Low power when running - goes out in idle

[kjems]

Hi all.

With a ton of help from this forum, I have fixed so many issues on my Like. I am now stuck with a problem and need advise on what to try next.

Problem: The scoot looses power when riding or is unstable and goes out when running in idle.

I fixed the problem by cleaning the injector (carburator cleanerspray and 12v battery from both sides) and all was fine for maybe 100 km. Then the problem returned. I ordered a new injector, but problem was still there with the new injector. I will try to clean the old one one more time, to see if that can fix it again - but dont like the idea of cleaning that every 100 km

The whole fuel line is more or less new - new fuel pump, new hose from pump to injector, and now also new injector. Also got a new fuel cap, to make shure there was not vacuum in tank. Also got a new battery and changed the spark plug.

My next step will be to make shure, pump deliver correct pressure - what tool is needed for that?

Also i wonder how i can check that pump and injector get the right amount of electric power - a failure here could explain why problem consist after exchange of pump and injector. And maybe a bad electric connection was better the first 100 km after cleaning and then got bad again?? - really just wild guesses here, so would be great to know how to test that it is not an electricity/connection issue.

Any advices appreciated

Kindly Jesper

[Ruffus]

I would as a first measure, put a transparent fuel filter in this line between pump and injector.

To check your pump pressure, go to a car shop and they should plug it into an SunTester or similar.
Or buy/take a cheap manometer. Output should be around 3 bar of delivered fuel pressure

For electrics on your pump:
-ignition on- battery current on your pump              (multitester) either it runs or not, don't think less voltage makes a huge difference there

.

[kjems]

I would as a first measure, put a transparent fuel filter in this line between pump and injector.

To check your pump pressure, go to a car shop and they should plug it into an SunTester or similar.
Or buy/take a cheap manometer. Output should be around 3 bar of delivered fuel pressure

For electrics on your pump:
-ignition on- battery current on your pump              (multitester) either it runs or not, don't think less voltage makes a huge difference there

.

Thanks, good idea with a fuel filter, to make shure and get a visual on eventual dirt coming that way. Looks all clear in the tank though.

What about electricity to the injector. Can i messure if thats ok some how. Must be a lot of small current peaks when pushing the starter i guess?

[Ruffus]

Dont know for sure but,
 put a multimeter on this two pins, either without linjector direct or sting two needles through the isolation. Should be around 5 Volts arriving in this magnet switch there.
Start button of course.
If the injector is pulsing, then it has current.

Maybe something like that, pls see links
https://www.kymcoforum.com/index.php?topic=33488.msg235252#msg235252

https://www.kymcoforum.com/index.php?topic=33488.msg235227#msg235227

[jeeves]

I would as a first measure, put a transparent fuel filter in this line between pump and injector.

To check your pump pressure, go to a car shop and they should plug it into an SunTester or similar.
Or buy/take a cheap manometer. Output should be around 3 bar of delivered fuel pressure

For electrics on your pump:
-ignition on- battery current on your pump              (multitester) either it runs or not, don't think less voltage makes a huge difference there

.

Won't the fuel pressure be an issue with a plastic transparent fuel filter that is usually used for carburetor engines?

[Stig / Major Tom]

Regarding the injector circuitry  -

disconnect plug from the injector -

- In this plug you should have battery voltage on one wire when the key is turned on, the voltage is coming from the ECU so it will show 11.77-12 VDC. You can disconnect the injector when checking this. The other injector wire gets the signal from the ECU for the injector to spray which is a very fast pulse.

There should not be voltage on the other wire, it should be a ground. If you switch your meter to read ohms, disconnect the fuel injector connector and check the other wire -  it should show resistance when the key is on and OL or open lead when the key is off. This shows it is getting a signal from the ECU.

Because the injector wire may go through some 90 degree turns - it can get damaged - you may want to open up the protector For the injector wires and check for damage.

Stig

[Ruffus]

Maybe go in this direction...

https://www.kymcoforum.com/index.php?topic=11768.msg235410#msg235410

[kjems]

Won't the fuel pressure be an issue with a plastic transparent fuel filter that is usually used for carburetor engines?

I had the same thought, but found a filter that was specific for pressure injector scooters and mc. (hope that's correct).

I have now cleaned old injector again and put that filter ind the fuel line.

And again it's running perfect.

I guess I now have to ride a 100 km again and see if problem returns ones more??!?

I also mesured pressure with an old manometer to just above 3 bar when pump is running. Falling to 2 bar when pump stops (but might not be accurate since it's cheap and old).



Jesper

[Ruffus]

Well done👍
Always put a pressure-proof filter in between, particulately when I change to FACET fuel pumps. But in this case BEFORE the pump.

Why should a tiny  layer of plastic mesh lower pressure in a closed system 50 cm of lenght.
Around 3 bar is good enough for this small one cylinders/injectors.

[kjems]

Well done👍
Always put a pressure-proof filter in between, particulately when I change to FACET fuel pumps. But in this case BEFORE the pump.

So the filter you see in the video is not OK for 3 bar pressure, when placed after the pump on the way to the injector?  It says in the shop description, it should be in systems with fuel pump?  But i really wouldn't like in to brake it during riding.

The filter used is this:
https://wixeurope.com/en/find-a-filter?action=showFilter&backAction=showSubmodelFilters&engType=74AWF&hp=177&kw=220&partNumber=WF8130&prodFrom=2015-01&sp=2&vehicleMake=VALTRA+%2F+VALMET&vehicleModel=T-Serie&vehicleSubmodel=T174EV+%28T4-Serie%29&vehicleType=agri

If allready have af filter before the fuel pump - but that is placed in the tank leaving no visual possibility. (Came with the pump.)

Best Jesper

[Stig / Major Tom]

I'm glad your injector clean solved the issue (hopefully!).
Fuel in the tank first goes through the filter on the fuel pump of course.....so unless there is some contaminant occurring in the line from the pump to the injector....there should be nothing for your new adornment to find 

Nevertheless - if it doesn't leak - what harm could it do.

Stig

[Ruffus]

The idea putting a filter was:
-to see whether your fuel tank filter or your rubber lines  in there are disintegrating.
-filter darkish filled, YES -^

Anyway, this kind of filter will stand that pressure, if properly installed with hose ties.

[kjems]

UPDATE: First it worked, but I'm back to absolutely dead scoot.

Okay, so on my last post a had a perfect idle, but turned out it would not ride, when I drove and gave it more on the handle.

So i took of the filter as I saw air in there - maybe because of the angle "lying down".

And it worked and my scoot was back in super conditions when I took it for the first test drive.

Just like last time after cleaning the injector.

But did not get far - after maybe 3- 4 km it went out completely. Could still crank the starter and rotate engine, but scooter just would not start.

Luckely i had mainly run uphill, so I managed to drag it all the way back home.

Now I'm back to zero and this is my testing:

First a video of the scooter not starting:
https://youtube.com/shorts/G1G1klR4u5o?feature=share

Then a video of the injector spraying gas


And lastly a video of the sparks from sparkplug



Anything not looking like it should?

or any other ideas on where to move on from here?

Kindly (a little frustrated) Jesper

[Stig / Major Tom]

Regarding your injector spraying video......
THAT looks nothing like a proper nicely misting fan-spray pattern from your injector.
Looks like a broken squirt gun .....not good. Squirting dribbles.

I forget - you have installed a new Kymco injector?

Stig

[kjems]

Regarding your injector spraying video......
THAT is nothing like a proper nicely misting fan-spray pattern from your injector.
Looks like a broken squirt gun .....not good. Squirting dribbles.
I forget - have you installed a new Kymco injector?

Stig

No it is the original injector, that has worked (temporarily) after cleaning.

I did order a new cheap injector, that I never got to work.

But thanks a lot for guiding me. I will test the pressure from the pump again and then maybe begin looking for a new original injector I guess, if pressure is OK.

Kindly Jesper