7.3 fuel leak

[cjken]

My 7.3 van is leaking fuel. The valley on top of the motor is full. I pulled out the fuel bowl assembly but am un able to identify the source of the leak. I was hoping I would find obvious degraded o-rings or something like that
Does it make sense to rebuild the fuel bowl and put it back in, see if it is fixed.
Or do I dig deeper and change out the fuel pump while I am in there.
I wish that I could have identified the leak point before I pulled the file bowl.
I think I would have to pull apart the turbo to get the pump out.
Has anyone done this. If it were a pick-up. Everything would be easier to get at.

Ken

 

[Martyn]

Assuming your leak is diesel fuel, the most common leak is from the water separator drain valve. It's the yellow valve on the back of the fuel bowl. The tell tail signs are diesel in the valley and diesel on the front axle (at least on the trucks it is).

The drain on the trucks discharges to the bottom of the engine via a tube connected to the valve via a rubber hose.

Remove the rubber hose and using a flash light you should be able to the diesel leak when the engine is running.

You can either replace the complete valve or just replace the O rings. Instructions on rebuilding are here

Napa also stocks the drain valve.

 

[cjken]

Thank you.
Yes. I am hoping that that is my problem
I took the drain off and the o rings look ok.
I'm going to change them anyway.
I also plan to change the sensor on the back of the fuel bowl. It's a shot in the dark but I heard that those can leak as well. It is so hard to see anything when it us running due to the turbo in back and air cleaners up front.

 

[Martyn]

Thank you.
Yes. I am hoping that that is my problem
I took the drain off and the o rings look ok.
I'm going to change them anyway.
I also plan to change the sensor on the back of the fuel bowl. It's a shot in the dark but I heard that those can leak as well. It is so hard to see anything when it us running due to the turbo in back and air cleaners up front.

My experience with the O rings is that they don't appear to be damaged just compressed. Flash light and a mirror on a stick or a good friend who is a dentist always helps in these confined spaces

 

[truck mechanic]

if you have the fuel filter housing out, and you dont know when the last time the pump was changed, i would do it at the same time.
just my .02
Paul

 

[naterry]

Oh boy, this is the first thing I had to do for my van which mostly sat in Texas for years and the o-rings on the nose of the fuel pump had dried out and started to leak.

Martyn's comment above is a good first check. If it's not the petcock or fuel bowl o-ring then you are likely facing a fuel pump R&R. Does your van have the large mechanical fuel pump (pre 98 I think)? If so: Clean and dry the valley out and then watch the area around the base of the fuel pump from inside the van (doghouse removed of course) while the engine is running (mirror and headlamp req'd). This will tell you if you are in for the pump R&R treat. In my case the push rod for the fuel pump had corroded and ate the bushing that guides it. There is a built in weep hole on the nose of the fuel pump that will start squirting when this happens. This shows as a squirt of fuel that comes from the mating surface between the block and the fuel pump.

Getting the turbo off isn't as bad as it sounds, maybe 30 minutes. The challenge comes from the small fuel lines that connect the pump to the fuel filter bowl. The bottom two lines are under 3" long. Then, to compound the issue, the bosses coming off the fuel pump and the fuel filter bowl are ~1" long each. This leaves you with little to no room to push the line onto each boss, let alone get hose clamps on. Take the turbo off, it will save you hours and lots of blood.

The method that proved successful for me was to leave the fuel filter and fuel pump loose, connect the lines while they can still be jiggled about, and then insert the fuel pump in the bore and bolt down the fuel filter at the same time (after the connecting hoses are clamped). Also be very careful with the hard fuel lines going to each head via the large (I think 22mm thread?) banjo bolt. Bending these too much is no good.

Expect bloody knuckles and numerous quality epithets. BUT, once it's replaced you should be good to go for a long time!

Hopefully this helps,

N

 

[cjken]

Thank you for all the advice
Will be changing out the fuel pump while I have it all apart. Hopefully that will have me running trouble free for a long time to come.
Nate, what year was your ambulance??
Yours was the first 4x4 rv ambulance that I stumbled across. One of the coolest things ever!!
Ken

 

[maXTERRA]

Also, all the rubber hoses to & from filter, pump, regulator, etc are notorious for cracking and leaking.
I just replaced all of them on my '96 (not fun).

Also found the pressure sensor that screws into the back of the filter housing leaking internally. Per some searching on related forums, deleted the sensor. And plugged with 1/8" plug and JB weld, as they are prone to cracking around the sensor hole..

Fuel pump leaking out of the weep holes is another source. Also the o-ring on filter housing cap can leak.
As previously mentioned, fuel drain valve can leak.

There is an upgraded filter available as they don't make this one due to all the problems (duh) but I've heard sometimes near $500...

Also an aftermarket upgrade to an electric fuel pump and different filter??

Just search up 7.3 power stroke fuel filter leaks, and unfortunately you'll find a ton of posts on the subject.

After all the work on mine this year, just noticed the fuel smell by the hood yesterday again.....

 

[naterry]

Thank you for all the advice
Will be changing out the fuel pump while I have it all apart. Hopefully that will have me running trouble free for a long time to come.
Nate, what year was your ambulance??
Yours was the first 4x4 rv ambulance that I stumbled across. One of the coolest things ever!!
Ken

Cheers! The Amby was a 97, and the current van is a 96. Good luck with that pump, removing the turbo saves a lot of headaches-

 

[cjken]

Thanks for all the great advice!!
Got it all finished up on Sunday. Ran it drove it no signs of leaking now!!

 

[maXTERRA]

Anybody else experiencing related problems, just go to
http://www.dieselorings.com

They have all the parts you need, and at fair prices!

 

[Bikersmurf]

X2 on DieselORings.com. Fast shipping, reasonable prices, instructions, & even ships to Canada.

I replaced all the ORings on my 97 E350 Ambulance using his kit. The job was a pain in the *****, but no more leaks. I rebuilt the fuel bowl and replaced the filter with parts from DieselORings.com for the price of a filter locally.

 

[cjken]

Yes that is where I ended up getting all of my supplies.
The owner was very helpful and accommodating.
X3

 

[maXTERRA]

For sure. Bought a fuel pump thru them as well.
NO MORE LEAKS!!!

 

[ujoint]

We just got 2 fuel bowl o ring kits from them, nothing but god things to say too!