Fuel Pump Runs Constantly - Honda RC51 Forum : RC51 Motorcycle Forums
 
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post #1 of 6 (permalink) Old 07-22-2016, 06:26 PM Thread Starter
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Fuel Pump Runs Constantly

Hi All -

I have come back to the fold, I was an RC51 rider in 2000 bought a brand new one rode it for 5 years and then moved to other things.
(Took a job at another bike manufacturer.)

Just last week I picked up an 03 SP2 , it is an old warhorse but the price was right and it is as fun as I remember the RC being, I always missed that first one, and in this forum I wont need to justify my choice.

When I KeyOn this bike runs the fuel pump and it won't stop. I have seen some say it could be ECU, maybe grounds / earth.

My question is has anyone had this happen and figured out a solution ?

I look forward to being a member of this forum and being back on the RC

Cheers

tr0y
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post #2 of 6 (permalink) Old 07-22-2016, 11:38 PM
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check to be sure that the previous owner hasn't wired it to be this way. sometimes the switch in the ecu that controls the negative side of the coil on the fuel pump relay fails, if this is the case the previous owner may have wired around it.
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post #3 of 6 (permalink) Old 07-23-2016, 06:37 AM Thread Starter
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Thanks later today when the plastic comes off I'll check it out

T
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post #4 of 6 (permalink) Old 08-18-2016, 11:25 PM
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Wibby - Sounds like you are saying something in the ECU has gone bad. Mine was rewired by the previous owner and runs all the time (SP1). Is the fix to replace the ECU? Thanx in advance.

2004 BMW R1150SR Project Touring Bike (in-work)
2005 Honda RC-51 SP-2 - future track tool
2014 Ducati HyperProject (Hyperstrada)
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post #5 of 6 (permalink) Old 08-18-2016, 11:56 PM
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yes. see if you can find a known good ecu to try it on.

there is a contact in the ecu that switches the negative side of the fuel cut relay coil to ground. this is the same contact that primes the pump then shuts it off when you first turn the key on.

if this contact fails your pump won't run at all. you can't wire around the contact and retain the timed prime then shut off as the ecu does. hence the run all the time situation when this contact has been bypassed
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post #6 of 6 (permalink) Old 08-19-2016, 08:39 AM
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Wibbly, thanks for the explanation.

This makes me think, why not convert the whole bike over to SP2 electronics. Please tell me what I missed to do so:
-SP2 ECU
-SP2 harness
-SP2 Throttle bodies/injection
-SP2 radiator thermal sensor for ECU to know when to turn the fans on

My assumptions:
-I will be able to reuse the SP1 radiators
-I will be able to reuse the other sensors on the engine and snorkel (all 2000 SP1)
-I will be able to reuse the dash
-I will be about to use the same clutch and brake switches

What have I overlooked (I confident I did as I'm new to these bikes)?

Thanx again.

2004 BMW R1150SR Project Touring Bike (in-work)
2005 Honda RC-51 SP-2 - future track tool
2014 Ducati HyperProject (Hyperstrada)
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