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Vexxing BF40 problem above 2k RPM

I did yeah. I meant to post this earlier, but here's what I bought and replaced so far (purchased and installed the fuel pump earlier). I can tear it all apart again and do it all over again.
honda parts.jpg
 
Well, I did find something at least interesting this morning. I haven't taken out on a sea trial but I did spray carb cleaner on the carbs at a high idle and when I hit the middle carb it cleans up and idles a little higher and when I hit the top carb it bogs a little. I tightened the bolts and nuts from the manifold to the block and long ones from the air box through the carbs into the manifold to no change. Again, these are all new gaskets. Do the plastic insulators between the gaskets warp or go bad somehow??

I'll try this test again under way today and report back.
 
Welp, I'm making progress. Today I pulled the manifold off to give it another once over and wouldn't you know it... I found the fuel line on the backside of carb #2 unhooked. Sigh. Got it put back together and tightened up and, with my newfound fuel pressure, found a few fuel leaks on the 3-way tee that I'll have to remedy with new line and clamps. I think this is all new and unrelated to the main problem (which could very well have just been the carbs) but am hopeful that I'm gaining ground on it. I don't know when the fuel line came off but it couldn't have been that way for too long as I was able to tune it and adjust it. Additionally, I unplugged the top spark plug and it ran fine on just the two remaining cylinders so obviously the fuel line couldn't have been disconnected when I was doing that.
 
alright. It has to be those damned insulators. They're definitely sucking in air (and carb cleaner) on the middle and top carb. It's so bad that it runs a lot better when the engine cowling is off. I fixed all the fuel leaks and she's purring but still has the leak. When I use carb cleaner with the straw, there's a definite uptick in the idle that lasts for 15 seconds or so. I feel like we're close!
 
You know... looking at the parts diagram, I think the insulators might be upside down if there's such a thing. They fit just fine and the holes all line up, but in the diagram, the little "notch" is on the bottom and they're on the top in my set up. Wonder if it's not making a good seal because of that?
 
Alright, got everything slapped back together the way it's supposed to be and she seems to be running much better. All idle screws are set to 2 1/8 and she's purring in idle. Haven't taken a test spin nor have I synched them yet but the idle is really high and the idle adjust screw on the bottom carb is all the way out already. Any clue on what I should do to slow this girl down before she grenades the gear box? Turn the idle mixture screws on all the carbs in until I can dial it back to 900? It's idling at 1100-1200 rpm right now.
 
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Must be something to do with the choke linkage as this raises the idle when activated, make sure the throttle plates can close fully. If they do close then you still have an air leak
 
Another update. Just when I think I'm making progress... two steps back. So I was able to take her out for a spin and she ran fine! She's not getting the full speed she should be but she sounds great and there's no bogging of any sort. I think I need to get one of those spark plug wrapped type digital tachs because I'm not sure my Sierra is reporting right. It's running well, a lot better than it was when I started this debacle, but on my tach it's only hitting about 2800 RPM. It does coincide with the speeds I'm seeing. I'm still right about 1/2 to 5/8s what I had before. On the way back in, I noticed that the idle slowed back down and I thought "great!" but then it stalled... I had to give it half throttle to start again and when I took the cowling off, gas is spewing out of the overflow port on the top carb. Sticking float?
 
iang6766 said:
Must be something to do with the choke linkage as this raises the idle when activated, make sure the throttle plates can close fully. If they do close then you still have an air leak
Click to expand...

Forgot to mention above that I sprayed carb cleaner up and down the carbs and it made no difference so I THINK that the air leak is contained.
 
Sorry for the constant bumping of this thread with updates but alas... I feel as if I'm close again. This morning's update:

Got the fuel leak contained by draining the bowl plug, removing the gas line from the top back of the carb and spraying sea foam in it. Of course, the middle carb started doing the same, so I preemptively struck and sprayed them all. No more fuel leaks (at least for the time being). She fires right up from cold now (used to take two or three turns) and sounds good. In neutral, the throttle is smooth and responsive but the idle is still a little high at 1100. She starts right around where it should at 800-900 and, within 30 seconds or so builds up to 1100. In comparing linkage photos (before, after and parts breakdown), they're all the same so I think it's time to move on to throttle adjustment. I'm wondering if that's why the boat's not getting to full speed. I haven't made any adjustments to it, but if you recall (from a month ago when I started this lol) I had someone else tear into the carbs originally. He may very well have screwed with it. In any event, it's good for me to break out the service manual once more and confirm.
 
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Update 2 for the day: I adjusted (shortened) the throttle a bit because it wasn't between the marks on the cam. It wasn't out by much, but the entire roller was outside of the marks so maybe 1/2" total. She's running good but not coming close to the RPMs or speed it should be achieving. I ordered a digital induction tach that'll be here tomorrow. Hopefully that'll confirm what I think I know already in that I'm not achieving the necessary RPMs. Of course now the lowest carb is spewing gas now so I've been through all three of them. I can buy new floats and needles for about $75 off eBay so I might do that just to eliminate them as problems.

Is there anything electrical that could be limiting the RPMs to around 3k under load? I know there's a rev limiter on this engine but I guess I'm not sure what activates it? I'm wondering if I have two problems (carb and electrical) and I'm screwing around with one while I should be focusing on the other.
 
Ok last post to this thread. I think we can call this one solved. I still have fuel dumping from the lowest carb, but I can address that. I believe my Sierra tach is not reporting right because I bought one of those induction digital tachs and I'm seeing 5300 RPMs at WOT which is in line with what it should be. She sounds good too, so I'll call this ghost solved and thank all who offered feedback!

She's still not achieving the speeds she used to but that could be for myriad of reasons, none the least of which is growth. This is on a sailboat that's been in the water since November. Even though I've got bottom paint on it, there's probably enough growth to slow things down. Cheers and thanks again!
 
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