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Post by skuttadawg on Apr 19, 2014 22:04:38 GMT -5
Here is the Mikuni fuel pump pump |
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Post by ezgoin28 on Apr 20, 2014 7:03:02 GMT -5
I may be way off base here but here is an idea. Is your gas tank filled to the very top? When i fill my gas tank level too high it wont run because it blocks the air supply line into the tank. I had the same problem years ago also on a polaris 4 wheeler with a clogged vent hose.
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Post by william42 on Apr 24, 2014 7:48:13 GMT -5
Ok, one last update before I let this thread die.
I've been riding my Scoot again and it's been running fine. I even took her for a jaunt down the highway and had her wide open most of the way, (because the speed limit was 55). Not even a hiccup in the 10 mile round trip.
I have no hard evidence on what the problem was but I'm leaning toward the over-filling of the gas tank. It's the only thing that makes any sence at all. But even that doesn't make a lot of sence. Time will tell I guess. Thanks for all the replys...
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Post by william42 on May 13, 2014 6:42:34 GMT -5
I just had some hard evidence on what this problem could be because it happened to me again yesterday, but only for a moment. I was fighting not only a strong headwind but also going up a long hill and it was all my little machine could do to keep the speed limit of 45 with the throttle wide open. Just as I crested the hill the engine lost power. I let off the throttle and in just a few seconds the engine came to life again.
I'm surmising that there is just not enough vacuum at WOT to supply the whole system to operate efficiently under heavy load and at WOT. I'm convinced now that the Carburetor float bowl isn't being supplied with enough fuel under heavy load and WOT.
There are a number of things I could do, I suppose, to correct the problem.
One would be to assure the fuel pump is getting enough vacuum to operate under heavy load but that would mean sacrificing elsewhere. Specifically the emmision system. But I like the idea that I'm polluting the air we all breath with as little polutants as possible so I'd like to avoid that as a fix.
Or I could try lowering the fuel pump as Alleyoop suggested but little vacuum is little vacuum so I don't see how that will work to rectify the issue.
Or I could get a better pump as suggested by skuttadawg but again, with very little vacuum under that kind of load, will that pump work any better? Does that Mikuni pump need less vacuum to work well?
If I could just find a way to free up some vacuum in time of need...
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Post by william42 on May 13, 2014 8:09:45 GMT -5
Ok, I have two vacuum lines coming off the intake manifold and they both "T" off so there's four lines that split the vacuum between them. If I remove the canister set-up will I not get 25% more vacuum in those lines, including at the fuel pump? Would that extra 25% vacuum at the fuel pump be enough to keep the float bowl filled in times of heavy load? Is it at least worth the effort to try that set-up?
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Post by tvnacman on May 13, 2014 8:54:39 GMT -5
Use larger fuel line , it will give you a little more fuel in the line for reserve .
John
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Post by william42 on May 13, 2014 18:55:20 GMT -5
I changed my fuel line about three weeks ago, which might explain why it has been working a bit better.
When I got home tonight I "T'd" in a vacuum gauge on the line that supplies vacuum to the canister. I loose just about all my vacuum when I rev the engine but when I pinch off that line the vacuum remains constant through the entire range of throttle positions. It idles much better too.
I'm going to remove the canister from the system and see how it performs without it. Unless y'all know of a reason why I shouldn't.
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Post by william42 on May 15, 2014 19:29:14 GMT -5
Ok, so I removed the canister hose from the vacuum supply hose and left it hanging with the "Y" conector still attached. I put in a straight connector to reattach the other hose to vacuum. I removed the hose from the canister that went to the airbox then plugged it off. I left that hang too just in case it didn't work and I needed to hook everything back up.
The scooter started a lot easier and idles better too. I took her for about a 5 mile spin down the road and there didn't seem to be any ill effects. Now I need to find a really big hill to climb to give it a real shake down. But so far so good.
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