free website stats program Interesting EFI Information | Harley Davidson Forums

Interesting EFI Information

Rod Stewart

Active Member
So I was down to the local dealer, Kanes HD, today, just to pick up some stuff for under the tree "from Santa".
I got into a big discussion with the resident tuner there and he told me some interesting news about HD's EFI system.

Does it ever seem to you that when you stop for gas when your reserve light has come on, that once you get going again the bike seems to be running better?
It seems there is a good reason why this happens.

Quite by accident he made a discovery while tuning an '04 Ultra on the dyno using an exhaust gas analyzer. At first the mixture was just about perfect, then suddenly the reserve light came on immediately followed by the mixture going very lean.

So he tested this by putting in some gas while it was running in cruise mode on the dyno, and as soon as the reserve light went out, the mixture was right back on target.

His theory is that the EFI is programmed to go to lean mixture and reduced power mode so as to get more mileage out of reserve. He has talked to the regional HD tech rep about this, but no one has confirmed anything.

Glider, is this something you or anyone else is familiar with at all?

Never heard of that but anything is possible.

Two things that should be considered is that a lower pickup level of gas may make a difference or that dreaded pinhole in the fuel line inside the tank the other possibility.
A fuel pressure test may tell a story here when it is in this condition with the light on but all in all it may be the truth after all. If you see the fuel pressure drop or the pulse width of the injectors change, then you know you are on to something concrete.

It's one of those guarded Harley secrets that we will never know the truth about.
i gotta say my fuel light seems to come on alot more with this 07:17: and i did notice that once i made it to a station and got gas and rode off i was much happier but i thought that was because i made it to the station without pushing the olé boy :bigsmiley11: