Help about motorcycle

[Johnny25]

Hello Bitog,

I haven't been active for a while, but I'm close to desperate.

I have a Bajaj motorcycle.

It's a small cc, air cooled single cylinder engine.
The bike is electronically fuel injected.

I have a problem that has been on the bike for quite some time.

Between oil changes the oil level rises.
I am having to suck some out with a syringe to keep it from going above the MAX.

The oil smells like gas, and the power of the bike seems low. The pickup isn't the same.


I have tried everything:
New filters;
New map sensor;
New O2 sensor;
New temperature sensor;
New idle control solenoid;
New plugs;
Checked for leaks and couldn't find any.
Everything that came to mind, I did.

Spark plugs are getting fouled with carbon, so I deduce that my mixture is rich as hell.
That makes the oil level rise.

Problem is that I cannot find any problem, no fault codes, nothing.

The bike never stalls.

It had some random starting issues (didn't started randomly with cold or hot engine), temperature sensor fixed it.

I need your expertise, if you can!

 

[JohnnyG]

Leaking/bad injector.

 

[FowVay]

I agree with Johnny, you most likely have a leaking fuel injector that is letting gasoline drain into the engine while the fuel system is under pressure during the times shortly after you shut the engine off.

Get a new injector and your problem should go away. What specific vehicle is this? I looked up a Bajaj Pulsar 250 and the injector for this machine is incredibly inexpensive so buying a new injector should fix the problem.

 

[Boomer]

Sounds like the computer that controls the injector or the injector itself is bad.

 

[Johnny25]

Before anything, thank you for all your responses.

I doubted the injector because the intake manifold is bone dry.

I forgot to mention, but both the spark plugs and o2 sensor were covered with carbon soot.
When I accelerate it feels like the bike is drowning itself.

Would a vacuum leak cause this shenanigans?

 

[Bladecutter]

It may be the wrong injector, and is spraying too much fuel.

 

[meep]

It is definitely getting too much fuel. how does it meter fuel? Mass air flow? Map pressure? Could be a vacuum leak somewhere if it’s map.

 

[Johnny25]

The fuel is metered by parameters from temperature, map and o2 sensors.

All of the above has been changed.

The only thing yet to be done, is searching for vacuum leak.
I suspect one, because if I spray the throttle body with brake cleaner , the idle changes.

 

[DuckRyder]

...

The only thing yet to be done, is searching for vacuum leak.
I suspect one, because if I spray the throttle body with brake cleaner , the idle changes.

if brake cleaner on the outside of the TB is changing idle that is definitely pointing to a vacuums leak. How is engine temp measured is there a cylinder head temp sensor? Do you have a way to monitor it if so?

Edit: I see you changed the temp sensor is there more than one? is there an inlet air temp and an engine temp? When you say plugs are fouled does it have dual plugs in a single cylinder or do you just mean you've changed plugs several times.

 

[Johnny25]

if brake cleaner on the outside of the TB is changing idle that is definitely pointing to a vacuums leak. How is engine temp measured is there a cylinder head temp sensor? Do you have a way to monitor it if so?

Edit: I see you changed the temp sensor is there more than one? is there an inlet air temp and an engine temp? When you say plugs are fouled does it have dual plugs in a single cylinder or do you just mean you've changed plugs several times.

It has a temperature sensor mounted on the cylinder wall.

It only has one temperature sensor, it was fairly expensive though.

It has 2 plugs on the cylinder.
I changed them at the same time I changed the o2 and temp sensor.
They were fouled with carbon, a lot.

I notice less carbon fouling now, but it is still there as well as the gas smell in the oil.


The thing about the vacuum leak is that I don't see anything wrong with the throttle body components. Ruptured hoses and stuff.
I even used a bit of teflon tape in each sensor mount to be sure that it wasn't leaking.
The only thing left to change are the injector oring and grommet...

 

[The_Eric]

Pull the injector and pressurize the fuel system - the injector shouldn't drip. This bike will probably be pretty heavily reliant on throttle position, so check to see if it has reference voltage and check its output and compare to known spec. You'll need to check it at closed throttle and also as you're opening it up to wot (bike not running)

 

[vwmaniaman]

Using the teflon tape may be your problem. May use the chassis or engine ground for the current path. Remove the teflon and try liguid sealer.

 

[JohnnyG]

A vacuum leak would normally cause a lean condition, but with fuel injection, who knows.
So you are saying that this is not direct injection, but manifold (throttle body) injection? Anyway, due to the design and amount of air flow/heat in that area, that area may not show any liquid.

 

[wpod]

Before anything, thank you for all your responses.

I doubted the injector because the intake manifold is bone dry.

I forgot to mention, but both the spark plugs and o2 sensor were covered with carbon soot.
When I accelerate it feels like the bike is drowning itself.

Would a vacuum leak cause this shenanigans?

Too rich.

 

[Johnny25]

Yes, it is throttle body injection (IDI or MI).

Just came from testing the injector.

No leaks!
Left power on for a few minutes, no drips from the injector whatsoever.

Just installed new oring and grommet on the injector, will test during this week.

Also, one weird thing is that my map sensor is wet with petrol!
Which confirms that the mixture is way too rich, but I'm stuck what is causing this.

 

[partspro]

Just had a similar problem on my friends car, 1 injector was stuck open and dumping fuel, replaced that injector now plugs foul very quickly, replace plugs ok for 5 mins plugs messed up with oil. story ends with 2009 cobalt being towed and being used as a Trade on a 2019 chevy Cruze, 60k miles. The 4 injectors that i ordered off Ebay arrived 4 days ago !! They allowed her $1k for the cobalt.

 

[The_Eric]

Yes, it is throttle body injection (IDI or MI).

Just came from testing the injector.

No leaks!
Left power on for a few minutes, no drips from the injector whatsoever.

Just installed new oring and grommet on the injector, will test during this week.

Also, one weird thing is that my map sensor is wet with petrol!
Which confirms that the mixture is way too rich, but I'm stuck what is causing this.

Where is the map located at?

 

[Johnny25]

Where is the map located at?

Just before the valve port.

Throttle butterfly>injector>map sensor>valve port.

 

[DriveHard]

Just before the valve port.

Throttle butterfly>injector>map sensor>valve port.

Your MAP sensor is after the injector? That seems ODD...

 

[Bladecutter]

No kidding.
MAP sensor shouldn't be in the actual intake stream, but just hooked up to a vacuum port downstream from the throttle body via a vacuum hose.

What year, actual make and model of motorcycle is this?

If you have a vacuum leak between the throttle body and the intake valve, you need to figure out exactly where on the engine the leak is at, and replace the bad part with a brand new OEM part. No point cheaping out with crap aftermarket parts from questionable sources.