OBS no start

powerstrokinfirefighter · Feb 18, 2016

Posting for a buddy. It's my old truck, 94.5 with close to 300k on it. He called a few weeks back and said the injectors weren't firing. He's replaced CPS, ICP, IPR and is still having the same issue. I don't think he used Ford CPS or ICP which I recommended he change those out. Anything else to look into? I'm no 7.3 expert at all, as it ran great for me. Any help is appreciated.

79jasper · Feb 18, 2016

Is it chipped?
Maybe check the idm for water.
Check the fuel heater and pcm fuse.

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powerstrokinfirefighter · Feb 18, 2016

79jasper said:
Is it chipped?
Maybe check the idm for water.
Check the fuel heater and pcm fuse.

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It had a TS 6 position when I sold it. I'm pretty sure he pulled it a few months back after it gave him issues. IDM was our next thought.

Magnum PD · Feb 18, 2016

Oil level, is rpm gauge moving?

6.0 Tech · Feb 18, 2016

Fuel pressure? Seen quite a few hi pressure fuel pumps die. Havent seen many of the low ones die.

Constructionworker · Feb 18, 2016

A fried IPR circuit in the PCM can cause a no start.

powerstrokinfirefighter · Feb 18, 2016

Oil is good, and tach is moving. He said he's talking with TJ (isootmypants) on here, he's got a he'll of a lot more knowledge then I do so hopefully it'll get figured out.

79jasper · Feb 18, 2016

6.0 Tech said:
Fuel pressure? Seen quite a few hi pressure fuel pumps die. Havent seen many of the low ones die.

You haven't worked on many 7.3's have you? Lol
Just one pump on these. Mechanical in the valley on the obs. Electric on the frame on the SD.

Seems like should be a easy fix.

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6.0 Tech · Feb 18, 2016

79jasper said:
You haven't worked on many 7.3's have you? Lol
Just one pump on these. Mechanical in the valley on the obs. Electric on the frame on the SD.

Seems like should be a easy fix.

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You forgot about the lift pump n the side of the block...

Unless im getting idi and obs put on the same truck in my mind. I thought there was one athere too.

Magnum PD · Feb 18, 2016

One cam operated fuel pump in the valley. That's it for the 94-97 7.3's

Magnum PD · Feb 18, 2016

No smoke from tail pipe I guess. Need to see if he's getting High pressure oil to the injectors.

6.0 Tech · Feb 18, 2016

Ok my bad, i thought i remembered a lift pump like a carbuerated car. Explains why i aint seen many of those fail

LOL

6.0 Tech · Feb 18, 2016

No smoke from the tailpipe could also be 0 fuel pressure.

Patrick Feeley · Feb 18, 2016

Fuel pump on the OBS PSD is a 2-stage pump right in the middle of the engine valley. Does the WTS light come on?
Is the CEL illuminated?
Oil Level good?
What's fuel pressure at the shrader valve (driver's side of the filter bowl) when cranking?
Check the condition of the wiring connections at the valvecovers for evidence of melting/burning.
Check the condition of the fuel bowl wiring harness, especially the IPR wiring. Fuel leaks do nasty things to the wiring insulation.
Cheers!

powerstrokinfirefighter · Feb 19, 2016

As far as I know, he's checked all the common stuff to no avail. He's about 300 miles away from me so it's all just phone calls and texts.

rusty1161 · Feb 19, 2016

I know it's been mentioned, but my IPR harness was bad, causing a no start. A picture is worth a thousand or so words, here you can seen the exposed copper of my harness

Rusty

Constructionworker · Feb 20, 2016

Any luck?

powerstrokinfirefighter · Feb 20, 2016

Constructionworker said:
Any luck?

Nothing yet, I know he was out on his bike earlier so I don't think he worked on it today. I'm gonna get ahold of him tomorrow and see what he's found out.