Fuel Pump Resistor

[Mr Jenks]

In your diagram above just connect the suppressor (condensor/capacitor, call it what you like) lead to the +12v pump supply and the body to a good clean earth.
When a motor turns it produces a back emf on the supply which can be seen with a scope, not normally on a meter. The suppressor does what it says and supresses this ripple effect to reduce electronic noise in the wiring.

[SILICONEKID343HP]

I thought if you put live to ground it will blow the relay or fuse..

[Mr Jenks]

SILICONEKID343HP said:

I thought if you put live to ground it will blow the relay or fuse..

Picture cut from the wiring diagram in manual. Supressor fitted across fuel pump terminals, simple as that

Edited by Mr Jenks on Monday 22 July 19:56

[Mr Jenks]

I just had a look at the link to the capacitor that you got, thats a distributor one, it wont last long fitted to the fuel pump.
A typical ignition condensor has a rating of 0.25 - 1.25uF. A noise suppressor for a pump will need to be 10uF or higher, it is matched to the inductance of the motor that it is connected across.

[Sardonicus]

Strange the old jap ones I have are 22 uf .

[SILICONEKID343HP]

Can you do me a simple drawing

[Mr Jenks]

Sardonicus said:

Strange the old jap ones I have are 22 uf .

I know the japs like to do things a bit different but that does seem a bit excessive. A closer inspection may reveal that it .22uF. Even the good old Mini, Metro, MGB lucas dizzies only specify .18 - .25uF

[Mr Jenks]

SILICONEKID343HP said:

Can you do me a simple drawing

Sorry I dont do drawing very well, as you can see

[blitzracing]

Mr Jenks said:

Sardonicus said:

Strange the old jap ones I have are 22 uf .

I know the japs like to do things a bit different but that does seem a bit excessive. A closer inspection may reveal that it .22uF. Even the good old Mini, Metro, MGB lucas dizzies only specify .18 - .25uF

The capacitors on the points form a tuned circuit that controls the rate of discharge of the coil, affecting the peak secondary voltage and duration, its not just arc suppression like it is on the fuel pump.

[SILICONEKID343HP]

Mr Jenks said:

Sorry I dont do drawing very well, as you can see

Thanks if the suppressor went wrong would it put live to ground and blow something..

[Sardonicus]

SILICONEKID343HP said:

Thanks if the suppressor went wrong would it put live to ground and blow something..

No in all my years in the motor trade I have never witnessed a Cap short a circuit

[Mr Jenks]

If, big if, it should go faulty and short out, the only thing I would expect to see is that the cap itself would go open circuit internally and fail safe.