I have a 2000 ambulance that has the 7.3 power stroke. It runs like a scalded dog at times and then will stall out to absolutely no power at all and sometimes will even quit running. When I say no power, it may only muster up 20 mph. When I say like a scalded dog, 80 mph is easily obtained. The ambulance did sit for over a year (which could mean bad fuel). I have changed the fuel filter with little gains in the performance. It does seem to make a little difference when it is acting up if I pull the drain for water in the fuel. It will at least start back up when it has stalled out. I have just started messing with this project so I don't have much history. It was a county ambulance and then given to the fire department for a rehab truck. It sat for a while waiting on someone to spend some time getting it in service. I wish I had gotten a hold of it when it first came out of ambulance service and not after it had sat for a year or so. It has just over 200,000 miles on it. It was in backup service before given to the fire department so I am guessing that it was in tip top shape when we got it.

Any help is appreciated

 

I have a few ideas but you must first entertain me. Why did you obtain an ambulance?

 

The fire department will use it for a rehabilitation vehicle which means when we have a fire, a fellow could get in the rehab truck to cool off or warm up depending on the weather conditions at the time.

 

Welcome to FTE. First off have you changed the oil yet? Step one needs to be new oil and filter with the proper rated oil. The fuel injectors run off of pressurized engine oil so this is very important.

When the truck is low on power, does it run rough like it's not firing on all cylinders? Does the CEL (check engine light) come on? Any other symptoms you can tell us when it's low on power?

 

I have not changed the oil yet but will put that on the top of the list of things to do. It does run real rough like it is not firing all cylinders. The CEL does not come on and the water in fuel light does not come on. A couple of times the transmission overdrive "off" light has been flashing but resets once truck has been re-started. It just acts as if there was water in the fuel or an air leak neither of which I can confirm or dismiss. I have checked all over for both but wouldn't want to bet either way for sure.

Thanks

Ken

 

change that oil fast!!

 

If the oil is really black, or there is a possibility of questionable maintenance, you might want to suck the oil out of the HPOP (high pressure oil pump) also. If you watch the video in the first post of this link https://www.ford-trucks.com/forums/7...il-change.html
you'll see how to do it. There's been debate on sucking the oil out more than just one time. You can do this 3 times like in the video if you prefer, or just do it once.

This isn't a required step in an oil change, but if the oil has been neglected, it might be a good idea. You'll need 15 qts of oil, plus 1 qt for each time (if any) you do the HPOP oil.

Let us know how it runs after the oil change.

 

excellent help Chris!!

Edit: I'll rep ya when I spred it around...lol

 

Crappy fuel in the tank if it sat that long. Might have to clean out the tank and pickup assembly.

 

Good point Mike. I completely forgot about that one.

 

There is also a screen in the fuel line coming out the right side of the fuel filter housing as you ae looking at it. There are 2-10mm bolts holding the block on the side of the housing, and the fuel line connects to the block. You can usually clean this screen by removing the 2 bolts and pulling the block away from the housing. Removing the line isn't really necessary. Be careful, there is an o-ring between the block and housing, don't lose it. Once the block is pulled away, you can remove the screen and clean it. Mine was so dirty, I don't know how it even ran.

 

OK guys, I thank you very much for all of the replies.

This morning I started out with the oil change with filter, and changed the oil in the HPOP 1 time.

I then pulled the fuel filter and pulled all of the fuel out of the housing. I sucked out all the residue in the housing and pulled the screen off the housing and cleaned it and changed the fuel filter.

I then pulled all of the fuel out of the fuel tank, pulled the tank off and cleaned everything out of the tank.

I checked all of the air hoses and connections for leaks.

I believe that all above items can be checked off as NOT the problem.

Then comes the test drive... everything started out pretty good, and about 1 mile from the shop, power is gone and about 30 mph is all that I can get out of it. Then on the way back to the shop, it is barely able to pull itself back.

Like I said before, thanks for all of your feedback but I need more help please. All of the ideas made since and I don't have any regrets with going through the process so we could say for sure they are not the problem.

What other ideas do you guys have?

Thanks,

Ken

 

Still no check engine light? How bad did the oil look, and what did the inside of the fuel tank look like? Getting some live data from a scanner would be helpful. You may need to hook up a fuel pressure guage since your problems seem to happen at speed.

When it's running rough. If you pull over do you get a smooth idle, or is it still rough? If it smooths out at lower rpm's I'd suspect a fuel issue. If it's still rough you may want to check the UVCH (under valve cover harness) wiring. Have you watched the engine temps to see if the problem only shows up after the engine is warmed up? If the engine runs good cold and poorly when hot we may need to look at oil / IPR issues. What type of oil did you use?

The UVCH wiring can be checked with an OHM meter. Look on the inboard side of each head for a rectangular plug with 9 wires in it. Those are the ones you want to test.

The connector at the valve cover has a plug on both the inside and the outside. The one on the inside is usually the one that comes loose. You can disconnect the outside plug and ohm the wires for resistance to determine which side needs to come off. The valve cover gasket is re-usable.

The 9-pin plug is wired as follows:

G G I I C I I G G

G=Glow Plug +
I = Injector +
C= Injector Common

The injectors fire with a 115VDC signal from the IDM. Do Not pierce the wires to test.

Test between "I" and "C" to test the injectors, should be less than 5.0 Ohms.

To check glow plugs Test between "G" and battery ground. Should be between 0.6 and 2.0 Ohms

 

Where are you located maybe a member can help you pull any codes to narrow it down.

 

Any smoke when it falls on it's face? and if so, what color?