2011 Optimax Pro XS - In service date Jan/2012
Engine# IB861903
287 hours
Tracker Valve maybe 30 hours. Rebuilt the pulse pump, replaced tracker valve, cleaned out the VST, replaced all the fuel lines last year all at the same time.
New plugs ran once.
Same engine in another thread, but thought for clarity I'd start a new thread.
Problem is rough idle, almost knocking, down on power, doesn't want to come up on pad. Will... but last time out it took 2~3 tries. NOT going back on the water till it's fixed.
First diagnosis by a local shop, NOT a Mercury shop (Yamaha/Suzuki dealer): Air in fuel rail, fuel in air rail, #4 running hot. The owner at this shop is a good kid, he's helped me out reading the ECU and doing an oil pump prime for me for free. Then looked at it 2 weeks ago for free as well. Good kid, but not equipped to dig into the Opti. They sell mainly pontoons.
I have the shop manual, and do all the work myself that I can possibly do. Been working on engines since I was a kid picking up races in the Shoney's parking lot in the early 70's.
Bought the Merc air/fuel gauges, as well as the tool to replace the air and fuel diaphragms, even a Mercury injector pulling tool. Along with a vacuum gauge and compression tester. What can I say... a man should have the right tools to do the job.
Today first diagnosis:
Pressurized 80# air to the port side rail. Didn't hear any leaks, especially around the compressor. Depressurized starboard fuel rail via Schrader valve nothing came out. Tried to vent air rail (port side) fuel spit everywhere. Like an IDIOT I didn't have my safety glasses on. ALMOST took it in the eye (got an earful though).
Decided to be smart and hook up these newfangled air/fuel gauges and vent the SAFE way.
System pressurized, fuel comes out air rail.
Cranked it up:
Air pressure 92~94 (didn't have my reading glasses on).
Fuel pressure 112~114. (seems a bit high)
Vented both sides in short bursts via the gauges while it was idling, engine would sputter as expected, and recover fine. Idle is rough though and it's knocking (detonating?).
Air rail spitting fuel.
Pressure after shutting down:
0 seconds, 92 - 112
5 seconds, 92 - 110
10 seconds, 88 - 100 maybe
15 seconds, 86 - 100
1 minute later 82 - 82
(I'll have to record these better tomorrow, no glasses, and getting dark today.)
I can get low pressure fuel readings and vacuum at the pulse pump tomorrow hopefully. I'll also get air pressure, fuel peak pressure, and both air and fuel volume readings per the manual. Will also get cold compression readings, (hot maybe, but it's really skippy sounding).
Don told me how to check for a leaky fuel injector in the rail (before I'd read the procedure in the manual) so I'll get that done FOR SURE. Easy enough to stick a piece of paper behind the rail and look for 'spitting'.
Seems it's pointing to fuel injector #4 having leaking o-rings (because it's obviously skipping, and via infrared running hotter, and the plug is 'sooty' after not an hour run time). Either that AND/OR the fuel pressure diaphragm, especially with 20~22 pounds differential.
I'm thinking with the pressure differential the tracker valve may be in good shape. As noted above, it has maybe 30 hours on it. Perhaps its 'holding' the air pressure fine, but the fuel is high from either the leaky injector, and/or the diaphragm, which it's also holding.
Would it help to run 90# air to pressurize the system and listen for leaks. *Considering the specs call for 92 air - 106 fuel.*