This is the story so far: (Sorry for the long intro but I have to get it out of my system!!)<br /><br />Bought a 152 Donzi Medallion with a 90Hp force SportJet engine (OEO54226). When I bought it the engine was not working because the previous owner had blown it up. So I took it to the mechanic and he rebuilt it. New Pistons..the works...<br /><br />After the rebuilt I tried the boat and I couldnt get it to plane. It seemed to give out power in the beginning but at the end it would sound as if the rpm's drop a bit and that was it. In order to plane the boat I would have 2 people sitting right at the edge of the front of the boat. When it would finally plane out the boat would go at a maximum of 25mph.<br /><br />I went back to the mechanic and he told me that he couldnt help me because the engine had no problem. He said that it must be something else in the jet.<br /><br />So I checked the jet (Different mechanic) The jet was fine. Time was passing by and frustration started to kick in.<br /><br />Then I discovered this Bulletin Board and my life changed!!!! I decided after spendind $2000 that I would take matters into my own hands. So I started reading and performed the following test.<br /><br />I started the engine out of the water and started pulling the spark plug cables one by one. When pulling cable on cylinder #2 and #3 I could hear the engine losing rpm but #1 made no difference. So I took the boat back to the mechanic that rebuilt the engine saying that the problem was OBVIOUS! He told me that I should never test the engine this way and that I might have burnt the ignition system. He then did some tests and told me once more the engine works fine!<br />PLEASE HELP!! Could this be true????<br /><br />I decided to re-built the Carb on #1. I've opened the carb but it looks very clean. The only thing I noticed was that middle tube a long nail kind of thing was not completely straight and was touching one of the sides of the tube it was in. (Sorry for the description Item no:21 on carburator diagram). How can someone calculate how much to turn the screw that adjust the mixture?<br /><br />I also discovered that the spark plugs where wrong. It had BUHW instead of BZUHW-2 (I got BUHW-2 without the Z). Could that make a difference?<br /><br />I have measured compression on all 3 and it is fine #1 148 #2 155 #3 155<br />Also When I take out the spark plugs they all give spark.<br /><br />The only thing I dont have (still trying to find) is something to count the rpm at WOT.<br /><br />My mechanic also mentioned that I might have the wrong impeller. What would be the right impeller?? How can I check my impeller. Do I need to take the whole engine apart???<br /><br />PLEASE PLEASE HELP. LOTS OF QUESTIONS.. NO ANSWERS!!!!!!!<br /><br />Lucas
. I got a new impel or once (this is the water coolingtype) they would not order me the Impellor to fix myself so I let them do it, I said only replace the impellor... When I got back two weeks later I had a 500 hundred dollar repair bill. they said I had pistin and gas probs (I did not I fixe all my engines my self) I asked if I could see these replace items. they did not, I then had the father of the Marine place come over and yelled at the mechanic..... he was trying to get more mony so replaced unesesary parts.... got it all and the old parts for free