Hi! Please help me figure out what is going on! Here's the history:

I bought a used 2002 F250 SD w\ the 7.3l PowerStroke diesel and automatic tranny in March of this year. Shortly after buying it, my stepson "topped off" the tank w\ 10 gallons of regular unleaded (there was about 20 gallons of diesel in the tank at the time). Fortunately he realized his mistake right away and didn't drive it (except the 1\4 mile home). I siphoned out the tank and refilled it w\ diesel, replaced the fuel filter, and it didn't seem any worse for the experience.

A month or so later, he blew the transmission. I had rebuilt w\ all HD components and had a cooler added.

My check bettery light came on last week. I had the alternator tested- it was pushing 308 amps(!) and 12.1v. I replaced it.

So- I have 3 potential contributers to my problems- gas in the tank, something botched in the tranny rebuild, or electrical gremlins from too much current.

Now- here's the problems I'm having:

Starting about a month ago, when I got down to about 1/8 of a tank the engine would start behaving as if I was running out of fuel. Refuel and it ran no problem. I figured maybe I still had some gas in the tank, so drained it completely via the fuel pump and changed the filter again, but did not help. It also sometimes didn't seem to quite have the power it should, but wasn't missing or anything.

Last weekend I pulled a trailer w\ a Jeep Grand Cherokee from Phoenix, Az to Moab, Ut, which involves an elevation gain of about 6000 ft., and it was awful! Shortly after starting into the mountains I had a dramatic loss of power and the truck started bucking like a manual transmission in too high of a gear. The only way I could go up a significant incline was to hit it running and downshift as I lost momentum, ending up in first or second gear at the top (I probably should have turned back then but there was no way I was going to miss that weekend!).

Over the course of the drive, I found that the truck runs almost normal when the tank is >3\4 full. If I really push it uphill w\ the trailer w\ a full tank, it will slowly lose "oomph" (like it's starving for fuel) and the check engine light will come on. Get to level ground and it will go back to normal after a few moments and the check engine light will go out. Get below 3\4 of a tank and I lose almost all power and can barely limp to the next station unless it's downhill.

To make things even more interesting, my transmission was randomly overheating. It mostly would overheat if I didn't turn off overdrive, but would sometimes get a little temperamental in 3rd. It didn't seem to matter if I was on a hill or not- If I ran it in OD for any length of time, even on level ground, the transmission would act normal for a while, then rapidly overheat. To cool it off I tried turning off OD while driving, pulling over and idling in park and in neutral, with and without OD on- the only thing that seemed to work was to pull over and turn the vehicle off for 30 minutes or so, then drive slowly w\ OD off- once it started to drop it would go back to normal rapidly. If it was engine temp., I would say it was acting like a faulty water pump, but I don't know if that's a good analogy with an automatic transmission.

I talked to the Ford dealer in Moab- they said it sounded like the fuel pump, but didn't have time to look at it. I don't like "throwing parts at it", but went ahead and replaced the fuel pump anyway. It seemed to help a little, but definately did not solve the problem. I limped it back to Phoenix yesterday, fortunately this way is downhill. Just to keep things interesting I had a trailer tire blowout an hour from Phoenix.....

When I unhooked the trailer, it drove exactly as it did before I left- normal above 3\4 tank, almost normal, just maybe a bit short on power below that.

So- I have no idea what's going on. The possibilities I see are that the gasoline ruined something due to lack of lubrication (that's why I went ahead and replaced the fuel pump), or that there is some wierd electrical fault stemming from a fried sensor or some such. I can't figure how the transmission figures into this- I think it may be a seperate and unrelated problem. One person (autozone salesperson) told me there is a pickup or sending unit in the tank which may be bad ($800ish...ouch!), but the dealer said this isn't so. The problem DEFINATELY is affected by the fuel level in the tank -above 3\4=almost normal, below=yuck- so you'd think something in there was the problem, but I'd also think the dealer would know what they're talking about.

My ODB II doesn't pull any codes, and I haven't been able to have the dealer hook up their computer yet.

This has me stumped! I'm thinking that whatever is inside the tank is the problem, but the price tag is a bit steep to just start replacing things and hoping it works. Any help is greatly appreciated!!!

 

you could try posting this thread over in the diesel forum. there is a lot of knowledge about the 7.3 there. sorry i cant help you out i have no idea what the problem would be about the fuel problems but your tranny overheating in od could be because that is a lot of weight to pull in overdrive and could cause overheating especially if it was warm out. did the shop flush your tranny coolers before they put the new one in? if the old one blew, some pieces that broke off could have gotten stuck it the cooler lines so no fluid even goes through the coolers. im sure someone will be able to help you out more
this is the link for the diesel forum
https://www.ford-trucks.com/forums/f...splay.php?f=31

 

sounds like it could be your fuel pump, you need to do a pressure test on it to be sure, you want to do that by locating the schrader valve up by the filter, and running it up the interstate with it on. find a hill and give it the grapes!!! you need to get a good load, ford wants something like, min, 50%load. and with the trailler it would be more noticable because of the load. and the tranny. DONT TOW IN OD!! it says it in your manual. you WILL burn up the new tranny. you should tow only with the OD off.

and the gas has the possibility to take out your fuel pump and injectors.

you may not have recived any codes because they are P1 OR B1 codes, wich are manufacturer spacific codes, and can only be retreived with a ford scan tool like, NGS, WDS, IDS, OR PDS.

Oh just for some comfort to you, i work in a ford truck shop, I see this type of thing in and out. just be glad you dont have a 6.0 and put gas in it, or lost a fuel pump. they dont like that.

 

Wow. That is quite a post, but good because of the details. I seriously doubt that your pump was gone as you've probably concluded by now with the new pump and lighter wallet, and same problems. There is nothing inside the tank that costs that much money except the labor to fiddle with it.

I would say that your problem exists somewhere between the pump and the tank. Your screen on your intake line pickup foot may be clogged making "lifting" just that much harder with less fuel in the tank. Going downhill improvements are likely just a function of less power demanded to do it.

I recommend dropping the tank and inspecting/flushing everything out along with doing the in-tank mods while you are there. That includes blowing out the line from pump to tank.

As for injector damge from the gas, maybe, but not likely if for a short duration then changed. Somebody will be smarter than me on this and it would depend on the density of both fuels to determine how much was actually picked up by the pickup before it was changed out.

I have no input on your tranny issue as that is beyond my armchair quarterbacking at this point. Good Luck.

 

Sounds like your pick up in the tank is messed up. There is what is called a mixing chamber where the return and the pick up lines are located next to each other and if something goes wrong it can draw air into the pick up line. usually doesn't happen until below 1/4 but in your case it may be different. here is a link with pictures to show how to fix that problem. A little time consuming but not expensive.


http://guzzle.rbmicro.com/hutch.html

 

OK, I've just reread the post and have 2 recommendations:

1: Have whoever fixed the tranny inspect or explain the problem.

2: Keep stepson out of the truck.

 

the tranny problem sounds like a plugged cooler line if the shop did not fulsh out the coolers before they put in the new tranny and some carnage form the old one is still plugging the cooler lines

 

Tranny - Do you have a real tranny temp guage or are you going by the factory guage? From what I understand, the factory guage is junk. Get a real guage and then see if it is overheating. If it is, take it back to the rebuilder and stay on him until he makes it right. Ditto on dropping thr tank and installing the mods. An easy project.

 

hehe, I figured that step out after the tranny. He's a good kid, just expesive to keep...

Someone suggested I do the prepump\intake mod and the harpoon mod.
Step 1: learn what these mods are.
Step 2:.....
Looks like (another) project for this weekend.

Thanks for the good info!

-edit- just read the writeup on the tank mod, looks very straightforward. It will either confirm the problem or rule it out, and is one I'd do in any case. Thanks again!

 

I'd say you're not developing enough power to keep up line pressure and slipping clutches. which is causing your trans to overheat. I agree w/ PBR MAN, the pickup in the tank is messed up. Almost sounds like computer problems I've seen causing low power.

 

I know very little about how a transmission works, but that would be consistant with the symptoms I saw. I also wondered if there may be a computer problem resulting from the really high amperage the alternator was putting out. Is this possible?

 

The amps should not hurt anything, just as long as the voltage did not get over 14.6, but if there was a spike, it may have damaged computer located behind the left fender. Dang, I cannot think of the name for that unit.

As gas is considered a high flash solvent, it may have disolved sediment in the tank and it is clogging the intake tube. I would do the tank clean and the mods suggested first. Also, I would do the line mod to get rid of any air entering the system. Air being sucked into the system will definately cause problems, especially on a long hill climb.

One other thought, when was the last oil change and what did you use? Low and/or worn out oil will cause a multitude of problems. I had a little problem regarding power on a long hill. After changing the oil (I use Mobile Syn 1300) and filter, most of the problems went away. I still need to do the fuel tank, line, and fuel pressure mods, but they are in the future (hopefully not distant).

Also, the the rebuilder of the trans did not do a complete flush, garbage left over may be blocking your filter and this will definately cause an overheat and burnup of the trans.

 

I seriously doubt it. I don't think the PCM is wired directly to the alternator as I think it lives off of the batteries, but anything is possible in electronics if something is awry.

 

I would ditto the fuel tank mods as it will allow you to clean everything out between the pickup and the puel pump.
On the tranny overheating, if the shop that "fixed it" won't take care of it, I know somebody mentioned this from Dieselsite: http://www.dieselsite.com/index.asp?...ROD&ProdID=172
as a possibility for random overheasting issues. It would also make sense if some of the remnants of the old tranny clogged this bypass line maybe. Just a thought.

 

I had the oil and filter changed two days before I left. Don't know specifically what the shop used, but as it was a diesel shop I *assume* they used the proper grade.


There was a LOT of crud in the fuel filter when I changed it. My thought was that the gas loosened stuff up. When I'm doing the tank mod, I'll be sure to take a photo if the internal filter looks anything like I'm thinking it might