915iS Hard 1st Start

[martin-av8r]

do you try switching fuel injector from cylinder 2 from another cylinder to try to find if trouble follow the injector swap or not ?

same for ignition coils wires and sparkplug cap ?

your problem is similar to the OP and you are correct to talk about it here , you are not taking over the thread

and i wish the OP give us more info

 

[Abid]

Thanks for this info. I was told to put the tailwheel up on a stand at flight level and attempt cold start. 3 mornings it started perfect while in flight level with the tail up. I dropped the tail back down on day 4 and rough start again. I don't know what this means but it's the first thing that has made the engine start right. This is when the fuel bypass line was moved from the fire wall to the #2 injector and back into the return line. This did fix some of the planes that tried it. Not sure why it didn't work for me. Lucky I guess, Haha

That is interesting. Can you do this reliably repeatedly?
If so this is some kind of specific issue on the fuel circuit and positioning of fuel lines, the vapor lock prevention orifice size etc.

 

[Kitfox Pilot]

That is interesting. Can you do this reliably repeatedly?
If so this is some kind of specific issue on the fuel circuit and positioning of fuel lines, the vapor lock prevention orifice size etc.

I have only put the tail up on a barrel the one time for 3 days and it started every morning. I knew it would start on the 4th day when I sat it back down before starting but it didn't. This worked on 2 other highlanders that have the same problem. This is when they moved the orifice up to the fuel line at number 2 cylinder. It worked on the highlanders I am told. It made no difference on mine I am sad to say. Nothing else has been offered to try or do since this at about 3 months ago.

 

[martin-av8r]

If you really fix your cold start problem with the tail up and engine level , it is a simple thing

for me turbo fuel system is simple

fuel tank , fuel pump , fuel hose , fuel pressure regulator , fuel rail , fuel hose suply, fuel hose return


you know it is not easy to fix a problem when you can touch... and see the engine live

the rotax fuel system you have look to be a bit biz... a rare... problem with a brand new quality set-up..


Abid said:
That is interesting. Can you do this reliably repeatedly?
If so this is some kind of specific issue on the fuel circuit and positioning of fuel lines, the vapor lock prevention orifice size etc.


with what Abid said
the vapor lock prevention orifice.... size etc.


this orifice stuff is only possible for me on the dead-end fuel rail set-up with the fuel pressure regulator

before the fuel rail

you will never see this on a normal turbo efi system with the fuel pressure regulator at the other end of the fuel rail with a return style to the fuel tank

fuel from the pump come and enter the fuel rail at one end of the fuel rail , supply all the fuel rail and injector

and on the other exit side of the fuel rail the fuel regulator to keep the boost reference fuel pressure in the fuel rail

at the correct differential fuel pressure , and a good return hose from the pressure regulator to the fuel tank

with no restriction or less possible , simple no problem , when you turn the pump on this automatically bleed an pressurize

all the fuel rail and fuel injector , no orifice sheabang star-up problem , but it is not rotax method it seam...

 

[martin-av8r]

I dont know if rotax remove the original parts number on your fuel pressure regulator

they do this many time to resell the parts they dont produce

like the BRP... NGK sparkplug

and the NOLOGY ignition coil on the IS

look if you can see the Bosh part number on the fuel pressure regulator

look like this mobel if it is the 3bar 43.5psi with intake manifold pressure reference line input

and retained by a circlip on the intake manifold?

Fuel Pressure Regulator Insert 3 Bar

In the search for the perfect regulator to use in my EFI packages, I couldn't find one. They either didn't mount correctly, have the proper ports or just didn't look good. So decided to design my own. I have chosen the use the Bosch interchangeable regulators to cover a wide spectrum of...

thedubshop.com

 

[Kitfox Pilot]

I will check this the next time I have the hood off. We are in the middle of harvest right now so it will be a while before I get to that. Thanks