85 force low rps at wot

[mwagner]

I am new to this forum but have been reading and searching for possible causes to my problem.<br /><br />1988 85hp force, mod 856x8b, sn 1577.<br /><br />it starts very well after rebuilding the fuel pump and replacing all gas lines. pulled out all three plugs and they are black and oily. can't really see much difference in them other than the amount of oil on them. seems the closer to the bottom of the engine is oilier. last year at wot it would reach almost 5000 rmp so i think the prop is fine at 13X17. this year it takes about a minute or more to plane out and only reaches 3600 to 3700 rpms. no misses or backfires and sounds very smoothe just no power. needless to say impossible to ski behind. have been reading about coils and cd modules but all posts talk about different plugs and mine seem the same. <br /><br />i do not have alot of fancy tools and in my area it seems this motor is an orphan. no one wants to work on it. i do have a seloc manual. i did find a person who said he has experience and told me a coil was bad and replaced it for me. since then the rpms have been very slow and not out of the hole shot. i've since been leaving him messages but no returned calls yet. if it keeps up like this my 90 warranty will be up before he calls me back. <br /><br />would love to hear anyones' suggestions. also many here have mentioned 'seafoam' decarbon cleaner but not sure what it is or how i would use it if i could find around here.<br /><br />last but not least do these motors have parts available without spending and arm and a leg? i think i am able to replace most bolt on parts as long as nothing other than a set of normal sockets and a vtm is required. <br /><br />thanks in advance for any and all replies. i will check this forum frequently for suggestions and note my replies where applicable.<br /><br />mike<br />Oregon WI

 

[Realgun]

Re: 85 force low rps at wot

WELCOME to iBoats mwagner!!!<br /><br />There can be a few things wrong. <br />1. you have a carbon buildup.<br />Try this method. <br />2. Carbs need a rebuild or wrong jets possibly.<br />3. Timing needs adjustment.<br />4. The Stator is not putting out enough voltage.

 

[mwagner]

Re: 85 force low rps at wot

Admiral Realgun,<br /><br />Can this carbon buildup just happen from one year to the next? Also is there any way I can verify that the wires from the stator to the cd and from the cd to the coils are correct? Reason for asking is a coil was replaced and I am wondering if the guy put all the wires back in the correct order. Or maybe it wouldnt even run if he had? I will get seafoam tomorrow on the way home from work and give it a try. Will keep you posted.<br /><br />Do you know how much different the plugs would look if I don't have all three cylinders lighting off?<br /><br />Thanks,<br />Mike

 

[Realgun]

Re: 85 force low rps at wot

I was pulling that information from my head. I have the same issues you have except i never got Full RPMS! And these are the solutions in order of how hard they are to do!

 

[mwagner]

Re: 85 force low rps at wot

Admiral,<br /><br />Juat back from the lake and a gallon of gas and seafoam later it does run somewhat better. This time it was just my wife and I so two people instead of five. Got up on plane rather quickly, say 6-8 seconds of full throttle and RPMs got up to about 4500. Not sure if it would repeat that with five onboard again. I will check into rebuild kits for the carbs to see if I can get them locally or need to use the internet and search for them. Are they easy to rebuild?<br /><br />Thanks,<br />Mike

 

[Realgun]

Re: 85 force low rps at wot

I don't know I will be doing mine soon too. Hopefully its not electrical as thats bigger money I don't want to spend!

 

[mwagner]

Re: 85 force low rps at wot

HI Admiral,<br /><br />That is quite a project you have undertaken. I hope it continues well for you. Did you ever get to rebuilding your carps. Just wondering how they went. Reading in another post about the diameter size of the fule lines. I did replace mine all with 1/4" as that is what it looked like to me. Other posts say 5/16 to 3/8. Could that our would that make a WOT reduction? I could just swear that the fuel lines running up the sides of the carbs are 1/4 and not any larger but it would definitely be an easy switch. Then I suppose the fuel pump bulb would also have to be changed?<br /><br />Thanks,<br />Mike

 

[Realgun]

Re: 85 force low rps at wot

No money squeaks areound here when I touch it. <br />I will be rebuilding it very soon which could mean tomorow or next month! I was told you need at least 5/16 fuel hose or it will be choking off the motor. Hope that helps!

 

[monkeyboi]

Re: 85 force low rps at wot

m,<br /><br />when did you "rebuild fuel pump & replace all fuel lines"?<br /><br />you said that last year it ran well. was the work done before or after the performance fell off?<br /><br />also read 5/16 minimum line and of course the only time that would come into play during higher engine speeds.

 

[mwagner]

Re: 85 force low rps at wot

Realgun and Monkey,<br /><br />When I first got the boat very wll used it would go up to about 5200-5300 RPMs then it started running very badly, hard to start when cold and finally not at all except when I pumped the carbs full of fuel with the primer bulb. After not finding anyone in the area to work on this type of Force (Chrysler) I ordered a Seloc book and started to check things out. First was to look at fuel system and the lines were very brittle and the pump bulb would make my hand black every time I used it and it kept going soft. I replaced the bulb and fuel lines and still couldn't get it to run for more than a few seconds. I opened up the fuel pump and found little slivers of brass stuck through the rubber diaphram. I disconnected the fuel line from the carb feed and made gas come out with the primer bulb. Then I cranked the engine and very little gas trickled out so ordered a rebuild kit. When kit came I removed fuel pump assembly from the side of the motor and found the little valves inside to be in pieces and falling apart on my work bench. Called supplier of fuel pump rebuild kit and explained my problem and he sold me a used fuel pump and I used the rebuild kit on it. Rebuilt the fuel pump and after assembly checked to see if it pumped gas to the carbs while cranking the engine and got a pulsating stream. I guess it ran better since the fuel delivery was much better and it started. It ran well or at least relatively speaking and it was only I and the dog out fishing. I can't recall checking the WOT RPMs at this time. This year wife, daughter, son-in-law and grandson wanted to go out and they of course like to go fast. But boat wouldn't accomodate them very well. I get anywhere from 600 to 1000 higher (4200-4500)RPMs without them in the boat with me. Also alone it planes in 5-6 seconds instead of well over a minute. Guess I never gave it much thought untill I started to read the manual and looking at the tachometer. Would a smaller gas line keep it from running at higher RPMS without making it miss or die out? I didn't replace the lines coming from the fuel pump to the bottom of the three carbs. Would they also be 5/16 in stead of 1/4? Boy that would be one cheap fix if it turns out to be it!<br /><br />Thanks to both of you for your responses,<br />Mike<br />Oregon, WI<br /><br />By the way. Do either of you know of a place on line or by phone I could get parts from reasonably? Anything I find seems very very very pricey.

 

[eurolarva]

Re: 85 force low rps at wot

The damage to your old fuel pump may stil reside in your carbs. That old fuel pump can be rebuilt. The fhree fuel valve in your pump are still availible at mercury for 5 dollars each and the gaskets for those valves are fifty cents each. If you had crap in your fuel filter and it got into your carbs your jets could be partially plugged. It would not hurt to take one of your carbs apart and look carefully at the insides to see if you have any brass or rubber debris in thee

 

[monkeyboi]

Re: 85 force low rps at wot

possible restriction of main jets. if brass was in fuel pump, it probably made its way into the carbs. orifice in jet is small and would not take much to clog. like eurolarva said take a look.<br /><br />yes parts are expensive for these. depending on what you need, parts can be found for less.