Starving for fuel .

[dubman1959]

Hi There,
Ran my 52 minor out of gas earlier this week , ( I now know the gauge is faulty ) 4 days later it started cutting out while driving along, I think i might have sucked some crap up off the bottom of the tank, It has no filter on the fuel line, But it will very soon . thinking bit of crap in carb??? any ideas please,
Cheers Steve.

[Boomlander]

Check that the petrol pump is not clogged and is producing a steady constant delivery, if all is well move on to the carb which will require a stripdown and clean out.
The pump has its own filter so you should not need an inline unit between the pump and the carb, these can cause fuel vaporisation problems.

[philthehill]

The filter is located under the main body of the pump and is item No: 54 in the attached link.

http://www.moss-europe.co.uk/shop-by-mo ... minor.html

Undo/remove item No: 56 in the link above for access to the filter.

[dubman1959]

Check that the petrol pump is not clogged and is producing a steady constant delivery, if all is well move on to the carb which will require a stripdown and clean out.
The pump has its own filter so you should not need an inline unit between the pump and the carb, these can cause fuel vaporisation problems.

Thanks for that Boomerland,

[dubman1959]

The filter is located under the main body of the pump and is item No: 54 in the attached link.

http://www.moss-europe.co.uk/shop-by-mo ... minor.html

Undo/remove item No: 56 in the link above for access to the filter.

Thanks Philthehill, i had no idea there was a filter in there. we replaced the contact points in there a few hundred miles ago, It was a single contact set and the replacement was the twin contacts.

[philthehill]

SU electric fuel pumps can be fitted with either single or dual contacts - the idea of dual contacts was to cut down on the arcing and contamination of the points so that the fuel pump would operate for longer though I do not remember them lasting any longer.

[myoldjalopy]

My SU pump has had a capacitor fitted to prolong the life of the points..........whether it does so or not, I don't know. The coil has one also.
Any thoughts, anyone?

[oliver90owner]

Any thoughts, anyone?

A waste of time and materials, I would guess. The contacts are basically 12V low current with only the likelihood of a relatively small back emf from the tiny solenoid type operation.

Not at all like the coil, which has a much, much larger stored energy content and is operating at as much as 80 times a second compared with the pump at an average of seconds per tick at most normal driving loads.

Ignition points last only a very short time (minutes or sconds), if the capacitor fails, before the system totally stops working; pumps (should) last years or decades without a capacitor.

What value capacitor are you using? Probably not a correct value for the application, anyway. There is no 15 000 volts involved with a fuel pump. Go with the equipment designer's ideas. He/she would have fitted one if it was really necessary!

RAB

[philthehill]

I had capacitors fitted to the coil and fuel pump to cut down the interference to mine and others radios.
I cannot see the need for capacitors in any other capacity.

[myoldjalopy]

Hmmmmm...well, seems they are of no value in my car then. Oliver90 - it is just the same type condensor as fitted to the points.
They were fitted years ago by a local mechanic (now retired). He must have thought they were of some purpose but, then again, he was always better with mechanical stuff than electrics

[StillGotMy1stCar]

A capacitor across the supply to the pump doesn’t do anything for contact life.
The capacitor needs to be across the contacts to stop arcing.
The pump on my pickup originally had evidence of something being fitted across the points, it had broken off and just left the leads behind. I fitted a .1uf disc ceramic capacitor as a temporary replacement and it does stop the contacts arcing so it got left fitted, should really be a polyester film capacitor, all under the end cap so not seen.
Regards John.

[dubman1959]

21231722_1628104767263013_1841280079108377282_n.jpg (89.8 KiB) Viewed 2543 times

Thanks Guys for all you input, Cleaned out the pump filter and we checked over the points, Etc. Running sweet as now, We cleaned up the earth contact as well, So not a hundred percent exactly what the problem was, but put 30 miles on it today , Cheers Steve

[Boomlander]

Happy to help!

[dubman1959]

Happy to help!

Cheers

[biomed32uk]

If it's a tiny black device inside the end cap across the contacts then it's a Transorb - a Transient Voltage Supression (TVS) Diode.

In simple terms they clamp the voltage once it exceeds its specified value, the back EMF from any DC coil can be quite considerable, flick the contacts on a pump without one with your fingers and you stand the chance of getting a good jolt.

It is the high voltage spike when the contacts open that cause the arc, and the burning of contacts. Limit the voltage limits the arc and burning of the contacts.

My SU pump rebuild kit came with one to be fitted in the kit, along with dual contacts. That was three years ago and I have not touched the pump since, merrily ticks away doing its thing.