Hi. So, this is an interesting one. Been trying to get max performance out of the car. Have done lots to it problem solving. Changed both pumps, all coils and swapping of coils, maf cleaned then repalced. FPR checked and seems ok.

So my hunt continued. Went out without fuel cap on to see what would happen. Better but still not getting full power and it would still not run through the revs easily without stuttering and not feeling at all happy.

So, to check fuel pumps. Pulled pump 1 relay and car would stall after 3 second- repeatedly. Put back in and pulled pump 2. Car starts fine.

Jumped pump 2 after pulling pump 1 relay, car then starts. So. pumps are both fine. Swapped relays about and relays are fine.

Whats the signal that switches on pump 2.

And it is said that if you pull pump 1, pump 2 will eventually work as primary. This doesnt seem to be happening for me, after 10 starts.

All else checks out. O2 - lowers hover around 0.02 to 0.025. Uppers are ranging between 0.2 or 0.3 up to 0.9v

Short term trims are very very low, dont pop above 2%

Runs so smooth at low revs and not too much load, if you want to get on in more of a hurry then the problems start. If your on a 'private road' and want to get high speed you can get there if you just take it easy. So its when the secondary is asked to chip in on the workload that all this occurs.

My next step is to test continuity from ecu to the relay as all else, fuses, relays are fine.

About 10 years ago my pump 1 died and 1 never had it run on pump 2. About 3 months ago i replaced both 1 and 2 and they seem to work fine. As does the wiring from relay to pump..

Thoughts?

 

Did you change the fuel filter?

I would run wires from the fuel pump 2 contact on the relay (pump side) to the cabin and watch what it is doing on a multimeter. It should come on at WOT.
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Has your car got a kick down switch at the throttle pedal stop? Some do - does kickdown work?

 

I just 'JUMP' the relays with a wire to individually run each pump directly.
Fuel filter change every 30K miles is recommended.

 

Filter isnt that old, probably about 10K. I have it I will change it, I dont think it is that though but you will all want me to rule it out so I will.

But, isnt the ecu supposed to switch to the secondary pump when it realises the primary isnt working? This is the basis that I have for the secondary not being utilized.

Does have kick down but I never want to go to the switch while driving as it stutters and misses so intensely under full throttle.

Pumps have been 'jumped' to check they are working

 

Test it:-

I would run wires from the fuel pump 2 contact on the relay (pump side) to the cabin and watch what it is doing on a multimeter. It should come on at WOT.

 

I am new to the Jag V8, but is there some method of checking the VVT is functional?

 

No VVT on the XKR.

 

ok, back on this one... its been a while but have had starter (turned out to be earth leads..) oil cooler line (replaced with braided all round, that wont happen again) and cluster (all seems fine now)
But, after replacing sparkers, coil packs, fuel filter it still wont get past around 3k. Purge valve replaced too.

Fuel both pumps had been replaced with
https://www.berkshirejagcomponents.c...l-pump-c2n3866

Fuel pressure seems to be inline with whats expected, around 40 at idle, take the vacuum off and it rises to around 45.

I know the second fuel pump works as i can jump it...

I feel i may have to go out for a drive with the fuel pressure gauge on it to see whats going on. It can only be, correct me if im wrong, fuel pumps arent that good or the fuel pressure regulator isnt functioning as it should.

I only have a cheap gauge with short tube lengths.

Did a smoke test and found no leaks.

Any further suggestions? It really is holding back on power..