How do you know when injectors are bad?
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Senior User
Joined: Jan 2008
Posts: 172
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How do you know when injectors are bad?
I have a feeling something is wrong with my truck.
92 f-250 7.3 auto
So I have a 28' enclosed car trailer and the truck is really lacking power big time. I don't know if it is just that weak or if something is wrong with it. It has 220K on it and everything is bone stock.
I cut the soup bowl out.....it has been well maintained...filters/fluids etc. Recent glow plugs, other than that eveything is stock......anyway to check it or is it just weak?
Trailer is 9500#, I have asked before...and tried a few things but this truck is just weak. It has 3.55 gears and 33" tires.
I get 14-15 mpg highway and 7mpg with the trailer.....it just seems way off to me. I know other people use these truck to tow with......are they struggling this bad as well?
92 f-250 7.3 auto
So I have a 28' enclosed car trailer and the truck is really lacking power big time. I don't know if it is just that weak or if something is wrong with it. It has 220K on it and everything is bone stock.
I cut the soup bowl out.....it has been well maintained...filters/fluids etc. Recent glow plugs, other than that eveything is stock......anyway to check it or is it just weak?
Trailer is 9500#, I have asked before...and tried a few things but this truck is just weak. It has 3.55 gears and 33" tires.
I get 14-15 mpg highway and 7mpg with the trailer.....it just seems way off to me. I know other people use these truck to tow with......are they struggling this bad as well?
Elder User
Joined: Jan 2008
Posts: 698
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From: Guymon
I would think that the 3:55 gears might be holding you back with that big of a load. I would think you would need something like 4:10 or lower if you pull it all the time. A turbo would probably help alot too If you have the money. The turbo from banks helped mine alot. Before, mine was fairly week, now it does much better and I have 4:10 with the e40d. It will also be alittle more efficient when pulling trailers. After that, theres not much more the 7.3 will put out.
I would definatly try a gear swap to 4:10 though, I know you will feel a difference. Your fuel mileage running empty will probably decline a little but if you tow all the time, it will be worth it. It may even increase your pulling fuel mileage since your not floored all the time.
Also, Does it blow a little black smoke when you floor it. If it does, your getting plenty of fuel. If not, you may try turning the fuel up a little.
Just my opionion
Good luck
I would definatly try a gear swap to 4:10 though, I know you will feel a difference. Your fuel mileage running empty will probably decline a little but if you tow all the time, it will be worth it. It may even increase your pulling fuel mileage since your not floored all the time.
Also, Does it blow a little black smoke when you floor it. If it does, your getting plenty of fuel. If not, you may try turning the fuel up a little.
Just my opionion
Good luck
Post Fiend
Joined: Nov 2003
Posts: 21,285
Likes: 16
From: Nutter Fort, WV
This chart shows the amount of HP required for a given frontal area at a speed of 55 MPH.
Area in Sq. Ft. - HP required
50 -------------- 56
60 - -------------66
70 - -------------78
80 - -------------89
90 - -------------99
Go measure the front of your truck and then the front of the trailer.
My guess is you will be over 100 square feet.
So you are using 99 HP to maintain 55 MPH just to overcome wind resistance on a calm day.
A NA engine puts out 185 HP - 99 HP for wind resistance leaves 86 HP to pull the load up a hill.
How fast are you wanting to go?
Area in Sq. Ft. - HP required
50 -------------- 56
60 - -------------66
70 - -------------78
80 - -------------89
90 - -------------99
Go measure the front of your truck and then the front of the trailer.
My guess is you will be over 100 square feet.
So you are using 99 HP to maintain 55 MPH just to overcome wind resistance on a calm day.
A NA engine puts out 185 HP - 99 HP for wind resistance leaves 86 HP to pull the load up a hill.
How fast are you wanting to go?
Thread Starter
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Senior User
Joined: Jan 2008
Posts: 172
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This chart shows the amount of HP required for a given frontal area at a speed of 55 MPH.
Area in Sq. Ft. - HP required
50 -------------- 56
60 - -------------66
70 - -------------78
80 - -------------89
90 - -------------99
Go measure the front of your truck and then the front of the trailer.
My guess is you will be over 100 square feet.
So you are using 99 HP to maintain 55 MPH just to overcome wind resistance on a calm day.
A NA engine puts out 185 HP - 99 HP for wind resistance leaves 86 HP to pull the load up a hill.
How fast are you wanting to go?
Area in Sq. Ft. - HP required
50 -------------- 56
60 - -------------66
70 - -------------78
80 - -------------89
90 - -------------99
Go measure the front of your truck and then the front of the trailer.
My guess is you will be over 100 square feet.
So you are using 99 HP to maintain 55 MPH just to overcome wind resistance on a calm day.
A NA engine puts out 185 HP - 99 HP for wind resistance leaves 86 HP to pull the load up a hill.
How fast are you wanting to go?
What about tq.?
Thats the max h.p. so what rpm does it make that at?
It will tow it but it struggles like a MF. Somehills I get to going 70 and I'm doing 45 by the time I get to the top and praying I make it up...Flat on the flooor. All I got....
Laughing Gas
Joined: Mar 2006
Posts: 1,083
Likes: 1
From: Fitzpatrick Alabama
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Elder User
Joined: Jan 2008
Posts: 576
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From: Central Coast CA
45mph isnt that bad, if you really want the hp, i mean REALLY, it will cost you, unless you find a good deal. but get a turbo, pyro/boost gauges, straight pipe it, and turn up the fuel.
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Post Fiend
Joined: Nov 2003
Posts: 21,285
Likes: 16
From: Nutter Fort, WV
I am over 20,000 gross in that picture.
But notice there is very little to catch the wind, the excavator cab is about the size of a phone booth.
And where you are is flat when you compare it to around here.
I am running 3.55 gears on 33" tires, and I can go about as fast as I want to go with that much weight unless it is a big hill.
After many years running a big rig pulling a reefer trailer, I know what a big frontal area and wind can do.
Many times out west I had to drop 3 or 4 gears on flat ground (Kansas, Iowa, Nebraska) to keep the EGT under control because of a 30 or 40 MPH head wind in a rig putting close to 600 HP to the ground.
Your problem is not the weight, it is the big sail you are dragging.
Intake and exhaust mods will help a little.
A new IP and injectors might help a bit more.
But if you want to go faster, your only real option is a turbo.
Postmaster
Joined: Dec 2002
Posts: 3,594
Likes: 2
From: Southern Oregon USA
So all I need to get up the hill is h.p.?
What about tq.?
Thats the max h.p. so what rpm does it make that at?
It will tow it but it struggles like a MF. Somehills I get to going 70 and I'm doing 45 by the time I get to the top and praying I make it up...Flat on the flooor. All I got....
What about tq.?
Thats the max h.p. so what rpm does it make that at?
It will tow it but it struggles like a MF. Somehills I get to going 70 and I'm doing 45 by the time I get to the top and praying I make it up...Flat on the flooor. All I got....
I'd be happy with 45 mph. With a load of 17K lbs gross, I hit the bottom of a 7% grade on the highway at 65 mph. By the time I made it to the top after 8 miles of losing momentum for 35 mph corners, I was doing a whopping 23 mph. On a straight up climb, it will hold 40.
Jason
Junior User
Joined: Mar 2007
Posts: 68
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Bone stock the old 7.3 IDI's really just dont have enough power to pull a big trailer.I just put new injectors in mine at 160,000 miles and it made no difference in power.
I'm usually towing 11-12,000 lbs that has quite a bit of wind drag and I get 6-7 mpg.I'm in 4th gear with my foot thru the floorboard and 45-55 mph is all it can do unless theres a strong tail wind.Most any hill I hit has to be pulled in 3rd gear.I could probably use 250 horses but theres no way to get it.
I'm usually towing 11-12,000 lbs that has quite a bit of wind drag and I get 6-7 mpg.I'm in 4th gear with my foot thru the floorboard and 45-55 mph is all it can do unless theres a strong tail wind.Most any hill I hit has to be pulled in 3rd gear.I could probably use 250 horses but theres no way to get it.
Postmaster
Joined: Mar 2008
Posts: 3,255
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From: Sweet Home, OR
I don't know if you care but I can give you some comparisons with a Cummins 4wd with 3:54s and 33" tires, mine's a 5-spd though so it may not correlate. It's a '91.5 so it's only 160hp/400 ftlbs. with intercooler.
I used to pull an old 10,000 lb. 5th wheel. I definitely knew it was back there without a doubt, on flat ground you could go about as fast as was reasonable, pulling a steep grade I was in 3rd. A LOT. I got way better mileage though easily 12-14. That was all back in the good-ol-days with high sulfer diesel though. I haven't puuled that much weight over enough miles to check mileage with the ULSD but I'd probably be down to 11-12.
So if you care you have another brand (with a turbo though) to compare to.
I used to pull an old 10,000 lb. 5th wheel. I definitely knew it was back there without a doubt, on flat ground you could go about as fast as was reasonable, pulling a steep grade I was in 3rd. A LOT. I got way better mileage though easily 12-14. That was all back in the good-ol-days with high sulfer diesel though. I haven't puuled that much weight over enough miles to check mileage with the ULSD but I'd probably be down to 11-12.
So if you care you have another brand (with a turbo though) to compare to.
Thread Starter
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Senior User
Joined: Jan 2008
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Well I can do 75 or faster but thats as fast as I have gone.....
But going back up the hil its scary....I'm not sure if I can make it lol
I'm 7 mpg. I'm about to go fill it up again so I will check it again and let you know.
What sucks is people with powerstrokes are getting twice that with the same trailer. I like this truck alot but If I can't figure something out then I will have to get something else.
What about wind jammers? They worth anything?
But going back up the hil its scary....I'm not sure if I can make it lol
I'm 7 mpg. I'm about to go fill it up again so I will check it again and let you know.
What sucks is people with powerstrokes are getting twice that with the same trailer. I like this truck alot but If I can't figure something out then I will have to get something else.
What about wind jammers? They worth anything?
Posting Guru
Joined: Oct 2005
Posts: 1,030
Likes: 0
From: Powell River B.C.
You should be getting better milage empty if we are talking highway milage, my 93 as per my signature gets about 20-21mpg empty, I pulled a 7000 lb trailer over the rockies from Alberta, to the BC coast, and got 12-13 mpg. Load was a 48 Ford F-68 loaded backwards on a flat deck, and I had the pedal to the metal most of the time. With the milage you have, I would definately consider new injectors and have your timing checked at least.
Thread Starter
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Senior User
Joined: Jan 2008
Posts: 172
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You should be getting better milage empty if we are talking highway milage, my 93 as per my signature gets about 20-21mpg empty, I pulled a 7000 lb trailer over the rockies from Alberta, to the BC coast, and got 12-13 mpg. Load was a 48 Ford F-68 loaded backwards on a flat deck, and I had the pedal to the metal most of the time. With the milage you have, I would definately consider new injectors and have your timing checked at least.
Empty I can't get anywhere near 20 mpg.