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Discussion Starter #1
Hey fellas, an old friend of mine has a 99' F-350 4x4 and a little probelm.

The truck has 75K on it and is mainly a distance hauler of one person and air.

The truck has an intake, exhaust, VB mods and chip.....get's almost 18MPG @ 75 MPH.

Ok, here's the problem. When he first got the upgrade, just over the 40k mark, the truck would belch smoke and run like a rabbit. And now, 30k later @ 75k it's just not performing like it did. There isn't as much smoke, it doesn't "peel" @ take-off, and it tends to kick-down a gear a little more. The truck was taken to the Ford dealer and they said everything was fine. Heck the dang oil is changed every 3,000 miles! The oil never seems to burn...but changing every 3k miles, how could ya tell? LOL


Anyone care to guess what the problem might be? :shrug:
 

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Rich said:
Hey fellas, an old friend of mine has a 99' F-350 4x4 and a little probelm.

The truck has 75K on it and is mainly a distance hauler of one person and air.

The truck has an intake, exhaust, VB mods and chip.....get's almost 18MPG @ 75 MPH.

Ok, here's the problem. When he first got the upgrade, just over the 40k mark, the truck would belch smoke and run like a rabbit. And now, 30k later @ 75k it's just not performing like it did. There isn't as much smoke, it doesn't "peel" @ take-off, and it tends to kick-down a gear a little more. The truck was taken to the Ford dealer and they said everything was fine. Heck the dang oil is changed every 3,000 miles! The oil never seems to burn...but changing every 3k miles, how could ya tell? LOL


Anyone care to guess what the problem might be? :shrug:
You never said anything about a fuel filter.

What kind of intake set-up does it have? It has a K&N filter on it...it could be getting "dusted" and lower in compression.

The injectors could be getting worn out also. When an injector gets weak, the PCM compensates by lowering output of all the other injectors to keep a nice smooth running truck.

Hammer
 

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Discussion Starter #3
Yeah, I mentioned both of those to him. He said he "cleans" the air filter every 9k. I tried to tell him IMHO most are not worth the gain and that could add to his problem. I mentioned the Injectors, he said they are still OEM. I mentioned the fuel filter and it's changed every 6 or 10k.

I wondering if the trans could be giving up the ghost ot maybe the turbo?

....has anyone seen a Ford IC get so clogged that the truck would become weak but not smoke much?:shrug:
 

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Rich said:
Yeah, I mentioned both of those to him. He said he "cleans" the air filter every 9k. I tried to tell him IMHO most are not worth the gain and that could add to his problem. I mentioned the Injectors, he said they are still OEM. I mentioned the fuel filter and it's changed every 6 or 10k.

I wondering if the trans could be giving up the ghost ot maybe the turbo?

....has anyone seen a Ford IC get so clogged that the truck would become weak but not smoke much?:shrug:
never seen a ic clogged but seen one with a small leek, that lead to a low power issue!:popcorn:
 

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No smoke means no fuel.I would start with fuel pump.Just a WAG.

Mike
 

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Have him check for boost leaks, pull the intake off and look at the turbo fins. Look for any uneven wear or excessive. Could build a rig and test for boost leaks, I'm rather proud of this...

BTW, my turbo has been dieing a slow death for about 10,000 miles. Used to be at 30+psi and now can just touch 25 with the water-meth spray... BB goes on soon!
 

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Fuel pump, thats a good one! Mine died and left me with a 300 tow bill...
 

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Ol Dirt Contractor
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Rich said:
The truck was taken to the Ford dealer and they said everything was fine.
My wife was in Oregon last month with her 99 7.3 and as Murphy would have it, blew the HX hose. The dealer reflashed the PCM when they eliminated the "aftermarket" hose and put the hp oil plugs back in.:shrug: Mileage dropped 2 mpg on the way home and truck was idling rough again and no power.

I put the Diablo tune back in and ordered a stainless HX line from ITP. New truck again.. Mileage is back.:Thumbup:

Point is, every time the dealer gets ahold of a 7.3 the reflash is mandatory. I think some of them do it with an oil change!:evil: If that truck was at the dealer the chip was probably reflashed..
 

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I would also look at the MAP sensor line comming from the y-pipe, make sure it's not leaking.
 

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Rich said:
Fuel pump....how much pressure?

Stock about 50psi.You should hear the pump running.Low or no fuel pressure the inj may or may not knock.I ran with 0 fuel pressure and any time I tried to give her fuel it would knock like no tomarrow.

Map I wouldn't have thought of that.It would give you the same problems that you are experiencing.Map sensor will through code if it is being a PITA.You will get a low boost code.

Look at it this way you have to have fuel to burn and air to make it burn.No smoke or lack of it with no power means you are not getting fuel to the motor.On the other side if you had a boost leak you would have a abundance of smoke or more of it with less or no power.It is a fueling problem.

Low compression will throw white smoke and will also show up on a cyl cont test.

Mike
 

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Max fuel pressure?If you don't have it shimmed or reg return system you will prob see a pressure drop with the chip turned up.

The max I have ran on my truck is a bb in the stock regulator.DO NOT DO THIS! The fuel will blow the gasket out of the lid then you will over tighten the lid and crack it then you will finnaly realize that the BB is too much pressure and remove it only to find it was too late and the lid is cracked and now you are stranded.

mike
 

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idunnoyet
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Read somewhere if fuel pressure gets below 45 psi on a 7.3 you can start kissing the injectors goodbye
 

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TDG Mafia - Booze Runner
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AlanB said:
I would also look at the MAP sensor line comming from the y-pipe, make sure it's not leaking.

Yep, that would be my first guess, too:Thumbup:

next would be the HPOP. The early 99's tended to fall of a little from a worn HPOP or maybe that was just mine and Check the MAP pull the hose off and clean it or heck just replace it, and it will make a difference, did for me.

If you do replace the HPOP go with an 03 HPOP
 

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snowaholic said:
Yep, that would be my first guess, too:Thumbup:

next would be the HPOP. The early 99's tended to fall of a little from a worn HPOP or maybe that was just mine and Check the MAP pull the hose off and clean it or heck just replace it, and it will make a difference, did for me.

If you do replace the HPOP go with an 03 HPOP
why a 03 hpop????????????????????????????????????????
 

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Simiular situation last year with the 7.3. It did end up being the fuel pump. The truck ran like a dog, but ran. Jody looked and sure enough the pump was going out. He got it done quickly due to the fact that you can ruin the injectors if you continue to run your truck. It starves the injectors. This will most likely not show a code if you check for them.

Hope this helps.
 

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Discussion Starter #19
Thanks.

Is 72 lbs good or bad? I thought the limmit was 80 unless you bought some kind'a wicked pump? :shrug:
 
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