Yup hatch is right. I've seem that happen on twincammers!

 

Hello Guys,

So here's whats going on. I have tested continuity between all wires, including w/bk ground from relay to ECM. EVERYTHING has passed all tests BUT, my brand new 360.00 fuel pump!!! The ohms on the fuel pump should be 8ohms, it is reading .9-1.ohms. Not even one ohm, but it is working to get me fuel, then blowing the fuse when I snap the throttle under load. My old pump is reading 8.9 ohms. Its greater than 8 like the book calls out, but not much higher, and that pump won't let me out of my shop with out blowing the fuel pump fuse. So now I am sitting on:
1. Did the Harley shop sell me a bad pump? (I know its not there fault) The crappy thing is we all know Harley's electrical return policy.
If I could get to open a new pump and test the ohms, at least that would give me a number to go off of.
2. If the ohms are greater, is my Harley doing something else to cause it to burn the pump up?

I have not yet taken this to the Harley shop yet, because I have talked to there Techs and Parts guys, and they are stumped. I am trying to save a 1,000 dollar diagnostic fee for them to tell me I need to replace everything electrically on the bike to get it to work.(I hope that's not the case)

In the mean time I am going to try and test the ohms on a new pump and go from there.

Thanks Guys, any input would be appreciated.

 

Sounds like a bad pump. 13V/1 ohm = 13 amps. POP goes the fuse. Current draw should be way less, like a few amps. Yeah, higher pressure heads will give you higher current draw. Why did you replace the old pump? Was it blowing the fuse? If I recall, your fuel system has some kind of weird regulator built on to the pump area. If that's too high, I wonder if that could be causing you problems. Also, I think there's a filter in that circuit somewhere too. Did you replace that?

Sure glad I use a generic $85 pump and an external adjustable fuel pressure regulator on Dr.Linda's Sportster.

 

I'll throw a few things into the mix, fuel pump regulator is mounted on the plenom and returns to the bottom of the tank, if it is restricted, the bike would run rich because excessive fuel will go in at injector openings, no O2 sensors to alter injection. The fuel pump stays at a constant speed by returning the fuel and the pump has no idea of what the throttle is doing so it won't spike during whacking the throttle, the spring loaded regulator will cut down on fuel sent back to the tank to keep pressure up.

I can't explain why whacking the throttle blows a fuse unless a bad wire or connection is being vibrated, strange enough crap happens when you get gremlins in a electrical system so going to throw some things out there.

I never had to tear into my EFI wiring because I removed it but from my occupation, the older plastic connector bodies that Harly used will heat up, allow the push in terminals to become lose, continue to change shapes causing heat and will blow fuses because of more load. I would put a eyeball on the connector bodies, terminals in the relays, you might have more of a load because a resisted 12 volt connection already in the fuel pump supply.

We are required to use a headlight to load a main 12 volt supply because a VOM will read 12 volts with just a small amount of connection, a headlight will load the circuit and expose bad wiring or connection quickly. You might also try the headlight load at your fuel pump wire and check the connectors for heat while loaded, if it doesn't blow the fuse with a headlight draw on it for a period of time, it could very well be pump. You might have to jump the relay because the ECM only supplies a timed 12 volts to the pump at key on.

 

At this point with all the "could be's" or "might be's".......I would connect the bike to the breakout box or at least a Scanalyzer. I have found out that it is nearly impossible finding EFI electrical problems without the breakout box. They save lots of time and frustration.

 

So,

Harley gave up on the bike. They can not get the fuse to pop, nor can they find anything wrong causing this issue. I am going to remove my big shot tuner and ride the heck out of the bike and see if it blows. If it does blow I guess my next phone call is to Arlen Ness to see if they have heard of this issue with their tuners.