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Bob Kelly · 10-03-2023, 08:46 AM

Sounds like your still having the issue... My RX4 started first try every try till the day I sold it ( too heavy for me) I suspect as you do a fuel issue as well, it just sounds like a fuel problem to me ! the only other thing that it might be is SPARK PLUG doubtful, but I have seen sparkplugs give a starting problem before only on starting but not in running but it is a 1 in a million chance if you know what I mean....
Like the other guy said it sounds like the fuel is leaving the line to the throttle body when sitting.... so it takes a second or two to get fuel to the engine when starting
pull the tank off and look for damp areas on the fuel lines, if you find one that looks suspisious just replace the line, there is no sense in messing with it ! sense fuel injected bikes use a really high fuel pressure to make them operate (something like 30 p.s.i.)
any leaks at all are suspect.... although I doubt you'll find any sense the bike runs great once fired up it could be a check valve in line if there is such a thing on the RX4
if so I would just replace it.
I do know there is a fuel filter on the RX4 that is in the gas tank I think hooked to the fuel pump..... but you said you replaced it so that shouldn't be it.
it's also possible that your new ECU is bad.... if you can put the old one back in for a test just to see if the problem goes away.
I don't suspect the sensors MAF or Throttle position, but I do suspect that the wiring to them could be getting bad, look for rubbed wires and bare spots while your in there.
if they were bad you would get a fault though I think.
......
I hope you find it without having to dismantle the entire bike !
....
Bob.

10-03-2023, 08:46 AM	#8
Bob Kelly Join Date: Jan 2022 Location: Weed, California. Posts: 271	Sounds like your still having the issue... My RX4 started first try every try till the day I sold it ( too heavy for me) I suspect as you do a fuel issue as well, it just sounds like a fuel problem to me ! the only other thing that it might be is SPARK PLUG doubtful, but I have seen sparkplugs give a starting problem before only on starting but not in running but it is a 1 in a million chance if you know what I mean.... Like the other guy said it sounds like the fuel is leaving the line to the throttle body when sitting.... so it takes a second or two to get fuel to the engine when starting pull the tank off and look for damp areas on the fuel lines, if you find one that looks suspisious just replace the line, there is no sense in messing with it ! sense fuel injected bikes use a really high fuel pressure to make them operate (something like 30 p.s.i.) any leaks at all are suspect.... although I doubt you'll find any sense the bike runs great once fired up it could be a check valve in line if there is such a thing on the RX4 if so I would just replace it. I do know there is a fuel filter on the RX4 that is in the gas tank I think hooked to the fuel pump..... but you said you replaced it so that shouldn't be it. it's also possible that your new ECU is bad.... if you can put the old one back in for a test just to see if the problem goes away. I don't suspect the sensors MAF or Throttle position, but I do suspect that the wiring to them could be getting bad, look for rubbed wires and bare spots while your in there. if they were bad you would get a fault though I think. ...... I hope you find it without having to dismantle the entire bike ! .... Bob. __________________ It's too late when you've gone too far !
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