Hello everyone im totally puzzled by this fuelling problem....

When I start my car the fuel pressure is sitting at 4 bar. (Cossie regulator). The car will idle fine for as long as u like. Take the car and give it a hammering then when the car idles again the fuel pressure slowly increases to 5 bar, twitches up to 5.5 bar, then drops back down to 4 bar. Then just keeps doing the same over and over.

Fuels pumps have been replaced twice. Tried 3 different brand new pressure regulators.

Can someone give me some ideas as to what this can be???

Thanks,
Pete

 

Leaky inlet valves can do it, watch the vacuum as it does it next time.
tabetha