reading injector pulses

[UNGN]

Will injector output show up on a voltmeter? Or do you need a "noid light"? Where do you get a "noid light" anyway?

I've got lots of spark and fuel pressure, and the cam sensor is timed right and the crank sensor is set, but it just won't start. The spark plugs look wet when I removed them after cranking, but when I cranked the motor over with an air hose in the spark plug hole, only dry air came out. No gas, anywhere.

After cranking for a few minutes, the upper plenum is warmer than the exhaust manifolds, so no combustion appears to be occuring in the combustion chambers

This is baffling. I verified all the valves were sealing (with compressed air) and verified the timing chain was installed properly.

Anyone have any ideas?

 

[John Larkin]

It'll show up on a digital voltmeter. I've done it. I used some paperclips to backprobe the wires but yes, it will work. I can't remember the numbers I saw but I was just looking for consistency across all 6.

 

[bruce]

Originally posted by UNGN
Will injector output show up on a voltmeter? Or do you need a "noid light"? Where do you get a "noid light" anyway?

Check your fuses first.
Then check for spark.
Then fuel.
The ecm needs power, and an ignition pulse before it does anything.

Most parts houses have noid lights, but any small bulb will get you by. You just want to see it flicker a few times when you crank the motor over.

 

[Chuck Leeper]

SPARK??

You say you have fuel and spark, but not starting.. Sounds strange. If both elements are present, even tho they be out of time. something would occur!! A backfire, a warm exh pipe, SOMETHING... Not just wet plugs.
If the crank sensor was removed.. was it put back in the right slot?? [slot away from the plug.]
Has the engine been disassembled??
The noid is available from most any reputable auto parts store.. Mine was $7.00

 

[UNGN]

Re: SPARK??

Originally posted by Chuck Leeper
You say you have fuel and spark, but not starting.. Sounds strange. If both elements are present, even tho they be out of time. something would occur!! A backfire, a warm exh pipe, SOMETHING... Not just wet plugs.
If the crank sensor was removed.. was it put back in the right slot?? [slot away from the plug.]
Has the engine been disassembled??
The noid is available from most any reputable auto parts store.. Mine was $7.00

I didnt say I have fuel, I've got fuel pressure. It appears that getting from the rail to the cylinders is a problem. The wet plugs may be from the injector leaking down.

The crank sensor was put back where it always was, but I slightly adjusted it to get the gap even. I still need to verify if its working.

The top half of the motor was disassembled, but the timing chain is verified to be correct (using two other timing chains for reference) and the valves seem to open and close properly, with none sticking.

What fuses could cause this? the fuel pump, fuel injector Fuse?

 

[Chuck Leeper]

FUSES, etc

If you have fuel pressure, the pump is coming on at least during the prime sequence. Does the fuel pressure stay up while cranking?? [the noid will tell you if they are pulsing during cranking]
When you said spark plugs were wet, one would assume you meant the inj's were working... I doubt all the injectors are leaking down If they are, I'd suggest they be cleaned and flow checked B4 continuing, or trying to tune the engine, once it does start.
As for the crank sensor.. if it's not working, there would be no spark...
Check all the fuses related to the engine operation.. Is the F pump relay bypass plugged into the pressure sw at the turbo oil line outlet??

 

[WarpSpeed]

Right,, also, you can check for power at the injector,, first, there should be a constant 12v+ on one side(at all 6 leads), second, the injector pulse is a negative signal....
(it'll look like @ 3v on a meter, but doesn't mean anything except the ecm is pulsing the injectors.) You can use the 12v power lead on back of the altenator for + when testing. Someone will have to crank the motor over of course.
Check the grounds on back of the head,, I think one of those powers the injector drivers.)

ps: Have you tried kicking it?

 

[Black Car]

Here is an old trick to try.
Remove the up pipe from the throttle body, open the tb blade and spray/pour some gas in it. You can also use starter fuel.
Then try starting the engine. This should tell you something.

Gary