For the last few weeks my ajp kept struggling staying alive at idle, and sometimes even at higher speeds too… I thought about all sorts of things that would cause that. And at some point I even started to think that my crankcase breather is at fault – letting some oil mist out into the intake box and covering the sensor with oil and causing troubles that way… 

After a long trip to Wales, i thought i’ll have to inspect that and fix it permanently as riding it was incredibly difficult with AJP stalling so often and at completely random times.

AJP PR7 Electrical Fault Finding

Back at home I took the throttle body out, gave it a good clean with a throttle body cleaner. Made sure that the sensor inside of it was properly flushed too. Inspected servo motor that controls the idle valve to make sure it operates smoothly, as well as the injector and spark plug.

AJP PR7 Stalling Problem

A few hours later I took it for a spin to make sure it was running fine. And it struggled to start, I tried to keep revs higher just to keep it going. The motorway had no troubles at all, but as soon as I hit the smaller roads, that was it- again stalling at random, struggling to start.. and that made me think again- if that’s not the sensor what is it then? Took the seat off, started poking relays, all the plugs and wires. And as soon as I touched the wiring loom next to the fuel neck – engine stopped. And it kept stopping every time I touched it! 

Inspecting Main Wiring Loom on AJP PR7

Back at home dug out the wiring diagram (link to the wiring diagram, manuals and much more HERE) and started checking wire by wire with a multimeter – all good apart from one red wire that leads to ecu. It wasn’t like it had no continuity either. With ignition on, all positives showed 13.2v – same as the battery itself, however that one red wire only 11.2 volts for some reason. And that’s with disconnected ecu. 

Unwrapped wiring loom to expose all the wires, and I couldn’t see anything wrong anywhere. Wiggled all the connections of all wires – nothing came apart and when I was just about ready to go and bang my head against the nearest corner – boom! Red wire popped out of the shrink tube. No wonder why it was intermittent – it was held in place by a shrink tube!

AJP PR7 Wiring problem fix

Soldered it back on, rewrapped the loom and no more problems! 

Not sure what caused that, but inside of the original wiring loom wrap I could see some green powder (copper oxide). So it might be the mix of water getting into it as well as me disturbing it while working around. In any case, I can’t say that I’m the only one who suffered from this problem.

AJP PR7 faulty wiring symptoms

Anyway, here are few symptoms that showed up while i had this problem:

1. Obviously stalling at random times. 
2. Fuel pump not priming at all, or priming at random times when it shouldn’t. (Ignition on – it primes and half a minute later it primes again.. and again and again…)
3. On the dash, Engine light is OFF all the time. 
4. When trying to start – spark plug gives no spark! 

If any of it sounds familiar – time to check your wiring! 

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AJP PR7 Faults, Fails and Fixes

• AJP PR7 Wheel Spacers.
• AJP PR7 Wiring Problem and how to fix it (random stalling problem).
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