After long long discussion with another AJP PR7 owner Paulo N., famously known for knowing pretty much everything about PR7’s ECU, electronics and a hell of a lot of other things, I decided to go ahead and check the original fuel pump’s pressure output – properly.

I have tested mine once before, but I was convinced by Paulo that I did a pretty sloppy job doing so because when I tested the pump, I left it in the original black housing with all the problematic o’ring.

On my very first test I was pretty sure that my pump was toasted, but not leaking as I could not see the leak anywhere (much like on the side of the road when I tested it before). Hooked to the car’s battery with 12v, it managed to pressurise up to 36-37psi (~250kpa) and voltage on the battery has not changed much.

On my second test after the discussion with Paulo, I made some changes to the original fuel pump and removed the plastic housing and the oring (more on that on part 2 – the mod), there was nothing on the hose, just a fuel pump and the pressure gauge, but this time the fuel pump pressurised to only 20psi (137kpa). I could not take it seriously, because it was a very cold morning, and the battery voltage dropped from 12v all the way to 9v in no time. Even though I could not take it as a “pump test”, it showed the struggles the bike has to overcome when starting with half dead lithium battery that PR7 has…

For the third test, I made sure the battery was fully charged this time, and at the start of the test it was just over 13v, and even though it was another very cold morning, voltage haven’t dropped much while testing, and pump pressurised fuel once again just up to – 36psi (248kpa).

I really wanted to see if that o’ring caused problems for me, however now I’m 100% sure it didn’t – and what a shame really, because if it did it would mean that I have a perfectly fine pump that I could keep as a spare one for emergencies. On the other hand, if that’s the maximum a perfectly fine pump can pump out – (judging by the 300kpa fuel pressure relief valve that is fitted on PR7) it seems like it’s “slightly” underpowered from the factory then!

In any case, while making changes to the original pump (here is a link to the second part – the OEM Fuel pump mod), I thought I’ll take some pictures and share it with you lot, as some might find it useful if that silly o’ring is causing problems to your PR7 but no spare cash to chuck away on the Quantum fuel pump upgrade thatyou can read about it here if you haven’t yet.