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Discussion Starter · #1 ·
Hello to all.

I recently purchased a k bike ,and am having trouble getting it running.It was sat in a garage in the dry for 12 years. I took it home,put a new charged battery on it,and it started. It ran,but the idle was terrible.
So...........
After testing the engine heat sensor,replacing the fan,sending the injectors off for a clean,replacing the crankcase 'z' pipe and vacuum pipe caps,changing all the fuses out for new,cleaning all the block connections and earths,and lightly cleaning the MAF sensor,replacing the tank fuel pump with a working one,and anti vibrio surround and pipes for it,and filter,air filter,oil filter and plugs...


It won't even start!

It cranks,the headlight goes out when it cranks,so the shed load relay is ok.
I'm a bit stuck for clues.
I read it could be the ecu,so I sourced another from eBay,should be here in a day or two,weather depending...


Any ideas please?
 

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Check for fuel pressure at the rail.
Check for signal to the injectors (with a noid light or meter.)

Is the ECU connection good and tight/clean?

Check for spark just for kicks.

Will it cough or sputter at all?
 

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Has the AFM been tampered with, or is it factory sealed? They're somewhat adjustable inside - sometimes folks will cheat them a bit richer to make up for vacuum leaks and such.
 

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Discussion Starter · #5 ·
Has the AFM been tampered with, or is it factory sealed? They're somewhat adjustable inside - sometimes folks will cheat them a bit richer to make up for vacuum leaks and such.
Hi.sorry about the delay,battery went flat in iPad.

Air flow meter? No,nothing's been touched on it for 12 years. I sprayed it with some dedicated air flow meter spray to clean it. I'm wondering if that's what did it,or f the ecu has had it,as I read somewhere that it could be fried if disconnected with power on,or age or moisture. Like I say,it's been sat for a while,but I did have it running quite well to start with,although the choke never worked as it should ( I'll call it a choke for arguments sake), and it would take a while to warm up so that ot could be revved without stalling.
 

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If you have the ECU on order might as well just swap it in and see if that does it - hopefully does.

If it's the AFM I'm familiar with you can pry the top off and make some adjustments if needed. There's a sliding mechanism and a clockwork spring that can be fooled with. It's best to leave things stock though and work on the actual problem though.
 

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Discussion Starter · #7 ·
If you have the ECU on order might as well just swap it in and see if that does it - hopefully does.

If it's the AFM I'm familiar with you can pry the top off and make some adjustments if needed. There's a sliding mechanism and a clockwork spring that can be fooled with. It's best to leave things stock though and work on the actual problem though.
Yes,agreed. I don't want to mess about with it,just get it to work as it was designed.
 

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Discussion Starter · #8 ·
If you have the ECU on order might as well just swap it in and see if that does it - hopefully does.

If it's the AFM I'm familiar with you can pry the top off and make some adjustments if needed. There's a sliding mechanism and a clockwork spring that can be fooled with. It's best to leave things stock though and work on the actual problem though.
Ok,got another ecu today,and same symptoms. Could be the Mass Air Flow sensor,I guess. I'm not really up on fuel injection,tbh.
 

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Dumb question for you cmonSTART. Is the ECU just a swap out and it will work or does it have to be connected to some external device that can tell the ECU to recognize that vin number? I ask because that's the case with my Indian. I think that's early enough that they were not that complex yet but asking just in case.
 

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No worries. When troubleshooting a Bosch FI system one of the first things you do is hook a fuel pressure gauge to the rail - if you're not making fuel pressure (or making too much) that can cause issues. Trying to start but sputtering and never fully catching can be a sign of low (or no) fuel pressure.

Try opening the fuel filler and listen there while you crank the engine. You should hear the fuel pump running when you push the starter button. If not, that's an issue.

If you have a can of starter spray you can try a quick spritz into the air intake - see if it will start and fire on that. Don't do much more than a quick spray though - not really good for it, but it is a good quick diagnostic tool.
 

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Dumb question for you cmonSTART. Is the ECU just a swap out and it will work or does it have to be connected to some external device that can tell the ECU to recognize that vin number? I ask because that's the case with my Indian. I think that's early enough that they were not that complex yet but asking just in case.
This is an older, very primitive Bosch FI system that really is mostly analog - nothing digital about it and certainly no memory. When I build my friend's K75 last year I found the system was very similar to Volkswagen's FI systems in the 70s - that's why I know how to work on it.
 

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How did you clean the MAF sensor? Hopefully you used a MAF sensor cleaning spray and nothing else.
 
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Discussion Starter · #16 ·
No worries. When troubleshooting a Bosch FI system one of the first things you do is hook a fuel pressure gauge to the rail - if you're not making fuel pressure (or making too much) that can cause issues. Trying to start but sputtering and never fully catching can be a sign of low (or no) fuel pressure.

Try opening the fuel filler and listen there while you crank the engine. You should hear the fuel pump running when you push the starter button. If not, that's an issue.

If you have a can of starter spray you can try a quick spritz into the air intake - see if it will start and fire on that. Don't do much more than a quick spray though - not really good for it, but it is a good quick diagnostic tool.
yes, pump makes noise when starter pressed. I tried easy start, but it didn’t work. Plenty of pressure, but I have no way of measuring it.
 
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