4RT has fuel (wet plug) and spark but won't start...

[rustyrider]

Hi, I had a similar problem with my 2005 model way back in 2007, turned out I over oiled my air filter, Sandifords advised me to remove rear mudguard, air filter top/air filter and fire trap, do the reset procedure then it started, a small lesson learnt not to over oil your filter, you could also try a brand new spark plug to 

[jonnyc21]

Come to think of it another issue I have seen with some of the older bikes is the throttle stop getting just a touch of ware on it and the position will read negative by the ECU.  If this happens it will not start at all.  Simple test is to put a tiny thin washer against the stop to lift it just a touch and see if it will start.  If so you should be able to glue a thin bit of something there to resolve the issue. 

I would still guess idle setting before this, but I know more than one person with an 05-09 4RT that have fixed a no-start with the washer trick. 

Good luck.

[unospeeder]

I had a 2006 4RT with the same issue. The fuel injector was partially blocked. I pulled the injector and cleaned it with some carb cleaner as that is all I had at the moment and wanted a running bike. I was lucky that the injector o-ring was in good shape so I was able to reuse it. The bike was spot on after the cleaning and, to this day, is still running like a top. 

[trevbul1]

UPDATE: PROBLEM SOLVED (with thanks to all)

Following advice from various sources, I;

Checked that the air filter was not over-oiled and that the fuel cap was breathing correctly.

Drained the tank and removed the top banjo from the injector so I could soak out that fuel with a rag, replaced the fuel with fresh 99 octane and checked the fuel was running freely from the outlet. BTW, I met a guy once who had (evventually!) found that atheft-detection transponder had come unglued inside the tank and blocked the fuel line!

Replced the plug with a brand new CR6EH-9

Reassembled and kicked it repeatedly with the plug out to hopefully draw throufgh the new fuel.

Checked the routing of the throttle cable and lubed it to ensure that the throttle was fully closing with an audible click at the injector end. (I'm sure everybody knows by now that 4RT's only start on a dead throttle)

Wound the idle adjuster out ONE FULL TURN anti-clockwise

Replaced the plug and fully rotated the kickstart twice SLOWLY with the throttle wide open to reset the ECU; I know the jury is out as to whether this is a real thing or not, but it can't hurt.

Carefully positioned the kickstart to find the top of the compression at the 5 to 12 position.

Kicked it smoothly all the way down and held the kickstart against the footrest.

It starts first or second kick every time now.

I had to readjust the tickover speed once it had warmed up, so don't put the mdguard back on until it is running!

Many thanks to all who offered suggestions and happy riding.

[trevbul1]

On 12/13/2022 at 5:28 PM, unospeeder said:

I had a 2006 4RT with the same issue. The fuel injector was partially blocked. I pulled the injector and cleaned it with some carb cleaner as that is all I had at the moment and wanted a running bike. I was lucky that the injector o-ring was in good shape so I was able to reuse it. The bike was spot on after the cleaning and, to this day, is still running like a top. 

One guy told me that the new E5/ E10 fuels can condense water droplets that won't atomise in the injector, blocking it, if there is a sharp change in atmospherics. Glad you could reuse the o-ring; never having worked on an EFI before, I did not dare separate the injector!

[lineaway]

That is why in the states we go out of our way to run race gas or ethanol free fuel.

[unospeeder]

On 12/18/2022 at 3:25 AM, trevbul1 said:

One guy told me that the new E5/ E10 fuels can condense water droplets that won't atomise in the injector, blocking it, if there is a sharp change in atmospherics. Glad you could reuse the o-ring; never having worked on an EFI before, I did not dare separate the injector!

The injector was just dirty from 13 years of use. The injector is the same as in some Honda cars so it's fairly easy to locate and I doubt subject to any ethanol issues. I ordered a few replacement o-rings after that cross referencing the part number and finding a match in the general auto parts.