I have a 90 F-250 7.3,The truck will not rev past 2200 rpm,I did a fuel pump,injection pump,and found out it was supposed to have a throttle position sensor,My wiring has no plug for it,it is a 5 speed truck,I want to know if it has a computer,I would think with a computer and no tps that it could be the problem.
This truck will not rev past 2200 no matter what,free revving,un loaded and loaded,all the same rpm.????

 

The only computer you have is the one you are typing on.
There is no throttle position sensor on a manual transmission in a 90 model.

Is the only RPM reading you have from the in dash tach?
Give me a tire diameter, axle ratio, and speed at 2200 RPM in 4th gear.

With the engine off have someone hold the throttle on the floor. Then try to push the throttle lever farther open on the injection pump. The cable bracket could be bent or the cable could be streched and about ready to break.

If you have someone watch the tach and push the throttle wide open on the injection pump will it still only rev to 2200?

 

The tires are 235/85-16 and the gear is 3:55,I am not sure speed in 4th gear,I am pretty sure I checked full throttle before I did the IP.Is there anyone I can callm on this?Nobody seems to know about these trucks.

 

2200 in 3rd should be 40 MPH
2200 in 4th gear should be 57 MPH
2200 in 5th should be 75 MPH

3300 in 3rd should be 60 MPH
3300 in 4th should be 85 MPH
3300 in 5th should be 112 MPH

The only thing that limits the RPM's is the amount of fuel the engine is getting.
That is controlled by the injection pump.
The only other thing that could limit the RPM is the injection pump is not getting enough fuel due to a blockage in the supply line, filter, or tank pickup tube.
But the amount of fuel that is required to rev the engine to 3300 RPM in neutral with no load on it is considerably less than what is required to rev it to 3300 going down the road. Fuel restriction problems generally show up as it will rev to 3300 in neutral but will only rev to 2200 (as an example only, could be any other lower RPM) driving down the road. We just had a problem like this with a 3406 Cat motor this week. Reved up fine in neutral, drove just fine in the first 5 gears. But when you went to 6th through 13th it fell on it's face. Turned out that there was a hairline crack in the priming pump. When you needed more fuel for higher torque output in the higher gears it was sucking air in the crack.

Since you changed the injection pump I have to wonder if the tach is showing the correct RPM. The chances of two injection pumps limiting the RPM to exactly 2200 RPM is almost astronomical.

If you have a diesel injection service close to you they would have the tools to check the RPM output and compare it to your in dash tach readings.

Even the throttle not getting opened to WOT would not limit the RPM to exactly 2200 RPM when you were in neutral with no load on the engine.

An air restriction coud limit the RPM, but that would show up as a huge cloud of black smoke when you had the throttle wide open.

Check you speeds at wide open throttle in several gears and get back on here with them.

 

What Dave said!

 

It has 6 pounds of fuel pressure,is that right? I am not sure on the speed to rpm,but the truck runs great until 2200,The people that built my IP are very well known in my area,I am pretty sure the new pump is fine,they both did the same thing,I cannot find any blockage in the fuel lines yet,Can I call you? You seem to know alot,or call me sometime,440 476 4114 Tim Thanks.

 

Left you a message on your phone and my number. Dave


Malcom, the man of many words. LMAO

I get a kick out of this place sometimes.

 

Dave,I took the boat out to the dock and it pulled decent,it is the first tow since the new IP,my RPM is 1500@70mph with a 3:55 gear and 235/85-16 tires,Iknow the speedo is accurate as I went to my parents the other day and they had one of those police speed things on the street,1500 seems low to me,but the truck is a 5 speed so I don't know???

 

With 3.55's and 235/75-16 tires the following speed and RPM should be very close.

5th gear and 2050 RPM is 70 MPH
4th gear and 2700 RPM is 70 MPH
3rd gear and 3300 RPM is 60 MPH

Different tire manufactures and types of tires have slightly different diameters.
Most of my spreadsheet numbers are set up for mud tires since that is what I usually run.
Mud tires are generally the largest diameter tire for a given size, followed by all-terrain and highway tires are the smallest.

If you have highway tread tires on your truck the RPM values given below will be somewhat low by probably 30 to 90 RPM

1/2" difference in tire height from 31 changes the RPM by 32 RPM in OD.

Or
30.5 = 2082
31 = 2050
31.5 = 2018



From what you have said, it appears the tach is off several hundred RPM.
What is your idle RPM? It should be about 650 to 700 when warm.