DF90 Performance Problems

[rrspin]

Hi, I have a 2007 DF90 with low hours. The last few times out I had trouble with the motor at anything but very low speeds. Since that time I replaced spark plugs, load tested the battery, checked compression, replaced LP fuel filter, HP fuel filter, HP pump suction filter, and new gas. Boat runs fine on muffs but took it out for a real test on the water and had lots of stalling and never able to eclipse 1200 rpms. Throttling up caused the engine to stall unless I immediately backed off. I was able to crank the RPMs up while in neutral and produce the 3-2 MAP sensor diagnostic code but haven't received any codes before or after that.

Took the spark plugs out today and they are pretty dirty. The cylinder heads are dirty as well. My guess is there is a sensor out of whack or an issue with the fuel air mix. Took a quick look at the MAP sensor 'port' into the intake manifold and it was very clean. Thoughts?

[catacom225]

Hi rrspin, what colour or what do you mean by your plugs are dirty, black carbon build up, wet and oily or a light coloured build up, this info will help the experts . Do you have a pre racor type filter and have you done a compression test . A bad batch of fuel may have caused an injector issues

[rrspin]

Hi rrspin, what colour or what do you mean by your plugs are dirty, black carbon build up, wet and oily or a light coloured build up, this info will help the experts . Do you have a pre racor type filter and have you done a compression test . A bad batch of fuel may have caused an injector issues

Black carbon, at least one was wet. No xternal water separating filter. Compression is good.

Right click for photo [IMG][/IMG]

[catacom225]

Hi . Not sure if this is relevant but Had a similar problem last year with my 2011 140, hard to start,excessive shaking, stalling when backed off etc: checked the plugs, 3 where black and dirty and 1 was black and damp. Ran the engine and pulled the leads to find 4 was dead! So I just started with the obvious. Changed coil pack,plugs to no avail. Next thing was to check if there was any signal at No 4 injector, 12.5 V.? This is when I noticed some green corrosive type build up on the injector terminal
So I removed all 4 ,cleaned and sprayed with electrical contact cleaner , fired it up and it ran perfect! ... This all happened within outings, One trip alls good, the next trip i had problems

[rrspin]

Hi . Not sure if this is relevant but Had a similar problem last year with my 2011 140, hard to start,excessive shaking, stalling when backed off etc: checked the plugs, 3 where black and dirty and 1 was black and damp. Ran the engine and pulled the leads to find 4 was dead! So I just started with the obvious. Changed coil pack,plugs to no avail. Next thing was to check if there was any signal at No 4 injector, 12.5 V.? This is when I noticed some green corrosive type build up on the injector terminal
So I removed all 4 ,cleaned and sprayed with electrical contact cleaner , fired it up and it ran perfect! ... This all happened within outings, One trip alls good, the next trip i had problems

Yes, so the dirty plugs definitely lead me to the idea that I'm not getting the right fuel/air mix. You are saying that in your case the injector filters were the likely culprit?