7.3 Dies Returning to Idle

Spire · Mar 28, 2015

Truck starts good, idles good, and runs good. It will die every time I let off the throttle. It does it in gear moving, it does it sitting in the yard in neutral. It only happens when its warm.

Last year I added a Carrier electric fuel pump and replaced the injector return parts. All hoses and belts are new also. Nothing else has been done to this truck. I have never checked or messed with the timing.

Any ideas where to start?

The Warden · Mar 28, 2015

I had a similar problem...it didn't die, but when returning to idle, it took a second longer than it should for the injector pump to start sending fuel to the injectors again...the idle would get so low that it almost died, then once the pump caught back up, it'd come back to idle.

I was told at the time that a metering valve in the pump was sticking and to severely overdose both tanks with a fuel lubricity additive. I did that and, after a few tanks of better-quality fuel and the overdosing, the problem went away and hasn't come back ;Sweet

gandalf · Mar 28, 2015

Spire said:
Truck starts good, idles good, and runs good. It will die every time I let off the throttle. It does it in gear moving, it does it sitting in the yard in neutral. It only happens when its warm.

Last year I added a Carrier electric fuel pump and replaced the injector return parts. All hoses and belts are new also. Nothing else has been done to this truck. I have never checked or messed with the timing.

Any ideas where to start?

My best guess is that the metering valve in the IP is sticking. This is a classic symptom.

Here's the fix which usually works. Pull the fuel filter off and empty it or replace it. Fill the new filter with ATF. Fill it through the outer ring of holes only. Very carefully replace the fuel filter on the engine. Try not to spill too much ATF. Start the engine (it will be quite happy burning ATF), and let it run only long enough until you hear a slight change in the sound, maybe 20 seconds. Then shut the engine off and let it sit overnight. Next dat start the engine and drive it like you stole it. Give it a workout.

The ATF will clean the metering valve, and driving it hard will help.

Report back with results.

bbjordan · Mar 28, 2015

Check the timing. If the timing is too retarded that can happen. If you haven't changed the fuel filter in a while, you might try that as well.
The Warden may be right about the fuel too. I am currently running an alternate fuel, and have the same problem with the engine dieing.

Spire · Mar 28, 2015

Filter is almost new (half tank through it). Dropped filter, drained, poured ATF in outer holes, reinstalled, ran truck for 1 minute.

Never heard it change sound, but shut it off and will let it sit till tomorrow.

SLC97SR5 · Mar 28, 2015

I had a similar issue with the Truck dying and stumbling when the transmission was placed in reverse on a cold start.

I dosed the rear tank with 80oz of PS Diesel Kleen and 32oz of 2 stroke oil. I topped off the tank with fuel and drove it normally.

My Truck runs pretty well but it has never run smoother than burning that tank of fuel.

The problem has not returned.

FORDF250HDXLT · Mar 28, 2015

mine will do this from time to time.a good couple quarts of atf in the tank cleans her right up as rain again.

Spire · Mar 29, 2015

Went out to start it this afternoon and cranked and cranked and no start, ran the batts low. Charged both batteries, and still wouldn't start.

Let the Carrier pump run for a few minutes and it fired right up. Runs better than it ever has (since I bought it).

Original issue of crapping out on deceleration is completely gone.

Dumped a half gallon of cheap ATF in the tank and ready to rock.

Thanks to all that helped!!!

7.3 Dies Returning to Idle

Spire

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The Warden

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gandalf

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bbjordan

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Spire

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SLC97SR5

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FORDF250HDXLT

The life of an Indian is like the wings of the air

Spire

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