25 Oct 2008, 12:41
Shimming the fuel pressure regulator:
Just done some tests on my car wrt adding shims and increasing the fuel pressure:
OEM setting for fuel pressure according to workshop manual is 5.1 to 5.3 bar (tolerance is 4.9 to 5.5 bar)
My car was 4.7 bar (and I have had this result from a few oem Delorean fuel pressures as part of fuel testings). Look at previous post K-Jetronic Page 45 primary fuel pressure regulator second design on how to remove the primary fuel pressure components.
I bought a few shims of varying thickness and got these results (note, keep the original shim that is already present in the fuel distributor in place)
Main Test 1:
Adding an extra shim of 1mm increased my fuel pressure from 4.7 to 5.3 bar (setting figure)
Main Test 2:
Adding extra shim(s) to increase by 0.45mm increased my fuel pressure to 5.6 bar (just outside setting tolerance)
I did some other tests adding smaller shims to plot a graph of the relationship of adding shim thickness versus fuel pressure. Shimming a spring tension isn't always a linear result but as a rule of thumb I work this out as approximately:
For extra 0.06 bar required, add 0.1mm shim thickness.
I purchased my shims from Ken Ken Mills injection (KMI) - +44(0)20 7385 7138 - he can supply any Fuel / air system parts (Not ignition) via post, highly recommended for all rebuilds too. Approx £1.50 per shim (although I will measure the internal and external diameters to see if a special washer size can be used an an equivalent)
On 1 car with the UK performance exhaust (the one from Nottingham) using, the primary pressure was set to 5.3 bar (workshop setting pressure) and all other adjustments eg CO settings including lambda were set to stock. There are no fuelling issues with the car at high revs.
I hope this information helps others set the cars up.
NOTE Disclaimer: Any fuel pressure tests/ settings done are to your own risk. This post was to supply information on what I have done on my own (and one other) car. Do not add extra shims without performing correct fuel pressure diagnostics before and after. Always have a working fire extinguisher to hand and take appropriate PPE safety. (Sorry about this bit.)
Regards,
NickT.
Just done some tests on my car wrt adding shims and increasing the fuel pressure:
OEM setting for fuel pressure according to workshop manual is 5.1 to 5.3 bar (tolerance is 4.9 to 5.5 bar)
My car was 4.7 bar (and I have had this result from a few oem Delorean fuel pressures as part of fuel testings). Look at previous post K-Jetronic Page 45 primary fuel pressure regulator second design on how to remove the primary fuel pressure components.
I bought a few shims of varying thickness and got these results (note, keep the original shim that is already present in the fuel distributor in place)
Main Test 1:
Adding an extra shim of 1mm increased my fuel pressure from 4.7 to 5.3 bar (setting figure)
Main Test 2:
Adding extra shim(s) to increase by 0.45mm increased my fuel pressure to 5.6 bar (just outside setting tolerance)
I did some other tests adding smaller shims to plot a graph of the relationship of adding shim thickness versus fuel pressure. Shimming a spring tension isn't always a linear result but as a rule of thumb I work this out as approximately:
For extra 0.06 bar required, add 0.1mm shim thickness.
I purchased my shims from Ken Ken Mills injection (KMI) - +44(0)20 7385 7138 - he can supply any Fuel / air system parts (Not ignition) via post, highly recommended for all rebuilds too. Approx £1.50 per shim (although I will measure the internal and external diameters to see if a special washer size can be used an an equivalent)
On 1 car with the UK performance exhaust (the one from Nottingham) using, the primary pressure was set to 5.3 bar (workshop setting pressure) and all other adjustments eg CO settings including lambda were set to stock. There are no fuelling issues with the car at high revs.
I hope this information helps others set the cars up.
NOTE Disclaimer: Any fuel pressure tests/ settings done are to your own risk. This post was to supply information on what I have done on my own (and one other) car. Do not add extra shims without performing correct fuel pressure diagnostics before and after. Always have a working fire extinguisher to hand and take appropriate PPE safety. (Sorry about this bit.)
Regards,
NickT.
TT