7.3L Using too much fuel - PowerStrokeNation : Ford Powerstroke Diesel Forum
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post #1 of 13 (permalink) Old 12-08-2009, 08:16 PM Thread Starter
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7.3L Using too much fuel

I have an issue with my 7.3L lately and it is bothering me. When I start the truck and let it warm up, I notice a smell of un-burnt fuel at the tail pipe. Furthermore, the snow on the ground at the tail pipe has a slight coating of diesel fuel after 20 minutes of high idling. When the truck is at operating temperature, it produces too much black smoke between 1800-2500 rpm. I have installed new boots on clean plumbing from the turbo to the intercooler and back to the turbo, and I am positive that I don't have a leak for boost to escape. My fuel economy has dropped from 17 mpg to 14 mpg. Otherwise, the engine runs beautiful. Do I have injector issues?

Thank you in advance for your thoughts and opinions.
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post #2 of 13 (permalink) Old 12-08-2009, 09:07 PM
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Re: 7.3L Using too much fuel

How are you measuring fuel economy? Lie-O-Meter or hand calculate? Also when we switch to winter fuel, we do lose some mpg. Could the stuff you see on the snow be normal condensation with a hint of diesel?

01 Excursion 7.3L Powerstroke. Gauges with AIH Delete, AIS, CCV Mod, 4' MBRP, BTS Trans, 6.0L Trans Cooler and Intercooler, DP-Tuner F5 chip, ITP In Tank Mod and Boost Annihilator, Diesel Innovation's Regulated Fuel kit, BTS Big Oil system, GTP38R Turbo with 1.15 A/R housing and BPD Stage II AC injectors. Bilstein Shocks with U front and A Rear.
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post #3 of 13 (permalink) Old 12-08-2009, 09:20 PM
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Re: 7.3L Using too much fuel

Do you have anything done to your truck, like a tuner, injectors, ebv delete and so on.

93 F350 Gasser
03 F250 6.0
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post #4 of 13 (permalink) Old 12-09-2009, 12:36 AM Thread Starter
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Re: 7.3L Using too much fuel

The modifications that I have done to the truck are as follows:
AFE Stage II intake kit
4" exhaust and gauges
Amsoil synthetic oil
Coolant Filter
Wicked wheel, CCV mod, HPO Sensor Equilizing Hose
I had a Superchips programmer, but have returned it to stock long ago

I calculated my economy for every tank used since I have bought the truck new. I fill it to the rim and record the mileage at that point and I have noticed a considerable decline in mileage within the last 26 tanks. I have used multiple fuel stations and always add treatment for every tank.

I have never seen this amount of diesel fuel on the ground at the tail pipe. Last year, if I let the truck idle in one spot for 20 minutes or so, the snow would have a little black soot, but this year it looks like someone had a pee by the tail pipe. It smells like unburnt fuel and irritates my eyes after a while.

When I rev the engine up to 2000 rpm and hold it for a few seconds then let off, the truck takes a second to recover to normal idle as it sounds like it ran out of fuel. When driving normally, I notice more black smoke than usual.

The truck has 90,000 miles on it and I have changed the oil every 4000 miles. It has never been over-reved or driven when it hasn't had enough time to warm up. I let it cooldown for 5 to 10 minutes if I have been pulling or using it hard. The Ford guys tell me to keep driving it until something lets go. That won't be happening. I just want to find what the problem is and correct it.

Thank you for your help
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post #5 of 13 (permalink) Old 12-09-2009, 12:46 AM
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Re: 7.3L Using too much fuel

Well...

You're obviously not burning all of your fuel, so either you lack compression, you've got a leaky injector, you're a mite low on air, injector o-rings maaybe(not sure).

How long has the AFE stage 2 been on there? Or how long since you cleaned it?

A compression test wouldn't hurt I suppose, the pressure should be, IIRC, somewhere in between 380-450 psi.

One of them truckless bastards.
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post #6 of 13 (permalink) Old 12-09-2009, 02:54 AM
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Re: 7.3L Using too much fuel

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Originally Posted by Coltaine View Post
A compression test wouldn't hurt I suppose, the pressure should be, IIRC, somewhere in between 380-450 psi.
More importantly, they should be within 10% of each other.

01 Excursion 7.3L Powerstroke. Gauges with AIH Delete, AIS, CCV Mod, 4' MBRP, BTS Trans, 6.0L Trans Cooler and Intercooler, DP-Tuner F5 chip, ITP In Tank Mod and Boost Annihilator, Diesel Innovation's Regulated Fuel kit, BTS Big Oil system, GTP38R Turbo with 1.15 A/R housing and BPD Stage II AC injectors. Bilstein Shocks with U front and A Rear.
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post #7 of 13 (permalink) Old 12-09-2009, 04:01 AM
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Re: 7.3L Using too much fuel

Another thing to look into would be your IPR.

93 F350 Gasser
03 F250 6.0
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post #8 of 13 (permalink) Old 12-09-2009, 04:09 AM
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Re: 7.3L Using too much fuel

It's the oil. Sorry, I had to.

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post #9 of 13 (permalink) Old 12-09-2009, 04:11 AM
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Re: 7.3L Using too much fuel

Change your oil to Delo 400 15-40 first and see if that helps. Your oil runs your injectors and when I had my 7.3, I had a similar problem with Amsoil plus other issues, and it disappeared when I changed oil to Delo. Can't hurt to try it.
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post #10 of 13 (permalink) Old 12-09-2009, 12:54 PM
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Re: 7.3L Using too much fuel

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Originally Posted by pappy19 View Post
Change your oil to Delo 400 15-40 first and see if that helps. Your oil runs your injectors and when I had my 7.3, I had a similar problem with Amsoil plus other issues, and it disappeared when I changed oil to Delo. Can't hurt to try it.
How does the oil change things like that in the last 26 fill-ups? Assuming Amsoil is a constant throughout.

01 Excursion 7.3L Powerstroke. Gauges with AIH Delete, AIS, CCV Mod, 4' MBRP, BTS Trans, 6.0L Trans Cooler and Intercooler, DP-Tuner F5 chip, ITP In Tank Mod and Boost Annihilator, Diesel Innovation's Regulated Fuel kit, BTS Big Oil system, GTP38R Turbo with 1.15 A/R housing and BPD Stage II AC injectors. Bilstein Shocks with U front and A Rear.
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