Need some help with an aprilia

[Jord]

My father in law has a 2018 Aprilia tuono 125cc. It has the weirdest problem I have come across. It is hard to start but it does eventually start then it runs perfectly for about 3-5 min then cuts out, then it won’t start at all until about 30 min later then the whole cycle starts again.....

im stumped. Any help or ideas would be great. 

[Triple Jim]

That is a symptom of a fuel flow problem.  Is the gas tank vent clear?  Does the petcock flow properly?  (etc.)

[Lone Wolf]

50 minutes ago, Jord said:

runs perfectly for about 3-5 min then cuts out, then it won’t start at all until about 30 min later...

Get some starter fluid, and when it "cuts out and won't start for 30 minutes" see if it comes to life with starter fluid sprayed into the air cleaner region. A healthy engine that simply ran out of fuel would briefly run and rev up.

If it remains completely dead, doesn't fire up, then the problem is electrical. I have not seen that on modern motorcycles, but chain saws do it all the time. Coils go bad, and when they heat up to operating temperature they die. They cool off, and will start and run, until they heat up, then they die.

That is kind of hard to test the spark because it will appear fine (cold) then you don't want to pull the plug when it is hot as hell, so the diagnosis gets missed.

Personally I don't know what is causing the problem, but that is where I would start.

[Triple Jim]

11 minutes ago, Lone Wolf said:

That is kind of hard to test the spark because it will appear fine (cold) then you don't want to pull the plug when it is hot as hell, so the diagnosis gets missed.

Another way would be to have a spare plug ready, and when it quits, connect the spare plug, lay it on something grounded and see if there's spark.

[Lone Wolf]

1 hour ago, Jord said:

It is hard to start but it does eventually start then it runs perfectly for about 3-5 min then cuts out

I just noticed the "hard to start". That is a huge clue.

Has the bike been stored? Fuel filter? Drain old fuel out? it is fuel injected so you wouldn't have clogged carb jets...

[Jord]

Thanks for the quick replies, I’m thinking fuel problem too, if it was a carb I would be thinking the bowl is not refilling quick enough or something along those lines, it’s fuel injected I can’t see any petcock. I’ve had the pump out of the tank to check to see if it was blocked but the mesh cover seems fine. I blew up through the breather pipe and it’s clear, I also opened the filler cap and let it run and it died after 3 or 4 mins again

il try the starter fluid trick and see what happens. Then il have to buy him another plug and try to swap it out quick and try and see if it starts back up 
 

thanks for the quick reply’s all

[Jord]

Just to add. No the bike hasn’t been stored, he uses it daily. I suspected dodgy fuel but that doesn’t explain how it runs and revs fine for 3 min 

[Triple Jim]

I had a fuel injected car that would suddenly stall after driving awhile, and if I let it sit for 15-20 minutes it would start and run some more.  I searched for the problem for quite a while until I decided to put a pressure gauge on the fuel rail.  I taped the gauge to the cowling just outside the driver's side windshield and watched as I drove.  Suddenly the pressure fell and the engine stalled.  Replacing the fuel pump solved the problem.  It seems that the pump would get hot and quit pumping. 

Edited April 3, 2021 by Triple Jim

[Jord]

6 minutes ago, Triple Jim said:

I had a fuel injected car that would suddenly stall after driving awhile, and if I let it sit for 15-20 minutes it would start and run some more.  I searched for the problem for quite a while until I decided to put a pressure gauge on the fuel rail.  I taped the gauge to the cowling just outside the driver's side windshield and watched as I drove.  Suddenly the pressure fell and the engine stalled.  Replacing the fuel pump solved the problem.  It seems that the pump would get hot and quit pumping. 

I feared it being a problem like this, pump or injector. The problem is there’s no way of knowing until you replace one of the 2, then it becomes expensive 

[Jord]

My in law is convinced it’s an electrical issue because his R.E.V. counter hasn’t been working for a few months but I’m uncertain. I don’t know if an electrical issue that will allow it to run fine for a set amount of time then die 

[Triple Jim]

28 minutes ago, Jord said:

I feared it being a problem like this, pump or injector. The problem is there’s no way of knowing until you replace one of the 2, then it becomes expensive 

But I posted a way to know if it's the fuel pump above.  You put a pressure gauge in the fuel line after the pump.

If you think the pump may be OK but is losing power, you put a 12 test lamp where you can see it and connect it to the pump power wires.

Edited April 3, 2021 by Triple Jim

[Jord]

I really appreciate your help but I am not as advanced as what you seem with this sort of thing, a lot of what you just said lost me.  I don’t have a pressure gage or a 12 test lamp 

[Triple Jim]

12 minutes ago, Jord said:

I really appreciate your help but I am not as advanced as what you seem with this sort of thing, a lot of what you just said lost me.  I don’t have a pressure gage or a 12 test lamp 

Then you have to weigh the cost of those tools against the cost of guessing the pump is bad and replacing it to find out.  Either that or find a shop with a good reputation to fix it for you.

Edited April 3, 2021 by Triple Jim

[Lone Wolf]

55 minutes ago, Jord said:

My in law is convinced it’s an electrical issue ...

If that is true then spraying the starter fluid into the air intake will have no effect.

A can of starter fluid is cheap. Just so you can tell what it does, spray while the bike is running "OK" and the engine will speed up. It is like Nitro compared to gas.