V4 115 does not quite reach WOT

[StillFishin']

MY 82 115 runs fine almost all the way to WOT, reaching ~5200rpm at about 7/8+ of the trottle handle pushed down. When pushing the trottle handle down the finall bit and get to WOT, the engine faulters alittle and drops about 100 rpm. I have been afriad to leave it a WOT for long in case it is runing lean. Other wise it runs great. At first I thought the engine was blowning out but that whould incease the RPMs but the drop in stead.<br /><br />I did have one spark plug wire that was bad and I fixed that, and they jump a 1/2 gap. <br /><br />The carbs were rebiult last year and it also did it then. Perhaps I didn't do it right.<br /><br />Doesn't seen to be any kinks in the fuel line except maybe the short fuel hose that goes from the the inside of the the quick disconect to the carbs. It's a very sharp bend but it certainly is not kinked but it maybe a little flatend. It's a beast to work in there especilly when the boat it in the water.<br /><br />Anyone have any other ideas or in what order I should try to attack the problem? It is very minor but something is not right.<br /><br />Thanks<br />StillFishin'

 

[ob]

Re: V4 115 does not quite reach WOT

Was engine capable of more than 5200 rpm before or are you mainly concerned with the drop in rpms when throttle is fully advanced?<br /><br />Remove the intake silencer cover and insure that the throttle plates are not opening past full horizontal when controls are buried to WOT.(You'll need to have someone turn the prop while shifting controls).If they are ,you'll need to adjust the throttle limit screw on the linkage.

 

[StillFishin']

Re: V4 115 does not quite reach WOT

Thanks OB,<br /><br />No, I never could get higher than 5200 and this is with new prop I'm trying(Stilleto 13 1/4 x15)this year. As I remenber from last year,my old prop got me about 5000 and it acted the same way. It seems like it wants to go higher but then it drops down in rpm.<br /><br />I'll check out the butterflies next week to see if they are going past horizontal. That makes sense. I checked them to see if they are closing together but didn't check to see if they are going past. I know that the little stop pin is close to the stop as pet the manual, but I'll recheck.<br /><br />One other thing I forgot to mention is that is almost seems like it wants to pulse-down 100 then up 100 and then maybe down a little more than 100 with maybe a second inbetween the pulses. I've never ran it at WOT for more than 15 seconds in fear that it was going lean. I'm I right in thinking that it could be leaning out the way it is action?<br /><br />Thanks for your help<br />StillFishin'

 

[ob]

Re: V4 115 does not quite reach WOT

Its possible you could have a lean condition if one or more of your carbs high speed orifices or carb bowl pickup tubes were restricted but I tend to feel thats not the problem.When you inspect the carb throttle flaps insure that the timer plate under the flywheel moves freely within its full travel and comes to rest on the rubber stop at WOT.<br /><br />What lenghth, style,and weight boat is this 115 pushing?

 

[StillFishin']

Re: V4 115 does not quite reach WOT

OB, I'm pretty sure it comes to rest on the rubber stopper and works smoothly but I'll check that also. The boat/engine is "upnorth" as we say arould here(Southern WI)and I will be up there next week to check it out.<br />I'm also going to recheck the spark with my homemade spark tester but I whould think a bad wire whould showup way before WOT.<br /><br />While mulling this over the only other thing that I did last year was finally put on a Racor water seperator filter. Maybe that's restricting the fuel flow just enough at WOT-but the prinerbulbdoesn't goflat when Ive checked that at WOT(wife driving the boat)<br /><br />StillFishin'<br /><br />Stillfishin'

 

[ob]

Re: V4 115 does not quite reach WOT

If your engine controls are equipped with the key switch primer you could try bumping the switch in a few times when at WOT lull and see if the engine picks up.If so equipped this would let fuel bypass the carbs and inject straight to the intake chamber.<br /><br />Boat lenghth,style,and approx weight??

 

[StillFishin']

Re: V4 115 does not quite reach WOT

Boat is a '82 18ft Sylan aluminum bow rider rated for a 135 and I have an 82 115 OMC on it with a 9.9 kicker that runs great off the same tank. I've got a new(rebuilt)powerhead on it this year and have just finished breaking it in. Runs fine except that last bit at WOT but ,as I've said before, I remmber the same problem lst year witht he old powerhead before she blew.(thats another story but I don't think it was related to the WOT problem. The carbs where redun two years ago and looked good after 20 years but I replaced all replaceable parts. Perhaps I didn't get the floats right. I thought I did all the tests to check for clogging of internal passage ways. <br /><br />The idle and hole shot are the best they have been in years.<br /><br />I did check the timing at running speed and it seemed to be reading at 28(per manual)but hard to read problably because of my anceint timing light and not dark enough. I'm going to recheck that also.<br /><br />Thanks for your help.<br /><br />StillFishin'

 

[nauti norseman]

Re: V4 115 does not quite reach WOT

Mentioned before and didn't hear if you tried it. At or near WOT, press in your ignition to engage the Primer. If there is absolutely no difference, then your primer may be stuck open. If you engage the Choke at/near WOT and it boggs down, then it's good and performing normal.<br /><br />Good luck

 

[jgrisham02633]

Re: V4 115 does not quite reach WOT

Hi Stillfishin,<br />Sorry to but in on you guys but I notice you said you were running the kicker of the same tank. Do you have two lines off the seperator or one? reason I ask is because you could be sucking air a wot through the kicker if they share a seprator. I guess this could cause your problem

 

[jgrisham02633]

Re: V4 115 does not quite reach WOT

I guess this post is a little old I just noticed the original post date. Looks like the nauti norseman didn't see the date either.