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Discussion Starter #1
Greetings all!

I have about reached the end of my rope with our ’06 Yamaha Rhino, YXR45FAVGR. I picked this great little Rhino up from a friend that bought it new in ’06 for his horse ranch and has had the same problem we are having for three or four years and just got tired of messing with it and just bought a newer model. He sold it to me for a song, knowing the problem.

Here is the issue; when it has been just sitting, it starts right up with nothing more than a bump of the key. That same thing will happen time and time again until after it has run around a while, then if you stop the unit and turn it off, when trying to restart it, it simply will not start.

When trying to restart, it actually acts like it is fuel starved. After it sits for a while; and hour or so, it will fire right back up. Weather does not have any effect — same thing summer or winter.

So what have we done for far to address this issue:

1. We have removed the Yamaha vacuum fuel pump and installed an electric fuel pump system.
2. Replaced the coil.
3. Replaced the CDI
4. Replaced the stark plug
5. Replaced the fuel

Nothing has made a difference; well with the new CDI performance has improved; however, just this afternoon once again we turned it off while working and when I tried to restart it, the starter ground and ground — nothing. Again, it sounded like it wanted to fire up, but again would not. We waited about an hour or so and it fired right back up.

SSSOOO, we are at the point that we are considering either rebuilding or replacing the carburetor. Before we do, we thought we would throw this out to see if anyone has had any experience with this pain-in-the-butt problem.

Any takers? Many thanks in advance.
 

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Try and remove fuel tank cap and start it after it has been run around


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Welcome to the site, like Brian said, your cap is vented might be plugged up.
 

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Discussion Starter #4
DAMN!! Vacuum set up in fuel tank, acerbated by engine heat! Spent all that $$$ and a plugged vent in the fuel cap could be the problem? I’ll be extremely happy if this fixes the problem, while being totally PO’ed I missed this simple answer.

Many thanks to both of you. I’ll follow-up down the road on how it worked.

One additional question – IF I end up having to replace the carb, since other than the cap vent not much is left, any thoughts on a good option/make?

Thanks again!
 

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Vapor locked ?

Very common on the old carbed 450 and 660. I had to insulate fuel lines to stop this problem. No problems in the last 5 years. Just a thought?
Good luck
 

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If it ran fine it questionable about the vac in the tank. Either pressure or vac should be evident when youre in a no start situation and you slowly unscrew the cap on the tank as you should hear a hiss. Vapor lock if the fuel line arent routed right or not insulated. ( my 660'are from yamaha) When you are dead have you verified you have spark? Believe it or not a screwed up plug sparking from the ide and not the electrode can wreak havoc. The fuel system...you sure the carb isnt drowning in fuel from to high of fuel pressure and/or a bad needle and seat? Re carbs a new rhino carb is $350 roughly, same as a atv I was wrenching on a while back. I got pissed at the Kehin on it and bought a amazon special for $45 and it worked great. Just a hunch but Im guessin its flooding it out once shut off and the sitting allows the flooded engine to dry out a bit and restart. Other than that the no start when hot is a symptom of a bad coil buy you replaced that already. Like said by others make sure the tank vent is not plugged to start.
 

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Discussion Starter #7
Hey Scooter4551, many thanks for taking the time to respond. Ok, so just today I installed thermo-armor silicone coated fiberglass fire sleeves on the fuel line from the tank to the EL pump, then on to the carb. Also relocated the fuel filter up to the top of the fuel tank. Also replaced the fuel cap with a new OEM one.

So considering everything else I have done, I’m thinking if this damn problem is not resolved, the carb is all that is left. Time will tell!!

Thanks again to all.
 

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Hey Scooter4551, many thanks for taking the time to respond. Ok, so just today I installed thermo-armor silicone coated fiberglass fire sleeves on the fuel line from the tank to the EL pump, then on to the carb. Also relocated the fuel filter up to the top of the fuel tank. Also replaced the fuel cap with a new OEM one.

So considering everything else I have done, I’m thinking if this damn problem is not resolved, the carb is all that is left. Time will tell!!

Thanks again to all.

If all the previous suggestions fail to solve the issue then simply remove the fuel cap, raise it up about a foot, and drive a new Yamaha under it..... :grin
 

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Discussion Starter #9
LMBO!! The truth is, I did “buy” this puppy from a friend, but for only a $100; so I still cannot complain. I knew the problems so the issue is just a mechanical puzzle to me. I have no intention of letting it get the best of me! At this stage — Money is not an option, pride is the game!
 

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I know the feeling on being driven to find out what wrong. In my experience of 45 years of 4x4's,bikes,atv's etc Ive seen stuff Id never guess was the problem. Sometimes its so simple but we dig to deep thinking it can be that easy. If it runs fine when running, then id say the carb is 90% ok and not plugged up from rotten gas or dirt, but there is always the worn needle and seat issue that could be affecting things when it sits allowing fuel to seep past. There are several parts suppliers that can get you new OE carb parts to freshen it up. Generally speaking you can put a clear piece of vinyl tubing on the carb drain and run that line up next to the carb body and above it a good 6" or so. Open the drain screw and the fuel that comes into the tube will reflect eek its height based off whats in the carb bowl showing the float bowl level. You can even run it like this and watch the level but be careful not to let the tubing fall off and burn things down. Are you sure you have spark when its not running? Have you ever adjusted the valves? when hot they lose that minute clearance and can be held open losing compression and causing hard starting. Think Kawasaki Teryx with known valve problems. You got me curious and wanna know what you come up with as you check things out.
 

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Discussion Starter #12
I am going to resolve this issue if it breaks me!!

Ok, so after insulating and rerouting all fuel lines and replacing the fuel tank cap, I took the Rhino on a long haul today. When I got back, I shut her off and after a few seconds, restarted it – She fired right up. Off again, waited about 30-45 sec and then it started right up.

So I let it sit for about 15-20 min and tried to start it up - NOTHING! Just ground away like it had no fuel.

Spark? You bet! (By the way, keep your damn fingers away from the end of the plug tester!!)

Ok, after going back over all that I have done, I am down to, or if you will, moving up to the carburetor. I just do not see anything else let. At the same time, my frustration level has reached the point where rather than just rebuild the existing carb, I am thinking of just replacing it.

Any thoughts?
 

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Have you pulled the intake boot off the carb to see if slide is moving freely?
 

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to me is acts like the fuel evaporates in the carb from heat. check any add on stuff that may be blocking air flow .
you may try driving it with the hood off .
jim
 

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Have you Tried to drain the float bowl when it’s does this problem? After you spin it over and it doesn’t start pull the spark plug and see if it wet. If it is you’re getting fuel but no spark. If it’s not getting fuel when it does this you could try the choke to see if it attempts to start.
 

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Discussion Starter #18
Well, well, well!! When all else fails - buy more stuff!

So I gave up and ordered a new Mikuni OEM Yamaha Rhino 450 carburetor for this puppy. While making the install, we discovered that the original OEM carb had apparently been replaced by the previous owner in an effort to resolve this issue.

After the install, she fired right up and ran great. Then the following day, after an hour of running around in the hot Texas sun – she totally shut down and would not start!

Observations: Electric fuel pump running strong but not sounding like it was pumping. Remembered one of you folks mentioned the fuel cap – Note: a new one – so I cracked it and I hear “hisssss” and the fuel pump goes under load. She fires right up!

Then I remember the ROV on the vent line and pull the vent line off the top of the ROV. Rhino runs great the rest of the day. That evening I pulled the ROV and no matter which way I turn it, it is all but impossible to blow air through either end.

We are over a two weeks out now and the sad reality has come over us; after installing an electric fuel pump, replacing the coil, CDI, stark plug, carb, and adding aircraft grade fuel line insulators to all of the fuel line, I am left is the reality that ALL of this may have been caused by the one thing we never even considered – the vent line ROV!

A $61.00 part on Amazon; $39.99 on eBay! As the old saying goes – “The different between men and boy is the price of their toys”!

Many thanks once again to all who offered comments and recommendations.
 

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Good deal, where u at in texas?


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