Hi, wanted some help with my bike issue. 1994 916…has always been a bit tricky to start when warm, so I replaced the temp sensor for the ecu, no change. took for a ride. Absolutely great for half an hour and then it bogs down, like it’s running out of fuel…I pulled over, changed both relays under the seat for new and the yellow one by the battery. I carried spare new ones with me as I thought I’d do exactly this and change them when it stops to see if it cures it. No change. Almost flatted the battery re starting. Gave up. An hour later tried again and it just about got going…but barely runs…needs fast idle to hold it at 1000rpm. Slow to rev. Anyway I was miles from home so I thought I’d do my best….had to keep the throttle wide open and ride the clutch and brakes so it wouldn’t die, could just about manage 50mph flat out! Bleeehhh bleehhhh that’s the noise, very blehhhh. Anyway after 30mins like this…..woofff it clears and there I am throttle wide open and off like a rocket! 20 mins later same issue again….comes and goes. I then noticed with tank filler open that there’s a spray of fuel in tank when running (I was checking for an air lock) but took pump out and pipework intact, still have the issue and now won’t start. I reckon I could get it started if I used the whole battery and tried for half an hour but it would probably feel starved again, but I’m sure it’ll clear again and be fine for half an hour . I’ve also cleaned the cps, it was clean anyway, have ordered a replacement. please help! Any ideas!? Thanks in advance
I think you’ll have to work through the fuel side of things and rule that out, then think about electrics - possibly ECU/EMU, mapping etc?
Tank pipes can be split and you won’t see it unless you actually look for a split. To really rule out the fuel filter and in-tank piping, I would remplace everything by new, and go from there.
I had the pump out and I disassembled all the pipes and checked them all carefully….all seam fine…I have ordered a cps….but fuel side of things does seem most likely. If it was an intermittent spark then it would back fire I’m sure as fuel would build up until that one spark…if I remove tank but leave the connectors al in place and just turn it sideways could I see down the trumpets and see if fuel is coming out the injectors? I don’t know if I read that somewhere or that’s BS!
Sounds like a split pipe as already mentioned. The spraying fuel in the tank is usually the give away. Worth checking the fuel pressure, that would confirm either a split pipe or a problem with the pressure regulator. The latter is usually pretty reliable but I reckon I’ve seen 2 or 3 failures this year.
