Suzuki 25 Oil Injection - low power and Alarm Buzzer

al40 · Aug 22, 2005

I have a '94 Suzuki 25 oil injection electric start. Got it on a boat which I purchased last week. The engine had not been used for a while but previous owner had been regularly turning it over, injecting oil into cylinders etc. When I took the boat away, engine was running pretty roughly (wouldn't idle and not much power) - Oil injection reservoir level was dropping so injection system is working. 2 problems: (1) Lack of power - feels like fuel starvation. I am assuming the carbs need a good clean out (I already replaced plugs). Sometimes it runs well - lots of power - but takes a while to get there (2) an alarm of some description came on just before I stopped engine (had been running for an hour or so). It seems to be cooling OK (cooling water coming out OK) and there is still oil in reservoir. Does anyone know if this engine has both temp and oil level sensors? I am still trying to source a workshop manual / users guide. Also, is the oil injection fixed in these models or can it vary it depending on load etc? Thanks. Al.

bossee · Aug 22, 2005

Re: Suzuki 25 Oil Injection - low power and Alarm Buzzer

Hi, What boat do you have this outboard on? (make and model, ft and weight) Is it a planing boat? Problem 1: If the outboard has been sitting for long time with fuel in carburators you probably need to clean them. It would not hurt to buy 3 carburator kits and install when You are working on the carbs. Also check the float in each carburator is OK and mounted in correct height according to specification. When You press the fuel bulb, does it get hard? Make sure it hard. Also make sure there is no fuel delivery problem from tank (including inside tank and tank vent), fuel connectors, fuel lines, filters. The fuel pump has a rubber diaphragm set that will not work forever. Replace that rubber if any doubt. Also, the plugs should be NGK BR7HS-10 with gap 0.35-0.39 inch /0.9-1.0 millimeter. Problem 2: If You have a Suzuki monitor guage with a) Temp lamp, b)Rev limit lamp, c) Oil lamp, d) Check engine lamp and e) Oil level (4 bars) lamp, then You should have a oil level sensor in the oil tank. The Suzuki Monitor guage (or oil level indicator) could be an optional thing on DT25. But it should be a Cooling water and Oil warning buzzer in the remote control box at least even if you do not have the Suzuki Monitor guage. So Yes, You have both a temp (overheat sensor) and a oil level sensor. Oil alarm can go on if oil level too low. Do You have a tachometer by the way? Orginal Suzuki Owners manual and Suzuki Shop manual for Your DT25 should be avaliable at brownspoint.com The oil injection system is variable so at idle it is 150:1 (fuel

il) and at full throttle (WOT) it is 50:1. That is why it is always best to use the oil injection system and not disable it. If it is diabled and mixing oil (2%, 50:1) in gas tank you get little to much oil at lower RPM. The Oil injection system is rather reliable on Suzuki outboards as far as I know. I had a Suzuki (DT65, 1991) myself until 2003 when it was sold with my old boat. I use Yamaha F115 4-stroke now and a new boat. /Bo

al40 · Aug 22, 2005

Re: Suzuki 25 Oil Injection - low power and Alarm Buzzer

Hi Bo, Thanks for your response. It's a 4m Searider (RIB) so yes, it's a planing hull. When engine decided to work properly, boat was planing nicely with 3 people in boat. When it was lacking power, it was not managing to get on the plane, even with just 1 in the boat! (1) When bulb is pumped, it does go hard (not so hard that you can't squeeze it, but there is a fair amount of resistance). I did wonder about the vents in fuel tank and tried opening the lid slightly but it didn't seem to make much difference. When the engine is in "low power" mode, pumping the bulb when engine was running did not seem to help. I'll strip down the carbs etc. I'm fairly happy getting my hands dirty (and have frequently cleaned my Merc 4 carb) - are there any pitfalls in doing this - should it be attempted before I find a service manual? The plugs that were in the engine were NGK B7HS. I replaced them with BR7HS. What does the -10 signify? (2) I don't have any engine instruments whatsoever. I couldn't tell for sure, but I think the beeping was coming from the engine itself and not the control box (but it's hard to tell exactly as I was in the process of docking the boat before quickly turning off the motor). Should any alarms activate before the engine is started because this doesn't happen on my engine. Thanks.

bossee · Aug 23, 2005

Re: Suzuki 25 Oil Injection - low power and Alarm Buzzer

Hi, (1) A carburator is not that complicated. I do not think You need a Service (Shop) manual to be able to clean the carburators. Cleaning all metal parts in carburator cleaner and use compressed air (from compressor or spray can with air). You need to know how much idle airscrew should be turned out (for DT25 1994 I belive it is 1 1/2 - 2 turns out). You must also know so You can check bowl height (for DT25 1994 it should be 0.47-0.55 inch, measured from float bowl mating surface with gasket removed to buttom of float). Idle speed adjustment: Varm up engine for 5-10 min. Adjust the idle air screw. Shift into forward (in water) and make sure idle rpm is enough so it does not stop at least(specification is for DT25 600-650 rpm when You have a tachometer). If needed, adjust with throttle stop screw. It is best if you at the same time as You clean the carburators install carburator repair kit for each carburator (new gaskets, new needle valve+seat) since they will wear out sooner or later. The NGK spark plugs numbering system: Link (-10 means it is has a gap of 1.0 mm from factory I belive). (2) If oil level in oil tank is too low it should be alarm before you start the engine if the ignition is on so the oil level indicator can signal a low level and buzzer go on. I do not know the exact level in oil tank when the low oil warning buzzer should go on but I would expect when about 1 liter or so is left perhaps (at least I belive that was the case for DT65 1991 I had before). It will be mentioned in Owners manual for DT25 if You buy that. Just have the oil tank filled up enough so the low oil alarm does not goes on. Normally the buzzer is located in the control box. Check at brownspoint.com and Parts Look-Up, DT25, 1994, and the Remote control box where the buzzer is located. /Bo

al40 · Aug 23, 2005

Re: Suzuki 25 Oil Injection - low power and Alarm Buzzer

Bo, Thanks for your great suggestions. I will remove carbs from boat next time I am down and let you know how I get on. Thanks, al.

bossee · Aug 23, 2005

Re: Suzuki 25 Oil Injection - low power and Alarm Buzzer

Hi, Since You have no tachometer you will not know if you have correct prop so You have at WOT (wide open trottle) about 5500 RPM (that is max upper recommended RPM range and what You should aim at). But you could buy a Tiny Tach, does not cost much. That way you will have a chance to have the outboard to use optimal RPM at WOT with suitable prop. Rule of thumb: 1 inch change in pitch change RPM about 150-200. Standard prop shipped with a DT25 C 1989-1996 was a 10 1/4 x 12, marked P1201, I belive. Other possible orginal Suzuki props could be 10 1/4 x 10 (P1001) and 10 1/4 x 11 (P1101). Tiny Tach: Link I belive there is a reseller in UK.

al40 · Aug 24, 2005

Re: Suzuki 25 Oil Injection - low power and Alarm Buzzer

Since I am in the process of cleaning the carbs, I thought I would also check the throttle posn sensor. It appears this is not a simple POT as resitance over the terminals is 100K (approx 50K each side to ground) but it does not change when throttle is moved. Can anyone tell me if I can check the sensor easily or if it's some form of electronic (hall effect?) device. (I am still waiting for my service manual!) If the sensor is not working, does the engine flag this as an error? Thanks.

bossee · Aug 24, 2005

Re: Suzuki 25 Oil Injection - low power and Alarm Buzzer

Hi, Throttle Valve Sensor adjustment on DT25, 1989-on: Back out idle speed screw so throttle valves are completely closed (on models after 1990). Throttle valves must be fully closed for proper adjustment. Use only a non magnetic insulated screwdriver to adjust. Throttle sensor voltage at closed throttle should be 0.45-0.55 volt. If not within specification turn clockwise to increase voltage, counterclockwise to decrease voltage. Advance throttle to wide open. Sensor voltage should be 2.7 volt or more (not adjustable). If not 2.7 volt or more replace throttle sensor. To the best of my knowledge You do not get any warning in buzzer if a TVS is defect on smaller Suzuki outboards (maybe You get a buzzer on warning and if You have the Suzuki monitor guage it could light "Check engine" warning lamp also). On DT115, DT140, DT150, DT200 and DT225 there is for sure a flashing mode in Check engine lamp for Throttle Valve Sensor failure. B/R=Black/Red B=Black Lg/R=Light green/Red Battery minimum 9 volt

al40 · Aug 25, 2005

Re: Suzuki 25 Oil Injection - low power and Alarm Buzzer

Hi, Thanks for all your help in carb questions. O/B is now working great, running better than ever. However, the alarm situation has got worse and I think there is a fault somewhere in the system. When I turned on the ignition this evening, the alarm sounded straight away with the oil reservoir pretty much full and obviously engine was cold (so can't be temp related). I disconnected the oil level sensor but it didn't make any difference. Alarm seems to pulse until engine is started then it sounds continually. The LED on front of engine is not lit. Oil injection is obviously working as there is smoke and engine ran fine for a good while. Any clues as to how to go about diagnosing this? Sounder is indeed in control box. Many Thanks. Al

bossee · Aug 25, 2005

Re: Suzuki 25 Oil Injection - low power and Alarm Buzzer

In general: check all electrical harness for opens or shorts. Also check in controlbox so no problem there with the electrical wires or the buzzer itself. Problem with Oil flow sensor (if DT25 has that)? It should be located near the buttom of oil tank inline with the oil feed house. Check sensor and its electrical harness if there is such sensor on your DT25. Problem with overheat sensor? Did the Trottle Valve Sensor pass the volt test? Basically You must test the sensors that can start an alarm/buzzer and its wiring harness so You know if the sensors work and not give false alarm. And also inside the control box where the buzzer is located. Oil and overheat alarm warning systems: Link 1 Link 2 Wiring (poor image quality, use zoom in tool in Acrobat Reader): Link 3

al40 · Aug 27, 2005

Re: Suzuki 25 Oil Injection - low power and Alarm Buzzer

Thanks for info. I will check this soon. The throttle posn sensor was different to the diagram in that there were only 2 wires in the plug instead of 3 so I didn't want to put 12v into it incase I damaged the sensor. Engine seems to be revving OK so, looking at the diagnostics charts, it looks like the critcal sensors must be working OK (oil level and flow) since engine rev's are not being cut. Thanks.

al40 · Aug 27, 2005

Re: Suzuki 25 Oil Injection - low power and Alarm Buzzer

Just back from a quick diagnostic. Unforunately I forgot my meter so couldn't check operation of the oil level switch. Engine does indeed have an oil flow switch. When ignition is turned on, the buzzer sounds for 2 seconds, then off for betweem 6-7 seconds, then repeats. This is VERY repeatable so I do not believe this is caused by a short or it would be intermittent. Does anyone know what the diagnostoic code for this is? I assume ECU is indicating which sensor is faulty. When engine is started, the buzzer then sounds continuously but there is no lack of power (ie it is not being rev limited to 3000). The OIL LED on the engine does not illuminate. I tried disconnecting oil level, oil flow and throttle posn sensors but it still did same thing (if one of these was faulty, disconnecting it wouldn't help anyway I guess). Thanks.

bossee · Aug 28, 2005

Re: Suzuki 25 Oil Injection - low power and Alarm Buzzer

Hi, I would guess it would be better explanation in the orginal Suzuki Users manual for DT25 1994. So I guess the indicatorlamp on the engine is a combined Temp and oil/oil level indicator or also a check engine lamp. If it was also a check engine lamp it could flash a code. For example the larger Suzuki outboards has flashing codes and what they are trying to tell You. The ECU has the self diagnostic function so when ignition switch is turned on the no signal is sent from sensor(s) the check engine lamp is activated. On larger Suzuki outboards a constant on for example tell You failure location is signal system within the unit itself or it could also indicate a battery problem. On DT25 1992-on I belive there are two seperate sensors: engine starting ignition timing sensor and overheat sensor (before that it was a singel sensor on DT25) Check both sensors. I do not know where ignition timing sensor is located, check Parts Look-Up at brownspoint.com Also, the Oil injection warning system: When oil level reaches predetermined level in oil tank the oil level lamp turns to red as the switch senses low oil condition. If the operator contiues to operate the outboard and the oil level drops further a warning buzzer will begin to sound at 7 sec intervals. All the time the red oil warning lamp will be on. BUT: After 10 sec of running the engine RPM will drop (and rev limit light on monitor will come on). If for some reason full RPM is needed during low oil condition and the operator does not have oil onboard the low oil reset button on the engine cover can be pressed when the engine running. This button over-rieds the rev limit circuitry but not the buzzer or light. The operator can continue to run with the buzzer and light on at wide open throttle for approximetely 30 minutes. So there You have probably the cause. It seems a faulty oil level sensor. I do not know the result when wiring it is disconnected (if alarm goes on then - but if it works that way You probably need a new oil level sensor). Try to test the oil level sensor:

al40 · Aug 28, 2005

Re: Suzuki 25 Oil Injection - low power and Alarm Buzzer

Hi, I'm confused as the oil level sensor on my o/b only has 2 wires connected to it, unlike the 4 or so shown in both of the diagrams. Serial number on my engine is 02507-23xxxx which may be a 92 model according to brownspoint and not 94 as I was told... The case style fits what brownspoint call "engine cover 1989-1992" so I guess that ties up with it being a 92 model. To further add confusion, the oil tank on brownspoint doesn't show the oil flow meter attached and just shows a filter. Oil flow meter on my o/b (again just 2 wire connection) is where the filter is in the brownpoint parts diagram. In any case, I have never had issues with the rev's being limited (despite alarm sounding) and the LED on the engine has not come on. I also don't recall seeing a reset switch on the engine (I'll check when I'm next down at the boat). If the oil level sensor is just a switch, I can easily test it by shorting the 2 leads to the ECU but I was afraid of damaging something in case it was a resistive type of sensor and not just on/off. It also could be that the LED on the engine is broken. I never checked it when I unplugged the sensor. Al.

al40 · Aug 30, 2005

Re: Suzuki 25 Oil Injection - low power and Alarm Buzzer

I've just been down at the boat this evening doing some more diagnostic work with some strangre results... I removed the oil level sensor and tested it externally. It works fine. I then re-connected the sensor to the engine and put it to the "empty" posn. The alarm on the control box was significantly louder than I'd heard before but beepedout the same pattern - 2 seconds on, 6-7 seconds off. When I put the sensor back to the "oil full" posn, the loud beeping stopped, and then beeping re-started with the same sequence but MUCH quieter (this is what I have been hearing all along). I then by chance unplugged the LED to check why it wasn't working and the quiet beeping stopped!!!! As soon as I reconnect the LED (or an alternative LED and resistor), the quiet beeping re-starts, beeping the same sequence as the oil level warning. It appears that the LED on the motor is broken. When I replaced it, the LED was LIT (with quiet beeping) until the oil level sensor was moved to empty. Then the buzzer sounded at normal loud level and LED went out... Checked for any obvious shorts but couldn't see any. Anyone got any clues on this one? Does this sound like a wiring loom fault? Should the LED be lit when ignition is ON? I also noticed that my engine does NOT have a reset switch on the front Thanks,

Suzuki 25 Oil Injection - low power and Alarm Buzzer

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