Rebuilt 1990 70HP VRO Losing Power

[bshellrude]

Hello All:<br /><br />Well... I feel like crying. Following an extremely costly rebuild, what was running like a top is now running like a piece of ****. If I wasn't so stubborn I'd definately scrap the whole idea of boating right now! Any how, here's the story... hopefully someone can help.<br /><br />Engine was running great, was up to 8 hours after initial idle break-in. WOT was awesome (i.e. for 1-2 minutes only of course)... crusing in style. Finally was feeling comfortable enough with the engine to do the throttle pickup and wot timing. Did that, seemed fine. Idling good, acceleration excellent (Picked up and planed within a couple of seconds). On the way back to the dock from a 2 hour excursion, all of a sudden she starts to miss a little... at this point I'm thinking a great BIG uhoh!!! Get her back to the dock without bringing the throttle back down to idle, then try to bring her back up to 3-4000 RPM and it won't do it... it's got nothing. Tears are welling in my eyes at this point... (not to be un man like... but c'mon, it was running perfect... thought I'd done a top knotch job... then...) Any how... Idling at the dock, pull each wire, each provides for an RPM drop, but no dead cylinder... hmmmm... hope reveals itself again! As a side note I am still running 25:1 mixture and have disconnected my VRO2 completely because of no oil alarms...<br /><br />Moving on, got it home, pulled the plugs. Rich on top, very rich on bottom, and good ol' tan in the middle. Also noted that apparently reed valve cage screws may have come loose, how I'm not sure, but need to pull and tighten them.<br /><br />So... perhaps someone can shed some light... I'm really hoping nothing serious, although I don't think it is given that it's recently rebuilt and I am running on 3!<br /><br />Could the loose reed valve cause the problem... important to note also that she was backfiring a little while idling back at the dock. Or despite having just cleaned the carbs... do they require another cleaning resulting from the 25:1 mixture?<br /><br />So close to being ready to give up.<br />Ben

 

[melbournegreg]

Re: Rebuilt 1990 70HP VRO Losing Power

why aren't you running 50:1? Has someone suggested 25:1 immediately after the rebuild?

 

[DJ]

Re: Rebuilt 1990 70HP VRO Losing Power

25:1 won't hurt the carbs.<br /><br />You may have a spark plug dropping out. Rich mixtures can make plugs act funny.<br /><br />Also, you mention "backfiring". Was it a true backfire or more like a "sneeze"?<br /><br />Sneezing indicates a lean condition. Make sure you have no air leaks (loose hoses, etc) or air leaks around the crankcase/carb seams.

 

[bshellrude]

Re: Rebuilt 1990 70HP VRO Losing Power

Yes... Everyone I spoke to mentioned that for the first 20 hours (Or according to manufacturer 2 tanks) that double oil be used.<br /><br />Yes, it was definately more like a sneeze. Blowing back out of the silencer...<br /><br />So next question is that would an air leak be possible if the reed valve cage screws were loose?<br /><br />Also, would the plugs not be whiter instead of blacker if it were running too lean?

 

[DJ]

Re: Rebuilt 1990 70HP VRO Losing Power

You betcha loose screws there will allow unmetered air in.<br /><br />The plugs were black most likely from double oil.

 

[marinemech]

Re: Rebuilt 1990 70HP VRO Losing Power

25:1 necessary for break-in<br />50:1 after 10 -20 hrs.<br />is primer bulb on fuel hose going soft<br />listen to vro pump is it clicking every second-rapidly?<br />did you cap oil side this is necessary when disconecting oil side of pump?<br />tighten all loose screws of course<br />have a dealer look up recalibration and cooling system modifcation service bulletins for you

 

[bshellrude]

Re: Rebuilt 1990 70HP VRO Losing Power

Thanks all... So basically what you're saying is that all is not lost... THANK GOD!!!<br /><br />So, here's what will take place. Correct me if you think I've missed anything.<br /><br />1) Remove carbs, tighten down reed valve cages, replace carbs<br />2) clean plugs<br />3) Put in water and see if it works<br /><br />The question DJ is this... why would the top and bottom be blacker than the middle if simply from double oil??<br /><br />To answer your questions Mech, no the bulb is not going soft. The VRO is clicking every second rapidly. The oil line is capped, albeit not at the pump but rather from just after the primer bulb if tracing the hose from the oil tank (in other words plugged the hose without bulb attached).<br /><br />The re-bore shop did mention a cooling system mod for the engine that I have not managed to complete yet. Changing the tel-tale elbow's location to the top of the exhaust/water manifold on port side of engine. This they say was due to air locks becoming present around the #1 cylinder (top). Was hoping to get the engine running properly first, then make the mod...<br /><br />They also recommended upsizing the high speed jets in the carb following a re-bore. Not too sure why as others have mentioned that it is not necessary...

 

[bshellrude]

Re: Rebuilt 1990 70HP VRO Losing Power

Ok, took her back out on the water yesterday after tightening the reed valve cage screws, cleaning plugs and checking compression.<br /><br />Cold compression is:<br />#1) 100<br />#2) 95<br />#3) 98<br /><br />Suffice it to say that I'm not too worried about compression or the reed valves. Much relief there!<br /><br />Now... I did manage to get her up to full RPM, but with quite a bit of coaxing (i.e. in neutral, use warm up lever to get the RPMS going, then put her in gear and pulse the throttle until she started to come up). Sometimes this would work and other times not. It is definately dropping a cylinder when advancing the throttle!<br /><br />So sounds like either of two things... either too much fuel, or not enough.<br />One interesting thing to note is that the clicking from VRO seemed to be intermittent... which might idicate fuel pump problems right? However, this at the same time doesn't make too much sense considering the primer bulb was good and solid and that pumping it had no effect. Correct me if I'm wrong but if the fuel pump was going, would pumping the primer bulb not speed up the engine?<br /><br />So, what am I left with? Carbs need to be cleaned again? Too much fuel not enough air? Any help would be appreciated...

 

[bshellrude]

Re: Rebuilt 1990 70HP VRO Losing Power

One more thing to note... not sneezing/backfiring this time around...

 

[bshellrude]

Re: Rebuilt 1990 70HP VRO Losing Power

Any suggestions?

 

[Walker]

Re: Rebuilt 1990 70HP VRO Losing Power

If that motor has a fuel recirculation system check the oneway recirculation valves. You may have a little carbon in one or more of them causing them to stay open both ways. That will play havok with the tune of a motor. I chased this problem for several months on my own V4 looper before I figured it out. It will also cause sneezing.

 

[blgrams]

Re: Rebuilt 1990 70HP VRO Losing Power

completly eliminate the VRO. that anoying alarm may not have been just the oil tank sensor. sounds like the VRO is not working properly and at $50 for the standard fuel pump, instead of $250 for a new VRO pump (there is no VRO rebuild kit any longer) choosing the standard fuel pump is a no brainer. <br /><br />by the way I agree that the reed block being loose can cause major problems.<br /><br />did you re-adjust the carbs after you tightened the reed block(s)? that would have thrown off the setup of the carbs as well. Do not assume that they were not at least a little loose or leaking a little.<br /><br />regards<br />Bruce Grams

 

[bshellrude]

Re: Rebuilt 1990 70HP VRO Losing Power

Ok... Thanks for the info all... looks like I owe you all a few cold ones!<br /><br />A couple of questions:<br />Walker: By recirculation system... what exactly do you mean? Do you mean the hose going from the silencer to the intake manifold where excess fuel from the carbs leaks into the silencer and then back into the crankcase via that hose??<br /><br />Bruce: Yes, re-adjusted the carbs. And am going to replace with standard pump tonight.<br /><br />Here's the plan for tonight:<br />1) 3 Carb Rebuild Kits with upsized jets (upsized jets recommended by the re-bore shop)<br />2) New Plugs (Who knows, talked to the local marine shop and they said that would be one of the first things they'd check)<br />3) Standard pulse style 3 cylinder fuel pump<br />4) Fuel filter<br /><br />Will perform timing pointer re-alignment process. Using Piston Stop Tool as I have a suspicion that it is out of alignment. When doing the throttle pickup timing, in order to get the timing to 1ATDC from 4ATDC I had to tighten up the adjustment nut all the way! Would not go any further, hence why I think it's out. The manual states pickup timing should be between 1BTDC and 1ATDC. <br /><br />Following that will come the slow speed carb adjustment, and throttle pickup timing.<br /><br />If after all of the above it still isn't working properly, I'm taking it to the local dealer and dropping it off!!!! <br /><br />Any comments, additional suggestions?

 

[walleyehed]

Re: Rebuilt 1990 70HP VRO Losing Power

If you have at least 8 hrs, as you say, I would start mixing 50:1. 20 hrs. is way too long at 25:1, 10hrs is the recommendation.<br />I would diffinetly change plugs, and go for the std. fuel pump, the jets...??? Don't go by what the bore-shope says. I don't think your jets have any issue on this one.

 

[bshellrude]

Re: Rebuilt 1990 70HP VRO Losing Power

Thanks for the suggestions Kenny! Will definately start mixing 50:1.<br /><br />Do you think there is merit in rebuilding the carbs taking into account that they were cleaned during the rebuild, but not actual rebuilt with a carb kit?<br /><br />Also, considering what I've mentioned regarding the timing... Does it sound to you like the timing pointer may be out of alignment?<br /><br />Cheers,<br />Ben

 

[walleyehed]

Re: Rebuilt 1990 70HP VRO Losing Power

If you have the kits now, do the carbs..I like to do that as a requirement of the rebuild.<br />The timing pointer "could" be off, it's a good idea to check it out, then ya know for sure.

 

[Walker]

Re: Rebuilt 1990 70HP VRO Losing Power

Netwiz, I don't have a manual for any 3 cylinders as new as your but I can't find a recirculation system on any of them, so I'd guess your doesn't have it. Its basically small hoses from the intake back to each cylinder with a check valve on each on at the intake manifold.

 

[bshellrude]

Re: Rebuilt 1990 70HP VRO Losing Power

Thanks again guys!<br /><br />Next problem, hunting around for a "piston stop tool" and can't find one here in winnipeg.<br /><br />Any one have any ideas how I might re-align the timing pointer without one. I've read some posts that suggest using a dial guage? How exactly would I use a dial guage to do this? Or even, would it just be possible with say two people, one holding a bolt or something similar to hold the piston while marking the position of BTDC and ATDC?? Would that be accurate enough?<br /><br />Thanks in advance<br />Ben

 

[bshellrude]

Re: Rebuilt 1990 70HP VRO Losing Power

Well, for any one that may be following... Everything is all fixed, timed, set and tested!!!<br /><br />All is well <br /><br />Moral of the story/lesson learned:<br />Locktite, Locktite, Locktite!!!!!<br /><br />Due to the rattling of the reed valve block inside the intake, the leaf itself had come loose and was rattling against the block. Not only did this loosen the screws holding the assembly together (screws fell out as I was removing... that close to COMPLETELY blowing a just-rebuilt engine... phewwww!!!), but this rattling had desintegrated the reed leaf ends... Luckily, looks like these fragments were blown into a million tiny pieces, and most were blown into the silencer... so, I think the amount that actually got into the crank/cylinders was negligible!<br /><br />Any how... I think every single screw, nut and bolt on that intake assembly has now been threadlocked... And suffice it to say, I will never do anything without it again!!! I've since added 8 hours to the engine... and It's great. Not a single problem!<br /><br />Thanks for all your help everyone... I would not have been successful without it!<br /><br />Despite my having said it before, if you're ever in winnipeg, look me up and I'll buy ya a few cold ones! <br /><br />Cheers,<br />Ben Shellrude