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Road King Fuel Pump Issue

Wow, this is a good one for sure. The period of time you can ride until it quits has me puzzled. When the bike dies, you still have headlights and dash lights correct? If you do, it can't be the main breaker.

You have to be loosing B+ power coming off of the fuel pump relay because codes 24 & 25 are to the coil as 23 & 32 are for the injectors. Either the supply side of the relay (pin 87) is loosing power or the relay itself is dropping out. I can't believe the ECM is telling the fuel pump relay to drop out (through pin 23 of the ECM) because if it was, it would not log any codes. It's logging codes because the ECM is instructing the relay to stay picked and at the same time the ECM sees power dropping off for the injectors (code 23/32) or coil (code 24/25). It's just like pin 87 of the fuel pump relay looses source feed from the fuel pump fuse.

To prove this theory, you could get yourself a simple on/off toggle switch rated at least to 5 amps. Attach a 3 foot piece of lamp cord to it. Place the switch in the off position. Attach 1 lead of lamp cord to the positive terminal of the battery. The other lead to the "B" terminal of the coil or pin #30 of the system relay.

What you want to do is supply your own power to the coil, injectors and fuel pump regardless of what the fuel pump relay wants to do.

Once wired You can do it either way. You can start the bike and flip the toggle to ON. Then see if the bike dies on it's own. Or... you can ride the bike till it quits, then flip the toggle switch to ON and see if the bike re-starts and runs.
Whatever the results are, it will give you something to work with.
This test is actually bypassing the voltage drop test from earlier. Regardless of the voltage drop, you will be supplying your own power source.
 
The bike does not die now. It ran for as long as I wanted to run it today.
But as soon as I shut it off, I cannot restart.

Let it cool down for hours, cold to the touch.
Still no restart.

I disconnected the neg battery and let it sit.
Reconnected and it fired right up, Engine light shut off and I shut it down within 1 minute.
Tried again, No Restart Again.

So it seems like rebooting the ECM is fixing the issue.

I will try the other ECM tomorrow to see if the problem follows the ECM or stays with the bike.


Keeping in mind, my ECM could be bad, and the other one I have is used, and I cannot verify
if it's good. (But for now that's all I have to work with)
 
Ok. I miss-understood. So the codes must be getting thrown when you try to re-start the hot engine and it won't restart.
Interesting.
Yes, I would try the other ECM. It may display some other odd behavior but that is OK. All you want to see is if you can perform a hot restart without any problem.

My guess is that terminal "B" of the coil does not have any voltage on it during hot cranking when the engine won't start. I would check it just to confirm.
 
Does anything in your manual talk about Pin 4 of the ECM. I know it is used to pick the "ECM Power Relay". The ECM ground shots pin 4 (of itself) to pick the relay. But it's strange to me because the ECM itself drives the ECM power relay. So how can the ECM tell the relay to pick if it doesn't have power for itself to do that. Then once it is picked, power is supplied to pin 35 of the ECM which is called "ECM POWER". HD likes to call relays one thing when they actually do something else. I don't understand the reason for that relay to begin with.
Does your manual talk at all about it? It's not used in any post Delphi ECM's.

Now if that relay was to be stuck in the picked position, you would have to remove the battery cable to reset the ECM.

Something to think about if the spare ECM performs the same way as the original.

It's too late now but another question I have comes up.
A stone cold bike starts fine w/ power cable reboot. You now run it for miles and all is fine. Without touching the kill switch or key, STALL the bike by letting the clutch out too fast. Does the bike restart using just the crank button. Even with the problem you currently have, it actually should restart.
I bet the problem happens only when you kill the engine using the kill switch or key switch. Which would point again to the ECM relay.
Just thinking out loud here...
 
That ECM relay had me wondering so this should be correct. Now it makes more sense, at least to me.

Pin 1=> Coil driver rear
Pin 2=>Idle stepper
Pin 3=>Idle stepper
Pin 4=>Ground shot to energize ECM relay
Pin 5=>Wire Deadheaded at speedo with tape
Pin 6=>Speedo Check Engine Light driver
Pin 7=>Engine kill from BAS tip over
Pin 8=>Not Used
Pin 9=>Not Used
Pin 10=>Data link Commo
Pin 11=>Crank Sensor -
Pin 12=>Not Used
Pin 13=>Engine Temp signal input
Pin 14=>+5 volt reference
Pin 15=>Data Link Commo
Pin 16=>Ground for +5 reference voltage
Pin 17=>Not Used
Pin 18=>Driver for front injector
Pin 19=>Coil driver Front
Pin 20=>Idle stepper
Pin 21=>Idle stepper
Pin 22=>Not Used
Pin 23=>Ground shot to pick fuel pump relay
Pin 24=>Driver for rear fuel injector
Pin 25=>Not Used
Pin 26=>From Kill switch. When in RUN position=battery voltage
Pin 27=>Cam Position sensor
Pin 28=>Crank sensor +
Pin 29=>Not Used
Pin 30=>TPS sensor
Pin 31=>Intake air temp sensor
Pin 32=>Map sensor input to ECM
Pin 33=>Frame Ground
Pin 34=>Frame Ground
Pin 35=>ECM Main power in

So when Pin 26 sees battery positive from the RUN switch, the ECM ground shots the ECM power relay to pick.
From there Pin 35 now receives main power. The ECM must get some power to launch itself right from Pin 26.

So maybe what you did by removing the cables and rebooting the ECM, is accomplished with the ECM power relay?
Because with the Run switch set to Kill and ECM relay is not picked, the ECM sees no power whatsoever.
 
Hoople this thread has been really interesting for me being basically new to Fuel Inj. I have a couple questions for you to clarify something in post #55
1st. in your statement:pin 10=>Data link Commo. Is Commo short for Common.
2nd. in the statement; the ECM ground shots the ECM power relay.What do you mean by shots or should it be shorts.I a little confused.
tourbox
 
TourBox,
Commo is just short for 'communication' or communication port/ Data Link port.
Ground shot just means the ECM takes that wire and connects it to ground. It is the same as "shorts" to ground like you said but I don't like the word "short" because it usually means seeing sparks. For me, shorts=sparks=nasty. Ground shot just sounds a little more gentle but both are correct..
 
Hoople said:
TourBox,
Commo is just short for 'communication' or communication port/ Data Link port.
Ground shot just means the ECM takes that wire and connects it to ground. It is the same as "shorts" to ground like you said but I don't like the word "short" because it usually means seeing sparks. For me, shorts=sparks=nasty. Ground shot just sounds a little more gentle but both are correct..
Click to expand...

This is why this is a great site, Tourbox u seem to have a lot of valuable info, Hoople is ALWAYS dead on:s
 
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