Injector Pop testing questions and results

turboman1

turboman1

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Aug 20, 2008
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Started checking the pop pressure on my injectors with my new tester. Injectors maybe have 3000 miles on them. I only tested the ones from cylinder#1 and #2 but both are cracking open and forming droplets on the bottom of the injector at about 3000 psi (~207 bar). Both were popping (I mean a weak but noticeable stream coming out of 2-3 orifices) around 3400-3500 psi (234.5-241.3 bar). Also when they would pop not all of the orifices (5 hole nozzles) sprayed fuel out of them. Even when purging the line of air (i.e. just straight pumping the tester handle up and down) the injectors didn't always spray out of all the holes.

These are performance injectors and from what I have read the pop pressure should be around 270-280bar. The side of the body says 240bar for pop but I thought they would be higher being a performance injector.

Any comments on what to do with the injectors? Also any comments on how to correctly test it with a hand pump tester?

Thanks
Adam
 
all the bodies have random bar numbers on them due to the different applications that they get cores from. i had a set i purchased a few years back that would spray a normal pattern but were way lower than the company said they were set at. i would consider contacting the company you purchased them from and getting them fixed. sounds like they were not modified correctly and are hurting your power and mileage substantially. also make sure you got a low micron fuel filter as you may have gotten some junk in there and plugged the orfice.
 
not sure exact micron but you should be good with that. i believe they use fleetguard filters. i used baldwin and i have heard that donaldson are good too. if you are gentle and pay attention if your comfortable try taking the nozzles off and cleaning them to see if you can open up the orfice. otherwise just send it to Seth @ DPE, Weston, SDX, or any other reputable shop. if you do take them apart be gentle as the nozzles are thin walled and break easy.
 
The pop tester I am using is found at the link below.
Mechanical Injector testor - Pop Tester, Diesel Care and Performance Inc

I took a video of the leakage today but still trying the upload it to photobucket. Turns out a drip starts forming around 2000 psi. The leakage rate starts to increase as pressure goes up till about 3400 psi where there is a visual squirt of the fuel from the injector (not even out of all 5 holes either).

From my understanding the injector shouldn't leak anything at all until it pops open at a preset pressure. Also when it pops it should spray out of all nozzles holes in a fairly 'aggressive' stream. Is this correct?

thanks
Adam
 
Finally got the video uploaded. This is mainly showing the leakage. You can see it pop a little at 3400 psi

[ame="http://s1057.photobucket.com/albums/t382/adammvp01/?action=view&current=InjectorLeakageTest.mp4"]InjectorLeakageTest.mp4 video by adammvp01 - Photobucket[/ame]

Adam
 
Looks like a Marine nozzle, you should take a video with the gauge closed and hitting the needle. Pop testers are not all the same, I have seen a 30BAR difference between different models/types.
 
it should not leak til its preset pressure and when it does pop it should create a mist, not a stream of fuel. at least the ones i did would mist i am sure the larger you go the more it would seem like a stream. in this video if you look at about 1:45 you will see how its supposed to pop

http://youtu.be/X97tNy5qtt8
 
Smokem, just so I get this straight, you want me to get a video with the pressure gauge closed and just pumping the handle to show it spraying? Similar to what you would do to purge the air out of the line?

Thanks
Adam
 
ChevyCummins, the injector are 5x.014". Not the largest injector so I would assume it would mist more than stream the fuel.

Thanks
Adam
 
yeah my 5x12 would mist really good. i wish i was able to measure the needle and what not to know what all was done to them. when i called the guy i bought them from pretty much told me it was secret squirrel stuff and wouldnt tell me any details.
 
Should never stream. But an injection pump drives a little different. Short hard bursts.
 
I don't mind if they stream a small amount when you sneak up on them, but they should chatter with any force behind them. They should not leak before OP, and any tester that cost $200 I would not trust.
 
When testing a set of injectors I like to set the spring and get some lube through by hard full throws right away. Then prime up the line and give quick even bursts. This method gives me the most consistent numbers. Hard to explain. Just something you learn over time.
 
AHall said:
When testing a set of injectors I like to set the spring and get some lube through by hard full throws right away. Then prime up the line and give quick even bursts. This method gives me the most consistent numbers. Hard to explain. Just something you learn over time.
Click to expand...

Seating the needle, if only everyone did this.
 
turboman1 said:
Would you still trust it for a leak down test?

Thanks
Adam
Click to expand...

Yes because you're not using the gauge. Just sending pressure to the injector. I usually use 10 bar under pop or use feel for my leak test.
 
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