'20 Merc ProXS 250 Upgrade issues

[gsb0824]

Just upgraded my '18 250 ProXS 2S to a '20 ProXS 4S, i.e. serial number 2B739267. Don't even have two hours on it yet. First time out, couldn't get past 5200 rpms. Took it back to the dealer who put it on the computer, adjusted the hotfoot and said it is getting 100% WOT. Put it back on the water and can now get 5800 rpms at WOT, but speed is 6 mph slower than my old 2S. Running a 23P Fury, have an Atlas JP that I have tried at different heights but found the sweet spot to be at level 8. I am doing half trim. I suspect I am still not getting 100% WOT but also wondering if I am doing something wrong. Does anyone else have a Ranger 520L with this motor, and if so, what rpms and speeds are you seeing.

Second issue, on the MercMonitor Level 0, when I trim the motor the trim gauge pops up, but it will never get past 25%. It will go to zero, but not past 25% even at full tilt. My water pressure gauge was not working but that was fixed.

Any advice would be appreciated.

[jchips]

My 19 520L Merc 4 stroke ran 72mph tourny loaded. I've got about 10 hrs on my 2020 and the performance is the same. That's with a 23P Fury on both rigs with the plate at 8 on the gauge. In cooler weather , it will run that with a 24P 4 blade Fury. You should be getting at least 6000-6100 rpm if the throttle is going to 100%

[jchips]

The trim sending sensor was bad on my new engine. Same thing was happening on the monitor. First time I ran the engine, it would get to 4200rpm and kick into guardian mode. I disabled it and the engine ran fine. Waiting on Merc to send another sensor. This could be part of your problem if the sensor is limiting your trim

[gsb0824]

Thanks, this helps a lot. I don't get near that with the same set-up. Did your 2019 have the hotfoot with the notch in the petal? My hotfoot has the cable at the top and I had read TH changed these for the 4S to include a notch so it had more room to travel. I am grabbing at straws trying to get this fixed.

[gsb0824]

Thanks! I would think my dealer would have caught this but at this point, I think they are getting tired of me. Wonder if I can replace the sensor myself? My MercMonitor is getting some sort of signal because it the trim screen pops up when I trim, but I never can get it past 25%

[jchips]

Truthfully either hot foot can be adjusted to bring the throttle to 100%. I'd have your tech check your trim sensor, and make damn sure you're getting 100% throttle. Sorry you're having issues. These engines are awesome

[jchips]

You don't want to tamper with the engine unless there is something that is simple to figure out. Your engine should easily reach 6000-6100rpm if it's set up right. Have you tried over trimming and looked at rpm?

[jchips]

The trim sensor is located below the trim switch on the shaft the engine pivots on . I simply turned mine around so it couldn't function and the engine ran fine. Pm me your cell number and I'll call and post pics. You could take the trim senor out of the equation one way or the other that way.

[EuropeanAM]

DO NOT MODIFY THE TRIM SENSOR OR IT'S INSTALLATION. Trim Level DOES NOT EXCEED "25" EVER on Smartcraft- 25 is "full trim".

So your gauge apparently is showing you what it is supposed to. Should be at approximately "10" when it reaches the end of the short trim rams, and "25" when it reaches the highest (safe) tilt angle.

What prop were you running with your last engine (and specifically what engine/gearcase did you previously have)?

I agree- it's likely that you have setup problem, very likely in the throttle setup.