Ok, so starting off the scooter had been sitting about a year, battery was dead so i bought a new one for it, and still wouldn't start. I've taken out the spark plug and its as dry as can be, I then took off the Fuel Injector to check to see if it was spraying fuel. I turned it on, and began to start it and it poured fuel out. I noticed that when looking down the throttle body neck that there was no fuel coming out of it and into intake. I've got spark, and compression, but cannot get it to fire except for a few times, and WILL NOT start on starting fluid. One thing I did check was the ECM up front. I did a test on it to see if it was getting signal to the engine, fuel pump, etc. I had it narrowed down to a new ECM, but I want to check timing on it first, but dont have the procedure on how to check, and adjust. This was an old mans scooter, less than 500 miles, and I was the last one to drive it, so I know it runs. Anyone have any ideas, hot to check timing, etc. I'm going to go pick it up off him today, and bring it home to work on in my shop. Just looking for some advice out there since its been a year since i was on here, and need to get this back together, and running, Thanks for the help.

 

You sound like you know what you are doing
Personally, I do not know enough about scooters to help
I pretty much wing it and go at it until it is fixed
Hope you get it fixed
Good luck to you.

 

also an update since many never seem to update after they work on them. I did a test on the injector voltage, 1 side reads 4v the other 12v, i checked all the components and they seemed to be working. One thing I did re-check was the fuel pump. At first it wasn't coming on, then I hooked it up to a 12v source and it came right back on. I did it several times to makes sure all the crud was out of it. I reinstalled, and cycled the key a few times to pressurize the lines. When I checked the injector after looking at the pump, I noticed it was spraying out of the 6 nozzles, so i hooked it up to a 12v source, and got it to click, signaling it was working. I did that a few times to verify liquid was coming out of the end, and since there was I reinstalled, and again cycled the key about 5 or 6 times just to make sure it was getting the lines pressurized. I then took the injector, laid it where I could see it and acting like I was starting it, and fuel came out of the injector, but not like I would expect. It shot a fine mist from the 6 nozzles, but it was a really small amount of fuel. Also to add, before I reinstalled the pump I sucked out all the old gas, and put in fresh gas, blew all the lines out, including the air lines. I reinstalled the injector, and tried starting it, and nothing. It would attempt to start but never would stay running more than a second. I readjusted the valves, checked for bright blue spark, and compression seems fine. The only thing I can think of is the pump is weak, because when I would remove a line, gas wouldn't be pressurized or there wouldn't be a large amount of fluid coming out, it would just barely trickle out. I would think that the pump would pressurize the line enough to not only spray harder, but also have the lines under pressure. So what's everyone's guess?? I am up to try anything, and remember it will not even start and run on ether.

 

The old carburetors needed about 4 lbs of pressure (PSI) to run the engine
Fuel injectors need around 40 to 55 lbs of pressure (PSI) to run the engine
If only a trickle is coming out then something is clogging the fuel line??
But, the injectors were working with 12 volts applied to the fuel pump??

The fuel injectors are basically like a coil.
The ECM uses ground side switching
So there is power when ignition on and the ECM grounds the other side of the fuel injectors to make them work
The 4 volts is just what is presented. Resistance or impedance to ground is high until it is grounded by the ECM.

 

yeah I checked resistance and voltage on all circuits, when I applied 12v to the injector it was the injector alone not with fuel, just to verify if the injector was still working. The injector seems to be operating correctly. I’m almost 100% positive the pump isn’t producing enough psi. When I opened the line to the injector the fuel should have sprayed all over the place. It was as if I had just opened a garden hose that was just barely open. Very little fuel came out, it was basically what was in the line but was not under any pressure. With injector working properly, and the pump the injector held pressure and wasn’t open, but somewhere below it down the line to the tank it’s losing pressure, or lack there of. That’s why I think it’s the pump because if you have a pump that’s fully functioning that line 1. Would have been a B to get off, and 2. When I took it off it should have sprayed fuel everywhere.

 

Okay, check the line and then if all else is well, then you got a fuel pump issue.
Good luck. Hope you get it back on the road soon.
The weather is starting to get warm.

 

now I’m really perplexed. Just to say the heck with it I decided to take fuel injector out of the intake and try to start it and see how much fuel came out of the injector and I’ll be damned if the dang thing didn’t fire off and start. It died about 4 seconds later but the closer to the intake the injector was just to get that fine mist the engine would try to run. Now I’ve never seen this before, and frankly I wish this was a carb bike, but it’s not so I’m still stumped. I really have no clue as to while it’ll run when the injector is close to the intake hole, but not in it, and that the injector seems to be working at start and full throttle

 

Well, being close to the in-take but not it means that there is air flowing into the cylinder
So, maybe it isn't getting enough air??

 

I have run into the exact same issue. When I remove injector and its near in intake port it runs.

Air filter is clean
Pump & injector work
Got spark
140 psi compression

will start and run 1st time of the day and then after that just crank. If I remove injector it runs.

Leads me to believe it's rich but no reason why

 

Any update or solution? I have the exact same issue and it doesn't make sense yet other than scooter is rich and once you remove injector it add more air and runs.