Having converted a V12 E to fuel injection 12 years ago we've been approached by the new owner on engine running problems...The system is a very early Jaguar system 1975/6 single fuel pressure regulator. Flat head, not HE. Opus.

The main one is cold start-up on 12 then it looses cylinders until it sounds like its running on 6 or less, then stalls out and doesn't want to even attempt to restart.

Both front 3 cylinders seem to die. Would this be a power amp fault?

It's also over fueling - fitted an extra air valve, tested fuel pressure and spark gap, plugs are brown in the middle soot black around the edge.

I spend a few hours checking things and it looks like it's been messed around, I spotted an odd injector, ecu's have been swapped so put the original back in.

I've gone back to basics but having ignition breakdowns doesn't help, I'm due to pull the fuel rail to replace the odd injector with the correct type and I'll check the distributor reed switches etc once down that route.

ANY suggestions on it's behavior would be most welcome

 

The power resistor of the Opus box may not be earthing well via the 2 brass screws, havoc follows shortly after start up usually.

The injection amps are robust, so I would not be real worried about it at the moment. I have never had a dud one, or a bad ECU on these D-Jetronic systems.

The reed switch board is a PAIN, especially if it is the 3 wire board. The newer (well years ago) 4 wire board, with hall effect switching is super reliable. Dont forget to change the rotor, the 3 wire and 4 wire rotors have a different magnet in the heel.

When you are saying "single FPR", I am assuming it has a HE square tube fuel rail, as versus the PreHE dual round tube rail monstrosity??.

Overfueling may be fuel pressure too high, I know you checked it, but you also say someone has messed with it. I run our PreHE at 29psi, both rails, and its fine. If I up that psi by 1 it gets hissy.

The MAF sensor may also be ruptured, this will cause all sorts of fueling issues.

 

Thanks for your thoughts Grant, appreciated.

You are right about the later fuel rail, my Dad decided on using the HE square, it's a lot neater! We may just fit a new (top quality) adjustable fuel reg. I think I've one kicking around.

Going over to see it later this week and I'll post back developments.