93 Ford f superduty 7.3 rollback no power - Diesel Forum - TheDieselStop.com
7.3L IDI Diesels (Not Power Strokes) Technical discussion of topics related to vehicles powered by the 7.3 Liter In-Direct Injection Navistar engines.

 
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post #1 of 7 (permalink) Old 07-22-2019, 03:56 PM Thread Starter
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93 Ford f superduty 7.3 rollback no power

Hello i have a 93 Ford f superduty rollback with 7.3 non turbo engine,my problem is i don't have power.When i start driving you can fill the truck doesnt have power to pull and black smoke start coming out from exhaust.Also if i stop in a hill to get 25 mph again take forever. I buy it the way it is and i looking to some one can help me with that problem and also that problem is without a load so somebody can help me please?
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post #2 of 7 (permalink) Old 07-24-2019, 02:53 PM
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The IDI non-turbo is not a power-house to begin with. If you were expecting it to feel like a PowerStroke, I can see why you would think it was broken. The naturally aspirated 7.3 IDI only makes 165 HP compared to the 215 HP in the next year Powerstroke. I have a 1993 IDI and the first thing I did was replace injectors and put an aftermarket turbo on it to deal with the power issues and the smoking. Good news, injectors for the IDI are fairly cheap, if that is your problem. How many miles are on the engine, and are they the original injectors? Black smoke signifies unburned fuel, and could be bad injectors not atomizing the fuel very well. Could also be you have a bad cylinder with low compression. When you crank the engine over to start, is it a hard start? Does it spin at an even speed, or does it sound like it speeds up slightly in a spot in the rotation? Is your air filter clean and free of any possible obstruction? Another thing I always do to kill black smoke is run a CETANE additive. It helps with the power and the smoking as it causes the fuel to ignite sooner and burns more completely. Bottom line though, the truck is not ever going to be as strong as the Powerstroke. Super easy and cheap to repair, and pretty bulletproof, but not anywhere near as strong. The IDI is a pretty great engine, but you are going to learn patience waiting for it to get up to speed.

Last edited by Ozhold; 07-24-2019 at 03:06 PM. Reason: Add another comment
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post #3 of 7 (permalink) Old 07-28-2019, 01:38 PM Thread Starter
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Ok the truck take like 3 or 4 second to start and sound like even crank the only problem is the power,even on flat road take like 30 seconds to get 25 mph,also on the highway at 55 mph the engine goes up to 2600 RPM in fifth gear,at 60 goes up almost 3000 RPM so idk if that is normal,also i need to know what size of Exhaust system is the right one for that truck cause right now it is 2 1/4 and i think is to small for it ,let me know guys and thanks everyone for the help
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post #4 of 7 (permalink) Old 07-28-2019, 01:40 PM Thread Starter
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I forget to tell the truck has 265k Miles and looks like it is the original injectors
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post #5 of 7 (permalink) Old 07-29-2019, 06:49 PM
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Is the clutch slipping? If it has as much trouble pulling, and runs as high RPM as you say, my first guess would be the clutch not holding. Try putting it in 4th or 5th gear and see if it stalls out when you try to make it start moving. If it doesn't, then there is a problem with the clutch. The engine being a little hard to start shouldn't make any difference to it once it starts running, unless there is a big fuel leak, then you would see it. Worn injector pump, and/or injectors might cause it to loose power, but you wouldn't have high RPMs. It would be lugging down. I have had them blow smoke when I bounced it off of the governor. Is that what is happening? More indication that the clutch is slipping.

At 265K miles that engine is just getting broke in.

1993 F-350 crew cab non-turbo 5 speed transmission
35 years a mechanic on large stationary engines natural gas and diesel fired, and other industrial equipment.
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post #6 of 7 (permalink) Old 08-01-2019, 10:02 AM Thread Starter
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The tranny,clutch,pressure plate,flywheel,throwout bearing everything is brand new,i replace the injectors and runs a lil better but on highway the rpms still to high. I used yestarday and at 60 mph it is running at 2800 rpms so i have a few quiestions,what is the right Exhaust size for that engine? What is the best tire size? What is the best rear end ratio for highways? Where i live is most of the roads it is70 mph highways and is hard for me drive at 50mph in the highway cause the RPM goes to high. Please let me know what i can do to fix that problem and thanks every one for the help.
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post #7 of 7 (permalink) Old 08-03-2019, 04:48 PM
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Exhaust back pressure would lug the engine down. Not make it run high. What is the rear end gear ratio? That might make the RPM high, but it wouldn't have any trouble pulling anything you put behind it. As for tires, I've seen every thing from a 225-75-16 to 245-85-16, and then you always have the guys who jack things up, and get ridiculous. Just depends on what you want, and can live with. As for the exhaust size my truck is stone cold stock, it is 2 1/4" from the manifolds to the Y, then goes a little bigger out the back, maybe 2 1/2"

1993 F-350 crew cab non-turbo 5 speed transmission
35 years a mechanic on large stationary engines natural gas and diesel fired, and other industrial equipment.
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