Why would the current stop at the injector ?

[Jonnyivy]

Getting nearer to getting this ski of mine's running properly by each passing week. I've got it honed down to something stopping the electrical feed to only one of the top injectors on the fuel rail. Every time I start the ski,.. it will rev up and 'sing' for a few seconds before it backs down and bogs out on one cylinder before spluttering to a stop. Difficult to start after that except with the help of some carb cleaner squirted down the plug holes, but this just repeats the proccess again. Had it at jetski garage to have compression, fuel pressure and timing checked. I ran out of time when the garage shut at 5pm and I had to drive back home (150 miles) so he didn't get round to checking the air pressure but I've had the air compressor dismantled and cleaned and it looks okay to me.
But its the electrical current that is stopping when it starts to bog down, ( I had a test meter on the injector)...... What would be the cause of this strange occurance ????

 

[Dr Honda]

The Di engines only idle on one cylinder. SO... after it starts, it will shut one off, but it should idle.

It's important to test the air pressure. Just because the pump looks good, doesn't mean that the rings in the pump are sealing... or that there isn't a leak... OR... that the regulator is doing it's job.


One other thing... when the fuel pump starts to fail... it will build pressure... but will slow down. You need a pressure gauge on it while you are trying to run the engine to watch the pressure.

Unfortunately... on a Di engine... you need your own set of gauges, if you want to work on them.

 

[Jonnyivy]

I was kinda hoping for an answer from yourself Tony,thanks... these darned Di's are crazier than I thought ! I get one problem sorted , then it leads to finding another. BUT,... I'm still aiming to have this one up and running soon.
I did have the fuel pressure tester on the ski when it was in the garage, it showed a good strong reading, and the Seadoo mechanic was happy it was working fine.
As for the air pressure,.. I've been thinking it's the root of the problem for a while, its easy enough to get at the compressor so I will get a new set of rings ordered for it . I was wondering about the small 'o' ring on the pipe coming out of the top of the compressor, it seemed a little slack, but I never replaced it,... maybe I was overlooking the fact how important the seal is ?
The annoying thing about this ski is that when it does fire up it sounds awsome, runs 'on song' for about 6 seconds then just bogs down. Very frustrating !!!

Thanks for your input,..

Jonny

 

[Jonnyivy]

Just another thought Tony;;;; if the regulator isn't doing it's job properly,.. is there a way to clean it ??
Would an untrasonic bath be worth doing ? ( I have access to one )

Thanks

 

[Dr Honda]

Just another thought Tony;;;; if the regulator isn't doing it's job properly,.. is there a way to clean it ??
Would an untrasonic bath be worth doing ? ( I have access to one )

Thanks

Couldn't hurt.


Any seal in the air system is important. The air pressure is what helps overcome the cylinder pressure.

Di's are great when they are working... but they are a bastard to try to troubleshoot.

 

[Jonnyivy]

What you said about the Di's idling on one cylinder has gotten me thinking. This ski sat ouside over our harsh winter and most of the electrics / engine parts were just lying in the hull(with a loose cover over).
I'm wondering if my TPS are not working properly and sending a signal to the MPEM that the ski is idling, where in reality it should be signalling that the throttle bodies are open. (hence only firing on one cylinder)
What's your thoughts on that possibility ???

Thanks,
Jonny