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Discussion Starter #1
I installed electric fuel pump from black rhino recently on my 06 660. I removed stock pump. Everything was working great for the first 4-5 rides. Then one ride it started acting like it was loading up from too much fuel when putting around slow and engine was hot. Was able to rev it up and get it cleaned out and ran fine rest of the way back. Next ride it continued to do the same thing when moving slow but still could rev it up and clean it out. The following ride it died and I cannot get it to start again. I’ve messed with it for hours and am at a loss what to try next.
Disassembled carb Cleaned carb and jets twice. Pump is working fuel in bowl is above top of bowl. I have spark tried two different coils. Brand new spark plug. Tried pouring gas into carb to see if it would fire that way. Plug is wet but still no fire.
Wondering if timing or valves need adjusted but still it never ran bad or backfired ever so I feel like that should be ok.
Anyone have any suggestions???
Should the fuel from the carb come up from the bowl and thru the port holes and into the intake on its own with the pressure from the pump? or does the vacuum from engine suck it up out of the bowl when cranking motor?
with carb not hooked to intake the fuel does not run out of the carb anywhere when the fuel pump is on is that right or wrong?? When I cleaned the jets and ports with carb cleaner the cleaner shot up out the 3 port holes where fuel enters the intakes.
 

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Should be a return fuel line to the tank, maybe something happened to it.
 

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Discussion Starter #3
Should be a return fuel line to the tank, maybe something happened to it.
There is no return line anymore. I’m pretty certain the instructions from the black rhino kit says to cap off the return line. I put a bolt in the end of my return line coming off the tank and tied it up.
 

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It sounds like it's pumping more fuel than the engine needs, is there an adjustment on the pump? Maybe Sean from Black Rhino will chime in.
 

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I agree, the engine is being flooded with fuel. Your wet spark plug is demonstrating that. The wet fuel shorts out the plug gap and prevents the electricity from jumping the gap. Most common electric pumps are designed to push at 15 psi or so. There are only a very few that are designed to pump at the 1 to 2 psi range. The fuel return line acts as a pressure regulator and limits the pressure to a matter of inches of water column (the highest point in the fuel line to the carburetor float valve. Too much fuel pressure simply pushes the float valve open and fuel gushes in and overfills the float bowl. The green return line shown below goes up to a point just above where the original fuel pump was before going down to the fuel tank.

 

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Discussion Starter #6
Thanks guys. That’s what I thought originally as well the obvious answer was it’s pushing too much fuel.
When I said plug was wet that’s when I tried pouring gas into top of carb to see if it would fire. Other than that I think the plug has been dry after trying to start.

If the pump is pushing to much would the fuel push up through the carb and should I be able to see it coming out the port holes inside the carb with the carb unhooked from intake??
I tried that once and no fuel was coming out of the carb anywhere with the pump running. At that point I took carb apart again and cleaned it and the jets a second time thinking something was clogged up. After putting it back together I never tried it again with it unhooked from intake so not certain if it’s still doing that or not.
 

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Thanks guys. That’s what I thought originally as well the obvious answer was it’s pushing too much fuel.
When I said plug was wet that’s when I tried pouring gas into top of carb to see if it would fire. Other than that I think the plug has been dry after trying to start.

If the pump is pushing to much would the fuel push up through the carb and should I be able to see it coming out the port holes inside the carb with the carb unhooked from intake??
I tried that once and no fuel was coming out of the carb anywhere with the pump running. At that point I took carb apart again and cleaned it and the jets a second time thinking something was clogged up. After putting it back together I never tried it again with it unhooked from intake so not certain if it’s still doing that or not.
Here is a way to check the fuel level in the float bowl without taking the carb out or disassembling it. Replace the overflow hose with clear tubing if it is not already this way.

 

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Discussion Starter #8
Here is a way to check the fuel level in the float bowl without taking the carb out or disassembling it. Replace the overflow hose with clear tubing if it is not already this way.

[/QUOTE]

Mines already setup with the clear line and I checked this already and the fuel is above the top of my bowl inside the clear line.
 

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Mines already setup with the clear line and I checked this already and the fuel is above the top of my bowl inside the clear line.[/QUOTE]

This is with the fuel pump running?
 

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Discussion Starter #10
Steve, I don’t remember if I had pump running when I checked the fuel level or not.

Should it be at a different level when it’s running versus not running?
 

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Steve, I don’t remember if I had pump running when I checked the fuel level or not.
Should it be at a different level when it’s running versus not running?
It is just that the fuel level will drop over time as the fuel evaporates. You say that it was over the top of the float bowl flange, by how much? I run mine with the fuel level being more or less even with the top of the float bowl gasket. The float bowl gasket is about midway between the top of the carb body flange and the float bowl. If all else fails you could try adjusting the tang such that the fuel level is similar to that.
 

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Discussion Starter #12
I’ll check it again. Pretty sure I turned pump on for a few and then shut it off to check fuel level.
I remember it was about 3/16” above gasket
 

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Discussion Starter #14
Steve is the fuel pump supposed to push the fuel thru the carb and into the intake or does the engine have vacuum in which it sucks the fuel up out of the carb bowl??
 

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Steve is the fuel pump supposed to push the fuel thru the carb and into the intake or does the engine have vacuum in which it sucks the fuel up out of the carb bowl??
Pushing fuel into the intake tract is Fuel Injection territory. All carburetors use engine "suction" (air flow through a venturi) to draw air into the airstream. The idle jet and main jet draw fuel up from the float bowl "fuel reservoir". The idle (low speed) jet controls the amount of fuel that goes into the intake when the throttle slide is closed. The main jet, in conjunction with the needle that is protruding into it, governs the air/fuel mixture at various throttle opening positions. The slide is governed by the vacuum that it sees: It is not controlled directly by the throttle cable (foot pedal). There is a butterfly valve just downstream of the slide that opens and closes according to the amount that the foot pedal is pushed. when you push the pedal, the airflow through the venturi increases. Hence vacuum increases within the venturi and this draws the slide upward to introduce the appropriate amount of fuel for that amount of air flow.

This scheme is used to prevent the engine from faltering when some lead-foot stomps down on the gas pedal before the engine has gotten up to speed. There is no injection pump (as in an automotive carb) that squirts a small shot of raw fuel into the intake tract to overcome this lack of fuel when stomping on the gas. In a motorcycle carb without this "constant velocity airflow" feature, the driver learns to "roll the throttle" on.
 

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Discussion Starter #16
Steve
So I finally got to look at this again and with my pump running my fuel level is about 1/2” above the top of my bowl.
I cranked the motor over for 20 seconds with no attempt to fire. I then checked spark plug which was dry as a bone.
Do you suppose motors not pulling the fuel in? What would cause that?
 

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Discussion Starter #17
So I removed valve cover all timing marks line up and valves are adjusted correctly.
Thinking maybe CDI not firing st right time.
Battery is 12.5 with no load and 11.3 while cranking. Is that enough for CDI to work right??
 

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Discussion Starter #19
Ok guys so I got my starting problem resolved by replacing CDI but rhino still acting like flooding once engine is hot.

Sorry for the book I’m about to publish here but not sure what to try next.

Electric fuel pump works great when engine is cool. Starts great and Runs good during long rides. Shut it off with motor hot let it set 10 minutes and as soon as I try to restart it starts hard and acts liked it’s flooded and I smell gas. When it does start I try to take off and it stumbles and dies. Start back up stumble and die. Almost like it’s starved for fuel at acceleration. Start backup rev engine in neutral put in gear take off and goes but misses a little so I nail it run it hard to clean out and runs fine proceed to park it and shutoff and won’t start after that. Trailer it home everything cools off and starts and runs perfect again until I get it motor hot again and I start the process over.
Wanted to mention that when pump starts pumping initially after engine has been hot it sounds like it’s pumping air and is loud knocking sound for couple of seconds and then it picks up the fuel and quiets down like it should be. I’m assuming it is still vapor locking after being hot and that’s why it sounds like it’s pumping air??
Do you suppose the hard start and stumbling at acceleration is from lack of fuel or flooding??? I can’t figure it out because I do smell fuel when all this is happening.

Any ideas??

Fuel pump is from black rhino Performance so I’m assuming it’s not to much pressure especially if it works great when cool.
 

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I see their instructions have you plug off the return line, can you redo the return line and try running the rhino that way to see what happens?
 
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