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Discussion Starter #1
Well folks, the project continues on the 660. Just when you take two steps forward you take three steps back it seems.... Anyway, I was having issues with the OEM vaccum pump holding prime. It was start and run great but die during a long idle. Checking everything it was just losing prime. After some posts and research here I found where several had installed a K&N Electric Fuel Pump to correct the problem. The setup was exactly how my stock Rhino was so I went that route. Ordered the pump which is a 1.5-4PSI pump, and did the install.

It started and ran great but I caught a smell of fuel. I checked the output of the fuel pump and had a small leak. Contacted K&N who was very helpful and was advised to try yellow teflon tape on the threads. The tape did the trick! No leaks and all was perfect. Starts and runs like a champ. I hadn't had it out much since then but got it out on Friday and thought I smelled fuel again... rats! Checked the same spot as before and nothing. Couldn't find anything leaking so I thought maybe it was residual. Took it out yesterday and smelled fuel again and there it was leaking off the bottom of the skid plate.... but where from? I took everything apart and it was the fuel drain hose coming out the bottom of the carb and leaking on the skid plate. I checked the return line again and it was clear - no obstruction. I opened up the drain in case there was debris in the bowl then tightened it back up and it still leaks.

So.... it sure seems like it is getting too much fuel and the carb can't handle it. There is no adjustment on the pump and I do not have a fuel pressure regulator either. I don't believe there are any issues with the carb and it sure runs great - perfect in fact minus the leak. Anyone else ran into this before? Suggestions on a fix? I thought about trying to choke down the amount of fuel being allowed into the carb by restricting the size of the fuel line? I have an idea that might work but wanted to see what the experts did to fix before I try my jerry rigged experiment.

Thoughts/suggestions?
 

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you need to run a T fitting about 3 inches where it leaves the factory pump into the carb , it will fill up the bowl and the rest will flow back into the tank .. this is how i run my setup but i use all clear fuel lines so i can see what my fuel is doing as it leaves the tank to the carb . I use a edelbrock electric fuel pump Edelbrock part # 17303 fuel pump 2-3.5 PSI . you can pick up a set of 3 # T fittings at Autozone around 10.00 if i remember right comes with 1/4,5/16,& 3/8 T fittings brass !!bought my 5/16 clear fuel lines on Ebay .. this is my setup on my 660 and I have no fuel problems .

Jake
 

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Discussion Starter #3
I am not running a factory vaccum pump - just the electric fuel pump only. However, when I was running the original vaccum pump it already had a T in the line. After watching some of the electric fuel pump install videos I kept it like it was using the T fitting how you described but with the electric fuel pump. The one exception - the T fitting is farther away from the electric fuel pump - more like half way from the electric fuel pump to the carb - is where the T fitting is located. It's roughly 6" away I'd guess if that matters. I am getting plenty of fuel back into the tank - just not enough apparently and without the vaccum pump I have more fuel even with this electric pump - at 1.5 -4PSI.
 

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I wonder if you have a carb float issue - maybe a tiny piece of debris stuck between the needle & seat, or a defective needle & seat assy? Seems like you got the pressure by-pass setup properly. You might try removing the carb, drain it, invert it, then try blowing through the fuel supply inlet (your air, not compressed air) to see if the needle fully blocks the pressure. Just a thought..
 

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Discussion Starter #5
Sandbuster - yeah I thought that could possibly be an issue as well but I'm learning so I thought I would ask those with more knowledge than me. I took the screw out and drained the bowl to see if that would clear any debris but no change. There might of been a spec or two of dirt but not dirty IMO. I also read on here where some use fuel pressure regulators but that seemed to have mixed results. Just not sure why mine is providing too much fuel in this setup. My FIL mentioned that we could create more restriction of fuel in the line to the carb by inserting a solid piece of copper tubing then drill out a port hole to only allow only so much fuel through the line. We could place that in the line before going into the carb which should theoretically reduce the amount of fuel. You would have to play around with the size of the hole but sounds plausible to me. It is just weird that I did everything like others have done with no issues but yet mine is getting too much fuel. That's why I keep going back to there might be another issue I'm missing..... I'm using 5/16" fuel lines by the way. I thought about getting a smaller T fitting to see if I could restrict the amount of fuel as well. I appreciate all the help and comments here. The Rhino runs so dang good if I could just get this issue fixed.
 

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Discussion Starter #7
Have fuel pressure regulators been used with a lot of success in similar situations? Most of what I read so far were older posts about using them and not with much success. Maybe I didn’t see the good ones.
 

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I honestly don't know - I haven't come across those threads BUT from spending 25+ years in auto repair there were a few occasions where I had to use them and I don't recall any issues. The regulators back then were fixed PSI - non adjustable. So I just went back and read the reviews - some were complaining that they didn't come with a mounting plate (ez workaround), some were complaining about fuel leakage (you have to use a sealant tape on the threads of any fuel fitting - if you don't it will leak) and a a couple stated the calibration was off - if that's the case you contact mfg and return it for replacement or money back. I think it's worth a shot... Do you have any kind of fuel pressure gauge handy? That would be nice to have in your toolbox even after the repair, just ensure that it's capable of reading low pressure (1-6 psi). I found this 1-15psi on Amazon that should be a useful diagnostic tool for ya:


NOTE: Should you some day end up with the fuel injected 700, this gauge won't work for you as the FI models run a much higher fuel pressure.
Mike
 

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Discussion Starter #10
So I found the Mr Gasket Fuel Pressure regulator at a local shop. After work ran over and picked it up and got it installed. While I can slow or increase the leak it didn’t stop it..... this thing..... Time to tear into the carb next I reckon. 😢
 

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Been There - Done That frustration wise - no how you must feel.
the logical next step does appear to be a carb float issue.
when disassembling it try real hard not to disturb the gaskets -there can't be too much to a repair kit for a single lung carbureted engine 660. Good Luck!
 

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Yeah... rats!!! Thanks again for the input. I appreciate it.
My guess is your needle and seat are out of adjustment or dirty. You now have good constant fuel pressure with the electric pump where you had low sporadic fuel pressure with the stock fuel pump. I think Sandbuster makes a good point on the float level. Search on how to check your float level with a clear tube. You may not have to take the carburetor out to do either of these fixes if your float level checks out O.K.
Good Luck
 

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Discussion Starter #14
I’ve been researching the things I need to check and ran across the float part last night on a good YouTube video. If all goes well I may tear into it later today. Thanks for the feedback.
 

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Discussion Starter #15
Got time to dig into the Rhino Fuel Drain issues this morning. I'm not a mechanic nor experienced with carbs but my FIL came over to lend his advice. He knows all that stuff and was very helpful. One thing I tried before we took the carb out was to turn the Mr Gasket Fuel Regulator down to the lowest setting - which is like 1/2 and it still leaked fuel out the drain hose. After that we started to work. We never saw anything to our eyes that indicated a problem but we only looked at the float side (focusing on the tang, needle valve and seat). No varnish or gunk inside the pan. There was a small sliver of what appeared to be a long plastic sliver off the edge of the float maybe. The float appeared fine though. I will try to post some pics below on some of the few things that left us with some questions.

1. How do you determine in the needle valve and seat need to be replaced? Nothing visible to the naked eye that we say but I probably should just replace them?
2. The tang on the float was bent slightly but I wasn't sure if that was correct or not. How do you test where the float should be? If the tang is bent to allow less fuel - upward slightly?
3. The seal around the bowl the float sits in had some grime on the gasket. It was stuck on pretty good but I finally wiped it off. Really - I need to replace that gasket/O-Ring IMO.
4. The pan head screws holding the bowl on that the float sits in - 4 screws. One of the screws had two washers on it while the others didn't had any washers which I thought was odd?
5. The main jet didn't look right to me. Appeared to be leaning if that is possible and not square with the other jet?
6. I'm gonna replace the air filter so I need to know which one is preferred? I cleaned the one in it but it had a few tears so it needs replaced.

Besides the air filter needing to be replaced. I think I wanna go ahead and replaced the O-ring gasket around the pan plus replace the needle value and seat. Is there a kit that includes what I need or buy them separately?
 

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Couple of things: One is to get that float in your hand and shake it. I have seen every kind of float material out there get fuel in them - you don't want that so if you hear any sloshing around then replace the float. Secondly, can you provide a close-up (as much as possible) of the needle and seat pieces? If you get a repair kit it should come with all new stuff, gaskets & needle& seat. If you want it to look pretty there is a product called Berryman B12, made by Chemtool, and sold at Walmart - usually. Get it in a spray can; you'll be amazed how nice it will look after a good cleanup. When you get it back together remember to invert the carb and hook your lips to the fuel intake fitting and blow away - if all is well you're ears will pop and no air will enter the float area. Looking at your pictures the main jet appears to be aligned with the stack it sits in - probably ok. Good luck..
 

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Discussion Starter #18
I will try to get some pics and post them here tomorrow. We shook the float and nothing inside it. Best place to go ahead an order the kit - have a link to it as well as the air filter? I could not find any numbers on the air filter that was in it. Thanks so much for the comments and help!
 

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Thanks for posting the pics - I can't really discern much from them but you're on the right track if you follow through and get yourself a carb kit - probably should look for a genuine Yamaha kit as a lot of folks on here have negative things to say about Chinese carbs vs OEM so I'm sure same holds true for rebuilding kits. :unsure:
 
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