.
Made a few adjustments yesterday (see the Powerloss thread), so will take her out on Wednesday for another test-run.

Thanks everyone for their input so-far, this has been the best learning curve to learn about the workings of an outboard - But I want the curve to end now