Possible IP issue

Rdnck84_03

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I have randomly been having some issues with my '83 that I believe are IP related. It will on occasion sound like the timing is really advanced and idle at around 1100 rpm.

A little back story so we're all on the same page here. I got this truck somewhere around '16 shortly after purchase I put injectors in it (parts store reman) hoping to cure the terrible smoking on acceleration and some other issues. That didn't help, in about '19 on the advice of Wes I swapped the IP for a low mileage rebuild that had been sitting a couple years.

On the first startup the idle was really high (1400ish), after a few shutdown and restarts and letting it run for about an hour the idle was down around 1100. After putting a couple hundred miles on it everything seemed to be working as it should.

About a year or so later I drove somewhere and noticed that the idle was hanging up around 1100 rpm again and that the timing seemed really advanced. Shut it off and did whatever I was doing, started it back up to leave and everything was back to normal. Have had it do this maybe 3 times total.

Now last Sunday I decided to go fill it up with fuel, had been sitting for about a month maybe more. Started perfect as always, drove the 6 miles of county roads to the highway then 10 miles of highway to the truckstop I always use everything is normal. Fill it up, drive the highway back with the cruise on, everything as it should be.

When I get back to town and turn on to a side street and start accelerating I notice that the timing sounds advanced and the idle was hanging around 1100 between shifts. By the time I got home with it everything was back to normal.

I have been driving it to work this week and it is all over the place. Sometimes when started it will be fine but by the time I get to work it is screwed up. Other times it will be screwed up when started but be back to normal when I get where I'm going.

I'm going to go get a new filter in the morning and do an atf treatment on it. I am thinking something weird is going on in the pump but I am open to anyone's thoughts.

James
 

The_Josh_Bear

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I'm going to go get a new filter in the morning and do an atf treatment on it. I am thinking something weird is going on in the pump but I am open to anyone's thoughts.

James
That's where I'd start too. Sounds like a sticking metering valve.
 

IDIBRONCO

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Here's another weird thought. Maybe try leaving the fast idle switch unplugged for a while and see what that does. Maybe something really unusual is happening with that electrical circuit? Honestly, I doubt that it will change anything, but it's free to try and is easy to undo if nothing changes.
 

Rdnck84_03

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@IDIBRONCO I definitely won't rule that out as a possibility but mine are wired independently on toggle switches.

I can also hear the timing advance more when I toggle the cold advance. Haven't tried playing with the high idle when it's screwing up.

James
 

IDIBRONCO

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I can also hear the timing advance more when I toggle the cold advance. Haven't tried playing with the high idle when it's screwing up.
Never mind then. In your case, it can't happen. Ok it can, but the chances of my W A G happening is probably around 5% or less. The chances of it happening to your truck is less than 1% of that. In other words, it's 0% for all practical purposes.
 

Rdnck84_03

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In other words, it's 0% for all practical purposes.
This was my thoughts also.

I did get a new filter and gave it an atf treatment this morning. Didn't let it sit as long as I would have liked because I had to drive it home. It got about 6hrs of soak time.

Took it for a run on the highway before I came home, drove it hard up to highway speed and then set the cruise and ran about 10 miles.

Turn around and head back and gave it hell in first and second, went easy on third and short shifted into 4th at a little under 40mph and hit the resume button. Pulled hard and fast back to speed.

I does seem to still be a little advanced but much better than it has been the last couple days. I also dumped a couple quarts of atf in each tank to keep cleaning it up.

Guess time will tell the story now.

James
 

Rdnck84_03

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Figured I would give a little follow-up on this. Truck is still running good after the atf treatment. Drove it to work all last week with no further issues.

James
 
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