Trim Pump Issue (Bravo 1)
 

Hello,

In prepping my Donzi 22 ZX for launch this year, I noticed an issue with what I presume is the trim pump. The trim will raise normally (pump runs and sounds fine when raising the drive).

When I go to lower the drive, the pump sounds like its laboring and it takes considerably longer than normal to get the drive back down. The pump almost sounds like it would if connected to a nearly dead battery (this isn't the case, two fresh batteries on board and no other electrical issues).

Just looking for some insight on what to look for to diagnose/fix the problem. I'm not experienced with servicing I/O sterndrives so I'm hoping this is a simple fix.

Thanks,

Rob

Don't know how bad it is but the pump makes a lot more pressure going up, about 3000+ psi compared to going down, about 500 psi.. Keep in mind while running the prop will be pushing it in when you operate it down.

i agree with this assessment but the pump shouldnt be laboring. did you do anything to the trim pump, hydraulics, or fluid?

its interesting that you would have that problem because usually if the trim pump runs/operates good one way (i.e. up) then usually it will run good down. reversing polarity on the motor shouldnt make a difference. hmmm. are your fluids topped off? if so, take a sample and make sure its clean (no water). maybe you have a bad seal somewhere.

Unhook the rams from the drive and cycle them in and out and see if it still labors when pulling the rams back in.

This weekend I will attempt to drain and refill the reservoir, bleed the system, and run it with the rams unhooked to see if there is a difference and report back.

What type of fluid is typically used in the trim pump?

Also I notice there are two solenoids on the pump bracket (I presume one is for up and one for down), could a bad connection or solenoid cause the pump to stutter?

You could clean the connections on the solenoid. Usually they either work or they don't.

The pumps can be filled with either Merc Power Steering/Trim pump fluid, 10W30 motor oil, or ATF.

Messed around with it again this weekend and here are my findings:

- Removed the trim pump bracket/solenoids completley and jumpered the pump leads directly to 12V; pump runs fine in the raise direction but shudders in the lower direction

- Removed the trim cylinders from the drive and verified that the drive moves freely

- Attempted lowering the trim with the cylinders removed from the drive and again the pump shudders

I've eliminated the drive itself and any possibly of an electrical issue, leaving only the trim pump/motor and the cylinders. Are there relief valves or anything in either the pump or the cylinders that could be stuck?

Since the pump runs in one direction without issue, I'm leaning away from it being an issue with the pump motor, thinking its more a hydraulic issue. Thoughts?

Thanks.

A Loooong time ago;
I had a 93 Bravo that the trim bled down on. Inside the reservoir are check valves that were leaking. The new parts were a revised design. After I installed them the drive trimmed in/out faster and didn't let it bleed down. It wasn't enough of a difference to warrant doing the other trim pump.
Easy fix for me. Hope yours is as well.

if you take the pump housing off the reservoir there are two screens that could be gummed up