Help getting higher voltage at my fuel pump
#1
![Default](https://passionford.com/forum/images/icons/icon1.gif)
s2 running efi with external fuel pump.
Battery voltage with engine idling is approx 13.65volts
Voltage at the fuel pump with engine idling is 12.75volts
a difference of 0.9volts
I've been advised to get the fuel pump voltage up.
HOW? any tricks?
Cheers
Battery voltage with engine idling is approx 13.65volts
Voltage at the fuel pump with engine idling is 12.75volts
a difference of 0.9volts
I've been advised to get the fuel pump voltage up.
HOW? any tricks?
Cheers
![Top](https://passionford.com/forum/images/smilies/smile011.gif)
Trending Topics
#11
10K+ Poster!!
iTrader: (1)
Join Date: May 2003
Location: Lancashire
Posts: 12,748
Likes: 0
Received 0 Likes
on
0 Posts
![Default](https://passionford.com/forum/images/icons/icon1.gif)
well if it's already a volt down at idle, something is high resistance somewhere! Higher than it should be. When on boost and the fuel pressure is up another 2 bar and the pump starts to draw some current, that'll drop off more than likely.
#15
Regular Contributor
Join Date: Apr 2004
Location: southampton
Posts: 349
Likes: 0
Received 0 Likes
on
0 Posts
![Default](https://passionford.com/forum/images/icons/icon1.gif)
yh a 1/4 would be a good crack buddy, i just had to buy a new battery
![Sad](https://passionford.com/forum/images/smilies/icon_sad.gif)
#19
10K+ Poster!!
iTrader: (1)
Join Date: May 2003
Location: Lancashire
Posts: 12,748
Likes: 0
Received 0 Likes
on
0 Posts
![Default](https://passionford.com/forum/images/icons/icon1.gif)
that's irrespective. The whole car will be at 14 volts and the pump is only seeing 12 of that which means something is higher resistance than it should be. This means that there is also a current supply issue to the pump and it can't get what it needs. Voltage is pressure behind the current that is there. Something is restricting the current from flowing, which in turn means the pump is drawing more current through the wiring than the wiring can handle.
#20
Part of the Furniture
Join Date: Jul 2009
Location: nottingham
Posts: 171
Likes: 0
Received 0 Likes
on
0 Posts
![Default](https://passionford.com/forum/images/icons/icon1.gif)
my mates mfi turbo has a decent volt gauge in and that read 12.5-13 volts earlyer running on tickover, so his wont be at 14volts!!
my point earlyer was why do you want more than 12volts going through a 12 volt pump? but the only thing you can do if your not happy is run a complete length of new cable and try that!
my point earlyer was why do you want more than 12volts going through a 12 volt pump? but the only thing you can do if your not happy is run a complete length of new cable and try that!
Last edited by mercgrey; 09-09-2009 at 11:36 PM.
#21
10K+ Poster!!
iTrader: (1)
Join Date: May 2003
Location: Lancashire
Posts: 12,748
Likes: 0
Received 0 Likes
on
0 Posts
![Default](https://passionford.com/forum/images/icons/icon1.gif)
it's nothing to do with the pump only being rated at 12 volts. It's the fact that the alternator is producing 13.7 volts so every thing on the car should be seeing that voltage. If it's not, there is a supply or return (earth) issue. Every thing on a car should be seeing charging voltage when the engine is running.
#23
10K+ Poster!!
iTrader: (1)
Join Date: May 2003
Location: Lancashire
Posts: 12,748
Likes: 0
Received 0 Likes
on
0 Posts
![Default](https://passionford.com/forum/images/icons/icon1.gif)
did you take a supply straight off the battery and return the earth back to the battery? Most of the problems are usually at the front of the car where it joins the loom and some times the terminals on the relay get hot and increase in resistance. It would be worth replacing the relay and putting the positive and earth on the battery. I assume you have used decent sized cable to account for voltage drop across the length of the car? It should have been rated at about 30 amps at least, 2.5 mm cable or bigger idealy.
Thread
Thread Starter
Forum
Replies
Last Post
JK12
Pictures, video & Photoshop Forum
33
26-04-2021 12:09 PM
TPM961
Restorations, Rebuilds & Projects.
19
15-01-2018 10:50 AM