When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Hi all,
I am installing a 928GTS fuel pump in my 89 951 to allow more fuel flow than the stock pump.
While reviewing the wiring diagrams of both cars, I noticed the 928 uses a larger gauge wire to handle the larger amp load.
With this in mind, is it necessary to run new power from the battery with larger gauge wire?
I know many here have opted to install larger fuel pumps and have read many threads, but did not see much in the way of changing/routing new wire.
Easy way to check - with car running put a voltmeter on the battery, then put it across the terminals on the pump. What's the actual voltage at the pump?
I would think the amps being pulled by the pump would vary with engine load, temperature, condition of the fuel system, etc. IDT a dry run of voltage drop in a static condition is going to answer the question. It's not a inconsequential task in running a large ga wire, but it may be the safest for the car.
Many thanks - will perform this voltage drop test first. I don't mind running a new, larger wire with a relay, but wanted to hear from those more knowledgeable than I.
wanted to hear from those more knowledgeable than I.
Did this idea of installing a fuel pump that's designed to operate in a 3.8 bar return system into a 2.5 bar return system come from someone knowledgeable?
These pumps are designed to work efficiently against and within a narrow range of head pressure. Unless the fuel system and engine in your car are modified I would not expect any benefit. In fact an increase in volume (due to running at lower pressure) could overwhelm the regulator and cause pressure variations and poor running.
Did this idea of installing a fuel pump that's designed to operate in a 3.8 bar return system into a 2.5 bar return system come from someone knowledgeable?
These pumps are designed to work efficiently against and within a narrow range of head pressure. Unless the fuel system and engine in your car are modified I would not expect any benefit. In fact an increase in volume (due to running at lower pressure) could overwhelm the regulator and cause pressure variations and poor running.
Yes, I am installing 80 lb injectors, larger Vitesse Stage 3 turbo modified by Evergreen, 3" Fabspeed exhaust, ported head, different intake/throttle body, MAF, cam, etc... so, need to ensure I have the capacity to adequately provide flow to support these mods.
The stock pump is too small, yet the 044 perhaps a bit too much, which is why I settled on the 928 GTS pump.
I would think the amps being pulled by the pump would vary with engine load, temperature, condition of the fuel system, etc. IDT a dry run of voltage drop in a static condition is going to answer the question. It's not a inconsequential task in running a large ga wire, but it may be the safest for the car.
you're right - at idle the load on the pump would be less than at WOT (because the vac-referenced FPR is making rail pressure lower at idle than at WOT) but it'd still be a representative test.
the stock FP wire is something like 14 gauge IIRC (tore mine out a few months ago to run a new 10ga) which is borderline given the length of it.
wouldnt surprise me to find that the stock pump with stock wiring only sees 10-11 volts instead of 13+.
10-24-2021, 09:28 PM
Need for larger gauge wire w/new 928 fuel pump?
