Gallf1
Well-Known Member
- Sep 26, 2018
- 316
- Boat Info
- 2000 Searay 380
- Engines
- Mercruiser 454 MAG MPI 7.4L
Custom Forward Hardtop
Whaly 270 Hard Dinghy, 4hp Honda
Bahamas Veteran
Hi:
I have an issue with the Stbd motor in my 2000 SeaRay 380DA that I hope someone can help me with.
Both engines long block rebuilds with about 300 hrs since. No issues prior to trip.
Prior to our 800 mile trip from Palm Coast to Gun Cay, Bahamas and back...in both engines: changed the fuel and oil/filters, seawater pump housings and impellers, new alternators and new batteries, new serpentine belts, new IAC's and cleaned the spark arrestors and hauled out for fresh bottom paint. Both heat exchangers serviced with no issues or leaks. Manifolds and risers are less than 1 year old. Total replacement of old "log style" wet exhaust to water lift style with all new hoses and mufflers etc. Props tuned and cutlass bearings are in spec.
The trip was great, zero issues except for one day while in Bimini the Stbd engine stumbled while leaving the harbor at around 1500rpm (sputtered and suddenly revved up to over 2000 rpm without me touching the throttle). It died and I was able to immediately restart it with no further issues all the way back to Palm Coast.
Never use ethanol gas and ran with Lucas fuel treatment the whole trip.
We have been back home for some time and about 2 weeks after the trip, the Stbd engine:
Starts normally, idles normally, runs at 167F max
Wont rev past 3200rpm (no matter how far I push the throttle), seems like it has no power.
I have:
Checked with my Rindal scan tool and the only thing was "MAP sensor voltage low", so I replaced the MAP sensor (even though when testing with vacuum it was within spec)
Checked vacuum in plenum and it has 15" at idle (factory spec)
Changed fuel filter (no water or debris in filter)
Changed spark plugs (they were wet/foul)
Used in-line spark plug tester and plugs were getting spark
Distributor cap has corrosion on each rotor/plug lead point (inside cap) so I am replacing caps and rotors to better OEM brass style (currently has aluminum style).
It seems to me that engine is getting fuel (too much) and it may be weak ignition from the distributor cap corrosion?
Also checked MAP and ECT sensors as per the Mercury Manual and it points to a bad ECM but when compared to the Port engine sensors(which is running great) it also says the ECM is bad so I wonder about these diagnostic instructions in the manual?
Fuel pressure?....injectors? I guess the only way to tell is to remove the intake plenum to get to the fuel rail and check pressure and remove injectors?
Huge thanks to anyone who can help me!!
Thx
I have an issue with the Stbd motor in my 2000 SeaRay 380DA that I hope someone can help me with.
Both engines long block rebuilds with about 300 hrs since. No issues prior to trip.
Prior to our 800 mile trip from Palm Coast to Gun Cay, Bahamas and back...in both engines: changed the fuel and oil/filters, seawater pump housings and impellers, new alternators and new batteries, new serpentine belts, new IAC's and cleaned the spark arrestors and hauled out for fresh bottom paint. Both heat exchangers serviced with no issues or leaks. Manifolds and risers are less than 1 year old. Total replacement of old "log style" wet exhaust to water lift style with all new hoses and mufflers etc. Props tuned and cutlass bearings are in spec.
The trip was great, zero issues except for one day while in Bimini the Stbd engine stumbled while leaving the harbor at around 1500rpm (sputtered and suddenly revved up to over 2000 rpm without me touching the throttle). It died and I was able to immediately restart it with no further issues all the way back to Palm Coast.
Never use ethanol gas and ran with Lucas fuel treatment the whole trip.
We have been back home for some time and about 2 weeks after the trip, the Stbd engine:
Starts normally, idles normally, runs at 167F max
Wont rev past 3200rpm (no matter how far I push the throttle), seems like it has no power.
I have:
Checked with my Rindal scan tool and the only thing was "MAP sensor voltage low", so I replaced the MAP sensor (even though when testing with vacuum it was within spec)
Checked vacuum in plenum and it has 15" at idle (factory spec)
Changed fuel filter (no water or debris in filter)
Changed spark plugs (they were wet/foul)
Used in-line spark plug tester and plugs were getting spark
Distributor cap has corrosion on each rotor/plug lead point (inside cap) so I am replacing caps and rotors to better OEM brass style (currently has aluminum style).
It seems to me that engine is getting fuel (too much) and it may be weak ignition from the distributor cap corrosion?
Also checked MAP and ECT sensors as per the Mercury Manual and it points to a bad ECM but when compared to the Port engine sensors(which is running great) it also says the ECM is bad so I wonder about these diagnostic instructions in the manual?
Fuel pressure?....injectors? I guess the only way to tell is to remove the intake plenum to get to the fuel rail and check pressure and remove injectors?
Huge thanks to anyone who can help me!!
Thx