Force90hp no power/wont plane

[sdk19056]

Hi Im new to this forum, this is my first post. There seems to be alot of knowledable people around here, hopfully someone can help. I will try to tell as much as possible about the problem/situation. Here is my problem, I just bought a 1994 bayliner jazz (yes i know they are kinda gutless and cheaply made, but i didnt pay barely anything for it) with the force 90hp motor off of my parents. The boat has sat for a couple of years without use. I have just had the impeller replaced as i knew the old one was in ruff shape. I am finding that in order to get the boat to get up out of the water or plane i have to have one person sitting on the front of the boat. it just doesnt seem to have that thrust out of the hole anymore. I have replaced all sparks plugs and added fuel and carb treatment to the fuel. I just finished doing a compression test and all cylinders are above 110 (is this good?) which i believe is ok. I also checked to make sure spark is getting to all plugs. I cant say for sure, but the engine does seem to rev out ok, its hard to tell without a tach. Does anyone know anything about these boats or motors that can give me some pointers on where the problem could be?

 

[eurolarva]

Re: Force90hp no power/wont plane

Hello sdk and welcome to Iboats. How does it idle? 110 compression is pretty good but it is probably better than that. The motor should be tested warm and the throttle needs to be wide open. I would not worry about that now. As long as all the numbers are within 10 digits of one another it should be fine.<br /><br />I am not a firm believer in fuel treatments and have never heard of them doing any good on an outboard apart from seafoam or other types of decarbon sprays. If you are using old fuel you should get rid of it and use fresh gas mixed 50 to 1 with marine grade oil. To start with the carbs and the fuel pump should be rebuilt along with replacing the fuel lines and clamps. A service manual by clymor or syloc is a must. A factory manual is the best but if you have never worked on a motor the syloc or clymor will explain how and why things work on your motor. Most problems outboards have revolve around fuel. The biggest problem is fuel left over from last year without some stabilizer in it. Here are the cheapest things you can do first.<br /><br />dump old gas<br />remove float bowl screws and drain all the gas from the carbs.<br />Replace the diaphram in the fuel filter (this is very easy to do and cost is under 10 bucks)<br />check all fuel lines by bending them looking for air leaks. I would just take a sample of your fuel lines to NAPA and replace all of them.<br />Verify your gas tank vents.<br />At the end of the year winterize your motor. (see frequently asked question forum)<br />You can start here and hopefully something will help

 

[sdk19056]

Re: Force90hp no power/wont plane

thanks for trying to help eurolarva. Yes there is fresh gas in it at 50:1 Its not idling all that great, but thats prolly becuase i was monkeying with the screw on all side of the carb (is that an air screw or a idle timing screw?) there is tilltson carbs on it. Also another things, i noticed the linkage arm that opens the carbs was not opening them ALL the way to i adjusted it so that it would do this. However when the carbs are opened that extra bit the engine rpm just kind of dies a little bit, but once i back off on the throttle again the engine rpm come back up again...could this be a timing or fuel issues? or just the carb not being set up properly for having the throttle opened up this far (since i dont think it was set to open this much from the factory) anyways thanks for the help, i hope to get this probs licked soon....

 

[sdk19056]

Re: Force90hp no power/wont plane

Opps sorry i meant Tillotson carbs are on the boat....another thing like I said the empellor was just replaced, the mechanic said he had a heck of a time getting ot of since it is of the type that screws on. According to him, whenever a rock gets in there it jams up on the prop and it tightens on the shaft even more. So basically he had to cut off the old empellor...now im just wondering if there is any damage to the shaft and maybe the empellor is slipping on the shaft?? could this be possible and how would i check for this?

 

[eurolarva]

Re: Force90hp no power/wont plane

The impeller should have no bearing on your throttle problems. It may be a concern when you replace it but it is not an issue with your other problems. I am not sure what your mechanics explaination means but lets get the fuel thing solved first.<br /><br />When you advance your throttle to max the butterflies in your carb should open to 90 degrees. At idle we will call them cracked or at 0 degrees. 90 degrees is the max opening. If you go beyond 90 degrees the butterflies will start closing in the other direction. This would make your motor start loosing speed.<br /><br />I would start by rebuilding the fuel pump. Then rebuild the carbs and the fuel lines. The cost is about 15 bucks per carb and 10 bucks for the pump. The kits are sold at NAPA. Carb kit is 18-7037 and the fuel pump kit is 18-7806.<br /><br />The screw that is towards the top of the carb above the choke is a mixture adjustment. The factory setting is 1 1/4 turns counter clockwise from lightly seated. YOu might try that or go to 1 full turn as a starting point.<br /><br />Do you have a manual on order. Check your local library. Look for under outboard motors and see if they have a syloc or clymor manual. The chilton book is not very good.

 

[duck-n-pond]

Re: Force90hp no power/wont plane

That throttle linkage, from what I can remember, is connected/related to the timing advance. Someone else may be more knowedgeable on this than me. Is the spark breaking down? I found out the hard way that a visual check may not suffice. Had to get a merc mechanic to measure the coil inputs to find out the voltage [peak-peak] was there, but too low. Spark looked ok just the same.

 

[sdk19056]

Re: Force90hp no power/wont plane

yes duck-n-pond the linkage is connected to the timing advance.What do you mean by the spark breaking down? Today I took off the carbs and cleaned them out. I also order a rebuild kit from napa. So what your saying is my coil may be bad? and i checked where I had throttle linkage setup was wrong. It would open the butterflies in the carb all the way and if you kept pushing on the throttle it would close them, so that prob is solved...but the boat still doesnt plane well or has low power, i still dont know wich one really. One thing i did notice is the base plate on the bottom of the boat on one side is not sitting flush with the rest of the hull, it sticks up about 5 or 6mm more than the hull and the other side of the base plate. I imagine this could cuase what flow problem into the impeller, anyone have any ideas on how to fix this problem? i hope the base plate isnt bent...

 

[sdk19056]

Re: Force90hp no power/wont plane

also I wanted to mention I tried finding seafoam up here in canada...kind find it anywhere yet...i would like to do that too...everyone just goes "huh never heard of that" and gives me some starnge look whatever, i will keep looking

 

[eurolarva]

Re: Force90hp no power/wont plane

Iboats sells seafoam. Here is the link<br /> seafoam <br /><br />iboats also sells this sea foam product. This will probably do a better job if it has not been decarbed in a long time<br /> deep creep

 

[sdk19056]

Re: Force90hp no power/wont plane

eurolarva i checked and there is no screw adjustment on the side of carb above the choke? there is screw however on the other side of the card where the throttle is...will that carb rebuild kit still work...or is this the wrong carb? if needed i can take a picture of it...

 

[eurolarva]

Re: Force90hp no power/wont plane

Is this what you carb looks like 90HP carb <br /><br />If so Item 14 is the mixture screw. It is in a different location then I am used to seeing them<br /><br />It still shows that the 7037 kit is the correct one. Post your model number and I can cross reference through the merc site