1997 7.3 will not start.
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New User
Joined: Jul 2012
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Ok thanks nate I will try and track one down to swap it with. Thanks Very much. A quick Q I was told above a bad O ring could cause it not to start. since a O ring could cause a no start then I assume one bad injector could cause a no start?
Post Fiend
Joined: Dec 2010
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From: Orrville, Ohio
Not typically. If the injector has a bad solenoid, the IDM may see that and shut down the entire bank, but if the injector is just bad internally, I would think it would start and just miss on that cylinder.
The reason that blown o-rings can cause a no-start condition is that the blown o-ring can allow enough of the oil to bypass that the HPOP can't build enough pressure to fire the injectors. If that were the case you wouldn't see any smoke from the tailpipe.
If you suspect a bad injector may have the IDM shutting down a bank, the best bet is to ohm them out individually and compare the readings. You're looking for around 3.2 ohms per injector solenoid. You can ohm them through the valve cover harnesses to eliminate that as a possibility as well. Use the center (common) pin and the two pins on either side of it. The pins lay out as follows: GP-Inj-Com-Inj-GP. If you have one that is bad, you will see that it is a lot different reading than the others.
The reason that blown o-rings can cause a no-start condition is that the blown o-ring can allow enough of the oil to bypass that the HPOP can't build enough pressure to fire the injectors. If that were the case you wouldn't see any smoke from the tailpipe.
If you suspect a bad injector may have the IDM shutting down a bank, the best bet is to ohm them out individually and compare the readings. You're looking for around 3.2 ohms per injector solenoid. You can ohm them through the valve cover harnesses to eliminate that as a possibility as well. Use the center (common) pin and the two pins on either side of it. The pins lay out as follows: GP-Inj-Com-Inj-GP. If you have one that is bad, you will see that it is a lot different reading than the others.
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Wow thanks for the info. You guys are great thanks very much I will try the IDM. Also could a short in the wiring harness somewhere be causing this? and can I put a meter on the plug that goes to the injecters to see if they are getting the command to fire?
Mountain Pass
Joined: Aug 2006
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From: Virginia
i know ive had problems with the solenoid on the fender and the actual starter i know it doesnt explain why your truck was running real rough but could be why its not starting.. i would look over the wire harness going to the valve cover gaskets again i know you said you checked already but before you go any spend a bunch of money on sensors and parts i would make sure the wiring for the idm all the way to the injectors looks good.. nothing worse then buying parts not needed..
Thanks and good luck to the original poster.
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The solenoid on the fender just engages the starter. when they go bad you hear a clicking noise. It can be jumped out with a screw driver. If your starter works when you turn the key then the solenoid is working.
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Well I took it to the dealer so they could hook the computer up to it and it didn't show anything but while the truck was running the the guy moved the harness around by the air intake box and 3 wires were just barely shorting out on my metal k&n intake box but when harness moved around it would run bad
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Try putting a different idm in like said before if you can find one .. that will at least tell you if that's the problem or not .. If its not I would go back to inspecting the harness .. sorry I haven't been very detailed its hard to type a lot on this dang phone..
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Hey guys update I got it running. Very rough though. I disconnected the injectors from the valve cover gasket 1 plug at a time starting passengers side with no difference either time then I unplugged the front drivers side and the engine shut right down. I tested the wiring using ( GB Remanufacturing - Tech Bulletin #103 ) this tech bulletins directions and all the wiring tested good with no shorts and all injectors tested 3.2 ohms. So my assumption is a bad idm that is only firing the drivers side. I cant find one to plug in and test to see if it fixes my problem so I need to buy one. But before I do I wanted to ask if anyone has any idea if it could be something else causing the passenger bank not to fire?
Post Fiend
Joined: Dec 2010
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From: Orrville, Ohio
Did you ohm the injectors back through to the connector at at the IDM?
I would ohm them back to the connector at the IDM, if it looks good to there, I think the next thing you need to try is a different IDM.
Essentially you need to check the resistance between the feed to the bank (pin 23 or 24) and the feed to the individual injector. That should net you the same readings you got between the common pins on the VC's and the Injector pins. So you would ohm pin 23 to 7,9,19 and 22 individually and that will give you the resistances for the wiring and injectors on that bank and then you check pin 24 against pins 6,8,19 and 21 to get the resistances for the other side.
I would ohm them back to the connector at the IDM, if it looks good to there, I think the next thing you need to try is a different IDM.
Essentially you need to check the resistance between the feed to the bank (pin 23 or 24) and the feed to the individual injector. That should net you the same readings you got between the common pins on the VC's and the Injector pins. So you would ohm pin 23 to 7,9,19 and 22 individually and that will give you the resistances for the wiring and injectors on that bank and then you check pin 24 against pins 6,8,19 and 21 to get the resistances for the other side.