Thread: CBR600 F4: Plenty of spark, no fuel

Make sure the fuel pump is working.

I hear the relay kick on when I flip the switch.

Check all of your fuses first.

Start at the tank, follow the fuel...

Disconnect the relay and reconnect it. It is located under the tail section. Could be a bad connection.

The jets are plugged from old gas.

Originally Posted by ND4SPD

I hear the relay kick on when I flip the switch.

But do you hear the pump whirr?

This sounds like a major issue!

You should definately bring the bike down here. We can then diag and repair.

Probably wouldn't be a bad idea to leave it here so I can follow up, and have it ready for FL trackdays for you.

OK, now really....

When is the last time it ran? It doesn't seem to have sat long enough for fuel clogged jets.

You need to establish whether you are getting fuel to the carbs, or not. This will determine if it is a fuel supply issue (pump and/or control circuit, or lines/filter) or a carb issue.

If you can get at the float bowl drains, open them up to see if gas drains, also, how it smells. Should be like gas, not varnish.

You can pull the line where it meets the carbs and point it into a bucket then flip it on and see what it pumps out. Just don't light yourself on fire.

Originally Posted by bda116

But do you hear the pump whirr?

I don't think it ever has. The most I've ever heard prior to hitting the starter button is the relay click.

Originally Posted by DrHall

OK, now really....

When is the last time it ran? It doesn't seem to have sat long enough for fuel clogged jets.

You need to establish whether you are getting fuel to the carbs, or not. This will determine if it is a fuel supply issue (pump and/or control circuit, or lines/filter) or a carb issue.

If you can get at the float bowl drains, open them up to see if gas drains, also, how it smells. Should be like gas, not varnish.

Haven't had it out since Grattan last year.

Originally Posted by slickwill

You can pull the line where it meets the carbs and point it into a bucket then flip it on and see what it pumps out. Just don't light yourself on fire.

Yeah, I'll start start at the tank and work my way down.

Originally Posted by ND4SPD

Yeah, I'll start start at the tank and work my way down.

Someone can correct me if I'm wrong but I would think that you may save time and effort by starting at where the line meets the carbs and work backward rather than starting at the tank and going down. If you have gas at that junction then you can head straight to the carbs for the problem. If you don't have gas at that point then go ahead and start working backward.

Originally Posted by slickwill

Someone can correct me if I'm wrong but I would think that you may save time and effort by starting at where the line meets the carbs and work backward rather than starting at the tank and going down. If you have gas at that junction then you can head straight to the carbs for the problem. If you don't have gas at that point then go ahead and start working backward.

That's how I would do it...though that might not necessarily be a positive endorsement.

Originally Posted by Hammer

Disconnect reality and reconnect it. It is located under the tail section. Could be a bad connection.

I read this twice and I swear this is what I thought it said. And I thought it was excellent advice.

Originally Posted by CBRVFR

I read this twice and I swear this is what I thought it said. And I thought it was excellent advice.

Plus I had the bike in the garage and worked through an issue similar as this.

The fuel pump will kick on but you may not be hearing it if it has fuel in it and not cavitating.

If you "Think" it has clogged jets, add Sea Foam additive to the fuel. This stuff works.

If you really want a quick fix to the possible clogged jet issue, empty the bowls and then close them back up and spray carb cleaner in the fuel hose so that carb cleaner is in the bowls instead of fuel. Move the bike around several times during the day and keep filling up the fuel hose to top it back off. Reconnect it and run the hell out of it.

Originally Posted by CBRVFR

I read this twice and I swear this is what I thought it said. And I thought it was excellent advice.

gives a whole new light to the "put your elbows on the table" scenario...

Yes, the F4 has a fuel pump just like the F3. The F2, however, did not.
Mostly to do with the effects of a pressurized airbox, which the F2 did not have.
The F4, like the F3, should start and run without the fuel pump if the hose from the petcock is re-routed directly to the carbs. However, once underway it will cough and buck without the fuel pump as it gets over 25 or so MPH.

But if the hose is still routed through the pump, and the pump isn't functioning properly, it will stop flow of fuel from the tank to the carbs.

Maybe you have some congealed chicken fat in there?

I guess I'll have to register on NESBA's site to find the answer.

Originally Posted by slickwill

Someone can correct me if I'm wrong but I would think that you may save time and effort by starting at where the line meets the carbs and work backward rather than starting at the tank and going down. If you have gas at that junction then you can head straight to the carbs for the problem. If you don't have gas at that point then go ahead and start working backward.

Do you have any way of removing the tank and running off of an aux tank (or put the tank higher than the bike and run a fuel line directly from the tank to the carbs)? That way you would definitely see if it was a fuel supply or a carburetor issue. For the length of time it was sitting, I would guess your pilot jets are plugged shut. You can try seafoam, but to do it right the pilots need to be removed, soaked, and blown out with compressed air. If bad enough, you may even need to run some wire strands through them.

Originally Posted by bda116

Yes, the F4 has a fuel pump just like the F3. The F2, however, did not.
Mostly to do with the effects of a pressurized airbox, which the F2 did not have.
The F4, like the F3, should start and run without the fuel pump if the hose from the petcock is re-routed directly to the carbs. However, once underway it will cough and buck without the fuel pump as it gets over 25 or so MPH.

But if the hose is still routed through the pump, and the pump isn't functioning properly, it will stop flow of fuel from the tank to the carbs.

Actually all CBR600's have a fuel pump, even the '87 CBR600F. And he's right on the money with the re-routing, it does the same thing I mentioned above, but with less hassle to find a way to support the tank above the bike.

The fuel pumps on the carbureted bikes are pulse type (you're hearing the clicking when you turn the key on or turn the kill switch back on) and the injected bikes make more of a whine. The pulse type pumps don't make much racket until your fuel supply is cut off or run low enough to make them run all the time.

Originally Posted by ND4SPD

I guess I'll have to register on NESBA's site to find the answer.

so is it running

Originally Posted by evl_twn

Actually all CBR600's have a fuel pump, even the '87 CBR600F.

Really? I know it's been a (long) while since I had my F2s, but I was quite positive they were simply a gravity feed system. Hose went right from the petcock to the carb T as far as I remember.
Oh well, like I said it's been a while.

Checked the fuel pump - it works fine. I've got the tank propped up with the airbox off, looking down the velocity stacks I can see some fuel coming in all 4 stacks where the needle from the diaphragm crosses over the throttle bodies. It's not a spray but the flow is consistent across all 4 cylinders.

I'm still leaning towards the carbs being the issue - is it easier to pull the entire throttle body assembly off the intake or should I leave it on the bike and deal with the carbs in place?