PROBLEMS WITH IMV - AND A SOLUTION

[triumph2.5man]

2003 1.5dci 114k miles. Recently an old problem returned under acceleration - level 1 warning and ordered to stop. Seen it all before - low fuel rail pressure. I ignored it and eased up on the accelerator and the warning disappeared. A quick test with clip using a spare IMV showed FRP was well down on the 1000 or so bar. The IMV has various names - Inlet Metering Valve etc. It sits on the end of the fuel pump and controls the fuel rail pressure internally.
As a starting point I replaced the IMV itself. I have amassed several over the years as they are handy to have for testing. (Ford Mondeo TDCI 130 uses an identical item.)
As soon as I started the car a serious problem was evident. The engine began revving like mad and rattling away before stopping (to protect itself from damaging the engine). I removed the IMV and tested the solenoid with 12v and could hear it operating ok apparently. However closer examination revealed that the solenoid valve was in fact stuck in the open position! It was delivering the full rate of fuel. Luckily it was only 400 bar and not 1000 bar plus! I then checked my stock of IMVs and found they were all stuck. Clearly I needed to protect them with a film of oil. Freeing them off was simple but I learned the hard way. If you have a spare, or buy one from ebay, check it is not stuck before you use it.
The way these work is that the valve is normally fully open. As soon as the FRP sensor sends a reading to the DCU, the DCU pulses the IMV to an appropriate pressure. All happens in the blink of an eye!
I solved the low FRP problem but that will be for another post if anybody is interested. If no interest I will not bother...

[lordmat]

Thanks for letting us know!