What engine is in a 1990 Ford F250 diesel?
The 1990 Ford F-250 diesel was powered by Navistar-built V8 diesels: the 6.9-liter IDI and the larger 7.3-liter IDI, both indirect-injection designs. A turbocharged version of the 7.3-liter IDI was available on select models.
In the 1990 model year, Ford’s heavy-duty F-Series trucks carried two diesel engine families sourced from International/Navistar. These engines predated the Power Stroke era and were known for durability and strong low-end torque, with outputs varying by year and spec. The smaller 6.9L IDI served as a more economical option, while the larger 7.3L IDI offered greater capability and, in turbocharged form, noticeably stronger performance for heavy hauling.
Engine options in the 1990 Ford F-250
Below is a concise overview of the two engine families that powered the truck in 1990.
6.9-Liter IDI V8 — An indirect-injection diesel produced by Navistar. This was the smaller option in the 1990 F-250 lineup, commonly found on work-oriented builds. Typical outputs were roughly in the mid-to-upper 100s horsepower with torque in the 320–360 lb-ft range, emphasizing low-end grunt and reliability.
7.3-Liter IDI V8 — The larger Navistar diesel, also indirect-injection. Available in both naturally aspirated and turbocharged forms on various trims. Non-turbo versions generally produced around 180–210 horsepower with torque near 360–420 lb-ft; the turbocharged variant offered higher figures, commonly around 210–250 horsepower and roughly 430–500+ lb-ft of torque, depending on year and configuration.
In short, the 1990 F-250 diesel lineup offered a smaller 6.9L IDI for efficient, durable service and a larger 7.3L IDI for heavier-duty tasks, with the turbo option boosting performance on select models.
Notes on performance and documentation
Exact horsepower and torque varied by model year and configuration. For precise figures on a specific truck, consult the VIN/build sheet, the original window sticker, or Navistar/Ford service literature corresponding to that chassis.
Summary: The 1990 Ford F-250 diesel used either a 6.9-liter IDI or a 7.3-liter IDI diesel from Navistar, with a turbocharged 7.3L option available on certain models. These engines are indirect-injection designs and represent Ford’s pre-Power Stroke diesel era.
How much horsepower does a 1990 7.3 Idi have?
A 1990 7.3L IDI engine has around 180-185 horsepower and 360 ft-lb of torque. These naturally aspirated (non-turbo) engines were known for being reliable and durable, though less powerful than later turbocharged or Power Stroke diesel versions, with a focus on low-end pulling power rather than high speed.
This video discusses the stock horsepower and torque of the 7.3L IDI engine and potential upgrades: 1mThe Diesel PodcastYouTube · Jun 12, 2025
1990 7.3L IDI specifications:
- Horsepower: Approximately 180-185 hp
- Torque: Approximately 360 lb-ft
- Engine type: Indirect Injection (IDI), naturally aspirated
- Performance characteristics:
- Strong low-end torque for pulling heavy loads
- Lower top-end power compared to turbocharged engines
- Focus on durability and fuel economy over raw power
Key points:
- The 7.3L IDI was an updated version of the earlier 6.9L engine with a larger bore, better cooling, and improved head bolts.
- Factory turbocharger options for the 7.3L IDI were not available until 1993.
- The 7.3L IDI should not be confused with the later 7.3L Power Stroke engine, which was introduced in 1994 and offered significantly more horsepower and torque.
What motor came in a 1990 F250?
MMP Rating
| Engine Specifications | |
|---|---|
| Engine: | 4.9L I6, 5.8L V8, 7.5L V8 |
| Displacement: | 4.9L - 7.5L |
| Horsepower: | 145-230 hp |
| Torque: | 265-388 lb-ft |
What year to avoid a 7.3 Power Stroke?
The 7.3L Power Stroke years to avoid are generally late 2002 through 2003 because they used weaker, powdered metal rods (PMRs) instead of the stronger, forged rods found in earlier models. These PMRs are a point of concern for anyone planning to modify the engine for higher horsepower. Otherwise, all 7.3L Power Strokes are considered reliable, though the older 1994-1998 models produced less power and may have more age-related issues.
This video discusses potential issues and areas to inspect when buying a used 7.3L Powerstroke: 1mThoroughbred DieselYouTube · Jun 19, 2020
Years to be cautious about
- 2002-2003 (specifically, late 2002-2003): These years are often mentioned for their use of powdered metal rods (PMRs), which are less durable for high-performance applications. However, they are still reliable for stock use and are not necessarily a "bad" year if you don't plan on heavy modifications.
- 1994-1998: These are the oldest models and have less horsepower than later versions, which might be a drawback for some users. They are still considered reliable but are more likely to have age-related wear and tear.
Why these years?
- Powdered Metal Rods (PMRs): The main reason to avoid the late 2002-2003 model years is the switch from forged connecting rods to powdered metal rods. Forged rods are stronger and can handle more power, making PMRs a potential failure point if you plan to significantly increase horsepower.
- Lower Horsepower (1994-1998): The earliest models had less horsepower, which may not be ideal for daily driving or heavy towing compared to later models.
General considerations
- Reliability: Despite these specific concerns, the 7.3L Power Stroke is widely regarded as a very reliable engine.
- Age: All 7.3L engines are now quite old, so any model you consider will likely require maintenance and part replacements due to age, regardless of the specific year.
- Modifications: If you're planning modifications like performance tuning, staying away from PMR engines (late 2002-2003) is the most critical guideline.
What diesel engine did Ford use in 1990?
The main Ford diesel engine for 1990 was the 7.3L IDI (Indirect Injection) non-turbo V8, also known as the International Harvester IDI engine. It was a durable, reliable engine often found in F-250 and F-350 trucks, known for being underpowered compared to later models. While naturally aspirated, aftermarket turbo kits were available, and the engine was designed to be simple and durable, even allowing for the use of alternative fuels like waste oil.
Key features
- Engine type: 7.3L naturally aspirated V8 Indirect Injection (IDI)
- Durability: Known for being a tough, long-lasting workhorse with a cast-iron block and heads
- Performance: Generally considered underpowered without a turbo, though it could be modified
- Application: Commonly found in 1990 Ford F-250 and F-350 pickup trucks
- Fuel: Capable of running on alternative fuels like waste oil
Common issues and considerations
- Cold weather starting: Can be challenging due to the glow plugs, which are prone to failure and can be damaged by starting before the wait-to-start light goes out.
- Cavitation: A potential issue where vibrations can damage cylinder walls, which can be mitigated by using supplemental coolant additives (SCAs).
- Fuel leaks: Rubber and plastic return lines on the injectors are known to crack over time, causing fuel leaks.
This video shows how to inspect and clean the glow plugs on a 7.3L IDI engine: 1mDieseled DragonYouTube · Aug 20, 2024
