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Another Fuel Pump Issue

12K views 17 replies 8 participants last post by  Jagger Pinto 
#1 ·
Has anyone had an intermittent or slowly dying fuel pump. My bike over the past few months feels like it hasn't had the same top end that it normally does it will still pull to redline just some days It will pull much harder and rev much faster.

Also for some reason my bike will not high idle when its cold. I will start it it will high idle for a second then drop to low rpm and be real loppy. Did this before I ever installed my Bazzaz.

Today I was riding making a pull to about 145 I let off and noticed that sound of the engine changed pitch and then I had zero power it would barely pull up hill it sounded like it was running on three cylinders but it was smooth and wasn't missing like something on three cylinders would feel like. I pulled to the side of the road and it idling on its on just at a different pitch and it doesn't want to rev.

Shut the bike off with the kill switch wait a second kick it back on the fuel pump is very quite i flip the kill switch again and the pump primes like normal and bike starts running like it should wtf :banghead:.


2008 CBR600rr, Bazzaz ZFI, Arrow header, jardine exhaust, gutted intake tube, bmc race filter, dyno tune.
 
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#2 ·
I just had the fuel pump on my other Honda die and presented just as you described. I had a few times where I could pull over and re-start the bike with no issue but then, finally, the pump just buzzes for two seconds as opposed to the normal priming sound.

Thing is, that bike needs a battery so I will do that first just in case....

On my 600 it intermittently gets crappy around 12-14000 RPM. It acts very much like a ignition mis-fire but it's very intermittent. Some days it pulls like a mad bastard and other days it's just not as fast. I'm wondering about it too....
 
#8 ·
It's really hard to get a replacement strainer. As far as I know, they come from the pump manufacturer so they are typically unique to the application. Honda does not list them and good luck getting a replacement from the manufacturer that makes the pump for Honda :smile2:

The good news is that you can clean them quite a bit. You can't get them spotless but you can get most of the crap out of them just with Brake Kleen and compressed air. I'm guessing the reason Honda put that red 'life-jacket' type filter in there as well is to screen out the really big contaminants before they get to the fine-mesh filter on the pump. They must be expecting giant flakes of rust or something!

I just got back from another ride since my previous post and it's really nice to see the entire RPM range work properly. I can hold it at 15K for as long as I like and it's much smoother up there. If the spirit moves me tomorrow I'll do a proper top speed run and let it sit there for some time. I'm quite sure given enough room it will now bounce off the rev limiter in 6th with no issue (-1/+2 gearing at present). Fastest recorded speed for the bike has been an actual/real 238 KPH and it's hit that several times, but never past it so it should be easy to see a real-world increase directly attributable to the engine getting more fuel. Clearly it was running lean around 13-14,000 RPM as it was stuttering a bit.
 
#7 · (Edited)
I don't know directly about any other 600 RR's other then mine ('06) but typically the 02 sensor is used specifically to determine the rich/lean condition of the engine specially so that the ECU can alter the AFR as you drive.

I do know my '08 CBR 125R (a MUCH lesser bike) has 02 correction and this is typical (99.99999 % of vehicles with 02 sensor will correct/alter fuel). I am fluent with the management system in my '08 125 and the '08 600 appears to be very similar. It looks like in '07 Honda went with a similar design as on my '08 125 in that they added in a real IAC and they have a real 02 sensor. Both systems manufactured by Keihin.

The ECU on my '06 600 runs in what would normally be called 'open loop' that is, it runs strictly on a preset program. It has no idea if it's rich or lean. On a newer model (say '07) with an 02 sensor I would be really shocked (floored, actually) if it was not running in 'closed loop' which means it alters fuelling according to load (MAP sensor) and also TPS and also from what it reads from the 02 sensor.

OBDII is a specification and doesn't relate to whether fuelling is altered. Even though I haven't worked on an '07 600 or newer, I did design a new ECU for my 125 making use of the existing OE Keihin sensors so I'm very familiar with how Honda/Keihin engineered the overall system. I would find it impossible to believe that the ECU on '07 or newer was not correcting fuel. Otherwise there's no real point in having an 02 sensor at all. It would be wasted cost.

In real-world terms, no-one (today) would design a fuel management system that does not have 02 correction. There are just way too many benefits to ignore such as fuel economy, performance, emissions etc. You pretty much have to have 02 correction to accomplish any of these things.

My '06 is really an oddball in that respect. It does not even have a real IAC (idle air control). All is has is basically a thermal switch :surprise: When cold, increase idle by means of what we used to call a fast idle cam in the carburetor world. It's really primitive on the '06.

On the '07 you get a real IAC which is a stepper motor with 255 positions so it can gradually decrease idle speed as the engine warms up or under a stalling condition can raise the idle on it's own. Honda/Keihin also uses the IAC in a novel way, other then just idle control, they also use it to eliminate 'jerkiness' during throttle transitions. They actually open or close the IAC while driving based on rider inputs (TPS most probably as this would indicate throttle transitions).

Kind of what I'm getting at is that up to 2006 it appears the Honda/Keihin fuel management system is pretty rudimentary, after 2006 it looks like they became much more mainstream with proper IAC control and also 02 feedback for fuelling etc. Pretty much the only way to achieve any kind of responsible emissions is with 02 feedback.

The 'Power Commander' and other cheezy (from my perspective) controllers are 'piggy-back' units that just intercept the stock ECU's fuelling commands and alter them. If I recall correctly, I think most of them require you to unplug the 02 sensor when you install them to prevent the ECU from correcting your corrections. This would lend credence to those bikes having 02-based fuel correction.
 
#11 ·
Easily possible (two bad pumps). The service manual should have flow rates for the pumps and perhaps even a testing procedure. If you know the specified flow rate you can determine if the pump is good/bad. Check 'em both while you're there.

Bad fuel economy? I've noticed a very real (and massive) decrease in fuel economy on the freeway at around 200 KPH. I've learned that if you beat it at high speed it will drink fuel very quickly...

I usually get 38 MPG or sometimes 39 on a tank.
 
#12 ·
My fuel consumption was based on me comparing it to a friend with the same bike and the same mods. On my last track day I had to fill up 4 times. Twice before lunch and twice after. While my friend only filled up once. Mind you that we are in the same group with roughly the same pace.

I'll pull my pump out this weekend and see if it's clog or just a bad pump.

Is there any other suggestions that I should look at? I replaced my plugs at the beginning of the season. Along with the normal maintenance.
 
#13 ·
I think your first inclination is the one to check first - the pump.

At idle it must put out 50 PSI and it must flow 6.4 US oz minimum for 10 seconds.

I personally would pull the pump and check the filter. In my case I removed the red life jacket and paid very close attention to the pickup screen on the pump. Clean as required.

Once you have eliminated or confirmed the obvious, then move on one step at a time.
 
#14 ·
Again thanks for your help. So I pulled the pump out. Pulled it apart and cleaned everything I could. There is still a mis-fire at 11k RPM. Still feels like it's under power as well. Any other suggestions? Is it common to have issues with the coils? Could it be possible that the spark plugs are not gap properly?
 
#15 · (Edited)
There are a couple of tests you need to do to properly diagnose a fuel pump issue. I see cleaning our your pump helped the problem. I would do the following tests to be sure that your pump is performing as expected, and not gauge just by the RPMs.

First test is flow. Remove your fuel pump relay and jump the Brown and Black/White wires. Disconnect the QD fitting going into your fuel line on the fuel line side, not the pump side. Place the open end of the hose into a measuring cup. Turn the ignition switch on and your kill switch to run for 10s. You're looking for a minimum of 5.6oz per 10s. If it's less, check your hoses for clogs, cracks and kinks and check the fuel strainer screen.

Second test is pressure. You'll need a fuel pump pressure tester. Attach the pressure tester and let the bike idle. You're looking for 50psi. If it's high, replace your pump. If it's low, Check your hoses for cracks and kinks and check the fuel strainer screen.


Do the flow test first as it doesn't require any special tools. Second test needs the pressure tester but can also indicate a need to replace your fuel pump.
 
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