2012 Df300 Suzuki Problems

[Razor 300hp]

Hi There everyone

New to this forum and am having some major issues with my 2012 Suzuki 300hp here in Australia. It's on a pod converted 25 Bertram flybridge single engine config. It's a bit of an essay but have tried to list all issues that have arisen over the last 3 months as we seem to be at wits end with this issue and about to throw it away. The problems started approx 3 months after warranty expired.

December - engine service by Suzuki agent approx 950hrs

The boat was not used again till late January

Late January: I had let the fuel tank run nearly empty as had a fuel smell / leak when the tank was full and wanted to paint the inlet manifold and breathers with soapy water as well as check the tank visually whilst fuelling to discover location of leak. It was found right near the top of the inlet manifold.

As tank now full we left for the days fishing to repair the leak once some of the fuel was burnt out of the tank.

We proceeded at normal cruise speed 5400-5600rpm for approx 1.5hrs (70km) with no problems at all and all of a sudden the motor dropped in revs and began to drop off the plane (approx 4500rpm). On inspection found that the fuel bulb was completely compressed and the water separator had small traces of water in the bowl. I had a spare filter on board and replaced it on the water. Whilst this relieved the motor somewhat we still could not get to full revs planing. We decided to troll, turn around and start making our way back to port.

Approx 4-5hrs later we tried to get on the plane again and the motor struggled heavily. The fuel bulb was compressed (not as much) again and as I also had a spare bulb on board I then replaced that also. We also pulled off the water separator bowl again to check and there was very small traces of water in the bowl - nothing too dramatic. Again none of this helped the motor rev out but we could eventually hold approx 5500rm and did manage to plane the rest of the way back to port (at least 1hr travel). The motor actually runs OK with no missing or vibration, just lack of power and the engine pitch changes.

Note: at this point believed the problem was fuel

Early Feb: Stripped down the inlet manifold of the fuel tank and replaced the gasket. Ran complete new fuel lines, filters and fuel bulb to the engine as well as the separator in the motor. We also pumped out the remaining fuel from the tank and cleaned internally. I found no traces of water in the tank and the bottom of the tank was incredibly clean, no garbage at all.

Filled up and took for test run. Now the engine would not go over 4200rpm and could not plane at all - need mechanic!

Feb: Contacted local Suzuki service agent and had them come and inspect. They diagnosed that the high pressure fuel regulator had rusted rusted and replaced the pump and vaporiser unit. (there is two water fuel filters prior to the actual pump with the second one had no water in at all so not sure how water gets to the high-pressure pump anyways we move on)

The subsequent test run let the motor get to full revs and plane quickly, but quickly dropped in rpm to 5600 whilst the throttle was at WOT.

Another test run with agent produced the same results and they then replaced the low pressure fuel pump and spark plugs as well.

Test run produced the same poor results.

March: Another test run with a fuel pressure gauge installed after the vaporiser unit indicated constant fuel pressure from idle to WOT. Note: this now rules out any issue related to fuel flow from the tank to the injectors) At this point agent removed the “blow off” valve pipe off the vaporiser unit to see if this improved. We decided leave the motor cover off as conditions were flat. Motor ran perfectly at WOT. Believing we had discovered the problem - We then replaced the hood and within hundreds of meters the engine had once again dropped in RPM to 5600. we replaced the pipe to the blow off valve which did not amen any difference....however... Note: Take the hood back off again and engine would happily sit at 6200rpm - put the hood back on and it drops rpm and power.

Next test run agent rigged up an extension lead to the air intake temp sensor so as it would read the outside air temp but the cover was on the motor. This again worked perfectly at 6200rpm with no drop in rpm or power.

Next test run Suzuki downloaded many data drops from initial take off right through to when engine dropped revs with the hood on. It appears that a rise in engine temp coincides with drop in rpm. Engine temp gets to 92 degrees celsius (197 farenheight).

Note: up to this point no alarms or alerts have shown on the gauges or the computer downloads).

I then went on a test run with little fuel on board and no load. I planed and then dropped the throttle to normal cruise rpm at 5200 the motor happily sat at this setting for 15 minutes, I then bumped to 5400rpm for another 15mins and again to 5700rpm - no problem at all. I then tried WOT and whilst it reached it - it quickly dropped rpm back down to 5600 with no real grunt. Whilst the motor was not under a great load it seemed to perform normally at these rpm except for WOT at the end.

April: on advice from Suzuki replaced the thermostats and pressure relive valve and was decided to try a longer test run, three people on board, full fuel and fishing gear. With the increased load the motor performed poorly and whilst took off solidly again quickly dropped to 5500rpm. Approx 15km away the engine overheat alarm went off (gauge at just above 90 degrees celsius but not near 100 degrees.) This is the first time in this whole process that an alarm has gone off. We idled until alarm went off and tried to take off again. Motor would not go above 5300rpm and could not even get the boat on the plane - just had no hp. Overheat alarm went off again after approx 1 minute. We again idled and turned the boat for home. We fished along the way. After 1hr, I put the boat on the plane again but really struggled to 5500rm but held the plane and did not over heat for 10km or more. I pulled off the plane and filleted the fish. The motor was turned off of 1/2 hr. Once again underway we planed struggling at 5600rpm until the overheat alarm went off within 500m.

Sunsequent replacements:
Checked water pump and action - perfect.

Note: at all times there is plenty of water showing through the telltale and besides the over temp alarm nothing is showing anywhere.

Test run - Same test result with subsequent drop in rpm and power.

Notes: The engine seems to run perfectly at idle and whilst taking off. Basically the engine pitch changes after a period of time and drops rpm with a distinct drop in boat speed and especially power - but does not miss or indicate that it's running badly just engine pitch and drop in hp. When under load the motor performs poorly and brings on the symptoms quickly.

Please help as nobody can seem to find a solution - even Suzuki!

[Bamahemi]

That's interesting to say the least! May need to swap the ecm, of course better to see if zuke rep will try it so your not putting the cash out, I think they owe it to u at this point in order to fix the prob once and for all, also check for shorts, on another motor I had the same issue with cover on an it was pressing on a wire to pump that was almost cut and it was causing the pump to shut down. Good luck.

[Bamahemi]

That's interesting to say the least! May need to swap the ecm, of course better to see if zuke rep will try it so your not putting the cash out, I think they owe it to u at this point in order to fix the prob once and for all, also check for shorts, on another motor I had the same issue with cover on an it was pressing on a wire to pump that was almost cut and it was causing the pump to shut down. Good luck.

[Moonlighter]

Hi Razor

Welcome another Aussie to the forum!

First up, where in Aus are you located?

I am in Cleveland Qld and locally we have one of the most experienced Suzuki spe******t dealers and master certified technicians in the country. He may be able to help you, often Suzuki sends him around the country to sort out the tricky problems. Jon Eadie is his name, Bayside Suzuki Marine. Ph mob 0407738731. Not too many issues that he cant sort out. May be worth a phone call.

Secondly there were a couple of things you mentioned that caught my interest.

First is the fuel bulb sucking flat. That can indicate a restriction in the fuel tank breathers - either in the breather hoses or the hull fitting. Im assuming that youve double checked to make sure that the tank is breathing OK? If you run it again and the bulb sucks flat, can you take the fuel tank filler cap off and see if you get a sudden intake of air into the tank?

The second thing is the fact that you said the engine runs perfectly when the cowl is taken off, even at full rpm? Is that still the case? Some possibilities there could include exhaust gases escaping under the hood and basically choking the engine at higher rpms, or it could be as simple as a plug lead shorting if it is somehow in contact with the cowl or diplaced when its fitted. Or a wire pinched somewhere or fouling on the cowl?? Or a plug or plug lead or coil breaking down when they get hot from running at WOT.

You have checked spark plugs and leads?? If new plugs were fitted in the December service and problems started immediately after that, if the plugs were replaced you could have a dodgy spark plug in there - consistent with the engine running poorly under load...?

My only other thought is a left-field one...... Do you have a NMEA2000 network fitted with the Suzuki linked up via the Szuki engine interface cable? I have seen a few cases of weird engine issues not unlike what you describe happening when the interface cable develops a fault. Quite simple to test this theory and either rule it out or in: disconnect the engine interface cable from the engine and go for a run. If engine performs perfectly, the interface cable is the problem and should be replaced. If it makes no difference then you have a different problem.

Good luck, check those things, talk to Jon, and let us know how you go.

Cheers

Grant

[Razor 300hp]

Thanks for the reply, working on a replacement ECM now to give it a try. Whatever the ECM costs will be worth it if it fixes the problem. Would be better then purchasing a new motor.

[Razor 300hp]

Hi Grant

Thanks very much for your writings. I'm way up in Darwin and my Suzuki rep has been speaking with quite a few dealers about the issue as well. I will ask if he has spoken with Jon and if not will give mim a call. He's really good as well but we just can't seem to get over the hurdle so I though I'd post around and see.

1. Yeah the tank has two breathers, double checked and have removed the filler cap many times - seems to have no affect. Even when the motor is dropping in rpm the fuel psi remains at the same level (they put in a gauge after the vaporiser unit. Seems to have ruled out any fuel related issues up to the injectors.

2. Yes engine runs perfectly with cowl off (albeit extremely loud) and we have explored the exhaust gasses however when we rigged an extension lead to the air intake sensor so as it read the outside air temp with the cowl on the engine, it ran perfectly as well (no choking). I will check under the cowl again but cannot seem to find any evidence of rubbing or touching. When powering up to WOT the engine works fine it's only after a period of time (500m - 5kms) that the engine rpm and hp start to drop. Like I mentioned the motor seems to run fine even when the rpm and hp drops it just has a different sound/pitch. Doesn't miss or do anything different.

3. They have replaced the spark plugs and checked leads since the service as well.

4. The problem did start after a service however we travelled for some 70kms before the problem suddenly started to occur.

5. last one might be interesting as I did read that somewhere else. Yes I'm on NMEA2000 lead through Suzuki interface to a lowrance sounder. However the agent has disconnected my leads at the motor plug and plugged in his service computer with his own connections. The same problem was replicated many times.

6. According to the many downloads taken the drop in rpm seems to coincide with the engine temp increasing. I don;t know at what temp the alarm goes off but the latest episode when it did the gauges only read 92 degrees and orange on the gauges is at 110 degrees??

[redlowrey]

It sounds like an exhaust gas problem to me, classic symptoms, take off, full power then starts to drop off in power temp comes up no missing. When you ran the jumper wire where did you run it, out of the cowl to the cabin and how did Suzuki connect it up to their software. What was the inlet air temp reading and I assume there was no change so they discounted an exhaust problem. What about a baffle in the exhaust blocking the gas off, you say you can hear the difference in the motor when the problem happens. If it was starving for fuel it would miss, if it was over fueling it would miss, if the engine has an o2 sensor the Suzuki sds would pick it up being rich or lean, if the timing went in to the retard position the sds would pick it up. Their sds would see every pid the pcm monitors.

[Razor 300hp]

I agree that this seems to be the most likely cause. When we did the extension lead to the air intake sensor out of the cowling (the cowling was installed and locked in pace) we did not have the computer plugged into the system so could not tell the air temp inside. However the symptoms did not appear in a 15 minute run where as it normally appears within 30 sec to a couple of minutes. They are doing some tests today to check out if there's exhaust gas rising into the cowl so will advise.

[redlowrey]

I am tipping when you had the wire under the cowl that there was enough air to get passed the seal to the throttle plate.

[bill2452]

Ecm?

Heat buildup can certainly cause issues if the ECM is defective. I had problems that weren't the same as yours but were heat related and causing my motor to stop for no apparent reason. ECM replacement took care of the issues. Here's the thread:
http://www.suzukioutboardforum.com/s...tor-stops.html
Bill

[Razor 300hp]

Hi Everyone

Firstly I'd like to thank everyone for their input. I'm incredibly relieved to say that the problem has finally been sorted. Especially thanks to Grant who put me onto Jon Eadie - saved me from much grief and a huge expense for a new motor.

It turns out to be heat related as many of you thought. On consulted advice to the above it was decided to remove the water pump, impeller, sleeve, housing as well as the spout and replace with new. Upon inspection of all the removed items there appeared to be nothing wrong with them whatsoever - the impeller and pump was new anyway from recent service. Upon reflection it appears that the actual housing was to blame by not creating a good seal to force enough flow water upwards through the engine - even though the telltale was powering all the time.

The engine is now running some 15 degrees cooler at WOT and working perfectly. The old cooling components must have been running enough water through the engine not to force the overheat alarm (damn close though) but not enough to cool it properly - therefore the computer was taking over and saying "its hot in here" and adjusting the ratio/revs to try to adapt to the conditions.

Again thanks again and hopefully this thread helps someone else in the future.

Very kind regards to all for their input and happy fishing!!!!

[Moonlighter]

Excellent news!

Ive head of a couple of instances where that pump housing appeared OK but obviously wasn't, and when replaced, the engine cooling performance returned to normal.

Glad that Jon was able to point you in the right direction.

I once heard someone ask the GM of a top motor racing team how important a good chief mechanic (crew chief) was and how you keep them. He said words to the effect of

"Well, when you find a great chief, you build a damn big fence around him/her and never let them escape"

Same thing applies to great outboard mechanics!

I've just put exta razor wire on top of the fence I have built around Mr Eadie! You lot up north in the NT keep your eyes off him!