how to check for leaky injectors

TK_05 · Feb 21, 2004

my car is dieseling and i think one of the injectors might be leaky.. how do i check for a leaky injector w/o taking off the actual injectors?

ironmedic · Feb 21, 2004

take the upper manifold off and prime the system off and on with your keys in the acc position about 5 times. just have someone watch

TK_05 · Feb 21, 2004

IronMedic said:
take the upper manifold off and prime the system off and on with your keys in the acc position about 5 times. just have someone watch

how would this tell if the injectors are leaky? i think there actually leaky in the combustion chamber.. causing it to diesel.. because the engine bay does smell like gasoline

jerry beach · Feb 21, 2004

You need to locate where the gas smell is coming from. If they are leaking into the combustion chambers, then you should get a puff of black smoke out of the pipes when you start it up. Run the engine till warm and shut it off, then start it up after only a few min. If you let it sit too long, the fuel will evaporate.

Pull the spark plugs and see if they are wet. Smell them. This is a good way to tell.

Your timing may be off, or your idle may be too high. Did it just start doing this one day, or was there something that led up to it? Have you worked on anything recently?

TK_05 · Feb 21, 2004

jerry beach said:
You need to locate where the gas smell is coming from. If they are leaking into the combustion chambers, then you should get a puff of black smoke out of the pipes when you start it up. Run the engine till warm and shut it off, then start it up after only a few min. If you let it sit too long, the fuel will evaporate.

Pull the spark plugs and see if they are wet. Smell them. This is a good way to tell.

Your timing may be off, or your idle may be too high. Did it just start doing this one day, or was there something that led up to it? Have you worked on anything recently?

sorry i wrote that wrong... my engine bay does NOT smell like gasoline... my car does not puff black smoke when it starts up... none of my plugs smell like gasoline.. none of them are wet... my timing is at 14* and my car idles fine... its been doing it since i got it i just never thought anything of it... i even did a head gasket swap and continued you to do it... all the injectors look fine visually from then

TK_05 · Feb 22, 2004

BlackFox5.0 · Feb 22, 2004

Acording to my Haynes book, it says causes for "Dieseling" are:

1: Idle speed set to high
2: Ignition timing incorrectly adjusted
3: Thermo-controlled air cleaner heat valve no operating properly
5: Excessive engine operating temp. Probable causes of this are malfunctioning thermostat, clogged radiator, or faulty water pump.

Hope that helps

TK_05 · Feb 22, 2004

BlackFox5.0 said:
Acording to my Haynes book, it says causes for "Dieseling" are:

1: Idle speed set to high
2: Ignition timing incorrectly adjusted
3: Thermo-controlled air cleaner heat valve no operating properly
5: Excessive engine operating temp. Probable causes of this are malfunctioning thermostat, clogged radiator, or faulty water pump.

Hope that helps

yea i read the book... im not even sure what, 3: Thermo-controlled air cleaner heat valve no operating properly, is...

jerry beach · Feb 22, 2004

TK_05 said:
yea i read the book... im not even sure what, 3: Thermo-controlled air cleaner heat valve no operating properly, is...

Your car doesnt have one. Is it possible that you motor is running a little hot? I would move the timing first and see if that makes a difference. You did set the timing with the spout out right? Just checking Is it possible there is carbon built up in your combustion chambers? Are you getting any pinging at high rpms or under heavy loads.

TK_05 · Feb 22, 2004

jerry beach said:
Your car doesnt have one. Is it possible that you motor is running a little hot? I would move the timing first and see if that makes a difference. You did set the timing with the spout out right? Just checking Is it possible there is carbon built up in your combustion chambers? Are you getting any pinging at high rpms or under heavy loads.

hot nope, timing nope (set it to many diff. degrees, same result)... CC's are clean because i just changed the headgasket not 500 miles ago... no pinging... car runs like a champ except when i turn it off lol...

jerry beach · Feb 22, 2004

I am guessing that your car is an auto. Shut it off in gear. This should stop the run-on. I had one running on because of a vacuum leak. That is something you could check for. Go up a grab a vacuum guage if you dont have one and test away. If you car is not heavily modded, this will tell you alot.

TK_05 · Feb 22, 2004

jerry beach said:
I am guessing that your car is an auto. Shut it off in gear. This should stop the run-on. I had one running on because of a vacuum leak. That is something you could check for. Go up a grab a vacuum guage if you dont have one and test away. If you car is not heavily modded, this will tell you alot.

yea but is there anyway to fix that? i dont really want to shut it off in gear all the time...

jerry beach · Feb 22, 2004

TK_05 said:
yea but is there anyway to fix that? i dont really want to shut it off in gear all the time...

I really didnt mean for that to be a cure, just a temp fix till you figure out whats up. So have you pulled codes? Pay attention to the EGR valve, block it off and see if things get better. Like I said start checking for vacuum leaks, visual test first...I am running out of ideas fast, but you will find it.

HISSIN50 · Feb 23, 2004

in the past when i was lazy (like im not now.LOL), swapping to a different heat range of plugs took care of it.
carbed cars use to diesel frequently compared to injected stuff. as usual, Jerry is like a greyhound when it comes to diagnostics; i like his ideas.

while playing with it, i might hook a DMM to the injector harness (specifically the computer input), and see if the input is being killed immediately with the key going off im tossing out the long shot idea that the EEC does not shut down immediately and is pulsing the injectors once the car is off. i think that one part of the EEC stuff stays awake after the car is killed to "reset" parameters of the sensors. im not positive on that (i really need to finally get a Probst manual. Jerry, did you get one?).

my random thoughts. good luck.

TK_05 · Feb 23, 2004

ill try the DMM on the injector thingy... i dont think its the plugs i think its something electrical because if i start it up.. key off then key right after it will stay running...

jerry beach · Feb 24, 2004

TK_05 said:
ill try the DMM on the injector thingy... i dont think its the plugs i think its something electrical because if i start it up.. key off then key right after it will stay running...

Are you saying that you have to fool around with the ignition switch to keep it running now? I would replace that switch, or pull it out a cable tie it back together like many do. Then like to fall apart.

Oh and the multimeter will not work at all on the injector harness. I never tried it, but that is what I have read and been told. That is the purpose of a noid light, but if they are still cycling after the engine is off, you would hear the clicking sound they make right after you shut it down.

HISSIN50 · Feb 24, 2004

Jerry is right about the noid light on the actual injector connectors. i was talking about checking power in the harness to see if there is juice/ground present once the car is off (i.e., bad EEC relay) before it goes to each injector. thinking about it now, i dont think one can do that (injector pulse comes straight from the computer, i think). my bad.

listening for clickin injectors is a good idea.
i like the ignition idea, based on what you said before and then again now. you can check for continuity when it does not work, or just swap it out. they smoke themselves all the time.
good luck.

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