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Discussion Starter #1
So I'm having a few issues with my M. About a month ago I abruptly had major surging and backfiring issues. After a good amount of trouble shooting I initially determined that the fuel system was completely gummed up and I had 1 majorly clogged injector(my tank had/has rust in it, had to clean it out, flush fuel system of brown rust-silty gas, change both fuel filters and pay to have the injectors flushed and tested, about a month of down time). Got everything back together, started her up and BAM everything worked great. Took it for a ride, was smooth, good acceleration and no symptoms. next day I start it up and have nothing but problems. Bike bogs down at all RPM's, stalled a couple times while riding and in neutral. troubleshooted some more and discovered the STP sensor was not within voltage spec(.5V was the spec, I'm at .1V). The M50 manual has a "STP sensor adjustment" procedure that I did, but the sensor needed to be adjusted so much that the bolt mount no longer lined up with it's hole(hence permanently out of spec methinks). I've also noticed that the STVA makes a semi-disturbing noise while the bike is running(although I just noticed this, I'm pretty sure I've heard it off and on for as long as I can remember).

I suppose my question is this: How far out of spec does the STP sensor have to be before it causes the bike to stall within a minute or so of starting up(with no throttling, just idle)? I'm kind of a cheapskate and don't want to blow $100 on a used throttlebody off ebay if the STP isn't the issue.

Oh and the bike is a 2007 M50 w/ 6000 miles. I bought it in 2011 with 1600 miles on it. no mods.
 

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I'm kind of a cheapskate and don't want to blow $100 on a used throttlebody off ebay if the STP isn't the issue.
I wouldn't do that either.

I encourage you NOT to spend money based only on a guess......as that often turns out bad.
At this point, a little money spent on a professional diagnosis might be a good investment.

Which do you value most, a little money or potentially a LOT of riding time ?? :mrgreen:
 

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yeah I had considered taking it in to get it looked at, although I don't have any warm and fuzzies about my local dealership. plus at this point it would need to be towed, then I'm sure they'd probably do the exact same thing I'm doing. I'd be in it for $200 just to find out the "problem", if they weren't just pulling a diagnosis out their ass. Wanted to run it by the community first and see if there's a really obvious answer I'm missing.

UPDATE: it now stalls about 10 seconds after firing up. I can keep it running by throttling it, but it's touch and go. battery has sufficient voltage at rest and at operation, but I'm pretty sure with the symptoms I have it's not the battery. STP still tests out of spec.
 

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, then I'm sure they'd probably do the exact same thing I'm doing.
I think not; I certainly HOPE not.
They should have more than one trained and experienced mechanic on staff......which apparently you are not.
They also have diagnostic equipment that you don't have.
They also have parts available for test swaps which you don't have.

I think you are pulling the conclusion about what they are likely to do out of your ass........
But do whatever you think is right in your circumstances.
Nobody else can tell you what to do.
 

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Allow me to elaborate: I'm certainly not assuming that I have the knowledge or equipment that a full fledged motorcycle shop does. When I say "doing the same thing I'm doing", I mean going through a process of elimination via symptoms and tests. My conclusion about what they would do is a "what if" scenario. as in, what if they misdiagnose it, I pay many hundreds of dollars and am left with a now more expensive(to me) chunk of useless metal? I can't afford to throw beaucoup bucks at this thing. Unfortunately my experiences with both auto and motorcycle shops has not always been satisfactory(if you can't tell), leaning more toward my "what if" scenario and less toward your "trained and qualified guy ready to help" scenario. On a similar note, never have your wife take ANY vehicle in for non-emergent repairs while on deployment.

All that said, I'd really like to keep this thread on subject with possible solutions that don't involve paying somebody else to figure it out. does anybody have a suggestion? I just can't get past it working fine one day and taking a complete dump the next.
 

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All that said, I'd really like to keep this thread on subject with possible solutions that don't involve paying somebody else to figure it out.
There is no magic.
You have not provided us (or yourself) any real test results to base an educated guess upon.
Therefore the best "we" can do is provide you with additional wild guesses......with even less information than you have because we aren't there.

Very often people in this situation end up spending MORE time and money than they would have with a shop visit.......sometimes MUCH more.

Good luck. If you fix it by blindly swapping out parts it will BE just luck.
 

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I de-rusted the tank using white vinegar. pulled all moving and non metal parts out of the tank(the pump, pressure regulator, fuel level indicator, anything electrical), sealed it up and filled to the brim. left for a day or so, drained and flushed a few times with distilled water to get all the broken up rust and traces of vinegar out of the tank. completely dried out the tank and sucked out the small amount of rust flakes left(I pulled ALOT of rust out of the tank, had to use an inspection mirror to verify it was truly empty). I replaced the low pressure strainer on the fuel pump, replaced the high pressure filter and even bought a brand new pump just in case the old one took a dump(the bike exhibits the same issues with both pumps). I figured out the fuel injectors were spotty by switching them. I had noticed one cylinder was misfiring considerably more than the other, so I switched them, lo and behold the misfiring switched cylinders. Logically one of the injectors was not flowing properly. When i had them flushed/tested they flowed(before cleaning) at 98% and 94% of optimum spec. after cleaning they were both in spec. the bike is still not throwing any codes.

UPDATE: I pulled the spark plugs. both totally black(rich fuel mixture i think). tried new ones to no effect.

I cannot let go of the fact that it was running fine right after I put it back together, and dying repeatedly the next day. What could have gone screwy in less than a 24 hr period? I suppose the injectors could be fouled again but the symptoms don't seem to indicate that. I can get the bike started but in order to keep it running i have to whip the throttle back and forth quickly or it will stall. Occasionally if i open the throttle completely it will rev up to a healthy RPM before stalling. there doesnt seem to be any difference in performance between the cylinders. When i first start it up it goes to a nice idle(for maybe 1-2 seconds) before stalling.
 

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I'm still going with dirty injectors. It really only takes 1 spec of grit to foul and injector.
I would take them off ,and clean them ,then install an inline fuel filter and be sure to use fuel injection clamps!
-CS
 

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Discussion Starter #10
i tested both spark plugs and both cylinders have good spark(on a whim i switched em out, the old ones were pretty black. when i tested the new ones today they had gotten just as black in maybe 2 minutes of cumulative running time over the last 24 hrs). so im definitely running rich. i also set up the FI system off the throttle body and charged it via the fuel pump(to check for leaks on the injectors and the pipeline). there were no visible leaks and there was no fuel in the container i placed under the injectors, which leads me to believe a leak is not whats causing the rich fuel mixture.

before all that I tried spraying starter fluid into the intake. definitely gave it a healthy idle for a couple seconds. i also cut my gas with seafoam, no significant effect.

my suspect conditions now are 1.)clogged or worn out injector is metering out fuel incorrectly OR 2.)fuel injectors are receiving wrong signal due to faulty electrical components or maybe a ground somewhere?
 

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I bet you they are just dirty.....
-CS
I don't quite follow that.

Dirty injectors would mean LEAN usually......unless they are stuck open,which the tests would seem to rule out.

If the plugs are sooty and dry, then it is likely too rich.
If they are black and oily, then it might be oil fouling.

In this case, one test says rich, another shows lean.
Confusing indeed.
 

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If the fuel isn't coming out as a mist,it wont burn right..If it is coming out as a drip it wouldn't burn right,and would foul out a plug. Dirty can make a lean condition by blocking fuel ,and foul it out by allowing the fuel to not spray/burn ,and instead drip.
-CS
 

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Discussion Starter #15
luckily the shop that serviced my injectors is willing to retest them for free. now i just gotta mail em out and hope for the best. if it is clogged injectors again i would be stupid to hook it all back up and hope for the best. there would have to be some sort of super fine material in the system(possibly rust sediment from the tank) that equally fouled both injectors(because it doesnt seem to be one particular cylinder causing the stalling). if thats even the case. should know here in a couple days.
 

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so we got it all figured out. I took the injectors back to the shop that cleaned them and determined that the flow rate had dropped dramatically to the tune of 75% less than optimal. the spray pattern and frequency were all fine so the guy tried a new set of basket filters in the injectors. cleaned that flow right up. guy gave me a couple extra filters just in case the new ones also took a dump. My best guess as to what happened was a combination of low quality injector filters and the injector cleaner i put in the day i put it back together. crappy chinese mesh filter+low quality injector cleaner(alcohol)= microscopically degraded filter resulting in severely limited flow. put her all back together and have been riding every day since then. I'm just happy it wasn't something more expensive.
 

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I am a nube.
I am having a very similar problem on my M50! starts well with starter fluid sprayed into the intake and i have spark, so i am guessing it's a fuel issu.
I replaced the pump and the low-pressure strainer.The pump "primes" but still will not turn over.
I am not getting an "FI" light.
You say that you changed the high-pressure filter?? i thought this was part of the fuel pump "assembly"?
How was this done? and where did you get the filter? any help would be grateful! I am sure the injectors are clogged but would like to change the filter before i get them cleaned.
Any help would be greatly appreciated!
 

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Hey everyone, I have no idea how to start a new post yet, still in my Caveman state. Actualy I have no internet & no tv, so im at the library. Alright, down to what matters. I have a 2006 boulevard m50, with cobra pipes, (not sure what kind), K&N air filter, and fi2000 fuel processor. The bike was running GREAT until i had it serviced at the 12,000 mile mark. Had spark plugs replaced, the whole nine. Last spark plug job was done early back when it had 4,600 miles on it. I rode 8,000 miles on it in 7 months with no problems. when i left the shop the bike was surging & really struggling to accelerate in 5th gear. took it back next day, they claimed fuel processor broke. I didnt trust the service manager's attitude towards me so I took it to another shop, found out the previous shop just unhooked my fuel processor. the guy wired it back up, (backwards by the way lol), but the bike was still surging & at this point couldnt get past 40MPH. So i took it to another shop (2nd shop couldnt figure it out), and they found it has rust in the gas tank, clogged injectors, etc. Cleaned it all out for me, bike ran great until the next day, even after a great ride home (45miles). Anyway, $230 later after the original $260 service job, my bike is still messed up, can go up to 65MPH but thats it. I wanted you guys' opinion on the matter, what do you think is the problem? Theres still rust in the tank, im taking that off today to clean it out myself with evaporust, obviously my trust for mechanic shops here has went down, and im gonna install a inline fuel filter. (Ideas ive got from reading this forum.) Is there a way to get the injectors cleaned myself or do i have to take them to a shop? and does anyone in NC have a trustworthy mechanic shop for bikes? The bike also stalls at idle, have to keep the throttle up to keep it on. is this a sensor thing or just rust gunk everywhere? PS: The shops couldnt get the ECM to throw a single code, which worried me about the ECM, but they also replaced that & had no difference. any help will be appreciated, or advice! thanks guys,
Adam
 
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