ZX Diesel - Fuel Pump Failure?

[RobinMasters]

I'm sure this will have been done to death before, but I've tried using the search function only to be told that the words 'fuel' 'zx', 'pump' and 'diesel' were ignored as they are too common.

Noticed a leak yesterday. Diesel, seemed to be coming out of the top of the fuel pump. Today, the car cut out (when my wife was driving-isn't that always the way?), then later on wouldn't start. Well it will start, but only runs for a second or so before dying.

I've read a few things that say a leak could well be due to failed o-rings, which sound straightforward to change. Is the failing to start likely to be indicative of a bigger problem, or should changing the seals do the trick?

[citronut]

i suspect this is a non turbo with the Lucas pump,
if so you used to be able to buy a repair kit which contained 2 O rings the complete pump lid and a gasket, i think it cost around £14 quid, the reason for replaceing the lid is once the Orings fail the throtle spindle statrs to wears the lid away,

this is a very simple part to fit,

i was also told another cause of leaky fuel pumps, is the one way valve/s in the banjo union/s at the fuel feed and returns becomes stuck so cause's presure to push fuel out were its not ment to go,

regards malcolm

[RobinMasters]

Thanks, Malcolm.

I should have mentioned that; yes it is non-turbo. I think it's a Lucas pump-based on the diagrams in the BoL (mine's got both cables at the front).

Used to be available? Where could you get these?

[CitroJim]

I've done a few reseal jobs on Lucas pumps in the past but not recently I must confess and I've never had to replace a lid because of wear... It's not difficult but you must work in total cleanliness as the pump will be wide open and any debris that might fall in can be disastrous...

Used to be available? Where could you get these?

You might give this mob a try: Merlin Diesel.

They'll need the full part number of the pump. It can be found on the blue plate that wraps around the underside of the pump. You'll need a mirror to read it and if memory serves the number begins 'DPC...'

[RobinMasters]

Thanks Jim

Merlin referred me to their local distributor, Thomas Autos, in Ashford. 20 minutes walk from my house-perfect!

Fitted the new o-rings, and cover, and now it won't start at all. I'm certain it went back together the way it came apart, and it's not leaking, but it doesn't even catch now.

Anyone have any suggestions as to what to look for next?

[CitroJim]

Robin, I expect what has happened is the cold start cam is the wrong side of or out of position with respect to the throttle plate and the pump in now in permanent emergency stop mode...

Slip the lid off and check the cam is correctly positioned and that the emergency stop lever is correctly placed... Often the cam ends up 180 degrees out...

That'll be all it is...

[RobinMasters]

Jim,

I wondered if it might be that as I reassembled it, as it did sort pf spring out when I took it apart.

I've just been back and had a look at it, and it doesn't seem possible to fit it the wrong way-the cam fouls on the side of the pump if it's on the wrong way round (assuming I'm not looking at the wrong part-the cold start is the shaft on the left?).

[RobinMasters]

i was also told another cause of leaky fuel pumps, is the one way valve/s in the banjo union/s at the fuel feed and returns becomes stuck so cause's presure to push fuel out were its not ment to go,

regards malcolm

It's not that either; the pump is filing up, and I've had the return banjo off and the valve moves freely. I'm stumped!

[RobinMasters]

Does anyone have any suggestions? not fixing this is going to seriously affect Christmas!

[CitroJim]

Robin, this diagram may help Lucas Pump Exploded Diagram

And this one, although not strictly accurate for the pump you have, shows better it's internal layout with regard to the throttle plate and metering valve (item 7) and how the throttle plate and spring operates this.

I think the next area to look at is the throttle shaft; it's easy to reassemble with this 180 degrees out and again the overall effect is to put the pump into permanent emergency stop mode.

The diagrams show the correct orientation. You can confirm it by ensuring movement at the throttle plate (item 1) transfers movement to the metering valve.

I've known the metering valve get stuck when moved beyond its normal range of travel but this normally only happens on badly contaminated pumps.

Ensure the metering valve does move and that there is no impediment to it doing so when reassembled...

[RobinMasters]

Thanks for all the help Jim. Very much appreciated.

Unfortunately, it didn't fix it!

However, I didn't know this:

Bleeding a Lucas DPC on the primer bulb MUST be carried out with the ignition on to open the stop solenoid.

Again, your advice Jim, on a thread about a stop solenoid problem. Thanks to you Sir, Christmas is back on!

[CitroJim]

Ahh that's excellent Robin So are you all mobile again now?