Very Confusing Issue

[iRide]

i will just make my own ecm spy cable and run it myself, let ya'll no how it went!

 

[jaimz]

Good idea

 

[iRide]

already read that the cylinders are set by the ecm to cut out at different temperatures which wud explain why the engine wud randomly cut out on the freeway at normal highway speeds after it was rebuilt. who knows what kind of damage having those injector wires crossed caused.

 

[Mark XB12r]

I would quit all the guessing and go with a fuel pump. You low fuel light should be the clue. I also think you need to clean the tank breather. Try driving with the fuel cap open, not with a full tank. See if that eliminates a symptom.... Cant hurt to try it.

 

[vance580]

The low fuel light is the clue that it is most likely the wiring harness within the fuel pump assembly. You can buy just the wiring harness. It is a bad design and rides in a mount for the pump and filter and with the vibrations and bumps it frays the wiring and will start shorting out. I had the same issue with mine. It started with the low fuel always being on then my fuel pump would continuously prime when trying to start. Here is what my wires looked like. The new one that I got from the dealer for about $75 has a sleeve that doesnt allow the wires to rub on it.

 

[jaimz]

Lol I don't know why but I didn't think about the fuel pump.

Also the wires being crossed on the injectors don't matter. They're DC not AC.

An injector is simply a small electromagnet when you give them power they generate a small magnetic field to open the injector a certain amount (that's what fuel maps do) the polarity doesn't matter,

Here's a quick idea, check your fuel pump relay, to do that just open up your relay/fuse box and just swap the relays around. The three relays are all the same so you can just swap them.

Also, if it was the wires to your fuel pump that were rubbing... Well that could be the problem especially if you have a few broken conductors.

If that's the case, your fuel pump is getting low power, which is harmful to things like fuel pumps.

When a wire gets cut, the conductivity is reduced by the depth of the cut.

For the sake of example I'm going to make up some stuff:
Let's say you have a wire that is 1in diameter, suppose that means it carries 100% power. Well if you put a cut 1/4 inch deep into the wire, well now that wire is only going to be able to carry 75% power now because 25% or the wire is broken.

A situation like that can cause problems other than low power as well, because now your trying to push 100% power through a wire that can only carry 75%.. The extra 25% of the power is being consumed, in the form of heat! The heat can cause wires, and other components to burn.

Overloaded = heat = burned/damaged components.

Just some thoughts.

 

[iRide]

thanks jaimz, i will test the relays. the pump was working even w the low fuel light issue for awhile. Its not priming continually or anything. Im going to test the pressure but the pump may work fine w the low fuel light acting up. Regardless I ordered a new fuel pump wiring harness and parrts for ecmspy cable. I see what ur saying about the polarity but im still curious how the bike even ran w the ecm having a separate map for each injector. Wouldnt the cylinders be getting a shot of fuel at the wrong time or opposite time?

It was a thick red wire rubbing on the drive belt, i repaired it. When I originally tightened the ground to the frame it started smoking which led to that discovery.

 

[iRide]

i pulled the START relay and the IGNITION relay. The ignition relay was really hot. when i plugged back in the START relay it blew. Then I plugged the ignition relay in the start port and it also blew. I did have the key on so thats maybe my fault. But should the ignition relay be so hot w the bike off and the key in the on position?

 

[jaimz]

I did have the key on

Yeah that's a fast way to blow up your relays.

Wouldnt the cylinders be getting a shot of fuel at the wrong time or opposite time?

The wires are either power on or power off. it doesn't matter. the injectors them self contain no logic what so ever. the ECU sends a predetermined amount of voltage down the wires at a predetermined time. The amount of voltage opens the injector that much.

For instance (this is all made up...)
if 14 volts is 100% open injector, 7 volts is 50% open.

it doesn't matter which 'way' the voltage goes in and comes out, all it's doing is powering up an electromagnet.

If you're interested, you can look up how the solenoids in n2o systems work, they're like huge fuel injectors.

TO REPLAY YOUR RELAYS FAST AND CHEAP... go to rockauto.com look up a 2002 ford focus DOHC. Open the "Electrical-Switch & Relay" section. Then, open "Battery Saver Relay" there you'll see "STANDARD MOTOR PRODUCTS Part # RY612T" for $4.25 that is the exact same relay!!!

I know this because I pulled that relay out of my 2002 ford focus and stuck it in my bike. they are 100% identical. that relay is used on ALOT of things. but buying it on rock auto will probably be the cheapest.

 

[iRide]

fuel pressure is steady 51 psi! Back to the drawing board. I guess next move would be ecm spy. The cam sensor wire runs near that belt that rubbed that larger wire. I will test continuity there. Also thinking that tps sensor cud be heating up and failing up there like the gentleman said above.

 

[vance580]

I would at least pull the fuel pump and check the wiring. It really isn't that bad of a job. There is a drain plug in the housing that you can undo and hold up a gas can with a funnel to get all your fuel just make sure you have a big enough gas can to catch it. The thing with the fuel pump is it using more volts at around 4000 rpms. So you may be getting 51 at idle but when you get into that 4000 rpm range thats when the current isnt able to go through a frayed wire. Mine would only stumble at 4000 and would continuously prime when I hit my run switch and I had the low fuel light on all the time. I never blew any fuses or relays and had no other problems. I pulled the fuel pump assembly trying to chase the stumble and figured since I had the low fuel light problem I'll pull it and check and sure enough thats what the wires looked like above. I ended up putting a new wiring harness, filter, screen, and o-rings and she purred like a kitten after that.

 

[iRide]

yeah im sure the low fuel sensor cud use some love, but its not causing it to backfire. The bike runs OK until it gets hot . Also the pressure is 51 no matter the RPM. Im going to try new gas as well, Suprisingly there is no inline filter. For some reason I thought there would have been.

 

[vance580]

The filter is next to the pump. The square on the bottom shifter side of the frame comes out and it is a whole assembly. It is an inline but you have to pull the pump to change it. There is part #'s for everything on the assembly except the pump which you can get from autozone anyways so you can just replace pieces of it since Harley wants about 300 for the assembly. Here is a good pic of the assembly.

The left pic you can see the wiring on the left it rides in a groove and just rubs the insulation off the wire. The new wiring harness had a sleeve that the wires run through so they dont rub on the mount. The pump is on one side of the mount and the filter is the other side. The right pic is an XB assembly. Not sure what bike the left side is off of but the wiring looks the same.

 

[christianmb]

I'm curious to see where this goes. I am having the exact same rideability issues except nothing wrong with the fuel pump. I'm leaning towards a fried O2 sensor though. Looking at a log, the signal is from 0V to 3.45V (per tunerpro RT)

 

[iRide]

i have a new 02 sensor recently installed just as a preventative measure since it was apart. That change in current is probably just the sensor doing its job

 

[iRide]

i have a new 02 sensor recently installed just as a preventative measure since it was apart. That change in current is probably just the sensor doing its job

 

[iRide]

i have a new 02 sensor recently installed just as a preventative measure since it was apart. That change in current is probably just the sensor doing its job

 

[iRide]

i tested the ohms and voltage on the TPS. Ohms came back .58 closed 2.7 open. Voltage came back about right. Another thread states ohms should be 1.2 to 4.4open. Can anyone confirm this? Also the cheap auto zone replacement is not apparently an option according to ASB, late model 06 and any model 07 use another type w 2 orange dots. Which mine have.

 

[aibu1101]

After 43,000 miles, my 06 SCg started to have this same issue. It only has this problem when its hot. I have checked all the sensors and wiring, all is good. I am going to try out a TPS and see what happens as well.

 

[iRide]

waiting on manual. tps was not it. rather than guessing im going to diagnose it as the manual suggests. but im also gonna replace the rear temp sensor. ive read they both should be replaced after 6 years.