SU Double Fuel Pump Set Up - XJ12 S1

[richardpierce]

Could anyone assist me with the set up of SU double fuel pumps

I've installed new points & resistors but they are only clicking occasionally

Any assistance always appreciated

Regards

Richard

[oldtimer]

Hi Richard,
I reckon I can help a bit here. Regrettably the SU pump is frequently maligned. This pump in all it's forms have given several generations of excellent service and employed in many areas well beyond the motor car industry.

Failure to service pumps or at least replace the contacts at intervals is a guarantee of failure.
Often incorrect fitment of replacement contacts continues to cause users problems and give the pump a bad name. For Guaranteed performance, overhaul by Burlem Fuel Systems is the better solution.

Just a few months ago my Series 2 XJ12 developed a fuel leak at the T piece between the nearside carburettors. I ended up overhauling the total fuel system. I replaced all the boot hose pipes with methanol proof hoses and steel braided hoses at the front. Tank and boot filters the whole lot. All the hoses were original and forty years old. Those in the boot had set like concrete.

Now the pumps.
I just happen to have an SU Butec Service Manual in my hand - not everybody has one of these.

Where do we start? I would suggest you remove the pumps because flow tests need to be carried out after servicing. The double pump you have is an extra high capacity pump, probably a AUF400/AZX1400 with a delivery capacity of up to 136litres / hour (30 Gallons per hour)
That's enough to make your eyes water!

Many years ago I just managed to grab a hand full of these twin contact sets which have been sitting waiting all this time. I installed the new points in accordance with the manual and nothing worked. When I checked for continuity across the points I found it was open circuit. Cleaning the contacts with them removed was a time consuming job. The easy solution is to use a fine wet and dry paper and promptly remove the tungsten coating and render the points useless. So its a case of using a cleaning fluid (meths) and keep checking by holding the contacts together until continuity is restored.

There are two styles of contacts, you need the later type with a stop finger which should be adjusted (bent ) to give a clearance of 0.090+/- 0.005 thou.

Richard ,I'm not sure of your Knowledge level of this pump, are you aware of the method of screwing on the new toggle assembly and setting so that it toggles over in the correct manner?

Just a bit about testing.
Please do this in the open away from kids, animals ,the wife, anything. these things do not mix with petrol and 12v batteries.

Please discard any notion of pressure we are checking FLOW ie 30 Gallons and hour or part there of.
The pump needs to be 18inches off the ground. Max suction or lift (garden chair) A receiving container needs to be raised to 48 inches ( garden steps) and a twelve volt battery and a SWITCH. Ensure the battery is several yards away from the rig up. I'll leave you to work out container sizes and time. No you do not need a thirty gallon tank of petrol. I used 6pint plastic milk containers. Go to B&Q for a few yards of plastic tube to link it all together.

You will be amazed at the rate that the petrol zips up the to the top tank.

Richard, I hope that's enough to start off

Oldtimer

PS do you know how to PM me