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Discussion Starter #1
Had damn fuel return line leak at the clamp on passenger side head. didn't have time to wait for new line so I removed cut and sleeved fuel line with hi pressure hose until new one comes in. In process I unplugged injector/glow plug harness passenger side for easier access. Upon putting together in rush I forgot to plug harness in and tried starting truck...no start figured was just air in lines so cranked for a while no joy....I then remembered harness plugged it in it started. Let idle for 10 mins or so looking for leaks. Got in for test drive max boost was 1 psi fuel pressure at 62 psi. Figured connector wasn't right so pulled and ohm out injectors at valve cover all 2.8 to 3.1 so reconnected harness and split at drivers side valve cover main idm harness juncrion....all driver and passenger side ohm within spec highest at 3.2 ohm. Started runs like ass....driver side exhaust manifold hot to touch passenger side was cold after 5 mins.... Could i have possibly burnt up IDM by trying to start while unplugged????
 

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No, but you could have dislodged the under valve cover harness connector while you were disconnecting the outside connector. They have a weak snap - Ford even sells a 2 cent piece of plastic (of course in a VERY expensive bag) to wedge into that clip to keep this from happening in the future. Some people cut a quarter to fit the slot - search 50 cent mod.
 

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Well - that's a good question. Missed the part about you ohming it. Still, the IDM doesn't care if it is plugged in or not - it will give a code - open high and/or open low when there isn't a connection, but it won't damage anything. Did you ohm to ground or to the center pin? I'm sure you know the connectors, but just to make sure GGIIHIIGG as you look across - G being glow plug, I injector ground, H high voltage. The injector ohm test being between the I and H leads.
 

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Discussion Starter #5
I tested using the center pin to all injector pins. Being the center pin is hi voltage can I test for 110v there?
 

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I've never tried that. You can check continuity back to the IDM harness connector. If you know anyone with any year 7.3 PowerStroke, you could try their IDM in your truck just to rule out a bad IDM.
 

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I tested using the center pin to all injector pins. Being the center pin is hi voltage can I test for 110v there?
You won't see 110V with the IDM just powered up. It only sends high voltage pulses when firing injectors, and the duration will likely be too short to even show up on a typical multimeter. IIRC, the base voltage on the center pin is less than 2V, even on a good IDM.
RT's suggestion of trying a working IDM is good. Even safer is installing yours in a truck that runs good. If it then runs like crap with your IDM, then that confirms yours is bad.
The 94-97 IDMs were prone to lose one bank. If you have a scan tool that can run an injector buzz test, that will tell you if the IDM is bad by coughing up a code.
 

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Discussion Starter #8
Gonna try test IDM understand there interchangeable 96 and up.
.just a weird deal. I did ohm out from the harness plug on valve cover all readings were about same 2.8- 3.0
 

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Gonna try test IDM understand there interchangeable 96 and up.
.just a weird deal. I did ohm out from the harness plug on valve cover all readings were about same 2.8- 3.0
You can use an IDM '94 or newer, as long as it comes from a Powerstroke.
There are slight differences in voltage over the years, but any will work.
IDM-100 early, IDM-110 later '94-97, IDM-120 '99 and up.
 

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Discussion Starter #10
Did more testing...all injectors buzzed and sounded same during buzz test. Codes pulled are p0263,269,275 cylinder contribution, p0476 ebp.
ICP DUTY CYCLE 26.1 at idle is early 99 7.3...any more ideas lol haven't tried idm yet was hoping buzz test would fail
 

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I’m thinking you aren’t getting fuel to that side. Maybe something with your repair. If that’s the case, I wouldn’t run it too much. You can crack a tip with low fuel pressure.


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Your ICP duty cycle is a bit high. You should be seeing around 10-12% at idle. Could indicate an HP oil leak, but your symptoms other than the higher ICP duty cycle don't indicate that.
 

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Discussion Starter #13
Would a pinched or clogged return line on passenger head cause it...confused Cruz getting good fuel pressure on gauges 60 psi which has always been
 

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There are no return lines unless you have an aftermarket setup.


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