90 hp Engine trim stuck in the up position can not trim down

DTC P0171: Fuel Trim System Lean Bank 1
DTC P0172: Fuel Trim System Rich Bank 1
DTC P0174: Fuel Trim System Lean Bank 2
DTC P0175: Fuel Trim System Rich Bank 2

Circuit/System Description
The engine control module (ECM) controls the air/fuel metering system in order to provide the best possible combination of driveability, fuel economy, and emission control. Fuel delivery is controlled differently during Open Loop and Closed Loop (CL). During Open Loop, the ECM determines fuel delivery based on sensor signals without heated oxygen sensor (HO2S) input. During CL, the ECM adds HO2S inputs and level of purge to calculate the short and long term fuel trim (FT) adjustments. If the HO2S indicates a lean condition, the fuel trim values will be above 0 percent. If the HO2S indicates a rich condition, the FT values will be below 0 percent. The short term FT values change rapidly in response to the HO2S voltage signals. The long term FT makes coarse adjustments in order to maintain an optimum air/fuel ratio. A block of memory cells contain information arranged in combinations of engine RPM and engine load for a full range of vehicle operating conditions. The long term FT diagnostic is based on an average of cells currently being used. The ECM selects the cells based on the engine speed and load. The FT diagnostic will conduct a test to determine if a rich failure actually exists or if excessive vapor from the evaporative emission (EVAP) canister is causing a rich condition.
If the ECM detects an excessively lean condition, DTC P0171, P0174 sets. If the ECM detects an excessively rich condition, DTC P0172, P0175 sets.


DTC P0017: Crankshaft Position (CKP) - Exhaust Camshaft Position (CMP) Correlation Bank 1

Circuit/System Description
The engine control module (ECM) uses the crankshaft position (CKP) sensor and the camshaft position (CMP) sensor pulses to monitor the correlation between the crankshaft and camshaft position. The crankshaft reluctor wheel consists of a 60-tooth pattern with 2 teeth missing for a reference gap. Each tooth is evenly spaced 6 degrees apart, except for the reference gap. The camshaft reluctor wheel has 4 teeth, 2 narrow and 2 wide. The 4 trailing edges of each tooth are evenly spaced 90 camshaft degrees apart. As the crankshaft rotates with the CMP actuator in the home or parked position, the ECM expects CMP sensor pulses to occur 36 crankshaft degrees before top dead center (BTDC) at cylinder number 1, and every 90 camshaft degrees thereafter.

Hi. Uncertain if you own a runabout or a larger boat but this might help. Because you have tried both control positions for the trim adjust, I suspect the trouble lies with 1. power to hydraulic pump (or electric ratchet motor if so equipped)
2. frozen, corroded or stuck trim plates or transom mount swivel points.
3. Check for correct levels of hydraulic fluid in system or test for correct voltage to ratchet motor(s) if this is the system used. Use a jumper cable to directly power the motors or activators if low, or irregular voltage found. Test again.
4. Any obstruction or debris deposition at or near the working parts.
Finally, a local marine mechanic will tell you what is wrong and the cost to fix.
Hope this helps.

Low fluid level will cause it to fail to actuate and not go up or down, can also let it not hold position as well. Filling to proper leevel with specified lubricant is recommended. If you allow the level to go too low, the pump will pull air and could burn out.

most of these will come off if you lift the engine to fully up and lock the lever up to hold it there ! Then you can access the trim motor , clean off around it then undo and remove the motor after disconnecting the wires near the carbs !

You have to remove starboard transom bracket,then remove circling from t/tilt release screw,remove screw,left hand thread.There is a flat washer that normally sticks to screw/valve,this needs to be replaced.Its easier to do this with motor trimmed up or if motor is off boat,lying on its side.Very little oil will come out if done in trimmed up position

check trim switch with multi metre ! check solinoids not stuck !

Stop! Dont replace the pump...I would bet that it is the "down" Solenoid that went haywire. I would begin by replacing the Down solenoid...it is a far easier and cheaper fix and if your pump works to raise the engine then that tells me that it is not faulty. The Down solenoid looks just like a starter solenoid and the one that you are looking to replace has a GREEN wire to it. Yellow with a red stripe is for the starter. Blue wire is the up solenoid. So replace the one with the green wire going to it and I bet it will fix your problem.

there is a support on left hand side you may not have noticed -lift motor and support and flick the lever down -it will then be on the power lift-they say to use this support to take pressure off of hydraulics

find the solenoid for the trim it will be a the engine or on the trim motor it self get a test lite and find the power wire on the trim motor and with someone pushing the trim button test the hot on the motor if there is no power it is the solenoid if there is power u my have a brush stuck in the trim motor itself but 99% of the time it is the solenoid u can tap the trim motor and see if that gets a result but dont hit hard