Injector pop testing

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Injector pop testing

Postby 79Powerwagon » Wed Nov 23, 2016 7:47 am

So I built a injector pop tester out of an old porta power hand pump. Made some 14x1.5 to 12x1.5 adapters so I could use a CAT fuel line I already had. First injector I tested is way low, about 2500 psi. Should I be slowly building up pressure or just mashing the pump handle? There's about a 300 psi difference between the two methods.

Also, has anybody used any shims other than what cummins sells? Homemade, hardened washers etc..
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Re: Injector pop testing

Postby edeus » Wed Nov 23, 2016 1:16 pm

About the shims, stock injectors are made by Bosch so every shop who does service injectors should have quality shims.

I have some old tester which requires kind of fast steady move on handle, not super slow but definitely not smashing.
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Re: Injector pop testing

Postby PToombs » Wed Nov 23, 2016 6:42 pm

Fast and steady is the best method. We have a real pop tester at work, if you go slow it tends to dribble instead of pop and going too fast makes the needle jump too much.
pete

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Re: Injector pop testing

Postby 79Powerwagon » Wed Nov 23, 2016 7:02 pm

Thanks guys.

Got them all set right around 3500-3600 psi.

Almost all of them were 800-1200 psi low but had good spray patterns.

Using 2nd gen nozzles that I was told were 5x16 (they're stock 215 as far as I can tell)

Now have a low idle/lope. Going to bump idle screw and add a bit more timing and see how it runs.

I'm not sure what pop pressures were with the stock nozzles but it always idled very smooth. Not sure why it would lope now.
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Re: Injector pop testing

Postby 79Powerwagon » Fri Nov 25, 2016 1:50 pm

Ride report - set the idle a bit higher, still loping but a bit smoother. In gear rpm drops and lope is bad. The idle is set high enough, maybe too high as it slams into gear. Runs out fine though.

Has to be these nozzles because it ran perfect before. spray pattern looked fine. 2nd gen nozzles are 145 angle correct? One thing is I am running the original 93 copper washers, do I need the thinner 2nd gen washers?

Anything else I'm missing?
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Re: Injector pop testing

Postby 79Powerwagon » Fri Nov 25, 2016 3:03 pm

Tried the thinner washers, not much different. Seems a bit down on power WOT.

Hoping the higher pop pressure isn't stressing my 300k mile VE.

Gotta convince the wife that I need some 6x13s from THD :)
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Re: Injector pop testing

Postby 79Powerwagon » Wed Nov 30, 2016 4:09 pm

OK thought I had this narrowed down to the nozzles but guess not. Swapped stock nozzles back on, popped at roughly 3500 psi. Same thing. Lopes like hell in gear. Anyone have any ideas?
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Re: Injector pop testing

Postby 79Powerwagon » Wed Nov 30, 2016 4:12 pm

Video taking it in and out of gear.

https://youtu.be/nBetxUxTVnc
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Re: Injector pop testing

Postby BC847 » Wed Nov 30, 2016 4:53 pm

With the engine running and loping, loosen (just a little, so as to leak enough fuel for the injector to not hit), one at a time, each high pressure fuel feed-line at the injector.

- If the lope goes to MUCH worse, that injector is OK.
- Move to the next injector, if the lope does not change . . . .. . DING!

But wait, swap that injector with a neighboring known good injector.
- If the suspect injector still presents as it did in the first test above, then sure enough, it's that injector.
- If nothing changed, as in, that same cylinder that didn't change, with loosening the fuel line doesn't change the lope, then, it's NOT an injector issue, it's something with that particular feed-line and/or its associated supply.

Make sense?
David

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Re: Injector pop testing

Postby 79Powerwagon » Wed Nov 30, 2016 5:39 pm

Thanks for the reply- Have went through and cracked lines, they all get worse.

I'll probably have to get a fuel pressure gauge on and try some
New fuel filters.

My main concern was if for some reason the pump can't handle the higher pop off pressures- not sure if anyone has ran into that before.
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Re: Injector pop testing

Postby DodgeFreak » Wed Nov 30, 2016 7:47 pm

when I upped my pressures I had to advance the pump. Wonder if you need to advance your pump some. When you up the pop pressure it retards your injection event slightly and shortens it. I upped pop pressure advanced the timing and now 4 months later my oring on the injection pump head is leaking lol.
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Re: Injector pop testing

Postby 79Powerwagon » Thu Dec 01, 2016 5:20 am

I had pushed the pump to the head when I first got the truck running, I can try to see if it will go any more. Otherwise I'll have to skip a tooth.

Is it possible for the pump to wear in a way that it retards timing over time?
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Re: Injector pop testing

Postby 79Powerwagon » Fri Dec 02, 2016 5:42 pm

Gutted FSS, no change. Cracked all lines again, all respond. Threw a fuel pressure gauge on, 25psi!! So the supposed low pressure pump I got is not so low pressure..don't seem to have fuel in crankcase so hopefully ip seal is ok....

Still haven't figured out this lope.
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Re: Injector pop testing

Postby PToombs » Sat Dec 03, 2016 8:31 am

Check the banjo bolt in the pump holding the return line. It has an orifice in it, make sure it is clean and free. That can up pressure if the fuel can't get out of the pump.
pete

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Re: Injector pop testing

Postby 79Powerwagon » Sat Dec 03, 2016 9:20 am

Orifice is clean. Thanks for the suggestion.
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