Indicators and fuel pump

[lee]

I have a Bosch pump newly fitted and when I flick the indicators on I can hear the pump pitch change in time with the blinking indicators. 

There’s a lot of current being drawn 

Is this normal.? 

[Waldi]

Hi Lee,
with the engine running this is less noticeable on my car, but maybe my Bosch generator which can supply 50-ish amps plays a role here. The std generators (different types) provide much less.

FWIW:
My Bosch pump draws around 9A.

You could measure the voltage drop from battery positive terminal to pump feed wire with a long wire and a multi meter.

And check the same voltage loss between the negative connection and the negative terminal.

Cheers,
Waldi

[lee]

Thanks Waldi that sounds a bit too technical for moi.  
 

it could simply be a lazy alternator 

[Waldi]

Hi Lee, 
working with a multi meter is not that difficult; if you have one, put it on “volts=“ then measure the voltage across the battery as a start, first with running pump (engine stopped) and then with the engine running. A simple test, say lesson one to become a car-electricity pro:)

If you increase engine speed to say 2000 rpm it should improve, because the generator can supply more amps so voltage increases. Does it?

Waldi

[lee]

17 minutes ago, Waldi said:

Hi Lee, 
working with a multi meter is not that difficult; if you have one, put it on “volts=“ then measure the voltage across the battery as a start, first with running pump (engine stopped) and then with the engine running. A simple test, say lesson one to become a car-electricity pro:)

If you increase engine speed to say 2000 rpm it should improve, because the generator can supply more amps so voltage increases. Does it?

Waldi

Gotcha yes. I have one with lots of knobs and stuff on.  I’ll give it a go. Thx for your help 

[Paul Hill]

I have my Bosch pump wired direct from the battery with an inline fuse, never have a problem.

[astontr6]

3 hours ago, lee said:

I have a Bosch pump newly fitted and when I flick the indicators on I can hear the pump pitch change in time with the blinking indicators. 

There’s a lot of current being drawn 

Is this normal.? 

I suspect that your car has the original low powered 15 ACR alternator which is not much more powerful than a C40 dynamo. To cure that problem change your alternator to an 18 ACR rated at 45 amps or larger one.

Bruce.

[Steves_TR6]

I think there are two possibilities here :

1, your alternator/battery cant keep up with the demand as suggested already

2, the way the bosch pump is wired in it shares wiring with the rest of the ignition controlled items, eg indicators, and THE WIRING OR IGNITION SWITCH cank keep up with the demand.

Bosch pumps work best when fed by a dedicated feed, controlled by a relay from the ignition circuit.

An 18acr alternator is a cheap and easy fit, boosting charging capacity considerably so not a bad idea in any case, but i recommend fitting a relay for the bosch pump if you don’t already have one.

steve

PS , also check the earth connections as these are as important as the 12v feed

Edited April 5, 2022 by Steves_TR6

[lee]

Thank you gentlemen 

 

great info as always.