Mercury pro xs 2009 1B551344 idle issue

[lpugh]

]Water pressure is good and I don’t see what that would have to do with dying when shifting into gear[/B]. And if compression was off I’d think it would run rough at idle or in gear. I plan on having them check fuel and air pressure when I can get it to them

You may not, I do, Important information to help diag accurately.
Just went thru this on a 200 opti, had a blown 0-ring head seal on #2 cylinder, only had 10 psi compression drop but 60% leak down. water pressure varied greatly at idle .5 to 2.2, mostly on the low side. Also came up to temp in less than 1 minute on port side. Hot combustion gas flowing directly on to the temp sensors until water pump could purge them.
Similar symptoms as yours.
Took 2 days for me to nail this one,

[RBwd8506]

I was debating removing the diaphragms to inspect to see if any had tears in them but I know one requires a special tool. Is there any way to do this without that tool?

[JOE54]

I was debating removing the diaphragms to inspect to see if any had tears in them but I know one requires a special tool. Is there any way to do this without that tool?

wouldn't recommend it , if you have no liquid fuel present at air Schrader when depressed at idle highly unlikely you have a ton diaphragm

[RBwd8506]

That’s the port Schrader, correct

[JOE54]

yes sir thats it

[RBwd8506]

No fuel out of port side just a touch of water. Still acting up and getting worse. Not able to get into the shop till after winter. Just wanted to post that I’ll follow up with results. Sucks I haven’t been able to get it in and still have the issue. Mechanic is having shoulder surgery so we made a plan to bring it in around February

[JOE54]

i just couldnt wait that long , come down mabe DEC and go fishn

[EuropeanAM]

+1... Continuing to run an engine in this condition can potentially affect the engine's longevity (perhaps significantly).

[RBwd8506]

I agree don. Don’t plan on it. I’m in Ohio so my season is basically over for me. Thanks

[RBwd8506]

Just thought I’d update. It’s been at the shop for a week. They finally got it to act up after a few days but haven’t found the issue. They found corrosion on the wiring harness that they thought was the issue but still acting up after that fix. They checked the reeds and they were good also so not sure what’s next for them to check. They said it has ran great other than the occasions it dies when putting in gear. Said the first day it was about the 25th time before it acted up. They also pulled the lower u it and looked at gears to make sure something wasn’t wrong there just to make sure. Everything is fine. I’m over this issue

[EuropeanAM]

Here's something I don't think we've looked at in this thread. Measure the gap in the throttle plate. Must be at the highest point between the blade and the body- 12-o-clock position, closest to the flywheel. The measurement needs to be within .001" tolerance. If you don't have wire gauges, use the solid end of a good set of drill bits (just don't drop in engine).

Pull the wire gauge or bit out and make sure the throttle plate doesn't "glitch" shut (making sure you're exactly parallel to the throttle body inner wall). Repeat several times until you have a very precise measurement from the bit(s), and return with the result.

Sorry... this one is more important to measure what it actually IS. For very good reason.

[RBwd8506]

Talked to the mechanic today and he said the throttle plate air gap was dead on. Compression was good on all the cylinders. Said he did figure out it’s getting to much gas at idle on one cylinder I couldn’t hear him on the phone when he explained how he came to that conclusion as my phone cut out. all the direct injectors tested good and the fuel injectors tested good but does believe it’s a faulty fuel injector I guess.

[RBwd8506]

With the throttle plate gap I didn’t ? Him as to what the measurements or what he meant by dead on. Sorry

[EuropeanAM]

Be interesting to hear what the measurement was.

Another thing that can cause excess (unmetered) fuel would be the pulse fuel pump diaphragms.

[RBwd8506]

I rebuilt the pulse pump last season when after this issue started and it didn’t help

[EuropeanAM]

I rebuilt the pulse pump last season when after this issue started and it didn’t help

OEM Kit? 110% certain there's no pin holes in a diaphragm, a gasket mis-oriented, etc? If there is unmetered fuel, it IS coming from SOMEWHERE...

[RBwd8506]

Yes oem and the issue didn’t change after rebuild so I’d say it wasn’t the problem. Rebuild is pretty straight forward and everything looked fine when rebuilt

[RBwd8506]

Just got the call they are done with it finally. Was an intermittent issue with one of the injectors dumping to much fuel. Changed that injector and ran it multiple times today and haven’t had the issue so. Hopefully that solved this on going issue. Thanks everyone for your input and help