7.3 Engine RPM's?

Alaskaman

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Finally I have all the fuel leaks and Brakes fixed on my 1993 F250 7.3 IDI Turbo with a 5 speed.

Took it out for the first test drive since I bought it and now I have a question about the RPM's.

It will only go up to 3000 rpm's unless I'm going down hill wide open and it will creep up to 3100-3200 rpm's.

Seems like I should have at least 3500 rpm's. If that is true, how can I adjust it up?
 

Clb

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Do not sustain "floored" for to long...
Just in case you ya do not want to let out the rods.
 

Alaskaman

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At 3000 rpm's, I can hold it there all day. My old 88 7.3 did that at 60 mph with the 3 speed automatic.

I'll check floored in Neutral tomorrow and get back with you.
 

Macrobb

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Do not sustain "floored" for to long...
Just in case you ya do not want to let out the rods.
Uh... no. It's not a gasser. The IP has a governor in it which is below the "indefinate safe limit" of the engine. Typically around 3400-3600 RPM. My Ford owners manual states to keep the engine RPMs below 3750 RPM(higher than the governed limit).

Flooring it will give it full fuel until it gets to about 3,000 RPM, at which point the IP will start throttling back fueling until it hits a steady-state(RPMs stay constant, fuel delivered is just enough to maintain that under current load) around 3400-3600.
 

Clb

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Yessir
In a perfect world, yer right.

Now is an eng. That refuses to tach up in a perfect world?
Do we know the op will know what a runaway sounds like?

Don't forget Justin makes a 4k governor spring....

Op check throttle linkage?
Check ip linkage?
Check timing?
Check go pedal for full swing?
 

Alaskaman

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After my maiden trip today, I have found out the most likely problem, but don't know how to fix it.

My tachometer is giving faulty readings. In neutral it will give up to 3600 RPM. However, when I'm driving it down the highway it may show 500 RPMs or 3000 RPM.

Bad gauge or electronic sensor?

I do know what a run away diesel sound like. I experienced it first-hand on my John Deere backhoe. Not a pretty experience.
 

IDIBRONCO

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The first thing to try is the magnetic pickup that is on the upper part of the injector pump gear cover. Check to see if the magnet has debris on it. Check to see if the wires are bare and touching. You could buy another pickup if everything else checks out. Maybe someone else will have another test that you could do before you start buying new parts.
 

MtnHaul

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My tach recently went wonky on me. Just tried cleaning the pickup and connector, the wires look OK but little improvement, though there was some.
 

Alaskaman

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Just an update, I have been swamped with company for a month & out of state visiting my new Great Grandson.

I'll post my findings hopefully this coming week. Thank you.
 

Alaskaman

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Well, its been more than a week and more pressing projects have come up.

However, I noticed that when I do drive the truck at speed, the RPM's are normal. The one exception is when I put my turn signals on, the reading drops about 500 rpm's.

Bad ground? Perhaps the installers of the after market stereo? The replaced Instrument cluster?

Since I just purchased the truck a couple of months ago, I'm not sure what has been done to it.
 

chris142

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Is the 6.9 governed higher? Mine will fuel right up to 3800.
 

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