My 99 E350 with the 7.3 liter has started seriously bogging under acceleration. If I pull over and let it sit 5 minutes it will run fine but after driving 5 minutes the issue returns under acceleration. When it happens I cannot get itg over 45. If I try accelerating it bogs worse,it never stalls but just bogs down. It had over heated earlier in the trip and lost oil pressure however after letting it sit and cool for two hours it started fine and ran fine for 200 miles. I have experienced this issue a few times prior to it over heating so don't think that's related but It might be. Some back ground info that may help is that I drove it from Pittsburgh Pa to Charlotte nc, 1,000 miles round trip Im hoping its a fuel restriction issue like fuel filter or something in the tank screens?

 

I could be way off here, but the first thing I would do is check all your turbo tubes and coupling boots... do you have a boost gauge??


I had a similar problem and it turned out to be part of my boot was blown out where it comes out of the intercooler.


Take each coupler off, clean them up and inspect them real good for tears or holes. when you put everything back together make sure all the clamps are tightened down really good.


Also while your in there check your turbo and make sure its not dusted and spins freely.


Start with simple troubleshooting like that and work up from there I guess

 

Hi Mike,

I'm moving this to the 7.3L forum, you'll get some better responses down there.

 

Can you take the fuel line off the pump and blow some air back toward the tank? Usually knocks some crud off the screens and gets a little flow back, you'll know if it runs better. Some data logging with a scan tool and rigging up a fuel pressure gauge you can see while driving will be your friends. Don't plumb a mechanical fuel pressure gauge in to your cab, could make for a bad day.

 

Which oil pressure did you lose? The one on the dash - or do you have a gauge that reads Injector Control Pressure? What is your oil level? Which oil do you use? Any smoke out the pipe? What color? If you are losing oil, what does the fuel filter look like?

 

And what caused it to over heat? What did you do to fix that?

 

First I should say the trucks back up and running normal. I changed the crank case oil and also the oil in the hpop even tho I had just changed the crank case oil a week before, I did it again since I over heated it, my thinking was maybe I had fried the viscosity out of the oil. I also changed the filters and just because the 7.3 are known for cps issues I changed it to. So its running great again but I notice some turbo lag from time to time. It is a large Box truck /E350 Chassis and I don't have another 7.3 liter vehicle to compare it to but it just seems like every now and then it lags. But that's not a huge issue for me and it probably has more to do with the fact that it has 350,000 miles on it. Ive looked at the boots and their all in place and seem visibly in good shape but I don't have any real experience or knowledge of what a faulty boot may or may not look like so are there things to look for? Ive been thinking about some turbo kits and other thongs to get a little more hp out of it but my question is this, With 350,000 miles is it worth it? How many miles are these engine good for before you call it a day and start watching how much money you invest in upgrades? At 350,000 is my engine a spring chicken, is it about to hit a mid life crisis or is it ready for the old folks home lol

 

Almost forgot the biggest question, what caused the over heating? Some where Between charlotte and the border of Virginia my radiator started dumping antifreeze. When I shut it down and pulled over I found a hole in the radiator that looked like it had been patched/welded at some point in its life by a previous owner which made no sense to me since I bought a new replacement for $125 bucks. Why anyone would risk blowing a 7.3 to save $125 is just plain dumb but it belonged to a Lumber company at one point so maybe their mechanic didn't want to do his job...

 

That all depends on too many factors. Many of us are burning on with 300K-400K and permagrins.

With the engine running, remove the oil filler tube cap and place it upside-down on the tube. If the cap hovers there, you have no significant blowby. If it lands in the neighbor's yard, you have an issue.

At that age with no significant work done to it, you will likely need a Hutch mod, maybe a sensor here and there is out of spec (like ICP and EBP), and maybe those injectors are due. You could be facing a couple of grand worth of work to restore the truck to it's former glory, or it could be a boost leak - which might be fixed with the turn of a nut driver.

Perspective - I have a little to share. Over the last three years, I spent over $25,000 (I proof-read that number, it's not a typo) on my 2000 that is sitting on 299,500 miles today. If that sounds crazy, buying a 2015 6.7L is like throwing $70,000 on one roll at the crap table, praying Ford made that one as economical to own as the 7.3L. Based on what I've seen with my own eyes and read here on the forum, I wouldn't place that bet. Oh wait! I didn't place that bet. I restored my truck to like-new (or better) running condition - the whole drive train.

 

No, Ive cheched the blowby and its minor at best. It sounds great,runs smooth but I am going to be investing in injectors.

 

You said it's a box that truck so it probably has a steel fuel tank.

There is a know Issue with the coating the steel tanks were lined with peeling off and clogging the fuel pickup in the tank. It is probably something you want to investigate.

As for mileage....if its running smooth and does not have excessive blowby she probably has plenty of life left in her.