rc51 fuel filter

yellow01tlr · 05-25-2009, 7:46 AM

My 2001 RC will not idle and is very hard to start so looking to see if anyone can help out. It is not throwing any codes and I have changed the spark plugs, air filters, disconnected the power commander, checked the lines for kinks and the wiring for bad connedtions or shorts and everything is fine but the bike will not run right. If you start it and hold the throttle steady at 1500 rpm you can hear the bike want to run faster and then it dropps down again-sounds like to me that it is not getting enough fuel. You can hear the fuel pump prime when you turn it on and I have a fuel filter on order but wondering if it could be a sensor or something else. Thanks for any help as I am almost ready to part the bike out and get something else. Bought this bike for my wife and she has only ridden it for 2 months so now she is getting upset.

Jetpilot07 · 05-26-2009, 12:43 PM

fuel pump or the pick-up screen in the bottom of the tank....check that first.

also check the throttle position sensor, may have gone bad or come loose.

greenracing · 07-28-2009, 4:35 PM

Hi, did you solve the problem as it sounds like exactly the same issue I have?

zerogara · 07-28-2009, 7:35 PM

If you ride the bike and it revs up and doesn't have surges I would think it is getting adequate fuel. At near idle and load the amount of fuel needed is a tiny fraction of what is consumed at higher rpm and loads.
So I would want to place my bet to a TPS sensor as mentioned above. Either lose, malfunctioning, dirty, or just not working properly.
If you have a PCiii you might want to reset that also or disconnect it while trying to isolate the problem. There is a routine of calibrating the PC with the TPS sensor as well.

greenracing · 07-29-2009, 5:10 PM

ok, I will check the tps, what is the "pick up screen"?

zerogara · 07-29-2009, 6:22 PM

Originally Posted by greenracing

ok, I will check the tps, what is the "pick up screen"?

Your fuel pump picks up gas in the bottom of the tank through a screen/net type of filter that would prevent hard solids from blocking the pump and destroying it. It is not an easy thing to get to, although I have not done it on this bike. Being an 8 year old bike for sure you will have something to clean there, but whether it is what is causing your problem I can not know.
Also, as someone else who hadn't ridden the bike for a while said, water in the gas will find itself in the bottom of the tank and make a first start difficult and rough. If you ride the bike as is for a while and refill it, see if there is an improvement. Injection systems can not tell whether it is gas or water they are pumping. The fuel filter will not restrict water from going through it either.

Unless the TPS has come loose, it is hard to check its function without proper diagnostic tools and specs. A small voltage goes through it and something like a rheostat sends back a signal of a range of voltage indicating the position of the throttle to ECU. Your injection based on the TPS, rpm, and a few other sensor readings will tell the injectors what quantity to spray each fraction of a second.

It could also be an air-leak somewhere, like if a throttle body/manifold has come loose and allows air through the intake, rare chance as I have not ever heard of an other RC51 doing something like this.

Stu494 · 07-31-2009, 7:22 AM

Just a thought... is it running rich? that may indicate a sensor...

Another issue I have seen is on the outside (at opposite ends as you look down on them) of each throttle body is a vacum inlet/ outlet. The rear throttle body is blanked off, but the front (on a stock bike) runs a tube to a vac canister for the flapper in the air intake. If one of these falls off it will play havoc with the idle and run rich as well.

There are a few vacume lines that run around the bottom of the throttle bodies; it wouldnt hurt to check them out while you are there as there are a few joiners in them.

Hope this helps- nothing worse than having a nice machine not working correctly

greenracing · 08-01-2009, 5:44 PM

Thanks for the advice, I am going to remove the air filter housing tomorrow and check for loos, blocked hoses etc. Spent all day today looking for loose wires & corroded connectors but couldn't find any. This problem is driving me mad, if it vdidnt work at all it would be easy to diagnose!

Just incase it helps, I have put below the sequence of event leading up to the problem, however, I cant understand how any of the below would cause the problem , but it wont hurt!

1. bike due for service
2. removed lower fairings, drained oil, removed and replaced filter, refilled oil. Oil done.
3. removed ridier seat, removed rear seat cowl to get clearance to lift up tank. lifted tank, removed air box cover, removed air filters, replaced filters, replaced air box cover and connected up air temp sensor. Filters done.
4. removed front indicators, fitted new front indicators.

After doing the above, replaced anything removed from he bike, started it up and found that it wouldnt idle and that if you kept it going by playing thr throttle, it had no power to even move itself once in gear.

Totaly confused by this, removed fairing panels and checked for obvious loose connectors as I though that I could have caused a problem with the front connectors while unclipping/clipping the front indicator wires but found nothing.

spent all day today checking for loose wires and contiunity at all the wiring connectors I could find, still nothing.

did have a strange problem where if i kept the bike running on the throttle and then put it into gear (with stand up) it would cut the engine out, but only sometimes!? so I disconnected the side stand switch and tried to run it again but the problem was still the same, however the the mil (FI) light flashed. once 9 times then 2 long flashes. checking these codes they seem to point to the IAT sensor and the ECU, will double all connections again tomorrow to the ecu.

zerogara · 08-01-2009, 8:36 PM

Have you touched both exhaust pipes once you get it started from cod to see if they both get hot evenly? It sounds like a bike running on one cylinder.

greenracing · 08-02-2009, 12:33 PM

ok, spent the whole day looking for faults etc. reset the eprom memory and started the bike, holding it running on the throttle, connected the mil light and no faults in memory. spent the rest of the day checking voltages and connects, still nothing.

could it be something to do with the starter valves, can these go? they control the balancing to an extent dont they?

honorcode3 · 08-05-2009, 5:06 PM

I'm having similar problems with my bike. I should be taking it to the dealership shortly and if they can figure it out, I'll let you know what the problem was. Good luck and I hope everything turns out well.

zerogara · 08-05-2009, 9:18 PM

Greenrc, you never answered if you felt the temp. front back check to see any imbalance. An exhaust that gets hot quickly is lean, the one that stays cold or takes too long to warm up is either too rich or not firing at all. Maybe a fouled plug or faulty coil?
An other easy check, what have you done with the flopper valve, still in tact, removed, air-hose plugged up? You may want to check if you have an air leak.

greenracing · 08-06-2009, 6:00 PM

hi, both pipes are getting hot, it is [FONT='Calibri','sans-serif']definitely[/FONT] firing on both cylinders. got a guy coming over on saturday with another sp1. going to try my cdi, ecu and rectifier on his bike, hopefully one of them will not work properly, problem solved! If not, I guess it is the loom!