_______
Phil
'09 Hewescraft ProV
'09 150 Optimax
Ok, the saga continues.
I ran offshore 50 miles this past weekend.
The motor was running great until about 15 miles offshore, while running about 4500 rpm, the rpm started fluctuating.
This happened when we got into 2-3 ft seas.
I shut the motor down, cranked it back up and was able to get back on step. This happened again after a mile or 2. I tried one more time and was able to run offshore 50 miles. Inexplicable, we were able to run in with no problems. The seas had flattened out slightly and we had wind and waves to our back coming in. When we got inland I decided to open up to WOT and there were a slight miss at 5500 rpm. Also, still a slight miss when I hit the trim button. I'm stumped.
Any traps I should run?
I'm thinking about checking grounds on the engine at this point since it seems electrical, but I have no facts to support that. Should I focus another direction on my testing.
Thanks again for the help guys.
Steve
I would be testing fuel pressures as the problem is occurring. Inspect fuel pump connections inside the VST.
Check fuel tank pickup for pin-holes or cracks. More likely to act up when you near the fuel level of the imperfection (especially in rough water).
Also check grounds as suggested above- especially ALL grounds on the STB side electrical plate (including the bolts that retain the plate to the block, providing the MAIN ground for the plate, Main Power Relay, PCM and Trim Relays).
And of course- check battery cable connections at block, Starter Slave Solenoid, and at battery (all should be WRENCH tight, unable to rotate cable on it's retaining hardware).
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
Ok, I will check grounds and fuel pressures.
This only seems to happen in rough water conditions.
I ran it inshore for about 2 hours prior to this trip with no issues. Very intermittent, may be hard to test while the problem is happening.
Savage, or Don, should I start with the pulse pump and work to the low pressure and high pressure fuel pumps to start with?
Will disassemble, clean and torque ground connections for sure since this is pretty simple and requires no parts or special tools.
Thanks again.. steve
Start by gaining data (clues)......fuel pressures as the problem is occurring.
Just curious, what should the smart craft fuel pressure be reading in PSI?
Smartcraft cant read fuel pressures on your motor.
^^^^Originally Posted by Savage
_______
Phil
'09 Hewescraft ProV
'09 150 Optimax
While cleaning grounds on the motor, I cranked it up to flush
and was shocked when I touched both of the two lower plug wires.
I went to buy a new set of wires, and after removing the old plug wires found THIS on the lowest port plug wire:
20190816_170817.jpg
I think this may be the issue.. fingers crossed.
Thanks,
Steve
Ran 60 miles today (mostly inland protected waters).
I did not have any issues the whole time.
No rpm loss while trimming either.
The real test will be on a 30+ miles run offshore in 2-3 ft seas.
Started running the 150:1 oil in the gas.
I was already running quickleen and quickstor.
Could this have been caused by the water
Inside the cowl when the temperature sensor failed?
Note: as mentioned, Both cylinders 5 and 6 spark plug wires were arcing and shocked me when I touched them. However, Only cylinder #6 had a visible hole. Needless to say, I changed all 6 of the spark plug wires.
Last edited by greauxpete; 08-18-2019 at 09:03 AM.
Definitely could be related.
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
Ran 50 miles offshore for the last week of snapper last weekend.
Flawless for 95% of the trip cruising at 4500 RPM.
This time when we get into protected water, we decide to open it up to WOT to blow the carbon out and there is a stumble at around 5200 RPM. (Earlier in the trip I was running 5500 RPMs for a brief time)
When I got back home, I decided to test all of the coils and coil drivers (particularly interested in the lower coils and coil drivers on cylinders #5 and 6), where the plug wires were arcing.
Sure enough, one of the lower coils failed 2 of the FSM resistance test and both the lower and upper coil driver failed a resistance test. I suspect, the arcing plug wires caused issues with the lower coils and coil driver.
Thoughts? Could the plug wires have caused coil issues?
Thanks,
Steve
Last edited by greauxpete; 09-07-2019 at 05:01 AM.
You performed the tests. If you are certain you performed them properly, and the results indicate a "failed" reading, don't second guess it.
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
Sure can and probably did. When wire goes open ckt it will have arc across that gap that keeps getting larger and it will burn the wire from the inside out and start following the path of least resistance to ground which is nearby components or even the insulating wire surface in some case. It will also cause the coil voltage to be driven to there maximum output. Which usually causes the coil to do the same thing the wire did internally
Thank You Leon Pugh
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