Fuel effiency
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Fuel effiency
I have a 1997 7.3L PSD, and I love it. it has treated me well and I have done so to it.
However, that being said, it used to have great "get up and go," however recently it has gotten sluggish. This is not to say it still doesn't have kick, but I have noticed take off is not as great as it used to be, and mileage has dropped off quite a bit. I was able to go 172 miles on between 1/2 and 3/8ts a tank of fuel.
Has anyone else expierenced this type of issue. I have changed my fuel filter and oil every 5,000 miles.
Could this be an injector issue? Any ideas would be appreciated.
However, that being said, it used to have great "get up and go," however recently it has gotten sluggish. This is not to say it still doesn't have kick, but I have noticed take off is not as great as it used to be, and mileage has dropped off quite a bit. I was able to go 172 miles on between 1/2 and 3/8ts a tank of fuel.
Has anyone else expierenced this type of issue. I have changed my fuel filter and oil every 5,000 miles.
Could this be an injector issue? Any ideas would be appreciated.
Postmaster
Joined: Jan 2005
Posts: 2,753
Likes: 3
From: Phenix City, AL
jamesm....Welcome to FTE! 
Might wanna try posting this down in the 7.3 forum, you might have a little better luck in there.
Here is the link to the forum:
https://www.ford-trucks.com/forums/f...play.php?f=170
Might wanna try posting this down in the 7.3 forum, you might have a little better luck in there.
Here is the link to the forum:
https://www.ford-trucks.com/forums/f...play.php?f=170
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Joined: Aug 2004
Posts: 93
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There's very little that goes wrong with those engines.
If your fuel milage suddenly drops off noticably and it doesn't quite run right, My educated guess is, you have a leaking O ring on one of the injectors.
To check it, pull your oil dipstick, if there is extra oil in it, that is your problem. Don't drive it with fuel in the oil, that will ruin a bearing on the crank.
These O rings aren't too bad of a deal to change.
Basically, you have to pull the valve covers off, and that requires taking loose the air intake and moving around a few wires and such, but no real big deal.
Once you get the covers off, You'll need to let the fuel and oil pressure off. To let the fuel pressure off, there are 2 plugs on the firewall side of the head. Remove these plugs with a 1/4 ratchet. They are a little tricky to reach, and you can't see them, but you can get to them with a small ratchet. Turn them until the fuel drains out.
For the oil pressure, there are 2 brass fittings in each head under the valve covers. Remove those and let the oil drain out.
Now, you are ready to pull the injectors.
First, remove the wiring harness that runs the injectors and glow plugs, then remove the bolts holding the injectors down. You'll need a nail puller to reach under the injector bracket and pop the injector out.
Be sure when you remove the injectors you keep them lined up so they go back in the same cylinder.
Once they are removed, take inventory of what you need parts wise.
You'll need 8 O ring kits for the injectors. You may need to replace the wiring harnesses for the injectors. They are relatively in expensive. I replaced mine, No reason to go back in there for that. I also replaced my valve cover gaskets and glow plugs while I was at it. I bought my parts at the Navistar dealer. They are the same as Ford's parts but about 1/3 the price.
Once you have your parts, you are ready to start putting back together.
Take and injector and an O ring kit. Remove the O rings on the injector and clean the tip with a brush and carb cleaner and carefully install the new O rings and the brass washer on the tip. Some of the older trucks have a different number of O rings than the kits. In the kits, I believe one of the rings is wider or maybe the kit has 1 more ring and it's narrower, I don't remember off the top of my head. At any rate, don't get excited over that. It's ok.
Now, re install the injectors one by one. You'll need a torque wrench. I'm not sure of the torque setting, but I'm sure they can look it up for you at the Navistar place.
Once the injectors are installed, remove all 8 glow plugs and crank the motor over a couple times. Fuel and oil will start to come out of those plugs on the heads. When it does, tighten them back up and crank a few more times. You are cranking without the glow plugs in to expel any excess oil that probably got into the cylinders when you removed the injectors.
Once the oil is expelled, put in the glow plugs, and install the wiring harnesses and valve covers. Button up the wiring on the outside and the air intake, and you are about ready to start the truck.
Change your oil before you start it. Bear in mind, it may have 16 or 17 quarts in it because you have fuel in the oil not just the 15 quarts of oil. It is important not to start the truck before changing the oil.
Once the oil is changed, it's time to start the truck. This IS NOT going to be fun. Make sure the batteries are fully charged, you will need it. You will crank and crank and crank and crank and crank some more. Finally, it will start, and it will white smoke and near about fog in the neighborhood. It will sound like it is coming apart, but just let it set there and carry on until it smooths out a bit. Once it smooths out, take off and drive it. Run it varying speeds for about 20 or 30 minutes to be sure you get the air out of the system.
That should take care of it.
Skipper
If your fuel milage suddenly drops off noticably and it doesn't quite run right, My educated guess is, you have a leaking O ring on one of the injectors.
To check it, pull your oil dipstick, if there is extra oil in it, that is your problem. Don't drive it with fuel in the oil, that will ruin a bearing on the crank.
These O rings aren't too bad of a deal to change.
Basically, you have to pull the valve covers off, and that requires taking loose the air intake and moving around a few wires and such, but no real big deal.
Once you get the covers off, You'll need to let the fuel and oil pressure off. To let the fuel pressure off, there are 2 plugs on the firewall side of the head. Remove these plugs with a 1/4 ratchet. They are a little tricky to reach, and you can't see them, but you can get to them with a small ratchet. Turn them until the fuel drains out.
For the oil pressure, there are 2 brass fittings in each head under the valve covers. Remove those and let the oil drain out.
Now, you are ready to pull the injectors.
First, remove the wiring harness that runs the injectors and glow plugs, then remove the bolts holding the injectors down. You'll need a nail puller to reach under the injector bracket and pop the injector out.
Be sure when you remove the injectors you keep them lined up so they go back in the same cylinder.
Once they are removed, take inventory of what you need parts wise.
You'll need 8 O ring kits for the injectors. You may need to replace the wiring harnesses for the injectors. They are relatively in expensive. I replaced mine, No reason to go back in there for that. I also replaced my valve cover gaskets and glow plugs while I was at it. I bought my parts at the Navistar dealer. They are the same as Ford's parts but about 1/3 the price.
Once you have your parts, you are ready to start putting back together.
Take and injector and an O ring kit. Remove the O rings on the injector and clean the tip with a brush and carb cleaner and carefully install the new O rings and the brass washer on the tip. Some of the older trucks have a different number of O rings than the kits. In the kits, I believe one of the rings is wider or maybe the kit has 1 more ring and it's narrower, I don't remember off the top of my head. At any rate, don't get excited over that. It's ok.
Now, re install the injectors one by one. You'll need a torque wrench. I'm not sure of the torque setting, but I'm sure they can look it up for you at the Navistar place.
Once the injectors are installed, remove all 8 glow plugs and crank the motor over a couple times. Fuel and oil will start to come out of those plugs on the heads. When it does, tighten them back up and crank a few more times. You are cranking without the glow plugs in to expel any excess oil that probably got into the cylinders when you removed the injectors.
Once the oil is expelled, put in the glow plugs, and install the wiring harnesses and valve covers. Button up the wiring on the outside and the air intake, and you are about ready to start the truck.
Change your oil before you start it. Bear in mind, it may have 16 or 17 quarts in it because you have fuel in the oil not just the 15 quarts of oil. It is important not to start the truck before changing the oil.
Once the oil is changed, it's time to start the truck. This IS NOT going to be fun. Make sure the batteries are fully charged, you will need it. You will crank and crank and crank and crank and crank some more. Finally, it will start, and it will white smoke and near about fog in the neighborhood. It will sound like it is coming apart, but just let it set there and carry on until it smooths out a bit. Once it smooths out, take off and drive it. Run it varying speeds for about 20 or 30 minutes to be sure you get the air out of the system.
That should take care of it.
Skipper
Postmaster
Joined: Jan 2005
Posts: 2,753
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From: Phenix City, AL
Originally Posted by jamesm
Sorry BFR, I thought this was the super duty/heavy duty forum, I'll repost
Wasn't trying to push you out.
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Awesome Reply!!!
THATS THE BEST RESPONCE I'VE SEEN IN QUITE A WHILE, YOU MUST HAVE DONE THE JOB YOURSELF, OR YOU ARE A MECHANIC. GOOD JOB. JCAB
Originally Posted by Kentucky Skipper
There's very little that goes wrong with those engines.
If your fuel milage suddenly drops off noticably and it doesn't quite run right, My educated guess is, you have a leaking O ring on one of the injectors.
To check it, pull your oil dipstick, if there is extra oil in it, that is your problem. Don't drive it with fuel in the oil, that will ruin a bearing on the crank.
These O rings aren't too bad of a deal to change.
Basically, you have to pull the valve covers off, and that requires taking loose the air intake and moving around a few wires and such, but no real big deal.
Once you get the covers off, You'll need to let the fuel and oil pressure off. To let the fuel pressure off, there are 2 plugs on the firewall side of the head. Remove these plugs with a 1/4 ratchet. They are a little tricky to reach, and you can't see them, but you can get to them with a small ratchet. Turn them until the fuel drains out.
For the oil pressure, there are 2 brass fittings in each head under the valve covers. Remove those and let the oil drain out.
Now, you are ready to pull the injectors.
First, remove the wiring harness that runs the injectors and glow plugs, then remove the bolts holding the injectors down. You'll need a nail puller to reach under the injector bracket and pop the injector out.
Be sure when you remove the injectors you keep them lined up so they go back in the same cylinder.
Once they are removed, take inventory of what you need parts wise.
You'll need 8 O ring kits for the injectors. You may need to replace the wiring harnesses for the injectors. They are relatively in expensive. I replaced mine, No reason to go back in there for that. I also replaced my valve cover gaskets and glow plugs while I was at it. I bought my parts at the Navistar dealer. They are the same as Ford's parts but about 1/3 the price.
Once you have your parts, you are ready to start putting back together.
Take and injector and an O ring kit. Remove the O rings on the injector and clean the tip with a brush and carb cleaner and carefully install the new O rings and the brass washer on the tip. Some of the older trucks have a different number of O rings than the kits. In the kits, I believe one of the rings is wider or maybe the kit has 1 more ring and it's narrower, I don't remember off the top of my head. At any rate, don't get excited over that. It's ok.
Now, re install the injectors one by one. You'll need a torque wrench. I'm not sure of the torque setting, but I'm sure they can look it up for you at the Navistar place.
Once the injectors are installed, remove all 8 glow plugs and crank the motor over a couple times. Fuel and oil will start to come out of those plugs on the heads. When it does, tighten them back up and crank a few more times. You are cranking without the glow plugs in to expel any excess oil that probably got into the cylinders when you removed the injectors.
Once the oil is expelled, put in the glow plugs, and install the wiring harnesses and valve covers. Button up the wiring on the outside and the air intake, and you are about ready to start the truck.
Change your oil before you start it. Bear in mind, it may have 16 or 17 quarts in it because you have fuel in the oil not just the 15 quarts of oil. It is important not to start the truck before changing the oil.
Once the oil is changed, it's time to start the truck. This IS NOT going to be fun. Make sure the batteries are fully charged, you will need it. You will crank and crank and crank and crank and crank some more. Finally, it will start, and it will white smoke and near about fog in the neighborhood. It will sound like it is coming apart, but just let it set there and carry on until it smooths out a bit. Once it smooths out, take off and drive it. Run it varying speeds for about 20 or 30 minutes to be sure you get the air out of the system.
That should take care of it.
Skipper
If your fuel milage suddenly drops off noticably and it doesn't quite run right, My educated guess is, you have a leaking O ring on one of the injectors.
To check it, pull your oil dipstick, if there is extra oil in it, that is your problem. Don't drive it with fuel in the oil, that will ruin a bearing on the crank.
These O rings aren't too bad of a deal to change.
Basically, you have to pull the valve covers off, and that requires taking loose the air intake and moving around a few wires and such, but no real big deal.
Once you get the covers off, You'll need to let the fuel and oil pressure off. To let the fuel pressure off, there are 2 plugs on the firewall side of the head. Remove these plugs with a 1/4 ratchet. They are a little tricky to reach, and you can't see them, but you can get to them with a small ratchet. Turn them until the fuel drains out.
For the oil pressure, there are 2 brass fittings in each head under the valve covers. Remove those and let the oil drain out.
Now, you are ready to pull the injectors.
First, remove the wiring harness that runs the injectors and glow plugs, then remove the bolts holding the injectors down. You'll need a nail puller to reach under the injector bracket and pop the injector out.
Be sure when you remove the injectors you keep them lined up so they go back in the same cylinder.
Once they are removed, take inventory of what you need parts wise.
You'll need 8 O ring kits for the injectors. You may need to replace the wiring harnesses for the injectors. They are relatively in expensive. I replaced mine, No reason to go back in there for that. I also replaced my valve cover gaskets and glow plugs while I was at it. I bought my parts at the Navistar dealer. They are the same as Ford's parts but about 1/3 the price.
Once you have your parts, you are ready to start putting back together.
Take and injector and an O ring kit. Remove the O rings on the injector and clean the tip with a brush and carb cleaner and carefully install the new O rings and the brass washer on the tip. Some of the older trucks have a different number of O rings than the kits. In the kits, I believe one of the rings is wider or maybe the kit has 1 more ring and it's narrower, I don't remember off the top of my head. At any rate, don't get excited over that. It's ok.
Now, re install the injectors one by one. You'll need a torque wrench. I'm not sure of the torque setting, but I'm sure they can look it up for you at the Navistar place.
Once the injectors are installed, remove all 8 glow plugs and crank the motor over a couple times. Fuel and oil will start to come out of those plugs on the heads. When it does, tighten them back up and crank a few more times. You are cranking without the glow plugs in to expel any excess oil that probably got into the cylinders when you removed the injectors.
Once the oil is expelled, put in the glow plugs, and install the wiring harnesses and valve covers. Button up the wiring on the outside and the air intake, and you are about ready to start the truck.
Change your oil before you start it. Bear in mind, it may have 16 or 17 quarts in it because you have fuel in the oil not just the 15 quarts of oil. It is important not to start the truck before changing the oil.
Once the oil is changed, it's time to start the truck. This IS NOT going to be fun. Make sure the batteries are fully charged, you will need it. You will crank and crank and crank and crank and crank some more. Finally, it will start, and it will white smoke and near about fog in the neighborhood. It will sound like it is coming apart, but just let it set there and carry on until it smooths out a bit. Once it smooths out, take off and drive it. Run it varying speeds for about 20 or 30 minutes to be sure you get the air out of the system.
That should take care of it.
Skipper
Senior User
Joined: Jan 2006
Posts: 349
Likes: 0
From: Louisville
I currently use Stanadyne (maybe I spelled that right) when I can remember to. It seems to give me a consistant 1+ MPG with a bit smoother engine. I have also read about diesel kleen, but have not used it.
With the ultra low sulphur diesel coming out, I would think additives will become a more important tool for keeping our powerstrokes healthy.
With the ultra low sulphur diesel coming out, I would think additives will become a more important tool for keeping our powerstrokes healthy.
Freshman User
Joined: May 2006
Posts: 28
Likes: 0
Have you checked the screen going to the FPR (fuel pressure regulator)?
After taking the fule filter out, look on the right side of the filter bowl towards the top and you will a hole. There is a screen in there. It get to the screen you need to loosen up the FPR on the other side. Be careful when doing so that you do not loose any of the parts in there.
After taking the fule filter out, look on the right side of the filter bowl towards the top and you will a hole. There is a screen in there. It get to the screen you need to loosen up the FPR on the other side. Be careful when doing so that you do not loose any of the parts in there.
Post Fiend
Joined: Oct 2003
Posts: 5,903
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From: MICHIGAN
Originally Posted by jamesm
I was able to go 172 miles on between 1/2 and 3/8ts a tank of fuel.
Too many variables without doing the math.
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Joined: May 2006
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My truck is experiencing the same symptoms. I have checked my mileage and am running somewhere in the 9 - 11 mpg range depending on how I'm driving and what I'm pulling. My truck is scheduled for a trip to the Ford house tomorrow to check the injectors. I suspect that I have one or more bad ones.
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