Originally Posted by Mark rsa2au
Thermostat is a 160. IR heat gun and Temp guage on dash confirms. ECT has been replaced, and all other sensors have been checked or replaced. Motor does not bog down on full throttle pull off.
I can still smell strong fuel smell at the rear of the boat with puffs of diesel like black smoke on some hard pull outs, but it is way better than before when I had black sooty residue up the transom. New fuel filter and pump, new fuel lines, new pressure regulator. Currently set at 32 PSI (factory spec is 30psi) but this 2 PSI should not create such heavy consumption - if it is heavy as I do not know what is "Normal".
It would be nice if adjusting the 2PSI down would make that much difference but I doubt it. I wanted to find out what the "average" was before looking for an issue.
If the collective intellegence on this forum suggests it is high I will be adjusting the PSI down, and then retesting all sensors, and perhaps spending a day with the 4 blade 13 x 13 to compare.
Check for codes- if code 33/34 comes up, it points to the MAP sensor and this could cause problems like you're describing. Also, if you want to check the fuel "cone" from the injectors, remove the flame arrestor, start the engine and shine a timing light on the cone. It's like stop-action, so the gas will look like it's not moving at all, if it even looks like it's moving. If you see any gaps (called 'tearing', as in 'tearing' paper), it could be that the injectors need cleaning, could be a faulty regulator or something along those lines. Also, the knock sensor's operation should be verified- run the engine and watch the timing advance as you increase RPM. I would recommend doing this while under way, not in idle, but it will advance in either case. When the timing has advanced, hit a motor mount with a hammer (on top of the large adjuster bolt at the deck is a good place) to watch for the timing to change. If it doesn't change, use a screwdriver and tap on the knock sensor and look for the timing to retard. You should have base timing at 10°BTDC and should see about 30-35° of additional advance, for total advance of about 40°. If you don't see this much advance, unplug the knock sensor wire and see if it helps. If it does, you may have a bad knock sensor.
If you didn't put it into diagnostic mode when you set the timing, you need to do that, or it's not correct. The timing mark will be stable when it's in this mode and when it's jumping around, it's not possible to be accurate. Watch the timing light on hard acceleration- if it skips, you may have mid-fire. If the plug wires haven't been changed (I don't remember all of what you wrote about changing) and they're more than a few years old, you could have cross-fire.