7.3 Intermittent Cutting Out

spencer922 · Jan 3, 2021

Hi all,

I apologize for the poor quality but I was lucky enough to catch the problem in action. Does anyone have an idea of what might be causing this type of RPM cutting out? Truck is all stock except for TS style rotary chip with 284,000 miles with automatic trans. It is a 1995 which rules out use of OBDII scanner for me.

Pedal input does not seem to change the situation, there does not seem to be characteristics between occurrences ie, it happens on both fuel tanks, at several different ambient temps, multiple locations within the heat cycle (hot/cold/etc). I do not have to re-cycle the key, the truck will somewhat stay running but its almost like HPOP/fuel system shuts off momentarily and rest of truck continues running.

Couple of things that I have already checked -

1) IPR Nut tight and body or valve is snug
2) ICP sensor relatively new and relatively dry (not a lot of oil in there and has been replaced in previous 10k miles)
3) Exterior valve cover harness plugs show no burn marks or other discoloration
4) Wiring harness appears in good shape in location that it comes into contact w/ valve covers.
5) Oil level

Things that I have not checked -

1) CPS - have not had a chance to replace yet, don't remember last time I did one. Planning to do this this week as work allows.
2) Removing my TS chip to see if its connection has something to do with the problem
3) Somehow testing IDM/PCM -?

I was unable to find someone that described this same situation online when I searched so I was hoping that posting a of the situation would help identify the issue.

https://youtu.be/HDQVMLqip3I

Spencer

psduser1 · Jan 3, 2021

If you can't watch hpo on a scanner, or fuel pressure, you'll need a mechanical gauge for both.
Aside from that, at 285k, I'd guess its time for new injectors, assuming fuel pressure and hpo are up to par.

spencer922 · Jan 3, 2021

The HPOP and in-valley fuel pump were replaced by a shop within the last 6 months (<5k miles ago) which leads me to believe that they should be working properly. Truck does run well with the exception of this hiccup.

That being said I made up a HPOP gauge 10 years ago so I can dig it up and check that myself. For fuel gauge I'd have to investigate how to rig one up...

Would injectors create that kind of issue? The reason I ask is that I am about 95% certain that these are the original injectors (the previous owner was family) and I have no idea what the symptoms of worn out injectors on 7.3's are.

gostrider · Jan 5, 2021

Im just a newbie myself but I think you can use an OBDII scanner on your truck. I have a 95 F350 and I use the BAFX dongle with forscan and car gauge apps on my android phone. It's very inexpensive(only around $20) and the data it provides is priceless at times. I hope this helps

Sent from my SM-N950U using Tapatalk

spencer922 · Feb 9, 2021

Went back through checked the harness. Could not find any noticeable nicks. Then I went to pull the chip and the wire had worn through on top of the emergency brake bracket. Wrapped it up and have not had trouble since. Granted it’s only been about 40 miles and 3 days...