Fuel rail sensor manifold connection V6 petrol lpg

[Norbertflyer]

Hello All,
I have an LPG conversion on my 2003 V6 and I've just changed the spark plugs under the inlet manifold and noticed that the red pipe from the fuel rail sensor was connected to 'thin air'. I presume this should be connected to the manifold in some guise. The small pipe from the top of the manifold appears to be connected to the LPG box. There is also an occasional whiff of fuel, which may suggest there's an unplugged hole in the manifold somewhere. Brakes also need a firm push to operate, also suggesting a manifold pressure drop for effective operation of the servo. The diagrams/pictures on the internet I've found don't show enough detail.

Anyone any ideas?

Thanks, Richard

[davidr]

Is this perhaps the vacuum connection for the file pressure regulator. As you run the car on lpg (but presumably start on petrol?) then you wouldn't notice as it wouldn't be doing much at idle.

[Norbertflyer]

Hello David, yes it's the vacuum connection to the fuel rail sensor unit. It does start on petrol for the first 2 minutes until the LPG unit has been brought up to temperature. I'll try to upload a picture of the pipe/sensor. There's also a lot of steam from the exhaust pipes, even after a 20 minute drive and mpg is about 14mpg suggesting something is amiss in this area. Richard.

[Norbertflyer]

This is the shot on the top of the manifold showing the 3mm (ID) black vacuum pipe going to the LPG box. I'll splice a 'T' connection into it and add a bit of pipe to the fuel rail sensor as a temporary fix. Richard

[Norbertflyer]

Replaced the fuel rail sensor and inserted a "T" piece from the manifold pipe to the sensor. Warning codes all gone and mpg has risen to 18mpg around town and 23mpg on a short run. All good. Richard.

[J44EAG]

Vac or pressure leaks can cause havoc with MPG, drivability, emissions and also brakes. Fault codes would not be unexpected.

The V6 also has two small rubber air elbows which are notorious crushers and splitters. They are not expensive but the inlet manifold has to come off to get to them.....well worth doing as again those two components can wreck V6 running. Hissing sounds from that area are the indication that something has failed.

Mike

[Norbertflyer]

Thanks for the heads up on the rubber elbows. I'll check for hissing sounds. Richard.