Injector pop psi question

[ghunt]

OK, so I got my tester rigged up today and tested my u-haul injectors and they tested as such:

#1-1800 psi
#2-1850 psi
#3-1850 psi
#4-1900 psi
#5-1800 psi
#6-1800 psi
#7-1800 psi
#8-1950 psi

Now, #8 is the injector that has caused me some concern. Besides the fact that it pops higher than the rest, there also isn't as much fuel that comes out when it does pop, and it tends to "chatter" when it pops (all the other injectors, if you do a slow steady pump it will spray a nice stream of fuel- this one will not do that at all).

What do I need to do? Also, do I need to bring down the pressure on the 1900 and 1950 psi injectors, or just the 1950 psi one?

 

[OLDBULL8]

Pump fast for a truer pop pressure and spray. .001 shim is = to 50 lbs. Try to match within 50 lbs of each other. Glad you got something working.

 

[icanfixall]

Yes..... What he said.... You might be able to remove shims from the 1950 and install them in the 1800.... Remember 1 thousands equals 50 lbs as posted above...

 

[Diesel JD]

Ideally you'd bring them all up to at least 1850-1900psi. +-100 works pretty well, +-50 is even better. I actually was taught that the chatter is a very good sign and a steady peeing stream is bad. Also a nice narrow cone spray pattern is a good sign.

 

[icanfixall]

This is what looks good poping an injector...
http://www.youtube.com/watch?v=G7YXCq4z1Ig

 

[Dsl_Dog_Treat]

I actually was taught that the chatter is a very good sign and a steady peeing stream is bad. Also a nice narrow cone spray pattern is a good sign.

X2 on the chatter. That is actually one of the tests to be done on injectors.

 

[ghunt]

This is what looks good poping an injector...
http://www.youtube.com/watch?v=G7YXCq4z1Ig

I think mine all pretty much do that if you pump them at a normal speed...I dunno, I may have to take a video of the last one, it just seems like it's acting weird.

And, so I want more than 1800 psi? I had thought 1800-1850 was the target range.

 

[Diesel JD]

I was thinking 2000 psi +-200 psi is in the fair to good range. The main thing is that they are at least 1800 and all fairly even.

 

[ghunt]

I took the #8 injector apart and it's got about .150" of shims in it

With .150" of shims it pops at 1950 psi, with .146" of shims it pops at 1800. So yeah I guess I need some .001" shims.

 

[MidnightBlade]

That is about the same results I got with my U-Haul injectors. I am setting mine to pop off at 2100. Then after 5000 miles I will pull them and rematch them to whatever the highest one is.

 

[Diesel JD]

Blade did you get new ones or remans. This procedure is not necessary with remans, as the spring has already taken a seat.

 

[mariner45]

Fuel injectors are supposed to atomize the fuel into a fine mist (very small droplets) - the smaller the better as ignition is faster when they are small.

Any fuel spraying from a fuel injector as a jet of fuel is a no-no. This is the equivalent to a minature flame thrower - a stream of fuel will be sent into the cylinder and only part of it will ignite properly - the rest will burn in a delayed fashion. The main cause of piston tops getting holes getting burnt through the alloys.

The same thing applies to all size fuel injectors - big or small.

HTH

mariner

 

[MidnightBlade]

Blade did you get new ones or remans. This procedure is not necessary with remans, as the spring has already taken a seat.

Thanks, yes they are remans