I don't know what kind of fuel injection system i have in my 740, i don't think it has an ecu because it doesn't have a mass airflow sensor, this is a link to a similar one, https://goo.gl/images/Q5s9B6
It has a rubber balloon-like hose before the throttle body and there is no fuel rail, seperate fuel line go to each cylinder. Thanks

 

That picture is a k-jet fuel injection system. Didn't know they put that in 740s.

 

What year is your 740 and what model. Please post a picture of the engine compartment.

 

This is a British registered RHD 1989 740, probably 2.0l. Volvo made various market choices as far as features and options.