Crank no start 03 Xb9r

[Performancesmith]

I just picked up a free 2003 xb9r thats in pretty bad shape. Paint work is bad, and the wiring harness looks like it has been on and off the bike 20 times. The bike does crank, but the fuel pump does not prime, nor does the CEL come on at all. I have voltage to the yellow "keep alive wire" at the ECM connector, but 1V only on the red/white 5v sensor wire, and no voltage going to the fuel pump. I suspect the ecm is bricked, but would like to see what other tests I can perform with my meter to confirm. The ECM does say "For Race Use Only" if that matters.

 

[Barrett]

It's close to 20 years old so a multitude of issues could keep it from firing. First clue of possible terminal ECM component is failure of dash mounted CEL to illuminate with initial KEY and KILL switch both being on. From your description could be a wiring defect at 1 or more terminals or break in the harness itself. I would also:

1-Check all fuses closely and fuse terminals for signs of corrosion or terminal breakage.
2-Pump fuse is 10A located in terminal---Check it closely
3-THREE RELAYS---clearly the starter relay is OK. Would consider replacing ACC and KEY SWITCH relay. Click my name and scroll threads for all OEM and cross-reference relays
4-2003 XB is only year with side-stand interlock switch. Check it for continuity and jump the 2 connector wires if switch has failed to test NO-start situation
5-BAS sensor failed or unplugged

 

[Cooter]

What body work is painted on a Buell?

Back up and get to the basics my friend. F.A.S.T. Well before any DVOM probing and the resulting barely legible post...
1) Do you have spark?
2) Do you have fuel?
3) Do you have compression?

the fuel pump does not prime,

There is no success in your future without fixing that first. Got key-on voltage at the pump connector? Then pull and fix the pump. No? Trace back to where you DO have voltage (relay).

Ultimately this isn't a Buell issue. It an old abused motorcycle issue. K.I.S.S. Do what Barrett said and check the fuses, swap the relays around (they are the same) and maybe you get lucky. Otherwise start from the beginning for each system (Fuel, air, spark) and you WILL find the problem.

 

[Performancesmith]

It's close to 20 years old so a multitude of issues could keep it from firing. First clue of possible terminal ECM component is failure of dash mounted CEL to illuminate with initial KEY and KILL switch both being on. From your description could be a wiring defect at 1 or more terminals or break in the harness itself. I would also:

1-Check all fuses closely and fuse terminals for signs of corrosion or terminal breakage. Fuses all good, however diode one was missing. Ordered two new diodes, will install in proper left facing orientation tomorrow.
2-Pump fuse is 10A located in terminal---Check it closely I do not see a fuel pump fuse on the bike, or on the diagram. However I can confirm 12v to pump at the grey wire, and .5v at the BR/Y wire at key on engine off
3-THREE RELAYS---clearly the starter relay is OK. Would consider replacing ACC and KEY SWITCH relay. Click my name and scroll threads for all OEM and cross-reference relays All three relays replaced at this point
4-2003 XB is only year with side-stand interlock switch. Check it for continuity and jump the 2 connector wires if switch has failed to test NO-start situation Jumped side stand switch right away to eliminate as possibililty
5-BAS sensor failed or unplugged BAS voltage was 4.97 IIRC when i connected the bike to ecm spy

Alright answers in red. I have full battery voltage to pump at the grey wire, but nada when i jump the brown/yellow to battery directly which to my understanding should run the pump. I think the plan is to install two new diodes tomorrow and continue searching for the fuel pump fuse.

 

[Endopotential]

Ditto to all the above.

But as old as your bike is, I'd say just go ahead and replace / rebuild the fuel pump. Confirming power there won't solve the issue, as if there's a leak within the internal tubing you won't see it without taking the pump out.

Many threads on the issue, including my own headaches. Biggest lesson learned - ALWAYS LISTEN TO BARRETT! [Cheers John ]
https://www.buellxb.com/forum/showt...r-hard-start-issue-fuel-priming-problem/page2

 

[Barrett]

Ditto to all the above.

But as old as your bike is, I'd say just go ahead and replace / rebuild the fuel pump. Confirming power there won't solve the issue, as if there's a leak within the internal tubing you won't see it without taking the pump out.

Many threads on the issue, including my own headaches. Biggest lesson learned - ALWAYS LISTEN TO BARRETT! [Cheers John ]
https://www.buellxb.com/forum/showt...r-hard-start-issue-fuel-priming-problem/page2

Greatly appreciate the very kind words. Merry Christmas to you and yours and thanks again my friend.

To this thread originator: My mistake on the pump fuse for a 2003 Firebolt. There is NONE. R models didn't receive modified fusebox with additional pump fuse till 2007 model year, I believe. Your pump feed wire on schematic. Pump signal wire activated via ECM signal. Schematic below Sir.

https://www.manualslib.com/manual/1058622/Buell-Xb9r-2003.html?page=557#manual

 

[Cooter]

If it cranks over... you can ignore all of the safety switches like kickstand, clutch, whatever. Those all stop cranking, which you say it does. Not ignition, which you say it does NOT. *The BAS is the only exception.

DO YOU HAVE SPARK? That is only one side of the equation, but spark plugs on Buells foul VERY quickly with repeated no starts.

I am more concerned with this: Page B-20 2003 XBR Service Manual.

IF...

full battery voltage to pump at the grey wire

Of course you checked continuity on the black wire to ground, right?
AND...

the fuel pump does not prime

THEN...
Get a fuel pump.

The esteemed Barrett above sells nice rebuild and replacement kits.