df250 2006 misfire hiccup @ 4100 rpms

[vitomirra]

hey guys I have a 2004 df250 with about 800 hours that misfires, skips or hiccups at 4100 rpms. its like multiple misfires but will run strong if I push rpms higher or allow them to go lower

i am 100% new from the fuel tank to the motor with fuel lines, filters and separators. plugs are brand new .


here is a link to the utube video showing skip

https://youtu.be/dS4aJ1IQmv8

[vitomirra]

Any help we really need directions

[Moonlighter]

Have you had it connected to the Suzuki SDS software? Results?

Did this start happening before of after you replaced fuel system components?

Before or after plugs replaced? I have heard of brand new plugs occasionally get a bad one.

Have valve clearances ever been checked and adjusted (as they should have been per the Suzuki service schedue)?

Were the high and low pressure fuel filters changed? And was the VST and its tiny internal filters cleaned?

Depending on the boat, 4000 can be a point at which there is max load on the engine - if that is the case here, a bad plug lead can cause what seems to be a misfire. Should show up with engine connected to SDS system.

I am not sure but it may also be the point at which VVTI system is activated - if that is the case then see my earlier point re valve clearances being checked and adjusted.

[vitomirra]

We had a suzuki mechanic over but motor would not replicate problem. Typically we will run here 32 miles offshore with no issues than dive for hours and on the way home the issue will start.....

I am replacing all plugs today with exact suzuki recommended plugs

I had a fuel restriction issue as the boat was new to me and the OLD fuel lines had never been changed. I am now 100% new from the tank to the motor including water separator and engine filter

I dont have SDS software but thinking of buying is the readily available to the average Joe?

speaking of the VST tank I have removed and cleaned all tiny filters the issue occurrence went down dramatically but still there..

Also recently had to replace fly wheel as the magnets failed.... could this be a stator issue?

never had the valve clearances adjusted ....

[Hoosmatroos]

Stator issues can cause weird things.

SDS software is available, look on ebay and find a reputable seller. Software and connection plugs are offered for around 40 - 80 dollars. Money good spent imo