Fuel Injector Clogged?....... need some insight fellas!

[PRE-H20]

ok so i have been having some rough running issues, saturday we pulled an injector and turned the car over to see if the injector passed the fuel.....

it did but it looked like it labored to shoot the fuel,.... the problem is that i dont know what it is supposed to look like if it was a healthy non clogged injector.

my question:

is the spray supposed to be a constant even spray if fuel LIKE A PAINT GUN constant?..... or

like a spray bottle squirt, a quick spray then stop?

sorry for the bone-head question but i am NOT.... repeat NOT a mechanic or even close....

by the way.... this is a bone-stock 1974 911 coupe 2.7 liter engine.

[Breeang]

bump

[ChrisBennet]

It sprays constantly. CIS = Continuous Injection System

If you remove the air filter cover and air filter you can get access to the air metering plate (it's round, about 4" in diameter). With the ignition on, lifting the air plate briefly will cause the injectors to squirt. You don't want to do it very long because the cylinders that have injectors in them still will be filling up with gas.

-Chris

[PRE-H20]

aahhhh sooo then i may have stumbled across a bad injector?.... cool.

well the injector i pulled was definately NOT constantly spraying... it sprayed like a spray bottle, one shot and it stopped..... hummmmm...

cool.

chris... thanks.

and thanks for the CIS definition.

[sammyg2]

I have a bosch fuel injection book at home that shows several different VIS injector spray patterns, some good, some acceptable, some no good. If you don't get a better answer before tomorrow I will bring the book to work and scan the pictures.
Basically it should have some semblance of a fog pattern on as fire hose, it can favor one side or the other but still fan out fairly evenly. If it dribbles or comes out in a semi-stream, it is no bueno.
I'm not positive but I think I still have a set of 3 liter injectors in my garage i replaced a few years ago, if I still have em you can use them to test or compare or whatever if you're interested.

[sammyg2]

I just found this with google, it may help:

[AZ1977911]

Have you used a fuel injection cleaner (Techron, of BG44K)? If not do a search on Techron here and try it. Lots cheaper and/or less labor and is always a good first step in my book. If that doesnt work then pick up where you left off.

Greg

[sammyg2]

The injectors have a spring loaded check valve that opens at a pre-set pressure, around 42 psi IIRC (but I have CRS).
If it is stuck it will do what you describe, or it may be that you simply aren't getting enough fuel pressure to it to open the injector.
Have you tried another injector?
The hot set up (if you can pull it off) would be to pull all six and put them in mason jars to compare the pattern and also the flow rate. that would tell you if it's one injector or more, or if the problem is in the distributor or in one of the pressure control system components.

[PRE-H20]

sammy,... hey!

thanks for the info....... and yea if you can find the injectors maybe that can work......... thanks so much for your insight.... i KNOW you know you stuff when it comes to this stuff....

my old tired 2.7 has been running rough, not sure why.... plugs are good, timing is set, cap and rotor are good, plug wires are new, i have petronic pointless ingintion in the dizzy so i dont have to have to worry about the points being set, WUR is good.

NONE of this stuff was checked by me... as i am NOT a wrench, but i was hanging out with PKASSO this weekend at his shop, he has a 74 also so we/he poked around a little bit.

my injector looked like the image 3rd from the left...... no good uh sammy?

total loss of power (not that the 2.7 had alot but you get my drift)

[PRE-H20]

az1977911,

no i havent tried that..... i will look into it though.......

sammy.... that might be more than im comfy doing, as what you just wrote looks like japanese to me..... sorry, im a suit and earn my living behind a desk (please dont flame me! ) yikes maybe i shouldnt have wrote that out in the open..... hehe

[JP911]

Alex-
I would pull at least one different injector and try the same thing (rather than pulling all 6 which would be good, but quite a hassle). I would do this before replacing any injectors. By the way, are you still thinking about having the 2.7 rebuilt and using mine as a spare? I'll send you a PM.
-Jon

[PRE-H20]

jon..... i have been standing bye and waiting patiently for you and bert to finish up your monster 3.5...... no hurry on my end. i figured that was etched in stone and i was just standing by..... we are still a go right.

my car started acting up a couple of weeks ago, i called bert but he has been swamped and my car has been in the garage since so i figued maybe i should ask around until i can get a lil of berts time.... i know all problems go away once bert get his hands on it..... so im not TOO worried...

also i dont want to sink to much $ into this engine since you and i will be doing a engine swaparoo.....

[JP911]

Alex-
Check out my PM. Maybe we can do the swap the first weekend in March.

[PRE-H20]

hey sammy,

please let me know if you come across those injectors in your garage.

is the 3.0 injector to same as a 2.7 injector?

alex

[PRE-H20]

triwave,

your question seems complicated enough to start your own thread,... would hate for you inquires to get lost here as i just have a relatively (i hope) simple problem......

good luck.

[PatrickB]

Alex~

Don't know how soon you will really be getting the other engine.... But you know the problems I was going through, and "new" injectors solved all the rough running problems on my car. If you were able to narrow it down to 1 injector, it might be worth replacing. However, you do have 300k on them.... Mine had 140k on them, and were really messed up... I had one injector that we suspected was the culprit. Replaced it, and 75% of the problem was solved... I bit the bullet, and went ahead and replaced the rest of them, and the car has never run better!!!

If you have a spare car, just park that tired old motor, and wait it out for the new one!!

[TimT]

Originally posted by triwave
Problem I have is the DME ties three injector grounds together on one output (labeled 1,2,3 and 4,5,6).

I don't quite understand how to inject fuel into only one cylinder when all three in that bank receive the same electrical signal and have fuel on their input.

Wouldn't fuel go into all three cylinders if this was true?? What am I missing here?

Whats you are seeing is batch fired injection, so yes three injectors fire at the same time.

This is not sequential injection where each injector is timed to fired according to the engine firing order.

[Wil Ferch]

I think the epiphany sensed by Chris is *not only* do they batch fire 3 at a time ( and are NOT sequential for the 3.2)...but also...I believe all 6 fire at a time once you trace the wiring all the way back to the DME....

Chris..do I have that correct?

Wil

[ChrisBennet]

Originally posted by Wil Ferch
I think the epiphany sensed by Chris is *not only* do they batch fire 3 at a time ( and are NOT sequential for the 3.2)...but also...I believe all 6 fire at a time once you trace the wiring all the way back to the DME....

Chris..do I have that correct?

Wil

The DME injector wiring came later. The epiphany for me was that they didn't spray just when the valve was open.

If you think about it, you can see why it would be almost (?) impossible to just squirt into the open valve. At 6000rpm the valve is opening 50 times a second.

I'm sorry for hickjacking the thread. Let's fix this:

triwave if could start a new thread, copy your original question to it and delete your post on this thread, I'll cut my and paste my response and put in on your new thread.

-Chris

[PRE-H20]

patrick,

hey thanks for chiming in.... i hopefully will be settling this engine issue in the next 2 months... so i am trying to get the rough running issue back to running and i will be happy.....

to respond to your cooment, i dont really have it NARROWED down to one injector, i/we only really checked one as we were finishing up looking at other things, i just randomly through out the question, "i wonder if i could be an injector" (cuz i thought about your injector issue and thought i would give it a shot) so we quicky checked one injector and thats when i noticed it was not a constant spray more of a squirt.....

and yes your right i have just about 300k on them, sammyg had mentioned he might have a set of injectors from a couple years back and im waiting for his response, i hope he didnt forget

im hoping my rough running issure will be painless as another motor is hoepfully around the corner.

i do have a 2nd car.... an explorer that i drive as a daily driver but i really like taking to car out, i guess im a bit guilty of being impatient....



alex