Running rich, 300xs

[DewRonInc]

I am removing engine to get hull repaired and blueprinted. But, pulling powerhead to tighten mounts and replace crank seal. So it will be a few weeks before I can test anything. Recently I pulled engine down and cleaned and checked due to dirt dauber ingestion. Had rails cleaned and injectors, replaced maf sensor and air temp. Had a 50 hour compressor, pulled apart and checked, went ahead and did a clean hone, compressor, installed new piston and rings, new o rings and soaked bearing for a month and put back together. Runs great but does not want to exceed 5500. TPS and crank position sensor will be replaced, tps, press in center of it and it drops to roughly 85%. Does anyone have any idea.

[DewRonInc]

To further this, have a smart craft gauge and temps are running about 125-130, compression is good, holeshot has diminished also. Reeds have been cleaned, head o rings and bolts replaced after inspection, thermostats will be replaced upon installing powerhead before running. Engine had little or no carbon buildup when broke down, hone marks still present, engine has 185 hours on it. Pulling flywheel to check all. That is why I am replacing crank position sensor, just because. I know maf could cause my issues is why I replaced it. I am going to inspect 2 and 5 plugs and getting new pulse pump prior to running after hull is done.

[DewRonInc]

Blake cleaned rails and injectors also

[2jz]

Blake cleaned rails and injectors also

Who is Blake
Is this a recently purchased motor
What # for compression test
Check tracker valve
Cheak air compressor pressure since you rebuilt it

[DewRonInc]

Injector service Canada

[DewRonInc]

Who is Blake
Is this a recently purchased motor
What # for compression test
Check tracker valve
Cheak air compressor pressure since you rebuilt it

all of this has been checked or replaced. Sending rails and injectors out again

[DewRonInc]

No not recently purchased, 185 hrs

[2jz]

What is compression test psi

What is fuel and air test psi
Voltage test tps sensor

[Davidlake]

Check your coils.
Mercury has had a lot of faulty coils on the 300XS's.
Mercury had a TSB several years ago that included the 300XS.
Had several go bad, some intermittently, with similar results.
Mercury replaced all 6 when one failed when just out of warranty.
It took some "coaxing" for them to do it, though.
DDT scan and manually fire the coils and it will show faults.

[DewRonInc]

Actually I replaced all coils with updated ones

[DewRonInc]

What is compression test psi

What is fuel and air test psi
Voltage test tps sensor

compression was averaged @ 132. Kinda high, air pressure and fuel pressure dead nuts on, next test after getting hull back, test fuel air under load. TPS was checked for percentage, 100 percent, but press on tps sensor and it would drop to nearly 85 percent. Have new one to install prior to rigging along with new stats and plugs. Cleaning rails and injectors again for good measure and check rates very close.