RPM top out at 3600

[Tomstill8569]

All, I have a ‘85 F350 with the 6.9 IDI of course. This truck runs great, my deal is that it tops out @ 3600 RPM at maybe 3/4 throttle. It is like it has a limiter on it. Is this an indicator that my IP/injectors are wearing? The motor only has 92k original miles. I have converted to electric fuel pump (Holly red) that runs between 4-6 psi.

Any thoughts from the group would be appreciated.

 

[DaveBen]

I believe there is an RPM limiter on ALL diesel engines. I used to hit the limiter on my DD 8-V92 a lot. I know the 6.0 had a limiter as did the 7.3.

 

[snicklas]

3600 is where the pump defuels. 3600 is close to the redline on these engines. Diesel don’t spin up like a gasser. I have a 6.0PSD and it reeves to like 4200, but that is really hight for a diesel. Most diesels in larger trucks (medium and class 8) top out at like 26-2800. The 2022-ish Peterbuilt rollback my son drives is around 2800

 

[Clb]

+1 on that.
Don't listen to the guy with a Screamin Jimmy

You aren’t going to be able to hit 4k on fuel, you will on deceleration (but try not to)

Eta
Seems like there's another governor spring available but those are usually put in built pumps, there's an unwritten guideline of 100k lifespan on pumps /injectors.
Yes "my truck has 200k on the oem pump" guys are out there.
Buuuuuuut...

 

[Tomstill8569]

Thanks all that info helps.

 

[FrozenMerc]

Don't exceed 3600 rpms, especially if you have a turbo that develops any kind of boost. The pistons will help close the valves at that speed, and typically that is a bad thing.....

 

[scsmith42]

. Most diesels in larger trucks (medium and class 8) top out at like 26-2800. The 2022-ish Peterbuilt rollback my son drives is around 2800

The 12.7 Series 60 Detroit in my ‘06 Sterling red lines at 1,800.

 

[Tomstill8569]

No turbo, all natural. Tach has 3800 as redline so I just wanted to check in and see if I had an issue. Thanks again.