Need schematic or diagram of Injection system 94 STS

[The Fred]

Good hell,

My injectors don't have the bottom o-ring none of them

What in the heck!!!

[BodybyFisher]

I can't be 100% sure but you don't have an O-ring on the bottom, you have a seal. See my link above to your SEAL KIT, there are 8 O-rings for the top to connect to the fuel rail and 8 seals for the bottom from what I can determine for 93 and 94

[The Fred]

Oh I missed that part about "compare to my car"..

I thought it was showing my injector with an o-ring on the bottom

I've seen that seal kit live and in person about six times and it doesn't have the one I need..

Since the heater hose custom made seal things I made didn't make any difference at all I guess I am back to needing injectors.. any last ditch ideas for fixing the injectors?

Also: How do I go about cleaning the.. Phenolic spacer plates??

[The Fred]

Can I jumper a hot wire to the injectors in order to test them?

And hopefully make the connection to the power.. away from the fuel

[BodybyFisher]

In a word, NO... They are fired by the PCM via pulse width and the pulse is measured in milliseconds.. If you direct wire them you will fry them... You are getting off track again! You were on the lower seals, stay there till you eliminate that. When you lift the fuel rail does each injector have a lower seal? Are any damaged? If you are missing or if any are damaged, I would buy that O-ring/Seal assortment for less than $30 from Rockauto and replace all of them to eliminate the possiblity that you are loosing vacuum.

Here is an interesting article on the FPR and injector operation posted by the GURU himself:

Subject : RE: how does FPR work?

MessageDate : 1/10/2004 12:00:52 AM

Posted By : bbobynski

Cadillac Year : 2003

Cadillac Model : 05 Bonneville GXP

Message : The fuel pressure regulator works pretty good...LOL

Seriously....The fuel injector is basically just a valve that is

opened by an electric solenoid. There must be some fuel pressure on

the injector so that when it opens the fuel will be forced thru. The

pressure that the system was designed to operate at varies depending

on the injectors used, the system, the engine, the fuel pump, the

fuel, etc.... Typically port fuel injected systems operate somewhere

in the range of 40 to 60 PSI as a general rule of thumb.

The first job of the fuel pressure regulator, then, is to maintain

this basic level of pressure on the system. Since the fuel rail

supplies fuel to each of the injectors around the top of the engine

if the fuel pressure in the rail is controlled then each injector

will see the same pressure.

Basically the fuel pressure regulator functions by bleeding off

excess fuel back to the tank to maintain the desired pressure. That

is why there are two fuel lines...a supply line and a fuel return

line. The supply line is always under the pressure that the

regulator is regulating at and the fuel return line is not under any

pressure, per se, it just routes the fuel back to the tank.

The FPR does this via a poppet valve and seat that is controlled by

a a spring. The fuel pump supplies a constant flow of fuel to the

fuel rail and the FPR is at the end of the rail. The pressure in the

fuel rail that will unseat the check valve is determined by the load

of the spring behind it. If the opening of the poppet valve or check

valve is 0.5 inches square inches and the spring is compressed to a

value of 20 pounds then a fuel pressure of 40 pounds per square inch

(40 PSI) will force the valve open and the excess fuel will escape

and travel down the fuel return line to the tank.

The fuel pressure regulator on the port fuel injected engines, such

as the 4.9 and the Northstar, controls the fuel pressure in the fuel

rail so that the pressure drop across the injector is always

constant. That is, the pressure drop from the fuel inlet of the

injector to the tip of the injector, must always be constant so that

the injector pulse width delivers a predictable amount of fuel. The

"pulse width" is the amount of time the PCM holds the injector open.

It is usually measured in milliseconds. For instance, it would be

common to see an injector pulse width of 5.0 milliseconds.

This is important because the whole basis of the fuel injection fuel

delivery system is that the PCM can calculate how much fuel to

deliver and then open the injector for a specific amount of time to

allow that quantity of fuel to enter the port.

You need to understand this because the only way the injector can do

this is if the fuel pressure drop across the injector from the rail

to the tip is constant. This would be relatively easy if the

injector tip was in a constant pressure environment. It isn't in a

port fuel injected engine as the tip of the injector is exposed to

manifold vacuum. The manifold vacuum changes constantly with changes

in the throttle, load, RPM, etc....so...the fuel pressure must

constantly change to keep the pressure drop or the pressure

differential across the injector constant.

Since the simple spring in the fuel pressure regulator is not

capable of comprehending any changes in vacuum the spring load is

modified by a diapragm in the FPR. This diaphragm helps modulate the

spring load to the check valve when vacuum sucks or pulls on it. In

this fashion, when vacuum from the intake manifold pulls on the

diaphragm it will change the load on the spring seat and the

resulting fuel pressure required to unseat the valve will change.

That is why there is a vacuum connection to the fuel pressure

reguator. That is also why, if you put a fuel pressure gauge on the

fuel rail you will see a fixed, constant fuel pressure when the key

is turn on and the engine is not running. When the engine starts,

and manifold vacuum comes into being, the fuel pressure will now

fluctuate, relative to the intake vacuum at the time.

Since higher levels of vaccum in the intake tend to "pull" or "suck"

fuel from the injector tip, there needs to be less positive fuel

pressure on the back side of the injector to deliver the constant

fuel pressure drop across the injector. As the vacuum drops to zero

(as it is at wide open throttle..the WOT condition) the positive

fuel pressure on the back side of the injector must increase to keep

that pressure delta across the injector constant. And you will see

the fuel pressure go to maximum when the vacuum is zero.

In this type of system the fuel pump just dumbly pumps fuel at a

constant volume to the engine all the time. It must pump enough fuel

to be able to keep the fuel pressure constant even at maximum power,

when a great deal of fuel is flowing thru the injectors and into the

engine. This means that at idle, when very little fuel is flowing

thru the injectors, most of the fuel is just bypassing the system at

the FPR and going back to the tank. It just circulates constantly.

This also explains why the engine will run poorly when the fuel

pressure regulator acts up. If it sticks open and bypasses all the

fuel to the tank then no pressure will build up and the engine will

not run...since no fuel will be pushed thru the injectors. If the

diaphragm in the FPR, that separates the fuel from the vacuum

chamber, starts to leak then the fuel will be sucked into the intake

via the vacuum line and will enter the intake manifold. This will

cause very rich operation and poor performance, poor fuel economy,

hard starting, etc. will result.

Hopefully this sheds some light on what the FPR does. It is a

relatively simple device but it performs a rather complex function.

If you want to understand how the system works it is important to

understant the reason the fuel pressure must do what it does....and

it is the job of the FPR to control the fuel pressure accordingly.

This is the description of the classic port fuel injection system

typified by the systems seen on the 4.9 and Northstar. The systems

have evolved in the early 2000's to "returnless" fuel systems. These

systems are much more complex in the control side of the electronics

but simpler mechanically as they do not have a fuel return line, the

fuel pressure regulator is fixed and does not "see" vacuum. The

complete explanation of how this is possible will wait for another

day, but, be aware that there are variations on the classic FPR type

systems in production today. The same logic applies as is described

above as to how they work...they just have a lot more electronic

bells and whistles allowig elimination of the fuel return line.

[Cadillac Jim]

Two comments:

1. The returnless DFI system can work with a well-calibrated vacuum sensor -- a good MAP -- by varying the pulse width to compensate for the vacuum, rather than letting the FPR manage the difference in pressure.
2. A nit -- at WOT or with the engine off, the fuel pressure is at a maximum, and at high vaccum the fuel pressure is at a minimum.

[The Fred]

As I say,

The seals I showed that are broken are not in any seal assortment I've seen thus far so I had to make them out of heater hose.. which really isn't very good..

I think that it should work, though, at least for now..

Darned injectors must be the problem

[MAC]

Two comments:

1. The returnless DFI system can work with a well-calibrated vacuum sensor -- a good MAP -- by varying the pulse width to compensate for the vacuum, rather than letting the FPR manage the difference in pressure.
2. A nit -- at WOT or with the engine off, the fuel pressure is at a maximum, and at high vaccum the fuel pressure is at a minimum.

Speaking of MAP sensor--Did you replace it? You should check to make sure the MAP is working properly. I remember in one post where someone (who was a technician) couldn't figure out why the Cadillac he was working on would not start. He finally checked the MAP and found out it was the problem.

[The Fred]

Good thinking,

I had a code for an out of range map singal or some of a thing a couple times

Today I am not allowed to drive so I can't go and get any parts because I bought some everclear and it is 90000 proof

Also I was reminisceing back to when I killed my 1991 Eldorado..

I still crack a grin when I remember that day smoke was everywhere and noise and the neighbors called the police on 911 it seized before they got there that 49 motor would not die it finally siezed after running forever with no oil or water

Question: If I disconnect the MAP sensor and start the motor, and it doesn't change anything.. is that how I know the MAP is the culprit?

[MAC]

Question: If I disconnect the MAP sensor and start the motor, and it doesn't change anything.. is that how I know the MAP is the culprit?

If the MAP sensor is the problem once it's disconnected the engine may finally run normal. However, one can only speculate. The individual that I talked about said that once he disconnected the MAP sensor the engine finally started. It was an immediate diagnosis. He replaced the MAP and the problem was solved.

[Cadillac Jim]

If you get a MAP code that is current, or you clear it and it comes back in a few minutes, then you should check the MAP. I got an intermittent MAP code once, "...out of range" and the car would start but it put the DFI in the open-loop mode and the transmission in the safe mode. It ran OK but with poor gas mileage, like a cold engine before the heated oxygen sensors come online, and it shifted really firm like a 1950 Hydramatic.

I found the problem from the code and used the FSM to find it and was holding it in my hand, and decided that the connector seemed loose but the sensor seemed OK, so I put it back togehter with the connector firmly on the MAP and have been driving for two years.

For what it's worth, I've had my car back from the body shop for over a week now and it's running with zero codes, not even ancient history. While I was having state smog inspection on Tuesday, I kidded the technician with "What are we going to do about all those codes????" His code reader is one of those PC-based things that is updated perioically with downloads, and is probalby better than the one at the dealer, particularly for new models. His reply bypassed my jibe completely: "Some people come in here for inspection with the Check Engine light on!"

[BodybyFisher]

Here is a photo of your injector, I found it at STANDARD MOTOR PARTS. You part number is 17113140 (standard part # FJ238). That Seal Kit/O-Ring Kit I posted above is the CORRECT seal/O-ring kit for you, you are only seeing those seals from the top. I am going to the dealer tomorrow and see if I can get one to look at. But look at the photo below

Look at the shape of the lower seal, it looks like what you found, pay no attention to the color! I think you are making a mistake trying to 'seal' your injectors with a rube goldberg fix, get the right seal kit. If she is leaking ANY vacuum at those ports you will get a misfire

See Rube Goldberg >> http://en.wikipedia.org/wiki/Rube_Goldberg

Do an application search at STANDARD MOTOR PARTS here http://www.smpcorp.com/home.asp

I just spent 4 hours finding this photo of YOUR injector with seal searching the internet:

[BodybyFisher]

Oh I missed that part about "compare to my car"..

I thought it was showing my injector with an o-ring on the bottom

I've seen that seal kit live and in person about six times and it doesn't have the one I need..

Since the heater hose custom made seal things I made didn't make any difference at all I guess I am back to needing injectors.. any last ditch ideas for fixing the injectors?

Also: How do I go about cleaning the.. Phenolic spacer plates??

My post #98 above contains a link detailing how to clean the phenolic spacer and mouse holes

[The Fred]

Here is a photo of your injector, I found it at STANDARD MOTOR PARTS. You part number is 17113140 (standard part # FJ238). That Seal Kit/O-Ring Kit I posted above is the CORRECT seal/O-ring kit for you, you are only seeing those seals from the top. I am going to the dealer tomorrow and see if I can get one to look at. But look at the photo below

Look at the shape of the lower seal, it looks like what you found, pay no attention to the color! I think you are making a mistake trying to 'seal' your injectors with a rube goldberg fix, get the right seal kit. If she is leaking ANY vacuum at those ports you will get a misfire

See Rube Goldberg >> http://en.wikipedia.org/wiki/Rube_Goldberg

Do an application search at STANDARD MOTOR PARTS here http://www.smpcorp.com/home.asp

I just spent 4 hours finding this photo of YOUR injector with seal searching the internet:

That's the seal!

17113140 I have seen live and in person several times,

It doesn't have that

Can you find a picture of 17113143?

I've said that same thing to 100 people "If it aint sealing up it will cause a misfire"

They all told me no, this seal wouldn't cause a misfire, I agree with you and I am so glad someone finally agrees with me

Question: If I disconnect the MAP sensor and start the motor, and it doesn't change anything.. is that how I know the MAP is the culprit?

If the MAP sensor is the problem once it's disconnected the engine may finally run normal. However, one can only speculate. The individual that I talked about said that once he disconnected the MAP sensor the engine finally started. It was an immediate diagnosis. He replaced the MAP and the problem was solved.

I've had it running with the map unplugged.. didn't seem to make a change...

[BodybyFisher]

According to AC Delco's site there is no 17113143 part number but there IS a 17113140 which is an injector and when you ask for what cars its used for YOUR car comes up.... Your correct injector number is 17113140.

See AC Delco's site here at http://www.acdelco.com/

And Standard Motor Parts is here http://www.smpcorp.com/

[The Fred]

17113143 is supposedly a seal kit which includes the ones I need..

According to Donovans (A Wichita dealership)

Couldn't find it on the delco site and the local delco parts house couldn't find it either.. odd and strange

[BodybyFisher]

I gave you a link to Rock Auto that shows the seal kit you need.

[The Fred]

According to AC Delco's site there is no 17113143 part number but there IS a 17113140 which is an injector and when you ask for what cars its used for YOUR car comes up.... Your correct injector number is 17113140.

See AC Delco's site here at http://www.acdelco.com/

And Standard Motor Parts is here http://www.acdelco.com/

I got mixed up I have seen 17113141 I think

I gave you a link to Rock Auto that shows the seal kit you need.

The one you showed me was the one I've seen three times in person..

[BodybyFisher]

Fred, you CAN NOT see the entire SEAL in that photo. You are ONLY seeing the top of it... That seal kit if for 93 and 94

[Cadillac Jim]

BBF -- I think you accidentally put up two links for ACDelco.com. The Rock Auto link is a no-brainer:

http://www.rockauto.com/

The page that the fuel injector seal kit is on is

http://www.rockauto.com/catalog/x,carcode,...5,parttype,6232

A picture of the parts in B/W is

http://198.208.187.182/internet/PartImage....partnbr=217-459

Their text for this part is:

ACDELCO Part # 217459

SEAL KIT,F/INJR(O RING) {#17112855}

In spite of what it says, the bottom seals are not o-rings in the picture -- the bottom seal looks just like Fred's pictures. It's listed as the fuel injector seal kit for the 1993-1994 Northstar. Price is about $25.

[The Fred]

I could swear that I've seen this in person on the counter three times... I will look at it again when I go back to the parts store because you folks are usually very knowledgable and so I'd expect you to know what is going on... thanks

[BodybyFisher]

BBF -- I think you accidentally put up two links for ACDelco.com.

Thanks Jim, I corrected the link, Mike

[The Fred]

I went to delco house and ordered that part # monday it will be here

I think it is a weekend,

They said parts dept was closed at the liarship

[The Fred]

Alright so the part I ordered is supposed to be in about an hour from now..

if it has the seal I need I might have a heart attack.

In the mean time while I have the cover off, I know I can't start the motor, but why can't I disconnect the coil packs (so the motor can't run) and crank the starter to see if the injectors are working(with the cover off)?

Is there any reason I can't do that to see if the injectors are working?

[The Fred]

HA! 217 459 is IT

"Substitute for 17112855"