98 Volvo D12 will not rev past 1500 rpm

loss of vehicle speed will only give you an engine speed derate. given that you've had the fuel pump recently replaced, i'd start there. on those years, volvo has two different styles of fuel pumps. i'm sorry but i'm not sure which one is which. i do know if you install the wrong one, it can cause low power. and the physical difference is hard to tell.

 

really D12C fuel pumps are interchangable.

 

i assume you have impact. identity 58085451... two types of fuel pumps that are NOT interchangeable.

 

It sounds like it's sucking air or has a clogged fuel filter.

 

I try to tell you what i the differen about D12 fuel pumps.

There are two types of pumps with short shaft and longer.

D12A D12B had short shaft pumps.

D12C, D12D, D12F has pumps with long shaft.

But you can use pump with short shaft on later engines, but pump with long shaft cant be fitted to D12A.

Really different is D13 pump. It is designed for rear end timing geartarain, and this pump is combined with PS pump like on Mercedes engines.

All other features of Volvo fuel pumps like fuel flow, pressure are the same. Min 1.5 bar at idle (old pump) and up to 4 bar at 1500 RPM.

 

this is why they're different. one pump is rated at 41 psi and the other at 65 psi, both at rated rpm. they are not the same.

 

really over 1.5 bar at idle - works fine
really pressure limiting valve is 3.5 bar, so additional pressure rating is no necessary

 

the pressure relief valve is also different, obviously.

 

different becouse fuel lines are different, valve location differs, but fuel pressure limit is usually 4 BAR

 

fuel lines and location are the same

from volvo's impact:

"350 kPa (51 psi) overflow valve.

New 450 kPa (65 psi) overflow valve can be identified by the groove cut into the hex portion of the valve as shown.

350 kPa (51 psi) fuel pump .

New 450 kPa (65 psi) fuel pump can be identified by the additional web in the casting as shown.

Note: When changing an overflow valve to the new 450 kPa (65 psi) valve, the fuel pump must also be changed to the 450 kPa (65 psi) version. However, when changing a fuel supply pump to the 450 kPa (65 psi) version, you are not required to change the overflow valve. "

i have no clue why you are arguing with me over this, go look it up.