DD6 Coupe Fuel pump

[jthorne]

Hi,

I have a 1977 DD6 Coupe. My fuel pump was getting noisy so I've replaced the pump with an aftermarket pump. No I can hear the pump priming but the car will not start.

Please help!

Thanks

Jon

[mike020150]

Your '77 coupe should be fuel injected (the very first few cars had carbs). Hence, the first question which comes to mind about an aftermarket pump is whether it is suitable for FI or intended to replace carbs. Why not refit the old pump, see if the car starts and if so, the problem lies with the new pump or its hose connections (it won't work well piped back to front although it will make a noise!)? If the car doesn't start with the old pump, follow the old engineering adage and sort one problem at a time. Good luck. Mike.

[jthorne]

Thanks for this. I struggled to find a new Lucas 7fp so had to go down the aftermarket route. The company said it was suitable. It has a 3 bar pressure and 170lt flow rate- is this correct? Car worked fine before but the pump was noisy and i suspected lean running hence the change.

[mike020150]

I don't know the flow rate for the standard pump but the two fuel pressure regulators limit the fuel pressure to between 28.5psi and 31.5psi so it appears your new pump should have sufficient capacity to allow the engine to start even if it couldn't supply enough fuel for flat out running. Have you checked the fuel pressure in the rail by fitting a gauge in place of the nearside cold start injector? If the pressure falls within the limits above, the starting problem is not down to the new pump. Mike.

[almcl]

3 bar (~43 psi) is not adequate. A new FI pump should be capable of delivering almost 7 bar (100 psi) into a dead head.

170 litres in how much time? In a minute, incredible. In an hour, barely adequate.

Replacement pumps are available in UK from the independants from £80 on, or up to a genuine Jaguar one at a whopping £226.

Have you tried refitting the old pump? Did the car then start?

[jthorne]

All sorted New fuel pump sorted it.

However I still think she runs a little lean when hot and at higher revs- you can hear her hesitating ever so slightly.

The idle is set to c1000rpm not in gear and c750 rpm in gear. Both when hot.

Any other suggestions?

Also the smaller fan only comes on when the heater is on and is constant. Is this normal?

Cheers

Jon

[almcl]

The small (electric) fan should come on when the air con compressor engages.

But it should also come on if the coolant temperature exceeds the specified temp (don't have this to hand just at the moment.) When this happens, the fan can run for some time after shutdown.

Have you replaced the fuel filter?

[jthorne]

I'll replace the fuel filter tomorrow and report back. Could you tell me where the temperature sensor is for the fan? It doesn't come on on it's own- just with the A/C

Thanks

Jon

[almcl]

On the inlet pipe to the water pump.

[jthorne]

Thanks for this. do you have a part number or is it just generic? If I replace it is all the coolant going to flood out?

[almcl]

EAC 2510 on the SIII V12, should be the same on your SII.

Available from Jaguar Classic Parts for £15.98

Some coolant will spill but if you're reasonably quick, not too much.

[jthorne]

As luck would have it I have one of these in stock! However looking at my car it seems only to have the one terminal going into it where the part has two. Also the part on my car does not seem to have the possibility for using a spanner as it's round! Any suggestions?

Cheers

Jon