Stuttering under load

[darrenptalbot]

hi Guys

1999 1100GS, with a recently developed problem.

When I'm riding and open up throttle over halfway, the bike loses power. If I reduce throttle back below halfway, it picks up again. If I hold it on the halfway point, it almost 'kangaroos' down the road.

It doesnt tend to happen in 1st or 2nd gear, and 3rd is ok if I'm going downhill, so opnly appears to be when teh bike is 'under load'.

I've opened the fuel cap while riding to make sure it isnt a blocakge there, and it made no difference.

If I leave the bike for a few minutes turned off, that can sometimes make a difference.

All I can think of is a possibly blocked fuel filter - is there anything else I should look at?

Cheers

 

[(RIP) DitchWater]

What's your rev counter doing when this is happening? Look to see if it's going UP as well as down.

 

[darrenptalbot]

It's not bouncing, so I didnt think it would be Hall Sensors.....at least, I hope not!

 

[DrFarkoff]

Leads or coil methinks

Under load is the clue here

Possibly TPS but suspect the above first

 

[darrenptalbot]

Thanks Dr Farkoff - is there an easy way to check?

 

[DrFarkoff]

You can examine them for cracking or splitting and replace

I would say that in reality no easy way to check unless you can recreate it in the garage then you may see sparking from the leads

While you are in there hoking about check the hall sensor wiring I had one do similar stuff but it was the sensor wiring was all cracked up it did not exhibit any of the "normal" symptoms

Also when was the fuel filter last changed?

 

[darrenptalbot]

I've ordered a second hand from Motorworks - i can always send it back if that isnt the problem.

I'll look at the Hall Sensor while I'm there

Fuel filter - thats probably going to be it ... arent they a real pig to get out?

 

[DrFarkoff]

With a bit of patience they are okay

The biggest and most important thing is to drain as much as possible out

Once you undo the hoses one will flow fuel If you haven;t got a fuel pipe clamp use a cable tie and fold over and tie it shut

I use an old tyre on a B & D workmate to set it in so the paintwork isn;t scuffed

Plenty of loose oil on the threads I use a brass wire brush on a drill to polish the threads as much as possible and remove as much rust as you can (Obviously tape up the ends and

then its a simple matter of undoing the nuts

Gently lifting the plate and getting those two small pipes unclipped inside the tank

Swivelling and lifting the pump flange out and undoing the two crimp pipe connectors

Note the direction of the filter arrow before you pull it out refit and use a pair of sidecutters to gently nip the crimps again

and vaseline the O ring IF it hasn't swollen up nothing else or it swells as you watch it LOL this is one I found recently that some one used silicone sealer the ring was well swollen when I cleaned it off and went to refit Luckily I have a couple I keep handy

refit it and just GENTLY nip up the nuts Don;t overdo it or you'll break one!

 

[darrenptalbot]

You make it sound so simple! I assume its teh same for an adv tank?

Thanks - I'll let you know how I get on - just ordered the filter from motorworks too

 

[DrFarkoff]

Yup you just have an extra crossover pipe to disconnect between the lower lobes it can be a bollix to wiggle back under the alternator to reconnect tho

P.S. Make sure you do not dislodge the throttle cables when refitting the tank

You make it sound so simple! I assume its the same for an adv tank?

Thanks - I'll let you know how I get on - just ordered the filter from motorworks too

 

[MattW]

Clutch slip?

 

[Delboy777]

Sounds like fuel starvation to me

 

[darrenptalbot]

Yup you just have an extra crossover pipe to disconnect between the lower lobes it can be a bollix to wiggle back under the alternator to reconnect tho

P.S. Make sure you do not dislodge the throttle cables when refitting the tank

I'll be careful

Clutch slip?

Yep, got some of that ... need to adjust clutch, but its not clutch slip on this one!

Sounds like fuel starvation to me

I think you're right, which is why I need to get in to sort the fuel filter first. I've got the coil on sale or return from Motorworks in case it isnt the filter

 

[tosh23]

Hope it helps
http://www.youtube.com/watch?v=KOaopF7HaPA

 

[darrenptalbot]

Hope it helps
http://www.youtube.com/watch?v=KOaopF7HaPA

Cheers - thats definitely one for low volume!

 

[DrFarkoff]

Handy Vid BUT Feck me talk about Clart handed !

Number one, it doesn't matter about marking the pipes one is a drain one is an in tank vent either can use either length of hose to the atmosphere But make sure the filler drain one is clear to blow thru while you are this far in !

Number two, Just use a pick to spread the crimped part of the hose clamps at the filter they will open enough and slide back very easily with out all the wobbling of the fuel level float you can bend it and it will stick against the filter and it all has to come out again

Keeping the work area clean and a touch of anti seize on the tank studs and vaseline on the sealing ring will allow it to move and centre and NOT get caught!

If you unclip the little vent / breather hose clamps they will slide on easy and a tile cutter or side cutters will clip them back over easily you can work easily thru a 2 to 3 inch gap as you slide the plate back into the tank again Make sure no cables or the hoses trap the float

Oh and a BIG tip when you undo the tank bolt lift the tank and refit it back thru the tank bushes the number of GS's that I see with the metal tank bushes missing

If this is your first time tippex a line on the tank and pump flange or you will wonder where the heck the plate fits

I also slap a brush or two of waxoyl in the seams and tank mounts and pump flange if they are rusty and Tippex on the mileage and date that you changed them so you know without opening the tank

 

[darrenptalbot]

Handy Vid BUT Feck me talk about Clart handed !

Oh and a BIG tip when you undo the tank bolt lift the tank and refit it back thru the tank bushes the number of GS's that I see with the metal tank bushes missing

It s GS - I've had the tank off loads - have done just about everything apart from clutch and fuel filter on it in last 2 years and 40k miles

I like the tippex idea

 

[darrenptalbot]

Whilst waiting for the bits to appear from motorworks, its cured itself, proven on a 130 mile ride yesterday.

Best I change teh filter, and I'm hoping that will be it. Oh, except for the clutch arm than snapped yesterday ... waiting on £90 replacement from motorworks

Anyone changed one of them? How much of a git are they?

 

[cookie]

Anyone changed one of them? How much of a git are they?

yes. an utter bastard

 

[darrenptalbot]

yes. an utter bastard

Oh good. I feel so much happier now!