I put together a homemade fuel injector test rig using a spare fuel rail, my old 4th gen injectors and my car's original fuel pump and a Vortech inline aux pump.

I tested the 4th gen injectors for flowrate at 44 psi and 58 psi. That was as high as I could get with just the oem fuel pump. When I attempted to raise the fuel pressure with the aux pump I overpressurized (it was waaay above 100 psi) and blew out an injector o-ring. So the rig is down until I get some new o-rings in.

Flowrate was calculated by doing several 30 second bursts into a graduated cylinder and averaging. Data scatter between tests was less than 2 cc's.

So here's the average data that I was able to get before blowing the o-ring:

44 psi ==> 270 cc/min
58 psi ==> 304 cc/min


Observations

1. I always thought the 4th gen injectors were 240 cc/min, although I can't remember seeing that number in any sort of official Nissan literature. But I tested three injectors and they all came out to 270 cc/min.

2. The flowrates correspond very nicely to a square root rule for injector fuel flow, i.e. flow is proportional to the square root of the pressure ratio.

3. The oem fuel pump is limited to about 58-60 psi.

4. It is possible to fail an o-ring at very high fuel pressure. I'm not sure what pressure it happened because the gauge I was using only went to 100 psi, but the needle was pegged at what looked like about 150 psi. I'm mystified at how the pressure got that high, though. It was the first attempt at using the aux inline pump. I used an 8:1 fmu pressurized to 10 psi to build up fuel pressure. Back when the fmu was in my car the fuel pressure never got that high at 10 psi of boost, but that was with a Walbro in-tank pump.



Future work planned

1. Flowrates at higher pressures.

2. Find injector lock up pressure.

 

Man...your post reminds me of monster garage. I love the home made rig

 

Good info...

 

Great work!

 

very ingenious

i could do this to make sure all my injectors flow consistantly instead of having to send them off. i have a spare rail and a spare pump

good job

 

Guy, you are amazing. You are doing incredible things for the Max community. Awesome work.

 

Stephenmax = the Maxima Mad Scientist Nice work!

I wish some one could officially confirm 270 or 240??

 

I always thought the general knowledge was that the injectors lock up around 115 psi or so, but it sounds like you went way past that without them locking up?

 

No, I was not activating any injectors when I overpressurized the system. The highest pressure I tested an injector at was 60 psi.