Lets talk injectors

[Silver91Hatch]

Well, I am need of some injector learnin'.

I have a 86 6.9 and a 91 7.3. The 6.9 has developed an injector knock, . So follows a buch of questions...

7.3 and 6.9 injectors are the same correct??

Where are the injector codes stamped??

Which injector codes are better than other? Ie. bb, aa, etc in order.

What should the pop pressure be?

What causes an injector to satick open? Spring broken?

If its not a broken injector spring, could fuel injector cleaner help at all?

Will it hurt to drive it with the injector knock, if so what will it harm?

How do you all diagnose which injector is causing the issue? Least invasive is better.

Why does it not knock cold? Only with a warm engine...

Will running it harder help flush contaminates if any are in the injector?

Thanks in advance for all of the help.

 

[icanfixall]

All the available injecters that fit the idi motors will fit any 6.9 and 7.3... I personally have found the BB code injecters the best. Both typ4 and agnem sell them. The code stamp is found on the wrench flats. I ran G codes for a long time. I even had a matched pop test set but they were no match for the Bb injecters. Around 1850 to 1900 lbs pop pressure seems to work the best.

 

[Agnem]

7.3 and 6.9 injectors are the same correct??

YES

Where are the injector codes stamped??

ON THE SURFACES THAT TOUCH YOUR WRENCH OR SOCKET

Which injector codes are better than other? Ie. bb, aa, etc in order.

THEY ARE ALL ABOUT THE SAME, BUT AVOID THE G CODE ONES

What should the pop pressure be?

1800-2000 PSI

What causes an injector to satick open? Spring broken?

A STUCK PINTLE IS BAD NEWS AS IT CAN ALLOW COMPRESSION AND EXHAUST GASES BACK INTO THE INJECTOR LINE. CARBON, WEAK SPRINGS, DEFORMED PINTLE OR ORIFACE CAN ALL CONTRIBUTE

If its not a broken injector spring, could fuel injector cleaner help at all?

POSSIBLY. YOU SHOULD BE RUNNING A LUBRICITY ADDITIVE AT ALL TIMES

Will it hurt to drive it with the injector knock, if so what will it harm?

THE KNOCK IS FROM SEVERELY ADVANCED TIMING IN THAT CYLINDER. NOT A GOOD THING.

How do you all diagnose which injector is causing the issue? Least invasive is better.

WITH THE ENGINE RUNNING, LOOSEN THE INJECTOR LINE NUTS ONE AT A TIME UNTIL YOU FIND THE ONE THAT MAKES THE NOISE STOP.

Why does it not knock cold? Only with a warm engine...

INJECTORS HAVE CLOSE TOLERANCES AND EXPANSION AND CONTRACTION AT DIFFERENT TEMPERATURES WILL EFFECT THOSE TOLERANCES.

Will running it harder help flush contaminates if any are in the injector?

DEPENDS. SOMETIMES IT WILL MAKE IT WORSE. BEST JUST TO NOT MESS WITH IT AND GET YOURSELF A FRESH SET OF INJECTORS.

Sorry for the hollering, but it seemed easier to answer the questions in this format.

 

[Devilish]

SET OF INJECTORS.

Sorry for the hollering, but it seemed easier to answer the questions in this format.

LoL!

 

[Silver91Hatch]

Is there any harm in replacing or rebuilding the bad injector and pop testing/matching my other 7?

 

[typ4]

It will cost almost as much as a new set.

 

[Taz94IDI]

Which injector codes are better than other? Ie. bb, aa, etc in order.

THEY ARE ALL ABOUT THE SAME, BUT AVOID THE G CODE ONES

New to this site. Seems very informative...thanks. I'm curious about avoiding the G code injectors as those are the one's that my truck calls for.
Scott

 

[typ4]

They are an emissions injector, bad spray patterns and just not optimum for these engines. I sell the matched bb codes and they work in all applications, plus they are the only ones that are readily available.

 

[Taz94IDI]

Thanks Russ,
I thought the G was the turbo app. Wish I would have seen all this before I put a new set in.

 

[typ4]

They are for turbo but not very good at it.

 

[Silver91Hatch]

It will cost almost as much as a new set.

Wondering why you say that? I have a pop tester, so basically I will need some shims, o-rings, copper washers, and one injector possibly.

 

[Andylad13]

Wondering why you say that? I have a pop tester, so basically I will need some shims, o-rings, copper washers, and one injector possibly.

I think he meant if you were to have someone do this for you. It can be very expensive.

 

[icanfixall]

When you take apart a used injector things need to be ER room clean. Any dirt will ruin the rebuilt injector. Can you do the job as clean as it requires??? If so have at it but be warned... This is a most difficult job to do correctly. I would like to try it but don't want the issues that may come of it... I don't like to do the job twice although I always have "spares" behind my rear seat...

 

[Black dawg]

its pretty tuff to make one run right with mis matched injectors. I have piles of old injectors that ive saved, and out of this pile matched a set from the very best and same letter code, and a new set runs much better.

 

[Silver91Hatch]

When you take apart a used injector things need to be ER room clean. Any dirt will ruin the rebuilt injector. Can you do the job as clean as it requires??? If so have at it but be warned... This is a most difficult job to do correctly. I would like to try it but don't want the issues that may come of it... I don't like to do the job twice although I always have "spares" behind my rear seat...

Well I rebuild transmissions and I keep my bench OR clean, ER is a little dirtier than I like, lol.

I have more time then money, so I would rather give it a shot, then if it doesn't run good I will buy a set, but my feeling is, if someone else is rebuilding them, I can give it a shot.

its pretty tuff to make one run right with mis matched injectors. I have piles of old injectors that ive saved, and out of this pile matched a set from the very best and same letter code, and a new set runs much better.

Well I have a Rotunda pop tester and one I am building from a porta-power, so I think with a lot of time and testing I think I can get a set within 50 psi and give it a shot.


Also what are the tolerances these injectors are matched to? I know there wasn't someone in Detroit pop-matching 8 injectors for each 83-94 F-250-350 that were built, so there has to be an operating range that is acceptable.