Hi all i have a problem with my Cosworth. When the engine is running the fuel pressure is fine but after shutdown it starts to drop. It takes about two hours for the pressure to drop to zero which leads to long starting times after that time has passed. I cant smell fuel near the lines under the bonnet or under the car so i dont think there is a leak. What could be causing this problem? Thanks in advance for any help!

 

change the fuel pressure regulator.

 

There is a non return valve on the pump. The banjo bolts to it. Which is also a possibility. Also a leaking injector.

 

Thanks for the replys guys! I'll get the injectors tested first. Is there a way to tell if the regulator or the fuel pump valve is bad? Or do i change it and see what happens?

 

Might as well change the pump valve and the regulator to rule them out....better to spend a moderate amount than a tow home failure?

 

Maybe read this, I posted it today.....


Sorry for the delay

I removed the fuel pressure regulator, piped to compressor and turned air regulator up until the fuel regulator started to blow off at 3.5 bar.
So all looked good....or so I thought!!
I placed the regular in a basin of water at 2.5 to 3 bar. The air from the compressor was escaping through the vacuum port.
Therefore, when the regulator is working on the fuel rail, some of the excess fuel is entering the engine via the vacuum hose!
Anyone out there selling a fuel pressure reg!!

Thanks for the help again,
Dave

 

Thats a common failure. You cannot get a weber reg anymore but MSD sell one.dont buy any off ebay they are not very good.

 

Sorry guys i forgot to update on what happened... I replaced the fuel pressure regulator with a weber alpha adjustable, set up the fuel pressure and all is fine again now it takes a couple of days of sitting without using the car for the pressure to drop back to zero. Many thanks to all for your help!