Injectors not firing after valve cover removal. *SOLVED!*

galatron · **Posted:** Fri Mar 09, 2012 10:06 am

Relating to http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=65084
TL;DR:
Solution Below
"The Fuel Rail's Pressure sensor, and the number 4 have the same style electrical connector and no labeling.
If your engine does not start after working "back there" swap the connectors, your engine will more than likely start..."
I had those two swapped. :banghead:

We (Turbobill and I) got the CRD all put back together and the engine won't fire off. I put a shot of starterfluid in and the engine will ignite but die off once the starter fluid is gone - pointing to a fuel problem.

We checked that the fuel lines were purged, put a clear line on the return block and saw fluid coming out.

The engine is timed perfectly.

We pulled injector number one and reconnected to the fuel rail, return line and the electronics; we cranked the engine... no fuel came out of the injector.

I'll assume that the other three injectors are doing the same thing since the engine will run with at least three injectors, and the engine does not even give an inkling of ignition.

Ideas?

The engine ran before I took the valve cover off and made the repairs, there's no way four injectors could go bad. I'm leaning towards a computer or wiring issue.

racertracer · **Posted:** Fri Mar 09, 2012 10:15 am

galatron wrote:

I'm leaning towards a computer or wiring issue.

X2.

Re-check all harness connections twice.

Especially check the computer harness connection, is the connector all the way in and locked securely?

I would remove each connector and re-attach using a little dab of dielectric grease

maxwellp · **Posted:** Fri Mar 09, 2012 10:20 am

Check the cam sensor and the crankshaft sensor. It sounds like the ECM does not know that the engine is being turned over.

galatron · **Posted:** Fri Mar 09, 2012 10:27 am

Ok, I did take the cam sensor out of the valve cover.
but it went back in the same way it came out.. o-ring and all
All the electrical connectors when unplugged throw a code - right?

racertracer · **Posted:** Fri Mar 09, 2012 10:38 am

Not necessarily.

On one occasion, my viscous heater was unplugged and it didn't throw a code.

Trace back your steps, could there be any other questionable electrical connections that you might have overlooked?

Inspect the wires for a crimp or a tare, a pinched wire is not an uncommon thing either that even the best overlook.

I would carefully re-check and re-connect every electrical connections ... it is the easiest and simplest variable to eliminate right off the bat.

galatron · **Posted:** Fri Mar 09, 2012 10:54 am

how does the camshaft sensor work besides "non contact method"?

from 14-79 2k5 FSM
"The camshaft position sensor is mounted on the
cylinder head cover toward the rear of the engine.
The camshaft sensor utilizes a non contact method
on one segment of the camshaft to record the camshaft
position. When the ECM receives the signal
from this sensor, it can then detect TDC of cylinder
number one. The signal from the camshaft sensor is
only required during engine starting. Injection timing
is synchronized by means of the camshaft signal and
the crankshaft signal (Fig. 5)."
and page 14-80
"On the camshaft sensor’s signal line, a high signal
correspons to a voltage of 0-5V. If the segment
machined into the exhaust camshaft sprocket is positioned
opposite the camshaft sensor, the camshaft
signal is low, approximately 0V. This signal is used
by the engine control module (ECM) for detecting
ignition TDC of cylinder 1 as the engine rotates. If no
signal is supplied by the camshaft position sensor,
the vehicle will not start because cylinder order can
not be detected. If the signal is lost while the engine
is running the vehicle will continue to run untill shut
off."

racertracer · **Posted:** Fri Mar 09, 2012 10:59 am

A question for Keith at GDE?

maxwellp · **Posted:** Fri Mar 09, 2012 12:18 pm

It is a Hall Effect sensor - I copied this for you.

A Hall effect sensor is a transducer that varies its output voltage in response to a magnetic field. Hall effect sensors are used for proximity switching, positioning, speed detection, and current sensing applications.

In its simplest form, the sensor operates as an analogue transducer, directly returning a voltage. With a known magnetic field, its distance from the Hall plate can be determined. Using groups of sensors, the relative position of the magnet can be deduced.

Electricity carried through a conductor will produce a magnetic field that varies with current, and a Hall sensor can be used to measure the current without interrupting the circuit. Typically, the sensor is integrated with a wound core or permanent magnet that surrounds the conductor to be measured.

msilbernagel · **Posted:** Fri Mar 09, 2012 1:49 pm

I haven't looked at the electrical diagram to see if it's necessary - but you might want to clamp a jumper cable on the body of the injector and onto the battery ground just in case being grounded to the engine is necessary for the test?

Just to confirm, you didn't take the pressure sensor off the end of the fuel rail and then re-install it, did you?

Sounds like you are homing in on the problem - that cam sensor appears to be required to tell the ECM to fire the injectors... if you have access to an oscilloscope you could look for the 5VDC pulse. :wink:

Good luck - we're rooting for a fast recovery! Only wish we were closer so we could kibbutz with a cold one.

Mark

galatron · **Posted:** Fri Mar 09, 2012 2:02 pm

I do have an o-scope I used it on the injector and saw what I thought was a square wave.
I did NOT remove the pressure sensor or the other thing off the fuel rail.
The injector is grounded through the fuel rail, and the valve cover.
I'll be hooking up the scope to the cam sensor tonight.

THANK you ALL for all your help. I really appreciate it!

Rabert · **Posted:** Fri Mar 09, 2012 2:03 pm

I don't know if our CRD has them but check the ground straps if we do.

galatron · **Posted:** Fri Mar 09, 2012 2:09 pm

I didn't haul the engine, and the engine ran before I did the valve-train work. I must have misaligned the cam sensor, or stretched a wire out... we did joke about burning a fuse.. but all fuses checked out.

Sir Sam · **Posted:** Fri Mar 09, 2012 7:51 pm

battery fully charged?

galatron · **Posted:** Fri Mar 09, 2012 10:24 pm

Battery fully charged
good compression
no fuel coming out of injectors

I checked voltage to the cam sensor
It has three leads. Ground. 2.5 volts and 5 volts

msilbernagel · **Posted:** Sat Mar 10, 2012 1:47 am

It's out of left-field, but this sounds a little like when we put the Cummins in our Suburban. The security module didn't come with the stuff from the wrecking yard - and the ECM is keyed to it by serial number. When the ECM failed to detect that module - which picks up the embedded chip in the ignition key -- it turns off the injectors.

Since they're both Chrysler/Dodge products... who knows?

I wonder if there's a code that could accessed with a consumer OBDII scanner, or if you need the service tech's DRB-III to find out if the security feature's been triggered.

Mark

Joe Romas · **Posted:** Sat Mar 10, 2012 9:17 am

Mark.

I was playing with a cheap scanner once and got my computer(s) confused :dead:

The engine would start but die within a few seconds.
When GDE flashed my ECM in the car the original computer locked up and would not even crank.
So I'm not sure if a crank but no start is a indication of a security problem :?:

Billwill · **Posted:** Sat Mar 10, 2012 10:28 am

I doubt it is a security problem...if you have the SKIM light (key symbol with a slash through it) flashing or ON all the time then you have a problem with the ECU not recognising the chip in the key. The motor will turn over but not fire.

You have not done any work near the SKIM area so I believe you need to stick to basics and go over step-by-step of what you actually did when you removed the valve cover....a scope on the cam sensor...measured at the ECU...should be a pointer in the right direction.

Are there no engine codes set?

galatron · **Posted:** Sat Mar 10, 2012 11:15 am

No engine codes set. That is what is really driving me nuts. I checked voltage at the cam sensor but did not get a chance to put the scope on it. No skim light on while cranking but I will try the other key. I had a dream last night that it started with the other key... so many there's something to that!

racertracer · **Posted:** Sat Mar 10, 2012 12:26 pm

I had a dream too.... mine was of winning the powerball, maybe there's something to it.

I've decided to play the lotto on the premise that your other key starts the car.

galatron · **Posted:** Sat Mar 10, 2012 12:56 pm

Don't do it :roll:

The other key didn't work...
I'm at a loss now.

Injectors not firing after valve cover removal. SOLVED!

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