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Jeremy
Jeremy, Certified Truck/Bus Technician
Category: Medium and Heavy Trucks
Satisfied Customers: 2789
Experience:  ASE Med/HD Truck Technician, NATEF Diesel Engines and Electrical/Electronics Technician, EPA 608/609 HVAC Certified, Steering/Suspension and ABS/Brakes Technician
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04 FUSO FH 4M50 ENGINE CRANKS NO FIRE OLD INJECTION PUMP NO

Customer Question

04 FUSO FH 4M50 ENGINE
CRANKS NO FIRE
OLD INJECTION PUMP NO FUEL AT INJECTORS
REMAN PUMP FROM D&W NOW SMALL AMOUNT OF FUEL AT EACH INJECTOR
NOT ENOUGH TO START AND RUN
AS IF THE THE DWELL ON SPOOL VALVE NOT OPEN LONG ENOUGH TO FILL INJECTION PUMP ROTOR WITH FUEL
THIS IS THE ORIGINAL PROBLEM WITH THIS TRUCK MANY SHOPS HAVE WORKED ON IT TO GET IT STARTED
AMPEL FUEL AT RETURN LINE ON HEAD
Submitted: 2 months ago.
Category: Medium and Heavy Trucks
Expert:  Jeremy replied 2 months ago.

My name is ***** ***** I will assist you with your question today.

I'm an independent contractor and I don't get paid until a rating has been made.

We can go back and forth as needed to help resolve the issue you are having. Follow ups are free after ratings, so rate in confidence!

What is the pressure coming off of the lift pump from the tank?

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Jeremy

Customer: replied 2 months ago.
Would prefer someone who is familiar with this system.This system is vacuum fuel from fuel supply.Asking for fuel pressure reading is discouraging.
Expert:  Jeremy replied 2 months ago.

I am a Fuso tech and 40% of the 2004 Fuso's have electrical lift pumps in the tanks. I wasn't given a VIN so I asked in case you had one of the exception vehicle.

You still need a fuel pressure reading. The fuel gauges offer both a vacuum and a pressure, depending on which side of the pump you are on. If you have a low vacuum on the back side of the pump, (like on the fuel filter showing low suction on the port) then there is an issue on the suction side of the injection pump causing the low fuel pressure to go back out. You already replaced the injection pump so my concern is if there is an issue with the fuel filter assemply or a line collapsing. These engines are notorious for line collapsing just off the tank where the lines run up along the rail at the back of the cab from them being exposed to the elements and softening just before it goes into the filter. I usually will rule that out by dropping the line off the suction of the filter housing then run from a bucket to the filter housing. I will then run straight to the injection pump to rule out the filter housing and make sure the issue is on the front side of the pump and not the suction side. That needs to be narrowed down first.

I'm going to presume the overflow valve was changed with the injection pump and wasn't reused? If that overflow valve is sticking in full open, it will have the fuel just dump off and not allow the rail to build pressure.

From what you are describing though, I will presume the issue is at the suction with wither a collapsing fuel line (very, very, very common on these trucks between the fuel filter housing and the first joint to the hard plastic line where the soft rubber is) or it is in the filter housing.

If you find it to be the fuel filter housing, it is usually in the head in the round section. If you drop the filter, you will see a little valve up in there. It is usually gummed up with debris or plastic pieces from the old desiccant filters. You can sometimes blow it out by removing the 2 lines, then blowing backwards from the pump side of the filter. If you blow from the tank side, you will lodge it more. There are times I will even remove it and drop it in a small container of mineral spirits for the night and reinstall it in the morning.

Customer: replied 2 months ago.
please pardon my frustration on this truck
vacuum gauge reads 0 between filter housing and injection pump
also there is fuel in return line at head while cranking
we did however just now bypassed filter housing and ran hose into a fuel can added pressure to remove any air.
no change, fuel slow drips from injector lines
pump did come with new overflow valvemy understanding the spool valve on this pump opens and closes each fire stroke
like you suggested a fuel restriction, what if the spool valve command is to open and close is to short
any info on how to check timing and dwell of spool (spill) valveas i mentioned before this truck has been at nearly a dozen shops
these items discussed have been gone over many times because we and other are familiar with them.what we
are not familiar with is the electrical function of the fuel system
I may be wrong but I believe this is an electrical issue
I have the factory wiring diagramvin # jw6cpk1s03L006338 should be 03 fuso FH with 4M50
Expert:  Jeremy replied 2 months ago.

It sounds very much like an electrical issue with the description you now have.

The spool valve is fully ECM controlled. When there is a short or misread in the system, the ECM will code for it. If you are not coding on it, then I would have the programming checked and maybe even be ready for a ECM replacement since the ECM controls the opening and closing of it.

I will upload the full troubleshoot. I know you have the diagrams, but the whole section might help you out in this to diagnose the valve.

CLICK HERE

This has the timing control sensor, the spool valve, and everything else in between to test the operation of the different components.

Customer: replied 2 months ago.
the download set off my virus protection unable to open
Expert:  Jeremy replied 2 months ago.

Odd...

Try this.

CLICK HERE for the full manual instead of the section. Only click the green button for the files. Not the stupid ads...

If you have drop box, I can send it to you that way as well. I'll just load the link. Let me know.

Expert:  Jeremy replied 2 months ago.

I see you viewed this and this is still showing as a open question due to no positive (3 stars or more) rating.

Did you still need assistance with this?

Customer: replied 2 months ago.
made an appointment to rid my computer of downloaded virus
if you are trying to send shop manual I have that
didnt find any issues with sensors listed
what i dont have is wave forms of timing sensor in front cover and spill valve

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