2004 DF225 Cutting out between 3,000 and 4,000 RPM

[lutherdog]

I have a 2004 DF225 that cuts out/off for a millisecond between 3,000 and 4,000 rpms. It never comes off plane because the problem happens so quickly. The motor runs great below 3,000 rpms and 0ver 4,500 rpms. I have had several mechanics look at it and have replaces the throttle position and crank shaft position sensors. The motor has less than 800 hours on it and I am hoping that someone on this forum has had the same problem and was able to fix it.

[Solarman]

Increasing speed (throttling up - going between 3k - 4.5k), maintaining steady speed (between 3k - 4.5k), how often does it skip? How often does it repeat this skip? Anything that might correlate the same each time it occurs? I'm guessing it has always been doing this? Something that recently started?
Any additional info you can give might help this forum help you?

Good luck.

[lutherdog]

Most of the time it runs normal when it's cold and the problem gets worse as the engine warms up. The problem happens 2-3 times per minute just between 3500-4500 rpms. If I hit full throttle as from hole shot it gets through the range with no problem. When it really acts up it takes a few seconds longer to get on plane as it sputters while in the "range" and then gets on plane and runs fine as long as it is at 4500+ rpms. When the waterway isn't crowded that speed if fine but when it's crowded I become that idiot that flies past everybody and get a lot of obscenities throw my way.

[Hoosmatroos]

Are there any fault codes from the engine? Did they use the SDS (Suzuki. Diagnostic System) to find any problems?

[lutherdog]

I am not sure if he used SDS. But no codes came up on his computer.

[pniksnut]

clean the injectors and change all the filters. including the high pressure filter.

[CaptainD]

I agree with what's said, the high pressure filter and pump inside the VST and also the diaphram fuel pumps

[lutherdog]

Thanks for the responses. Can these filters cause problems at just the RPM range of 3500-4500 and run perfect otherwise?

[pniksnut]

i think so . your problem occurs at the end of the lean burn rpm's and it doesn't have a lambda sensor to correct an to lean mixture.

[FourHeyDay]

I just came out of a similar, not exact situation, but close 2006 DF225. Drove me nuts for a week. This is what it did: Performed normal maintenance (low pressure filter, plugs, oil change) and replaced a failed low pressure pump along with checking the VST filter. Afterwards, it had low power, wouldn't really get above 3150 but after I did get it up onto plane, it would get to 4700 or so(not max). I went after fuel first then I figured I would go after electrical after since it ran well except in the "power band". I checked the fuel pressure to the injectors (36-38 psi). I changed all the other fuel filters, put it back in the water...same thing. Opened the VST again and removed the high pressure pump and found some more debris blocking the filter. Reassembled after cleaning the timble sized intake screen for the VST high pressure pump and put the boat back in the water. Ran perfect.
Therefore check fuel in my opinion. It basically costs you only your own time and simple tooling.
1. Check that the LP pump and the HP pump works. Not just by sound(locked pump may sound/feel like it runs)
2. Check the HP fuel pressure coming out of the HP fuel filter (Harbor Freight sells a simple fuel press test kit for cars that works perfect)
3. Clean the thimble size filter on the intake to the HP pump inside the VST (you will need a replacement gasket)


Don't bother with the fuel injectors yet. They require more effort to get to, more seals to replace and jumping to the end of all that filtration isn't needed yet. Start small and be methodical...

[redlowrey]

I just came out of a similar, not exact situation, but close 2006 DF225. Drove me nuts for a week. This is what it did: Performed normal maintenance (low pressure filter, plugs, oil change) and replaced a failed low pressure pump along with checking the VST filter. Afterwards, it had low power, wouldn't really get above 3150 but after I did get it up onto plane, it would get to 4700 or so(not max). I went after fuel first then I figured I would go after electrical after since it ran well except in the "power band". I checked the fuel pressure to the injectors (36-38 psi). I changed all the other fuel filters, put it back in the water...same thing. Opened the VST again and removed the high pressure pump and found some more debris blocking the filter. Reassembled after cleaning the timble sized intake screen for the VST high pressure pump and put the boat back in the water. Ran perfect.
Therefore check fuel in my opinion. It basically costs you only your own time and simple tooling.
1. Check that the LP pump and the HP pump works. Not just by sound(locked pump may sound/feel like it runs)
2. Check the HP fuel pressure coming out of the HP fuel filter (Harbor Freight sells a simple fuel press test kit for cars that works perfect)
3. Clean the thimble size filter on the intake to the HP pump inside the VST (you will need a replacement gasket)


Don't bother with the fuel injectors yet. They require more effort to get to, more seals to replace and jumping to the end of all that filtration isn't needed yet. Start small and be methodical...

'''''''''''' How could you say his problem is similar to yours, his engine runs well over 4500rpm your engine would not get there indicating lack of fuel, wouldn't you think if the engine ran alright at wide open throttle it would not be from a lack of fuel.

[redlowrey]

Thanks for the responses. Can these filters cause problems at just the RPM range of 3500-4500 and run perfect otherwise?

'''''''' If the engine runs good at 4500rpm and above, I would not think you would have a fuel supply issue, but it sounds like a fuel issue, caused by an electrical problem, do a throttle position sweep test on the signal line, and check supply voltage and ground at the ecu not the sensor, and check the map sensor signal line and power and ground at the ecu as well.

[FourHeyDay]

Most of the time it runs normal when it's cold and the problem gets worse as the engine warms up. The problem happens 2-3 times per minute just between 3500-4500 rpms. If I hit full throttle as from hole shot it gets through the range with no problem. When it really acts up it takes a few seconds longer to get on plane as it sputters while in the "range" and then gets on plane and runs fine as long as it is at 4500+ rpms. When the waterway isn't crowded that speed if fine but when it's crowded I become that idiot that flies past everybody and get a lot of obscenities throw my way.

redlowrey, I did actually state that I could get to 4700+ RPM. Additionally if I hole shot it and got onto plane, it would run at/above cruise rpm. Problem was, most times it would sputter from around 3150-3900 RPM and if I worked the trims and feathered the throttle I could work through it up to planing speed. It is MY opinion that if lutherdog can run on plane but sputters and surges thru the lower RPMs it isnt the MAP sensor. MAP works constantly and if it was failing, power loss and fuel mixture scheduling would likely be more random, low/high rpm but anything is possible. Throttle position sensor could be checked. However, just my opinion it doesn't scream electrical to me.

[redlowrey]

The map sensor is one of the most important sensors on the engine for information to the ecu for the amount of fuel to be injected into the engine, on a good engine with good manifold vacuum the signal voltage will be around one volt at idle and when you take off will shoot up to a bit over four volts, and when the boat gets on the plane and you pull the throttle back and manifold vacuum returns, it will drop the signal voltage back down, if it drops in and out it will lean the fuel off. It takes about half an hour to check the function of the sensor with a vacuum pump, just to make sure the voltage changes smoothly with no hanging on or drop outs. How would you know if the map sensor was fine without checking the operation of it. When I read his first post I was thinking more of an ignition problem the way it was dropping in and out very quick

[CaptainD]

forgot to mention,besides the VST and other pumps/filters I mentioned before there is also an oil pressure sensor that I've changed a year or 2 ago