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[Rimjam]

Talked with Rod AGAIN about lean fuel mystery on the SERG.  To answer Godeater's questions:   Without the Power Commander on the bike it runs slightly leaner than with it installed.   Yes, the firmware was checked to make certain its the latest version.   There are no intake leaks (one of the first things checked after the fuel wouldn't go up).  Bike is lean on both cylinders.   Fuel pressure does not drop dramatically after bike is shut down as would be the case if lines were leaking inside the tank  - pressure drops gradually.

Rod is going to order the check valves at the outlet/return just as a 'maybe'.
 
Any other suggestions would be appreciated & followed up.

[Twolanerider]

Rod is going to order the check valves at the outlet/return just as a 'maybe'.
 

You mean the couplers in the tank that the pressure and return lines attach to?  If so as just quick couplers for the fuel lines those seem far more unlikely than other potential problems.  Even more so for the retuern line thant he pressure line as the return line isn't repsonsible for feeding fuel to the system.

Have rarely seen those old lines collapse internally.  Though rare that seems a more likely thing to shotgun than the couplers (assuming all the other even more likely things have already been done).  Really hate diagnostics that are just shotgunned.  Sometimes it may feel that it's become necessary.  But even then a systematic approach will still best serve.

[grc]

You mean the couplers in the tank that the pressure and return lines attach to?  If so as just quick couplers for the fuel lines those seem far more unlikely than other potential problems.  Even more so for the retuern line thant he pressure line as the return line isn't repsonsible for feeding fuel to the system.

Have rarely seen those old lines collapse internally.  Though rare that seems a more likely thing to shotgun than the couplers (assuming all the other even more likely things have already been done).  Really hate diagnostics that are just shotgunned.  Sometimes it may feel that it's become necessary.  But even then a systematic approach will still best serve.

I agree.  There are some occasions where just trying the obvious part is a decent strategy, but on something complicated I think I'd be looking for a real diagnostic routine.  If fuel flow is suspect, it isn't very difficult to run a pressure and volume test, and then you know for sure if they are in spec or not.  I will admit that I've used the WAG method on occasion myself, but only on my own stuff.  No way should a paying customer have to put up with that method.


Jerry

[Rimjam]

Just so you guys will know   -   Rod has refused payment of any kind even though he's changed some sensors, the ECM, front exhaust pipe & had the bike on his dyno several times.  Welcome to the south.

[Twolanerider]

Just so you guys will know   -   Rod has refused payment of any kind even though he's changed some sensors, the ECM, front exhaust pipe & had the bike on his dyno several times.  Welcome to the south.

Don't claim to understand why a front pipe nor a functioning ECM would be swapped to chase the problem you're seeing.  But I didn't have eyes on the bike.  So not in position to say.  What did he swap the Marelli ECM with?  Did he have a good used one available?

[Godeater]

On that note if he used harly'a new replacement ecm it's made by s&s and will not work with a power commander. It is mappable, comes with cable and software. Just fyi.

[Twolanerider]

On that note if he used harly'a new replacement ecm it's made by s&s and will not work with a power commander. It is mappable, comes with cable and software. Just fyi.

That was my thought; that an original Marelli ECM isn't available new any longer.  The replacement doesn't use the same maps as the old so it is nothing close to an easy direct swap.  He'd have had to map it from scratch.  Even if the shop had an old Marelli ECM available the base maps between it and what was on the the bike wouldn't likely be identical.  So the Power Commander would still have to be remapped with a Marelli swap to compensate for the change.  None of which really speaks to why shotgunning a functioning ECM would be an early guess for a lean fuel problem?

[Rimjam]

I agree.  There are some occasions where just trying the obvious part is a decent strategy, but on something complicated I think I'd be looking for a real diagnostic routine.  If fuel flow is suspect, it isn't very difficult to run a pressure and volume test, and then you know for sure if they are in spec or not.  I will admit that I've used the WAG method on occasion myself, but only on my own stuff.  No way should a paying customer have to put up with that method.


Jerry
I quizzed Rod about a volume test for fuel delivery  -  he didn't do one & didn't know how.  A little help please.

[Rimjam]

OK, Rod doesn't know how to do a fuel volume test as suggested by grc, can anyone help?

[Twolanerider]

OK, Rod doesn't know how to do a fuel volume test as suggested by grc, can anyone help?

Don't remember ever seeing a published spec for volume on the Marelli bikes.  If I remember correctly spec for pressure was 40-45 psi.  Has he hooked up a pressure test set and actually run a pressure check?  I don't mean listening for "pressure" that you think you hear bleed off when the switch is turned off.  I mean actually measuring it.  That is the surest way to check for pin holes in the lines in the tanks, problem with the regulator or even a problem with the pump.

[Rimjam]

Yes, Rod used a real presure gauge attached at the tank outlet, that's how he knew the pressure dropped gradually after the bike is shut off (meaning no pin holes in lines inside the tank).  The ECM unit he swapped out was an original he had stashed from an earlier conversion to carb.

[Rimjam]

A second trip to Rod's has solved the mystery!!  It took a different Power Commander to richen the fuel to Rod's likeing.  We have no idea what was wrong with the first one because it checked out OK.  Lesson learned:  If everything else checks out, replace the Power Commander!!

[miker]

Can be common to some signal interrupters...kinda why I prefer to adjust the PID internally on the control device for whatever variable you are after...

[Midnight Rider]

A second trip to Rod's has solved the mystery!!  It took a different Power Commander to richen the fuel to Rod's likeing.  We have no idea what was wrong with the first one because it checked out OK.  Lesson learned:  If everything else checks out, replace the Power Commander!!

Glad you got the problem solved.  I was kind of surprised that Rod was unable to solve your problem in your earlier posts, but something like this could stump anyone, particularly if the PC was showing no signs of fault.  Just glad to read you got it straightened out.   

[Steve Cole]

I can assure you Rod is no dummy! I can and do recommend him and his shop for people down that way, as Bobby Woods does also.The fact that he stayed after it and didn't charge a penny until he fixed it says a lot more then some of the keyboard operators here. Glad your up and running properly now.