M900Sie won't keep running - fuel delivery problem?

[spuggy]

Bike down for a couple of years with a drained tank. I didn't run it dry, never occurred to me at the time.

"Running great when parked", indeed. Sigh.

New belts a while back. Fired it up right after - ran lumpy and kept getting worse until it fell back to one cylinder (the front) and/or died. Weather was pretty iffy anyway, walked away. Tried a few more times whenever it stopped raining with much the same results. Except it stopped running on the rear pot entirely, confirmed via the time-honored "lick finger, dab on header" test.

Yesterday, weather was really nice. Champions that came out were pretty grotty looking - had been cleaned/gapped with the belts. Fitted new NGKs, charged the battery completely, tried again.

Turn the ignition on a few times for pump prime & to wake up the lithium battery. Little slow to start on the button (2-3 stabs for a few seconds each), but fires both cylinders, revs to 3-4000 RPM, sounds a little ragged/woolly - but responds to throttle.

After a few seconds running, 10-20 maybe, will run slower and slower, until eventually drops below 1000 RPM - and then eventually stalls entirely. Sounds like it drops onto one cylinder (the front) for a little while before it dies.

Giving it more throttle once it starts to struggle just makes more induction noise - no throttle response at all. Hitting the start button again after it has died may get a few pops and bangs - but seems it'll never fire properly or run again.

Turning the ignition off/on a few times, letting the prime cycle complete, it'll fire right up (sort of), rev to 3-4000 RPM, respond to throttle. And, after a little while, the revs just drop on the same throttle opening until it dies. Again.

At least both cylinders are involved now according to the spit test.. So progress.

Kind of stumped and spitballing here...

It's got a gallon of fresh gas. Tried running with the tank propped up to ensure pickup entirely submerged while on the Abba stand - no change.

This really seems like fuel delivery. But can't be a clogged injector/bad spray pattern, borked pressure regulator or anything systemic - because that issue wouldn't change, it would never start/run at all, and doesn't fit these symptoms, surely?

My current working theory is that the fuel pump prime cycle gets the rail to something close enough to nominal working pressure that it starts/runs initially - but that the pump doesn't run afterwards (for whatever reason) - so as soon as residual rail pressure drops off, game over...

Is there a relay that runs the fuel pump - which operates independently of the "ignition prime" function? Because if there were, I think that'd be my prime (heh) suspect to poke at right now...

Or, any other ideas for these symptoms? Something clogged - like fuel pickup - would seem an obvious suspect...

[spuggy]

(yes, there's more - sorry!)

On another M900ie, I had a fuel line on the pressure side split inside a swapped tank (right after fitting the "worked fine in the other tank" fuel pump, thanks universe)... That had similar - but not identical - symptoms; it would idle - on both - for a long time, albeit roughly/badly - it just wouldn't rev over 1200-1500 RPM at all...

Bought a new fuel filter at the same time as the plugs on general principle - even though (a) I hate throwing parts blindly at a problem and (b) they're a massive PITA to fit if you happen to have regular human-sized arms.

Which will at least give an opportunity to eyeball the in-tank parts for condition, blow through lines etc - I've yet to need to do anything inside the tank on this particular bike. Maybe something will be clogged/unable to deliver fuel at the required rate. I should probably pull the fuel return and observe flow when it's running...

I've got both FI pressure test and injector cleaner/test kits showing up next week, so will probably try to confirm or disprove the working theory/collect more info before diving in deeper. I do so hate pulling/re-fitting the pump on these models...

[Mr Gazza]

That's annoying!

It's got to be a blocked filter, breather or the pump as you say.
My first thought was a dirty injector(s). That could manifest after a storage period if some gum or muck washed through with the new petrol?

The "tea bag" filter on the pump pick up takes a lot of blocking, so I wouldn't suspect that. Have you tried running it with the filler cap just cracked open?
It could well clear itself after a good run if you could keep it running long enough to do so.

I can only suggest reading Capo's explanation of the fuel system, which is a fine tome of info.
The section about the pump voltage and how load effects it might be of particular interest?
I'd be tempted to put a meter on it with the engine running if that's possible. To see if it does run when the rail needs pressure.

http://www.ukmonster.co.uk/monster/s...ad.php?t=39677

[Nickj]

I'd go with Mr Gaza on this and try the breather first as the simplest to test and fix.
Then the fuel filter
Then the pump

Quick and dirty would be start up run till it stops then open the fuel cap which will answer the breather question.
Then it's spanner time

[Darren69]

If you rule out venting, filter and fuel hose kinks then maybe fuel pump not keeping pressure? I agree they are horrible to do through the filler neck. Later ones with pump assembly underneath are better.

[slob]

check the superseal connector coming from the crank position sensor, i’ve seen corrosion in there stop a bike from reving cleanly

[Darren69]

Does the 2000 bike use the Marelli 59 ecu? If so you could use jpdiag to check for crank sensor or other errors. If it has EODB light on dash it should also be lit for crank sensor malfuntion.

[spuggy]

Thanks guys, lots of good suggestions. I did try opening the fuel cap after running, there was no tell-tale vaccuum release. None of my Monsters seem to have had an air-tight fuel cap, and pretty sure this one is no exception. Ran it with cap open anyway - no change.

Been thinking about this, on & off... Thinking I'll rig the fuel pump to run with the key on, and check the flow rate returning to the tank - that should show any obstruction end-to-end (and yield a direction for further diagnosis if anything is wrong)..

And back-probing the fuel pump connector and checking it actually is powered when the bike runs (obviously, you can't hear the pump over DP slip-ons) seems like a good idea - because narrowing down what isn't working right seems like it'd be useful...

Otherwise, I'll have a pressure tester soon. It's past time I fitted the QD fittings I bought yonks ago anyway - just haven't needed to take the tank off since. So I guess I'll start taking things off/apart and see if I can figure out where to go from there...

[spuggy]

Wow, can't believe it's taken this long. My excuse is that the garage has mostly been impossible to go into - like 45C during daylight...

But sucked down coffee and made it in there today before it got too hot...

TL;DR:

To fast-forward to the chase; the fuel line between pump and filter had completely lost integrity. In my efforts to dislodge the pump from the #$%$#% clip in the tank, I could see most of the outer rubber part of the hose had fallen off, completely exposing the cloth braiding.

By the time I worked the pump out, the only thing connecting the pump and the filter were the fibre braids; all of the rubber vanished entirely. I could hear the chunks hitting the inside of the tank.

Longer whinge:

So, Public Service Announcement. Pardon me if everyone but me already knew this, LOL...

I didn't fully appreciate until I did some googling to buy replacement hose a few weeks ago (it was obvious I was going to have to split the hose ends with a razor to get them off, as they acted like they'd bonded to the tank fitting), but injection-rated fuel line from an auto parts supplier will almost certainly be SAE 30R9 (high pressure). Carburettor fuel line is rated SAE 30R7.

However, SAE 30R9 has no business going ANYWHERE near the inside of an injection Monster fuel tank. Because what you want is submersible fuel hose, or SAE 30R10 rated (or higher).

30R10 is 4x, 5x the price of 30RJ9 - and this is not what you're going to get unless you specifically request "submersible" fuel line.

This is the second Monster I've encountered where the internal high pressure hose in the tank was something that presumably wasn't the correct stuff - and the hoses have waited until my ownership to fail.

Pretty happy I found the problem, at least...

[jerry]

yes I concur seen similar on S4 in Thailand had to replace fuel lines just doing a 1991 750ss it will get new hoses too could not get submersible hose in Thailand but replacing it every few years will be ok

[spuggy]

Originally Posted by jerry

yes I concur seen similar on S4 in Thailand had to replace fuel lines just doing a 1991 750ss it will get new hoses too could not get submersible hose in Thailand but replacing it every few years will be ok

Yeh, the wrong hoses obviously last a few years before they fail, and I guess it's acceptable if you (a) know and (b) can't get the correct hose... What confused me was the really quite different symptoms between my other Monster with a failed high-pressure supply hose and this one - the only common symptom being "ran progressively worse until it stopped", LOL.

Amazing this one ran at all really - this is what came out:

%^%$#^%$%^$. That's not even injection-rated fuel hose, you muppet.. That's low-pressure hose for carbs...

PO used a small shop he thought highly of; owner was an ex-Ducati dealer wrench, apparently. I have yet to be impressed by anything I've encountered that's been non-factory...

Things like

• replaced the aged out belts - shockingly slack when covers removed. 6mm allen? Coulda used my thumb LOL...
• incorrect chain - too many links. 75-100mm of play? The sticker right on the damned swing arm says "25mm mid-point".

And now these hoses. Not to mention the (mis-matched & obviously non-factory) breather hoses were just ridiculously short, one of them safety-wired(!) on, rather than clamped. And the main feed hose clamp to the tank fitting was the wrong size (too large) & binding on itself before it clamped the hose.

Remade the in-tank hoses with 30R10. Used Oetiker clamps where the factory did - correct crimp tool makes those a doddle. Used to loathe 'em, but am coming around...

Bike now starts first stab of the button and runs like it should. Even idles cold, not that I do that much to engines I want to keep around...

Heh. I've done the in-tank pump thing maybe 5-6 times now - but it took a YouTube video before I realized that the power cable is made that long so you can get the pump outside the tank to fiddle with it. I'd always done it with my fingertips inside the tank before - it is certainly a lot easier the other way, LOL... Still kind of a PITA job though...

[jerry]

The worst part is undoing all those tiny allen keys and getting the fuel filler out and later refitting it and making sure the green Oring and seal is not pinched once its open plenty of room for me to crawl inside ha ha