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[MartyNZ]

20 hours ago, TJH said:

With the tps in my hand but connected the minimum reading is 204 mv .
With very slight pressure using a screwdriver in the slot it will get down to around 150 mv.

While you wait for a better TPS, (see Phil's suggestion) try popping the bottom off and looking for the reason why you can't get enough travel. There may be plastic molding flash, or some other rework will allow you to get back on the road. 

I measured the resistance of an old TPS that was worn and erratic but gives some representative figures.

Top pin to mid pin: 2.65KΩ Throttle closed; 2.65KΩ Throttle open.

Mid pin to bottom pin: 3.84KΩ Throttle closed; 1.22KΩ Throttle open.

Top pin to bottom pin: 1.22KΩ Throttle closed; 3.92KΩ Throttle open. 

Edited July 6, 2024 by MartyNZ

[TJH]

Thanks again for the interest and responses gents.

I’ll check that out MartyNZ , thanks for the info and I’ll keep you posted.

Tony

[TJH]

Hi

In the way of an update. After I had exhausted my options/ limited knowledge I took my bike to an experienced MG mechanic. I got the bike back running nicely albeit a slight hiccup around 3000 rpm. He used the original tps and replaced the slightly perished inlet rubbers but didn’t really have any one thing he had found wrong.

Fast forward 6 months and a couple of thousand trouble free kms , and one day the exact same on again off again misfiring is back. 
This time I noticed a couple of things I’d dismissed first time around. I’d just refuelled and noticed fluid run into the tank when I popped the lid whilst on the side stand. The drain under the lid is blocked and when I washed the bike water pooled in that space under the lid.

I have drained and flushed the fuel system and have the bike running properly again but I am having trouble clearing the drain. The fitting on the bottom of the tank ( I am guessing it’s a one way check vale ) is very tight and I don’t want to go too hard and damage the tank. Does anyone have experience / advice removing this part?

any advice is much appreciated

Regards Tony

[docc]

11 minutes ago, TJH said:

Hi

In the way of an update. After I had exhausted my options/ limited knowledge I took my bike to an experienced MG mechanic. I got the bike back running nicely albeit a slight hiccup around 3000 rpm. He used the original tps and replaced the slightly perished inlet rubbers but didn’t really have any one thing he had found wrong.

Fast forward 6 months and a couple of thousand trouble free kms , and one day the exact same on again off again misfiring is back. 
This time I noticed a couple of things I’d dismissed first time around. I’d just refuelled and noticed fluid run into the tank when I popped the lid whilst on the side stand. The drain under the lid is blocked and when I washed the bike water pooled in that space under the lid.

I have drained and flushed the fuel system and have the bike running properly again but I am having trouble clearing the drain. The fitting on the bottom of the tank ( I am guessing it’s a one way check vale ) is very tight and I don’t want to go too hard and damage the tank. Does anyone have experience / advice removing this part?

any advice is much appreciated

Regards Tony

About thirty points down on this checklist there is some discussion of the two nipples under the tank . . .

 

[docc]

1 hour ago, TJH said:

Hi

In the way of an update. After I had exhausted my options/ limited knowledge I took my bike to an experienced MG mechanic. I got the bike back running nicely albeit a slight hiccup around 3000 rpm. He used the original tps and replaced the slightly perished inlet rubbers but didn’t really have any one thing he had found wrong.

Fast forward 6 months and a couple of thousand trouble free kms , and one day the exact same on again off again misfiring is back. 
This time I noticed a couple of things I’d dismissed first time around. I’d just refuelled and noticed fluid run into the tank when I popped the lid whilst on the side stand. The drain under the lid is blocked and when I washed the bike water pooled in that space under the lid.

I have drained and flushed the fuel system and have the bike running properly again but I am having trouble clearing the drain. The fitting on the bottom of the tank ( I am guessing it’s a one way check vale ) is very tight and I don’t want to go too hard and damage the tank. Does anyone have experience / advice removing this part?

any advice is much appreciated

Regards Tony

@TJH, Are you referring to this "fitting/valve" on the right side of tank? This is the pressure regulator and not to be messed with!

[TJH]

 Hi Docc

I’m referring to the fitting / nipple on the underside of the tank where any fluid around the outside of the filler neck drains. There are 2 fittings that have 6mm hose attached to drain fluids and allow the tank to breathe.

[docc]

21 minutes ago, TJH said:

 Hi Docc

I’m referring to the fitting / nipple on the underside of the tank where any fluid around the outside of the filler neck drains. There are 2 fittings that have 6mm hose attached to drain fluids and allow the tank to breathe.

Ah, yes, the two under tank "nipples." One is an "overflow" drain and the other a tank vapor vent. Many have joined them, with no in-line valve, to vent/drain below the gearbox.

One must ensure the path from under the filler cap to the nipples (under the tank) are clear . . .

[TJH]

Yes , that’s the one, the overflow drain is blocked solid just above the nipple which means water sits in that cavity after rain or washing the bike and runs into the fuel tank the moment you open the lid.

I am unsure whether the nipple screws out because mine is offering quite a bit of resistance.  I’ve tried soaking with wd40 , poking snipper cord, compressed air to clear the blockage with no success. I don’t want to damage the tank if the nipples aren’t removable.

[Pressureangle]

I had the same problem, plugged drains and water getting into the tank. The tube that the drains go through are not straight either, and I wasn't able to get any sort of wire through them. The short of the long story is I gave the holes an acid bath with Ospho (phosphoric acid, don't know what equivalent you may have) poked with wire to the extent I could, and blew with compressed  air to get the acid down as far as possible. After a dozen bath/blow/wait etc. I started to get some liquid out the bottom, and all the rust that had clogged the tube internally. I stuffed up the bottom with a bit of wood and let the tube soak a couple times for 5-10 minutes and eventually it came free and clear again. The Ospho dries and leaves any residual rust converted to iron phospate, so after drying with air and leaving overnight I sent some aerosol Cosmoline down the holes to be sure they couldn't rust again. I replaced my leaky cap and gasket with a nice aftermarket unit designated for Aprilia- dang if I can find the source at the moment. You'll also want to remove and inspect or replace the fuel lines to the injectors, and clean the inside of the little aluminum cups as they get the fluffy whites from ethanol and water. 
The end of the story is that I also sent my injectors to be cleaned and discovered that they were something like -3% and -10% from clean and it had never run as well after this cleanup. 

Aprilia cap

Ah, here it is- 

https://www.oberon-performance.co.uk/fuel-cap-kits

Edited 16 hours ago by Pressureangle

[Chuck]

Maybe a cable of some sort poked in the tubing to clear it? 

[gstallons]

It will be better / safer to remove the tank and work from the bottom to get this clog fixed and you can be done with it . This will give you an opportunity to turn it upside down and dump any water from the tank .