2007 150 Opti idle problems, Ser.1B506937

[goinfaster]

I've been having idle problems for the last two seasons. I've had two reputable marinas try to fix it but they have not been successful. They've of course changed plugs, a couple of coils, fuel filters, ultrasonically (supposedly) cleaned the fuel injectors, all the easy stuff. It sets no alarm codes. It still stumbles intermittently at anything less than 1000 rpm and dies. It will then start right back up and runs fine at higher rpm. I've scoured these forums looking for the solution and it seems the tracker valve may be questionable. The motor only has 254 hours on it so I can't imagine it has any damaged reeds. Any help will be greatly appreciated!!! Thanks in advance!

[JOE54]

if it was tracker it would run horrible,possible but i too dout reeds,we'll need some detailed readings of fuel/air psi when problem occurrs

[goinfaster]

if it was tracker it would run horrible,possible but i too dout reeds,we'll need some detailed readings of fuel/air psi when problem occurrs

Ok, thanks Joe!! Can you refer me to a method for these pressure measurements please?
Thanks
Don

[JOE54]

a set of dual glycrin filled guages will be needed to get reading when problem is occurring need to monitor fuel and air psi at same time search on here for fuel/ air psi testing, report back

[SilverFox579]

A genuine Mercury service manual is highly recommended got mine from board sponsor European Marine - If you want to order or price Mercury Engine Parts or Accessories

[goinfaster]

A genuine Mercury service manual is highly recommended got mine from board sponsor European Marine - If you want to order or price Mercury Engine Parts or Accessories

Thank you SilverFox, I do already have one but it doesn't give every troubleshooting step possible for this malady. Will be gearing up to measure fuel and air pressure when this weather breaks a little.

[goinfaster]

OK, I'm back with data:

At Idle, fuel read 90, air 80

Acceleration, fuel 90, air 80

After Shutdown

15 seconds, fuel 80, air 73

30 seconds, fuel 75, air 68

60 seconds, fuel 71, air 64

During acceleration the glycerin filled gauges read extremely smooth. At idle the fuel bounced about 8psi. The air gauge bounced about 4 psi.

Thanks for all your help! What next?

[EuropeanAM]

Those aren't really out of line.

Any signs of rust or flaky-paint on the lower teeth of the flywheel?

Check the under-side of the flywheel cover carefully for any signs of rubbing against pulleys or belt. If there is evidence, it's quite likely you have plastic shards/grindings stuck in the bottom of the air handler (and in the reeds), which can result in poor/intermittent sealing of the reeds.

[goinfaster]

Inspected the flywheel area upper and lower and everything there is clean as a whistle. No signs of rubbing or distress on the flywheel cover either. The alternator shows a sort of polished area about 1" long where possibly the belt has rubbed somehow. That edge of the belt is smooth as can be. Overall condition of the belt is very good.
I then looked with a strong light source down into the plenum. Interestingly could see about 10-15 very small shiny "particles" stuck to the wall of the plenum. I then used an inspection mirror to get a look at the reed area. Could see nothing unusual looking there although I know that wasn't a real good view. So, I decided to see if I could retrieve any of those shiny particles. Put a little grease on the end of a magnetic retriever tool and carefully contacted a few of them. Found that they would not move! I got a very good push with the edge of the magnetic and they are not coming loose. Almost looks like tool damage could have pushed up those pieces - about the size of a pin head or smaller. But I can see no damage to the wall surface of the plenum that would confirm this.

Thanks so very much for your help!!

[EuropeanAM]

That's good. Four more simple suggestions:

1. Inspect the adapter plate area for corrosion or white/grainy material (sand/salt residue) with the lower cowlings REMOVED. If this is found, report back for suggestions.

2. Double check proper spark plugs, proper GAP, and that plugs are seating fully against the cylinder head (seating the crush-ring and torqued to 20 lbs/ft). Have seen a couple that for whatever reason the spark plug threads simply didn't get threaded all the way through, plug would pull down to torque but didn't seat at the right depth (the "clue" was that the crush-ring never was crushed).

3. Just for one-time diagnostic purposes, disconnect the shift position switch (unplug it) and run the engine to see if any difference is noted. NOTE: Engine may be slightly difficult to pull out of gear so it's a good idea to plug it back in before docking/trailering.

4. If all above are fine or don't resolve the problem, see if you can borrow a known-good MAP sensor (from a friend, etc). Virtually any Optimax V6 built from July 2000 and on would have a compatible sensor. (Checking to see if an oil pocket or bubble has formed in the sensor causing it to fail "in range").

[goinfaster]

1.Adapter plate area is very clean with the lower cowlings removed.

2. Proper spark plugs were installed (IZFR5G). Found gaps ranging from .022 to .035. Also found two of them that were extremely tight (I'd guess at least 50 ft-lbs!). They came out with no thread damage than goodness. All crush washers were crushed and the plug seating areas are clean and smooth. Spark plug coloring and condition were pretty normal and consistent.

3. No difference was noted with the shift position switch disconnected.

4. I don't have a source to borrow a good MAP sensor. I could start asking around but am not optimistic about finding one.

Additionally, when I started from cold, I noticed that the engine was idling smoothly at about 670 rpm. per my MercMonitor. I watched it closely as the coolant temp came up and noticed that the PCM must lower the idle speed as the temperature increases. Once it got above about 90 degrees, the rpm had dropped below 600 and it started idling roughly again and shortly died. Hope maybe this observation might help!
Also, I have photos of the above observations if you think seeing any of them might help.

Thanks again for hanging in here with me!!!

[EuropeanAM]

No problem.

Coming to the end of what we can realistically check by keyboard/monitor- but here are three other commonly-overlooked items that should be verified:

-Alternator Mount(s) and Belt. This is a very long belt and tends to stretch- when it does, it often slips at idle (as it gets to slapping back and forth). Recommend belt at 4 years or 400 hrs, whichever occurs FIRST. DON'T overlook the mounts for the alternator- the aft one is notorious for being loose (or bolt damage).

-Reeds. Eluded to earlier- best inspected with the air handler REMOVED. If it still has steel reeds in it, recommend replacing with TDR.

-Rails/Injectors (LAST RESORT): Improper function or flow from injectors is often first noticeable at idle. Rails/injectors/direct injectors should be validated and serviced, all at the SAME time.

[goinfaster]

The manual indicates spark gap at .040. In your experience is that good? Seems a bit wide even for such a high energy system.

[EuropeanAM]

The later ProXS models used a wider gap, but most of these engines were at .033" gap (IZFR5G).

[goinfaster]

Back with another update - it’s been awhile. I haven’t had a lot of chances to be out on the water unfortunately.
I changed the belt even though the old one looked good. No improvement.
I’ve since had the motor to Gwinn’s Boat Repair, near Hot Springs, AR, one of the most reputable shops in the area. They had it for two months, tried changing every sensor that I’ve ever heard of, the compressor, the ECU, pulled the air handler and checked reeds, coils of course, and still no improvement. The good thing is they charged me nothing!! I tried and tried to pay for some of their time but they wouldn’t have it.
i had the boat out today and now it is cutting out above 4000rpm also. Runs great between 900 and 4000. I’m thinking it has to be fuel delivery related somehow.
Help ???!!!

[JOE54]

i did #4 ^^^^^ above , need for monitoring fuel psi at "above 4000 rpm" , imperative we know what fuel psi is doing at that rpm range to correct the problem

[goinfaster]

Thanks Joe! See #7 above. Those acceleration readings were right up to 5300 rpm.

[JOE54]

different set of plugs ?????

[goinfaster]

Joe54 - sent you a private message. Thanks!

[JOE54]

got it