Porsche Enthusiasts Club Forum

Hi team,

So, my slow rev issue still persiits.

My fuel pressure checks out as per Clarks when stationary in various conditions.

I have been told to fully test the fuel system this should be done under load and this maybe my problem. Does this mean driving the car through the gears on the road with gauge stuck to bonnet/windscreen? Or is there another/safer way!

Thanks in advance,

M

The fuel pressure at the rail only has 2 modes - at idle (high vacuum) the FPR reduces the fuel rail pressure approx 1/2 bar depending on which engine it is so as not to over fuel at idle. The other mode is the full pressure allowed by the FPR for higher engine speeds probably 2.5 bar on your engine.

Basically, the fuel pump provides fuel pressure in excess of anything that will be required at the rail (injectors) but it is not a stable pressure as the pump pulses. The FPR and rail damper work together to deliver the required fuel pressure and to smooth out the pulse's.

If your tests have been good according to Clarkes Garage then your FPR and Damper are ok. So, your problem lies with either the fuel pump or injectors. As the fuel pump output does not change with engine speed, it's a constant delivery, you can probably rule this out. That leaves the injectors, or you have a fuel leak. This is all assuming that the issue is actually fuel related.

If you want to test the fuel pressure under load then probably best to book a rolling road session - would be much safer.

Thanks Prophead...very helpful.

So, issue probably lies with the injectors. Will have a look to see how to test these fully. I have pulled leads off them one by one and the engine noise changes but guess I will have to delv deeper.

I can now get the revs up to 5500 rpm quite quickly when in neutral. However, I can not do this whilst driving, rev needle is about 3 times slower. The car is better than it was (strangely alot better when new instrument battery bulb charge light fitted ) but still doesn't pull properly. Everything else is all good and dandy....just can't fathom this out......

Cheers,

M