I just recently bought a E-350 (1989 7.3L) that seems to be hurting on power when going up hills and when traveling on the highway. It has an ambulance body and I believe 4.10 rear end behind a c6. Above about 50mph I can't maintain speed up any but the smallest grade.

I took it into a local diesel mechanic who thought it might be the injection pump which has never been replaced (with about 70k on the odometer).

Could this be the problem? I can see if the pressure was low not being able to supply enough at high RPM, but at least in my thinking it could be caused by any number of cheaper to fix problems...

Is there anything I should check myself prior to letting him put in a new pump (he also recommended that I change out the injectors at the same time).

Thanks,
Jon

 

Has the fuel filter been changed latley? I would change the fuel and the air filter and run some fuel treatment thought the system before I went to those extremes. Power Servive makes a good treatment that I would recommend.

 

Beyond the fuel filter in the engine compartment, I am vaguely aware of a screen type filter at the pickup in the tank. Is that correct and does it need to be cleaned? (if so how do you get it out?) or should I be fine just changing the normal fuel filter?

I did change out the air filter already... and the oil...

Jon

 

I will say that 70 K is no miles for a diesel, but ambulances sit there and run a lot at idle while on calls. I would also suspect that the 70 K is more like 170 K or 270 K if you knew the truth. Where I am at those guys run 70 K in a couple of months, not years.
One of my first steps would be to find out where it came from and what it's history was before I made any major decisions on the motor. A phone call or three may give you lots of info about what you really have. You may even be able to get a complete maintence history on the vehicle for future reference.

How much does that rig weigh as it sits?
You have a lot of frontal area that is not very aerodynamic which is probably fairly heavy. So it will never be a speed demon on hills.

Do you see any indication of black smoke when you are pulling the hills or any other time while driving?

If the answer is yes, then I would change the air filter, and look at all the air intake hoses for crimps or restrictions.

If the answer is no my first step would be to change the fuel filter and run a healthy dose of Power Service diesel fuel system cleaner through it. Use the to clean fuel system ratio on the bottle.
Then I would change the fuel filter again.

If you still see no black smoke and the power does not come up some, the injection pump pressure may need set up a little.
The timing may need to be checked also.

A statement like "thought it might be" does not sound like a mechanic statement, it sounds like a parts changer statement.

Duh, well, I changed the injection pump and the injectors and the lift pump and the fuel tank and the spare tire. It doesn't run any better and I don't know what else to do, that will be 4,000 dollars, and you can rest assured those parts are new rebuilt parts. I warrant them till you drive it off the lot.

 

It weighs around 6-7k and you're right it will never be a speed demon, but I would think it would still be able to hold 60 up a slight hill. Maybe not.

There is a puff of white smoke on startup but I have not seen any while driving.

I'll go with the fuel filter and cleaner option for now, a lot better than the 1500 he wanted for the pump and injector change out. I'll also try researching where the ambulance originally came from and get a better idea on the actual mileage, since I agree that it probably is 170 or 270 (the guy selling it obviously claimed it hadn't rolled over yet...)

thanks,
Jon

 

That is a bad claim if it is not true. Odometer fraud is bad news here in WV for any seller. If you know it has rolled over you better say it has, and we have to verify that the milage is correct.

As far as the power problem where are you at? If you are at a high altitude the pump may be cut down for clean air problems.
If the unit came from a high altitude place and you are at a low place you may be able to gain lots of power by turning a screw.

 

I am in Connecticut, about 3 miles from the ocean.... It came from Hellertown PA, spending a year in New Jersey enroute. None of which I would call high altitude.

Which screw do I need to adjust and what is the "correct" setting? or am I better off taking it to a mechanic (a different one, which I should do anyway to check the timing...)

thanks,
Jon

 

This guy did an excellent job of describing the process.

Go in very small increments, like one flat on the allen at a time.
You do not want black smoke bellowing out of it, just a little light black pulling a grade.

Do you have to go through an emission test there?
If you do then it better be a very light black smoke.

https://www.ford-trucks.com/framered...%20article.htm

 

nope no emissions for me so I'll adjust for just a little smoke on a grade, (although I will wait until after I change out the fuel filter).

Thanks,
Jon

 

Run some fuel system cleaner through it first also. Get all the crap out and good fuel in before you try to adjust the fuel pressure any.