Rover V8 / 14CUX

[100SRV]

Hello,
very satisfied with the 14CUX EFi on my Rover V8 save for a hot restart problem - this takes three "key on" events (i.e. HP pump runs three times) to allow a clean start otherwise the behaviour is like fuel has vapourised in the fuel rail - could the pressure regulator be the culprit in allowing pressure drop when hot or is this normal behaviour?

The pressure regulator has not been changed since I installed the system - should I replace this as a matter of course?

I will also check the values from the fuel and coolant temperature sensors to ensure they are within specifications.

cheers
100SRV

[pugwash4x4]

what vehicle is it in?

sounds a lot like vapour lock- does the fuel lines run well away from the exhaust manifolds?

[100SRV]

pugwash4x4 said:

what vehicle is it in?
100" bowler

sounds a lot like vapour lock- does the fuel lines run well away from the exhaust manifolds?

I suspected that too.

The fuel lines are a reasonable distance >150mm from the exhaust manifold but I suppose it would be worth insulating the gravity feed from the swirl pot to the HP pump and maybe the HP line to the rail too.

The system has an LP lift pump feeding a swirl pot that feeds the HP pump...return rail into top of the 'pot and top of the pot returns to tank.

[Steve_D]

You could try a non return valve in the pot to HP pump line.
It could be the fuel is draining back to the pot and the prime cycle is not quite long enough to resolve this.

Steve

[100SRV]

Steve_D said:

You could try a non return valve in the pot to HP pump line.
It could be the fuel is draining back to the pot and the prime cycle is not quite long enough to resolve this.

Steve

Hi,
good point but..the swirl pot is higher than the HP pump which led me to wonder whether the fuel was syphoning out of the HP line from the rail, back downhill through the HP filter...but HP pumps have a non-return valve in them, don't they?

I have wondered about a "hot start" button to run the HP pump when cranking from hot...

[Steve_D]

Can you edit the prime cycle time in the ECU.

Steve

[100SRV]

Steve_D said:

Can you edit the prime cycle time in the ECU.

Steve

I understand that Tornado Systems can modify various parameters in the EPROM but at a cost...a lot more than a push button and some wire would!

Incidentally my ECU is marked "Police", what changes would this have over a standard ECU of this era (1993 IIRC)? The EPROM is soldered in.

[blitzracing]

You cant reprogram the chip in situ' so its likely to be an origional Range Rover map of some sort if its soldered in.

[100SRV]

Hi Blitz,
I thought that more likely. For a 3.9 V8 with the following changes:
Cloyes timing gear
.020" rebore
Cold air box
2.5" free-flow exhaust system (EFi manifolds and Y piece
Standard heads and plenum / manifold
can you suggest any areas for improvement?


I suspect that I am best off leaving the EFi alone (and solving the worn out synchromesh of the LT77) then looking at the ignition system - is EDIS worth the effort?

I like your work on the V8 and EFi - very thorough.,

100SRV

[Steve_D]

EDIS and MegaSquirt.

Steve

[blitzracing]

Your mods are not that radical to throw the fuel map out, but some early Range Rover maps run horribly lean anyway, so it would be worth a quick rolling road session to see if there is an issue or not first. I had a bespoke 3.9 map done for my Ginetta to overcome this that I can replicate if needs be. If it is lean under high load you can also boost the fuel pressure a couple of PSI with a variable pressure regulator, and then readjust the CO trim value for the lower running range, but its a crude way of going about. I can adjust the mixture at will on mine with a bit of electronics I have made that goes inline with the AFM. Basically if its lean at any point you can raise the AFM voltage to fool the ECU into putting in more fuel, so it does give you some trim. As for upgraded Im happy that the 14CUX works very well in non catalysts engines (with a good base map), but its crap if you run a long duration cam on a catalyst fuel map, the two just dont mix!. In this case I think the Megasquirt has a lot going for it. The distributor is the weakest point in your setup, and if I had around £400 spare I would upgrade the entire ignition system with the Trigger wheels "megajolt" (son of megasquirt) set up with mappable ignition and wasted spark coil packs.

[100SRV]

I have found a possible cause of the need to re-prime the fuel system after being left when hot - there is a fuel leak around the outlet of the HP fuel pump. This would cause the HP system to lose it's prime.

The pump is a Bosch inline pump with barbed fittings, I used screw and nut type hose clamps rather than the worm drive type and all the clamps are snugly tight. Is it possible that the pump itself is leaking?

I am off now to remove the outer and inner wing so I can see the pump better and hopefully find the leak source.

100SRV

ETA:
replaced HP hose from pump to filter - it wasn't as tight a fit as I'd like on the outlet barb; the replacement seems to be much better.

Thank you for the suggestions!

100SRV

Edited by 100SRV on Thursday 14th July 19:06