Erratic Fuel Pressure DT 466-570 - EGR MaxxForce 2010

[mondao]

we have a truck, WorkStar (7400 with a fault code 372, low pressure diesel
I replaced the FUEL PUMP and fuel filter, diesel pressure is 43 psi at idle and full load is 50 psi
I think the pressure is good, the truck has very good performance, but the code is always present, and the board is always present (Fuel Filter Indicator Light)
we no longer know how to fix this, I would like to put out the lamp in the dashboard
This problem is very persistent in some trucks with this engine
I appreciate if anyone has a good idea

[mondao]

any help, I have the truck in the shop again
I would like to solve this problem

[usedcal]

any help, I have the truck in the shop again
I would like to solve this problem

try replacing fuel pressure regulator

[blackdragon125]

Also I would check the fittings at the fuel filter housing as they have check valves in them and sometimes they get depry that cause them to stick. The fuel pressure should be 90psi + or - 5psi's so it may need a fuel pressure regulator but again you might want to check for something stuck in there causeing it to loss presure. Hope this helps.

[540IROC]

Since you already replaced the filter, I won't tell you to replace it again however depending on how long it's been in there, the o-ring on the cap may have swollen and won't reseal when you try to put the cap back on. Drain the fuel and clean all the junk out of the bottom of the filter housing. The pressure regulator is down inside the filter housing. See if it's loose. Reinstall the filter and try again. If pressure is still too low, replace the regulator.

You should be able to get 60-70 psi pressure.

[mondao]

ok guys thanks for your answers, now remove the filter housing
to find the pressure regulator, all seems well in the filter housing tomorrow I will try another pressure regulator, another truck
thanks

[mondao]

Thanks for your help gentlemen, today we changed the fuel regulator, another truck, and the fuel pressure is at 60-65 psi
The fault code 372, is now inactive

[540IROC]

A 372 code will be set by the engine ECM if fuel pressure drops to between 44psi and 51psi depending on engine load and engine speed conditions. If fuel pressure is dropping and a 372 code is setting, clean the fuel pressure regulator and retest. If the condition is still present, replace the fuel pressure regulator.

If the code set after replacing the regulator and is now inactive, you just had low pressure because the fuel system wasn't primed properly. If the code is now inactive, clear the code and retest.

I only replace the filter housing mounted regulators. The ones that are inside the housing or bolted onto the bottom of the housings. The changeover years with the HEUI systems that still have the regulator mounted at the rear of the high pressure rail, you can remove the regulator and jam something into it to tighten it up and bump up the pressure. A 4 sided screw extractor works. I use the handle of a flat file. Tap it in the tighten it up. Boosts the pressure from 40-50 to 70-80. The engines run so much better with higher pressures. Those regulators are really expensive to change for just low pressure when they can be adjusted.

Unfortunately, the newer ones in and under the filter housing can't be adjusted.

Glad to hear to have good pressure now.