Yamaha Gsxr 750 in rhino fuel problems

[tucks15]

I've mounted the 05 gsxr 750 fuel pump in the old rhino fuel tank. I have cut about 2 inches out of the middle of the tank and plastic welded it back together. I cut out a metal circle and used that to bolt the fuel pump in place inside the bottom of the tank. The tank is mounted back in its original position under the passenger seat. Im having issues getting my engine to start thought and I'm guessing either my fuel pressure to low as the pump is having to pump it from undernieth the engine up about a distance of 36 inches. Since the pump is mounted above the engine on the bike does it need to be mounted above in my rhino to achieve the correct psi?

What I'm finding is that I'm getting spark on each cylinder when it is cranking over. However when it eventually starts it is only running on 2 cylinders, other 2 are cold. When I pull the plugs on these cylinders the plugs are wet and smell like fuel. It usually has to crank for about 1 minute before it will start up. When the engine warms up it seems to run fine on all 4. Engine revs and runs normally.

At first it would not fire on cylinders 1 and 4. I replaced plugs in those cylinders and now it wont fire in cylinders 1 and 2.

If the plugs are wet I'm guessing the cylinder should be firing but do I have to have the correct fuel pressure for it to fire.

I'm thinking of getting an inline gauge so I can check and see what the pressure is at.


Thanks for any help

 

[Thrill Seeker]

I agree, you need to know what the fuel pressure is...& make sure you have spark to all cylinders...Then go compression ect...

 

[tucks15]

I just went out and checked it again. Now it is firing only on the cylinders that I put new plugs in. I will try and pickup a fuel pressure tester tomorrow.

 

[tucks15]

So I've determined it is fuel. Took the airbox off and squirted some fuel down each throttle body and started right up. I will get a pressure gauge tomorrow and see where Im at. Either my filter inside my pump needs cleaned or I can't mount tank and pump in original location. Im guessing filter is dirty

 

[tucks15]

So my buddy had a fuel gauge and I'm right on 43 psi. Any other suggestions? Maybe clean injectors? Why would the problem be moving between all 4 cylinders though. Im confused

 

[Wild Earp]

Make sure you have a good vent on the tank. You might be getting ok pressure but no flow. The fuel thats pulled from the tank needs to be replaced with air.

Other than that, Im thinking an electrical problem, but I don't know enough about the GSXR motor to point you in the right direction. Maybe since the plugs were wet, the injectors are sticking open? Any black smoke out the exhaust or anything?

 

[tucks15]

Well don't i feel foolish. I pulled the fuel rail and injectors and they seemed to be spraying well. That got me thinking about Earp mentioning something electrical. I decided to pull me ecu cables out and have a look for possible pins broken off. Low and behold, WHAT DID I SEE?.........water



It seems water got into my connection to my ecu and was wrecking havoc on my electrical. Dried plug and ecu out and fired up and hitting on all 4.



Thanks for the help and suggestions

 

[tucks15]

Ok so the problem isn't solved, it fired up and ran good. Let it sit for a day and now won't fire up again. Checked spark again after adding a better ground strap. Nice bright blue spark at all cylinders. I decided to do a flow check on my fuel pump. From the manual Im supposed to be getting 1200 ml in 30 secs. In 30 secs I had about 800 ml. Im guessing I've found my starting problem.

Question:
I have relocated my fuel pump into the stock rhino fuel tank whereas the tank on the bike would sit right above. The difference in distance from stock location to my current location is about 3 feet. I've kept the fuel tubing size the same- 1/4" tubing. Not to mention the old location was above the fuel rails and now it sits about 2 feet below.
Would all this affect my flow rate? I have 44 psi with my current setup but obviously am not getting the fuel flow I need.

Should I increase fuel tube size? relocate tank so hose is shorter and above fuel rail- I dont really want to do that as I was planning on keeping the stock rhino tank.

I looked at my fuel filter inside the fuel pump and it looked not bad but I'm wondering if it's playing a part in the problem as well.

 

[Oc1]

Not sure if this will help you but I'm running 1/2" hose on my 04 GSXR 1k. The other things that might be having an effect are the clutch switch and the kickstand switch. The clutch switch changes the mapping so you turn it on to start and then turn it off. The other thing I did was to put a fuel regulator with a pressure gauge and a return. When I start the motor there is a fair amount of fuel going thru the return but the extra volume is there if needed. The gauge is between the pump and the engine and makes it really easy to get the pressure exact.

 

[Oc1]

After re-reading your post it could very easily be volume. Upsize your hose and see if that helps.
Good luck.

 

[tucks15]

I've upsized my hose to 5/16" and noticed a slight increase in volume. It is just under 1000 ml in 30 seconds. Im wondering if I'm getting enough voltage as manual states this test to be done with a full battery. When Im cranking engine over voltage gauge reads 11.2 volts. Will 11.2 volts give me an accurate voltage for fuel pump to run to its full potential.

Second thought is that the hose from the pump to fuel rail is just too long for enough volume to pass through. I have the pressure I need but cant get 1200ml in 30 secs without going to a bigger pump.

What aftermarket pump and regulator should I be looking for if voltage isn't the problem.

 

[crazywatson]

Is it possible the bump is sucking up some air? Maybe try filling the tank up all the way so there is no chance it's getting into any air.

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[tucks15]

Good suggestion....I added some fuel so the fuel pump inlet was covered by about 4 inches. Put a trickle charger on the battery. When I cranked it over voltage read 11.6 volts and pumped out just under 1100 mls in 30 secs.

Im not sure what cranking voltage should be but to seems to be the issue

 

[crazywatson]

Maybe hook up jumper cables to your truck it should have more then enough juice then.

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[tucks15]

My fuel pump is now within spec with 1200 ml in 30 secs with 2 volts to it. I got it running again but it runs very rough. Seems to idle steady but has issues climbing in rpms. Seems like its starving for fuel. But then the you let off the throttle is shoots a blue flame out the exhaust. My understanding of this was the flame is a sign of a rich condition. After the flame it usually always stalls. When you try and start it again it again seems like its starving for fuel and does want to idle at more than 1000 rpms.

I have posted a link to youtube to watch the video.

https://www.youtube.com/watch?v=bk9zpCkuyMs


Would dirty injectors cause this? Too much flow as I am using 5/16 fuel line?

 

[crazywatson]

If it's running rich it would put out black smoke. I think if it's shooting a flame you have an exhaust leak or a really short wide open exhaust. What do the plugs look like?

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[tucks15]

My exhaust is really short, i cut the mid-pipe out and pieced tubing up to the original exhaust which has been cut in half. Original yoshi can is now about 11 inches long. Could the issue be not having enough back pressure and that is why it's stalling out? and causing it to run lean?

 

[crazywatson]

Did it run before with that exhaust?

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[tucks15]

no I just cut about 5 inches off of the mid pipe and made a shorty exhaust can. Think it has something to do with my problem?

 

[crazywatson]

It could be if it ran ok before you may need to adjust the fueling. I am not to smart with fueling. I think if you go back and think what has changed since it ran good last and one of those things will be the problem. I know putting a free flowing exhaust can make a big diffrence with fueling.

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