Truck Dies When Rpm Brought Down

[NeverHave-I-Ether]

1993 F250 7.3 IDI N/A ZF5

Well it's an unfortunate day. When ever the engine is brought down from RPM it dies. I have fuel pressure. It used to only do this in cold weather on start up. I was told that not abnormal for IDI. Today when I let my foot off the accelerator on the highway the engine promptly died. Is this my IP?

Thanks,
Never-Have-I-Ether

 

[Jesus Freak]

I'd say fuel filter.

 

[NeverHave-I-Ether]

I'd say fuel filter.

Already changed it. I'm going to do the ATF trick next. Nothing else I can really do...

Truck stalls when rpms fall to idle! - Ford Truck Enthusiasts Forums

Pre-Power Stroke Diesel (7.3L IDI & 6.9L) - Truck stalls when rpms fall to idle! - Hello All, I have a 1991 F-SuperDuty with the 7.3 IDI and a 5 spd manual trans, The truck has been running great til a little while ago when it started doing something it has never done before. When the rpm's drop...

www.ford-trucks.com

Never-Have-I-Ether

 

[Jesus Freak]

Well dang. You could change it again, there was just a thread about messed up fuel filters. It might not just be the threads it might be the element too. Bad fuel maybe?

 

[NeverHave-I-Ether]

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Never-Have-I-Ether

 

[Farmer Rock]

Sounds like air intrusion to me...

Rock

 

[NeverHave-I-Ether]

Fuel system is 100% redone from IP to tank. E-fuel pump. Drive it 100 miles a day past two weeks. Air intrusion at the injector caps? It started doing this in my return trip home.

Thanks,
Never-Have-I-Ether

 

[gandalf]

This is the classic symptom of the metering valve sticking inside the IP.

Try the ATF treatment. Fill the fuel filter with ATF, start the engine and let it run until you hear it change it's note a bit, maybe 30 seconds. Shut it off and let it sit overnight with the IP full of ATF. The next day start it up and drive it like you stole it. If this works, if your engine seems cured, start saving your lunch money for a new IP. It will probably happen again. Your IP is starting to show it's age. It may last several years more, but be ready.

 

[NeverHave-I-Ether]

This is the classic symptom of the metering valve sticking inside the IP.

Try the ATF treatment. Fill the fuel filter with ATF, start the engine and let it run until you hear it change it's note a bit, maybe 30 seconds. Shut it off and let it sit overnight with the IP full of ATF. The next day start it up and drive it like you stole it. If this works, if your engine seems cured, start saving your lunch money for a new IP. It will probably happen again. Your IP is starting to show it's age. It may last several years more, but be ready.

I just tried running it off a gallon of ATF. I hard cut the fuel lines. It ran off it for a couple minutes then died on its own at idle

Going to attempt restarting it. If not I'll just let it sit overnight. Hopefully it'll start in the morning, but if it won't start now I feel like it won't start in the morning when I go to work.

If this doesn't do the trick, then what?

Never-Have-I-Ether

 

[NeverHave-I-Ether]

Upon recollection, I didn't have issues until I got 25 gallons of diesel yesterday at a CEFECO. I called and they said to speak to the manager in the morning. I don't know what they can do or if I got bad fuel from them. It ran like a top prior to that though. I doubt they'd do anything though and refund me, or cover a new IP.

I have the engine sitting in ATF. Ran if on a gallon of ATF out of a jug and will have to wait until morning....

Never-Have-I-Ether

 

[NeverHave-I-Ether]

After the ATF treatment;

Had to start with a gas rag, really hard to start. Ran for a minute, then died. Lots of grey smoke, a lot. Didn't restart. Instead of making it better the ATF made it worse. Darn.

Never-Have-I-Ether

 

[Jesus Freak]

Ya know, it's nice not having a truck payment. And it's nice having the title in your name. But from time to time, you have to "pay the piper". Fortunately, you know as well as I, when you make it over this hump she'll run good as new for a while longer and the repo man ain't going to take it away.

 

[NeverHave-I-Ether]

After the ATF treatment for 48 hours, wow.

It actually worked, it seems to be problem free. Ran it hard at 100mph for several minutes. The exhaust sounds deeper and puffs smoke. My blow by which was none existent is absolutely awful now. I'm guessing there was a LOT of carbon on the rings which is gone now. I literally had 0 blow by, now I have this:

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This proves how miraculous this treatment is in my opinion. After the 24 hours I for sure thought the IP was dead. After 48 hours, it's running and sounds different. Sounds amazing. Like it can breathe more. Disappointed with the blow by but happy it runs now. Going into ramp up my WMO/ATF as I believe the ULSD is the cause of this.

Never-Have-I-Ether

 

[Jesus Freak]

Woohoo! Sounds great. I wish my motor only had that much blow by. I'm still considering that maybe my turbo drain is clogged and causing it to drink oil outta the crankcase.

 

[NeverHave-I-Ether]

Well durn!

The truck started acting up again today! Running off the same tank of diesel I got from a CEFECO.l when it initially died. They swear it's clean fuel and to spec. I'm wondering if I got bad fuel or if the diesel is to dry.

Never-Have-I-Ether