Running on only the rear cylinder.

[AdamCA]

It does not, it is in the gas tank. I had someone else mention it could be a cam issue and suggested I pull the cover and look in there and see what’s going on and make sure that all looks right. So I’m in the middle of pulling the exhaust so I can pull the cover.

So I have checked continuity from the injector plug to the ecm on both and they are good. I checked the wire before the plug and at the plug and had continuity all the way back to the ecm plug. It has strong spark, no vacuum leaks that I’ve found either.

Not that familiar with the M8 motor but it's not "jumped time" and don't think it is the ECM. JMHO but following Joels suggestions would be the path to take before replacing the ECM and/or cam. Solve the curent issue and get the motor running properly first.

So I don’t think it’s jumped time but figured it isn’t out of the realm of possibility as well as it could be the ecm sending a bad signal. I’ve checked compression, spark, fuel delivery and it just seems like it comes down to either it is flooding the combustion chamber with fuel overwhelming the spark or it is somehow out of time. Granted I could just be inventing problems, I was an aircraft mechanic, not a motorcycle mechanic which is why I posted on this site. Is it possible that it’s the ecm? I had someone else basically tell me that there is no way that is the issue but to me everything is a possibility.

Just ordered the TMAP sensor, will see if that fixes the issue. Hopefully it is something as simple as that and at least it is something that is relatively easy to get to and change.

 

[AdamCA]

My Thundermax came in today and got it installed and my bike is finally running correctly again! So happy that that fixed it and can’t wait to get it out and ride it.

 

[Jeff Klarich]

Good Job, enjoy the ride.

 

[Harttoo]

So Thundermax fixed it,because previous tune was corrupted?

 

[joel]

I fixed a very poor running car once by unplugging the ecm and plugging it back together, started and ran better than ever.
Just dirty contacts.
I would definitely plug the oe ecm back into the harness just for fun , than keep it for when the time comes to replace the bike so the t-max stayed with me.

 

[Frenchie]

P0261 is low voltage to injector and P0262 is high voltage to injector. If you installed new injectors as stated and you are still getting the same codes. I would remove the tank to gain access then disconnect the injector connectors remove the wires and terminals from the connector and inspect the wires where they are crimped to the connector pins. Harley had these wires zip tied without any stress relief to the wires and this could cause the wires to break away at the connector. When you reconnect the wires to connector make sure you leave some slack.

 

[Alan Smith]

Hi first of all Welcome to this forum. As you mention the problem I think you need a test light on the affected cylinder. Check the vacuum leaks to the affected cylinder. Also, check the fuel pressure regulator. I hope your problem is solved because many times also face this kind of issue.

 

[Lesley]

Kinda sounds like my problem. They put in a S&S 475 and a tune. They said it ran good . I got it last night and rode it 300 feet to the garage , started it this morning seemed to run good was going to ride it started it and it started backfire through air cleaner and running like on one cylinder. Now it won’t start at all. Battery voltage is 12v no load with engine off.