How much difference is there.3-4 seconds.Mine run 9 seconds full up to full down starbord and the port runs 5 seconds.

A friend had this problem on a new boat. Merc's solution was to put a lighter weight oil in the slow pump. After a little while of trial and error they replaced most of the oil in the slow pump with a lighter weight oil which helped the problem but never completely solved it. I use the both switch. Mine work about the same speed but if they get off I just adjust with the seperate switches.

Ron

If both tabs are all the down or up there is about a 1/4"-5/16" at half way and about a 1/2"-5/8" at end of stroke measuring the cylinder rod itself. I know it doesn't sound like much but it makes a huge difference especially at cruising speeds.

I already have power steering fluid in both.

Okay, I am pretty mechanically inclined but I know very little about electrical stuff except basic wiring. When you say put a diode in line are you basically saying have a switch so I can use the two sets of switches seperately?

One thing you might check is to make sure the line are hooked up correctly, all trim pumps have a high and low pressure side. The high side should push the tab down and will usually flow more oil

If you used a Double Pole Double Throw (DPDT) switch you could activate two trim pumps with one switch. Works well if the switch is activating solenoids.

I had that problem once, tried all the electrical bs I ended up tearing the pump apart, and there was a bunch of **** in the resivor and in the strainers, I cleaned it all up and put new o-rings on everything.

Problem solved!

If you tie the two lines together then when the pump is not running if you apply preasure to one of the tabs and not the other for example when turning the boat,, the fluid will be forced out of the piston of the inside tab as it is forced up by the greater preasure thru where the lines are tied together into the piston of the other tab causeing it to move down. So the tabs will never be even and will flip flop up and down and you will have NO control of them and this will create a very dangerous situation.

You cannot put hydralic cylinders which are not mechanically tied to each other in parallel as one can act as a pump to the other.

To witness the effect the next time you have an out drive off and the two trim cylinders are no longer mechanically tied together by the outdrive push on one, the other will move out.

Just buy the diode kit from Merc used on the Zero Effort Shifters with trim switch in the handle of a dual shifter. It will work on tabs the same as it does on trim pumps because they're the same pumps and solenoids.