Please help - 6 Cyl Series 3 Fuel Pump

Didn't some of the old fuel pumps work that way? Once they got up to pressure the ticking slowed down and stopped. If thats the case it sounds like the fuel pump isn't getting the line up to pressure for whatever reason.

Eddie

I'm not familiar with a LR one (my series 2 and 3 were both driven off the block) but on the mgb a rapid ticking meant a blockage on the fuel feed to the pump, steady ticking means no fuel.

AJH

Rotten pick up pipe.... try disconnecting it and blowing from the pump input ... if you can blow bubbles in the tank then it's most likely fine.

If there is fuel at the input then there could be something wrong with the pump it's self.

Is the filter super crudded up? would have to be real bad though.

Lee D

Air leak at pump inlet - empty tank or leaking (broken) pipe from tank to pump?

noise coming

almost sounds

IIRC it is a standard SU fuel pump so you may have a stuck one way valve (there are two in opposite senses) or maybe a punctured diaphragm. All bits are still available from Burlen (

) who now make all the bits and alsorefurbish SU pumps and carbs. AWEM

On or around Thu, 13 Jul 2006 22:48:09 +0100, "Andrew Mawson" enlightened us thusly:

rapid ticking is pumping air. normal sequence if the feed pipe from the tank is empty goes a bit like this:

tickatickatickatickatickatickatickaticka (pumping air/vapour and sucking fuel up line)

ticka tick atick atick atick atick atick atick atick atick (pumping fuel to fill the float chamber)

atick atick.........atick...................atick................. .................................atick

(float valve shut and line up to pressure)

coo, that's handy.

That's the fuel pump telling you that tank is empty! It will always click/buzz for a couple of seconds when the key is turned, but should stop.

beamendsltd uttered summat worrerz funny about:

Still got that pump on the shelf I bought probably 8 months ago.... do you do the pipes that go into them, or at least some way to connect a fuel line?... theres nowt only the thread showing.

Lee D

Certainly do...

572535 Fuel Pipe Connector - External Fuel Pump (PRC3901) - Defender 90/Range Rover Classic £6.46 inc VAT Your diff bits are now on the shelf if you need them.

Richard

Thanks everyone - I've got lots of things to try out then.... I'll report back when I have a chance to look at it further.

Mike.

I think this pump is the same as that on the Rover 100 (basically the same straight 6 engine), which I've had some experience of. The way it works is that there is a diaphragm which is pulled in one direction by a solenoid and returns with spring pressure. The solenoid is activated by a contact which closes when the diaphragm has been returned by the spring to its "rest" position.

The sequence is thus:

1) The solenoid operates and the diapragm pulls petrol in from the tank to the pump chamber 2) The return spring returns the diaphragm and pushes the petrol from the pump chamber up the feed to the carb 3) When the diaphragm returns all the way, the contact closes and the cycle starts again. 4) When the carb float chamber is full, the backpressure in the feed from the pump stops the spring returning the diaphragm to its rest position, so the contacts then don't close until the carb float valve allows more petrol in. When they do, its back to 1 again.

either there is no petrol coming up the feed to the pump or if there's nothing to stop the petrol continuing to flow.

Unless you can see petrol emerging from where it shouldn't (leak) or you have a **very** flooded engine (stuck float valve or sunk float in the carb), then the problem is either an empty tank or a leak in the feed line which is bleeding air into the line.

A common fault with this pump, btw, (although not the problem in this case), is that either the contacts fuse or (more likely) the suppression capacitor (aka condensor) across the contacts fails short circuit. In either case, the pump will click once when the ignition is turned on and then no more. If this is the case, try disconnecting the capacitor - it's not a long term solution since the contacts will arc a bit, but it will certainly get you home.

Further thoughts to my last..

Although I haven't met them, the following faults would also cause the pump to operate continuously without any petrol arriving at the carb:

Feed pipe from tank to pump blocked Inlet valve in pump stuck open or leaking Inlet valve in pump stuck shut Outlet valve in pump stuck open or leaking Pump diaphragm perforated and leaking Any other leak in the pump chamber

I suggest checking out all the possible causes outside the pump before dismantling it or replacing it.

Regards, Arthur C

Further suggestion - blocked screen on the pickup pipe in the tank. If the pump is clicking continuously the problem is most likely (but this is not certain) not in the pump - the common problems with this pump are electrical not the actual pump, so since the electrical bit seems to be working the first place to look is the plumbing to and from the pump. JD