At wits end W/merc 250 Pro XS

[riggpigg]

2008 Mercury 250 Pro XS. Ser.# 1B47794
2008 RANGER Z521
ULTREX W/36 VOLT & 4 BANK CHARGER
144 Hrs on smartcraft

This all started three weeks ago, I now know the motor was going into guardian mode, I thought I had bad fuel. I was getting a temp shutdown.
Trial and error through the last few weeks, Water pump impeller changed, twice, both thermostats replaced and block washed, poppet inspected and re-installed, I posted on here last week to ask about Power head gasket/poppet carbon.....and today had authorized repair mechanic pull power head and change adapter plate and base gasket. Buttoned it up (all looked good) ran it and same thing...WOT 10PSI. idle. .4 to .8 PSI.......we have not changed plate and pump housing and are doing that now..........Ive raised and lowered motor on jack plate and moved transducers and even removed them.......we simply have a true to life marine mystery here.........any ideas???

[rbarne4]

Hole in hard pipe?

[riggpigg]

We will check, poppet spring was carboned up pretty good???

[Tdparrish]

I don't have a pro xs but a mariner supermag that had the same issue rebuilt the poppet valve been running fine ever since

[fishinforchrist]

Have you cleaned the compressor strainer?

[Mark Weare]

Your water pressure readings, where do you get them from? Both are low, should be no lower than 12 at WOT, I have and prefer far higher. Idle should be a few psi, not part of a psi :)

[JOE54]

check for water flow at thermos dumps/ you have flow at compressor ????? no flow at either problem is lower or poppett

[riggpigg]

OK, problem solved, I went back and read and re read posts of issues and recommendations from the guys in the know.......the answer was here all the time, I just was too dense to understand the answer. The old saying of" if you don't understand the question you asked you sure as hell aint gonna understand the answer given" applies to me.....in another post paralleling almost the same problems Savage wrote a simple one line suggestion, actually this is the cut and paste of it.............I would remove the shift shaft carrier and inspected the water intake passages.
I called my mechanic and made the suggestion, he actually was in the process of doing just that.......it was full of wood, I could blow air in it and feel a return but after cleaning there's a huge difference....now this evening with it all buttoned up its running 21PSi at WOT.......FIXD!!!!!!!!!........Had I been smart enough to realize that the help was here all along and the answer had been given already Id have saved $$$$$$$.....as it is, I have new Thermo, 3rd Impeller, new plate and pump housing, new adapter gasket and base gasket, and a lot of knowledge about this turd that I didn't think Id ever need...........Thank You Savage.........you were correct, I had the answer from you but I simply was too dumb to realize it.....Now, if any one ever needs help with a reverse solenoid on a boat trailer Im educated about that as well..................lets go fishing.......

[Savage]

Happy for you!!!

[tomloans]

Thanks for posting. All these post will help someone and we r all learning from these.

[EuropeanAM]

Good info.

BTW... be sure to check your serial number (it's incomplete) for next time.