1990 285 Pro 175 Evinrude XP

[k2rider18]

Alright folks I need some vast knowledge and experience sent my way. My boat will not run past 55 MPH at top end. I am currently running a 25P renegade and I am only turning 4800-5000 rpm. I had dropped down to a 24 with no RPM change it is still the same. My local place I go to fix it said that I needed a reverse wedge plate(i think he lied to me). So I put one on and it gave me more bow lift as desired. The only thing now is my prop throws a rooster tail 15 ft high. I had the engine rebuilt by Coastal Performance Marine about 24 months ago. The compression is good and all that. My water pressure guage also has always been about 13 PSI @ WOT. I have no clue why my boat will not turn the proper RPM's. I have tried 3 different props and the highest RPM change was on a 23P Renegade and it went to 5200-5350 RPM and that was it. If anyone can help me out it would be greatly appreciated. I guess all in all I love my boat but something has to be done about the RPM's rising or its outta here.

[ChampioNman]

First off what is the propshaft to pad height. Second verify that the throttle plates are opening all the way at WOT. Are you running a plate? Are you bolted directly to the transom? Has the tach been verified? Has WOT timing been checked? If so what is it?

[k2rider18]

I had a 6" set back on the boat but took it due to not being able to put the motor at the correct height. The jackplate was used and did not allow it to high enough. So the motor is bolted directly to the transom. The carb plates are wide opened at WOT. I can rev the tach all the way to 6500 RPM's in neutral and the WOT timing is 28 degrees. I will go run in again today to verify everything.

[Lockjaw]

Your boat may have taken on some water and have wet foam.

I had an 89GT175 on a basshawk with wet foam, and it would only turn a 24p raker to about the same RPMS you are getting. I did all sorts of testing on the motor, but it turned what it turned.

I did add the high compresion heads and boysens, which gave me 400 more rpms. But running super unleaded sux right now. It was totally different engine however.

It would be interesting to see if you took all your equipment out of the boat and weighed it. I bet you would find the hull weighs more then its supposed to weigh.

[go-fish]

I have the exact same boat and motor as you do. Only I run a 5" HiJacker. Yours should run about 62-65 (speedo) with the 25" Renegade, that's what mind does at about 5450 rpm. 25" Raker pushes it about 68, all speeds w/ one person, loaded. I quickly measured mind and it's about 3 1/2 " below pad. Owned since new and has run the same since new. How long have you owned it and has this problem been there since or something new? Like stated it may be water logged making too heavy to get up on the pad. Had chance to remeasure and it's at 4 3/4" below pad, sounds low but it runs great.





Modified by Igofish2 at 10:37 AM 1/5/2008

[Lockjaw]

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by k2rider18 &raquo;</TD></TR><TR><TD CLASS="quote"> I can rev the tach all the way to 6500 RPM's in neutral and the WOT timing is 28 degrees.</TD></TR></TABLE>

You need to check your tach then, because the rev limiter on those engines is 5850rpms.

[fastman151]

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by k2rider18 &raquo;</TD></TR><TR><TD CLASS="quote">. I can rev the tach all the way to 6500 RPM's in neutral .</TD></TR></TABLE>

Hope you're not doing all that revving in the driveway!!!!

[k2rider18]

For some reason yesterday I ran my boat and it ran a heck of a lot better than normal. The day started out pretty cold about 17 degrees and the river was iced over. Got the boat up on plane and went WOT. I ended up turning 5650-5700 RPM's but the speedo wasn't working and I could find my hand held GPS. So I don't know how fast I was going. I just recently had my water pump replaced and the water pressure is still at 12-15 PSI @ WOT. I don't really know whats going on with the engine if it likes the cold water and air? I did clean my carbs (not the bowls) out before I took it out there. Any more advice would be greatly appreciated and I will try and weigh my boat ASAP.

[go-fish]

I know that the older Evinrudes & probably all 2 cycle engines have problems with carbon build-up, that's why I have never ran a tank full of gas thru my 1990 XP 175, since new, without using OMC Carbon Guard. Use the OMC or Sea Foam and that will make this engine's rings & combustion chamber cleaner and run free and keep it running like it should. Never tried Sea Foam, but have heard from others that this stuff will really clean out an engine and make it run. The more it's ran the better it gets Good Luck

[Lockjaw]

My flow ran ALOT better in the cold then in the summer. So that has something to do with it. Of course there is a saying, they always run their best right before they blow.

When is las tiime you decarbed it?

I would get some epoxy and plug the top hole of the water intake on each side. You can use silcon to try it first if you like, see if it brings your pressure up. I could jack mine up where it had pretty good pressure, until I turned, then it went away. Be careful doing that, you don't want to rebuild one.

I got 2 power packs for the way.

[Lockjaw]

Seafoam is good stuff. I use it and also run carbon guard. Seafoam will clean one out in a hurry.

[k2rider18]

I have never decarbed my engine cause its pretty much brand new. I have maybe 12 or 13 hrs on the rebuild so its basically just got over the break in period. I will plug that top hole tonight with epoxy or silicone don't really matter i guess. Keep the ideas coming.
T/L