Am having issues with AFPRs losing all fuel pressure when the engine is turned off - resulting in excessive cranking to build up enough pressure to restart engine.
This problem only occurred after I installed an FSE Rising rate regulator - this regulator kept erratic pressure. Set @ 4.0 bar originally, it would fluctuate between 2.5 bar and ~5.2 bar!
I had another spare AFPR (Cheap eBay one) - installed this one, set it @ 4.0 bar and it has kept 4.0 bar since!... except when the engine is off, then it holds nothing :(
I checked everything else that I disturbed when installing the regulator, no leaks and no smell of petrol.
I've diagnosed it as both AFPRs being the culprit by clamping the return line from the regulator (engine off) and full pressure was retained for half an hour (until I took the clamp off).
I suppose my question is:
Is this Normal??? I would have thought that when there is no vacuum, the regulator would close the return line to retain pressure for the next time you need to start the engine?
On a car where the fuel pump is on a switched live, it's not necessarily an issue as you could switch the ignition on and wait a second or two for pressure to build up in the rail before cranking but my pump is on a switched earth which is only active when cranking!!!
Do I buy another (maybe more expensive?) AFPR and hope that this will hold pressure?
Or do I go back to standard?
I liked how the car drove with the rising rate regulator but, with such erratic pressure, it's not worth the risk - so that is out of the question.
But I also think the car drove better with 4.0 bar pressure than the standard 3.5.
I have a lot of breathing mods on the car (simota, asc delete, BBTB, M50 inlet, US S52 cams) but standard injectors and map.
I'm thinking of biting the bullet and buying the Dinin modified Bosch FPR for simplicity but I can't find it to buy without a useless US software package for $350!
Maybe 24lb injectors?
Any recommended AFPRs?
Any help is massively appreciated