7.3 looses power and dies every 5 hours

jbarnett31 · March 3, 2009

i have not been able to duplicate this yet but i am not able to explain to the customer i will be guessing if its not acting up. it has no codes, but after 5 hours or so it looses power and dies, after it sits a couple of minutes it will crank back and run fine for a few more hours. i have a couple of ideas but i wanted to ask the diesel gods their opinion. im just lookin for ideas. thanks.

Keith Browning · March 3, 2009

Debris in the fuel tank clogging the pick up? Just a guess.

jbarnett31 · March 3, 2009

that was one of my thoughts but the guy says someone has already looked at that but i may check it out any ways

jbarnett31 · March 3, 2009

i found it the two filters in the tank unit were clogged up, the guy either lied to me or didnt know what he was doin, lesson learned never listen to the customer diagnosis.

Bruce Amacker · March 3, 2009

Yes, the screens in the tank sender assy are a big time pattern failure giving the exact complaint you have- intermittent stalling on the highway, wait 10 minutes and it's fine. You can do a fuel pressure test at the head to check pressure, but in reality you need to duplicate the concern with a vacuum gauge on the pump inlet. The tool you'll need to check inlet restriction should be in your 7.3 kit, it's a hose assembly, PN 014-00931-2. Normal restriction is in the 4-6" HG range, I've seen them pull 29"+ when the screens are clogged.

We had a discussion about PN a while ago, normally you buy the whole sender assy when you have this problem. The 7.3 screens are on the left. If you do find this problem, warn the guy that his pump has been cavitating and could fail as a result of the blocked screens.

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Good Luck!

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Keith Browning · March 4, 2009

i found it the two filters in the tank unit were clogged up, the guy either lied to me or didn't know what he was doin, lesson learned never listen to the customer diagnosis.

Perhaps someone only looked in the tank and as you have discovered, those screens are not visible unless you pull the recirculation valve assembly apart. As Bruce mentioned, there is an older topic on this... although the screens are not officially serviceable they can be cleaned or replaced

Jim Warman · March 4, 2009

Justin... some friendly words of advice.... I often get vehicles that other techs have already checked "that". When you get something that has defied other repair attempts, the wise thing to do is start back at square 1.

There will be a test or an assessment that someone, somewhere has decided is "good enough" or has been overlooked (I don't need to check fuel pressure because it drove into the shop...).

It isn't luck that makes a tech good... being thorough does....

Bruce Amacker · March 4, 2009

The definition of an expert:

"Someone who does the basics better than anyone else."

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jbarnett31 · March 4, 2009

yea i those filters were the first thing i asked about him checking and he said yea there fine he replaced the whole assembly, i drove it around to lunch never acted up so i pulled the tank after lunch and the sender looked like it was never touched, i did not loose any time other than drivin it around but i learned not to listen to old men who think they know more than me, lol, thanks for the help though

jaysonfordtech · March 5, 2009

The other definition of an expert

the guy who has broken all the stuff before, and now knows to tell you what not to do.

Bruce Amacker · March 5, 2009

That would be me........

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Fordracer · March 5, 2009

I found a part number that is supposedly for the filters. I found it on the FMC Dealer message board. A guy by the name of Chris Worley from Hub City Ford said the part number is 4C4Z-9365-BA and the Motorcraft number is FD-4605. I have some coming in tomorrow from Motorcraft so I'll see if it's the filters we are looking for. It's strange that it has a 2004 part number. I had the parts guy try to look it up for a 7.3 and a 2004 6.0 and the basic number doesn't come up but Motorcraft said it's a good number so I'll see what it is and let you know.

eastendpowerstroke · March 6, 2009

I was in my parts room rummaging for a 6.0L fuel pressure regulator I knew we had but the third string parts man I was dealing with could find and I found a little box with what looked like a 7.3L fuel pick screen?? I'll have to check the number tomorrow.

Shlep · March 6, 2009

That would be me........

Yeah I kinda fit that profile myself Posted Image

Fordracer · March 6, 2009

We got the parts in today from Motorcraft and they are the filters that go in the sending unit. The plastic part of it is black instead of white. They are $10.22 retail.

Damon · March 7, 2009

I've pulled these out entirely and installed a suction side filter before the lift pump. That seems to resolve everything and make it a simple maintenance item instead of a tank R&R job every time.

Mekanik · March 7, 2009

i learned not to listen to old men who think they know more than me

We get a lot of these idiots that come in and want to talk. Mostly it's them just wanting to show us how smart they are. They come in and want to ask some questions about diesel fuel or something. But they don't want your information. They just want to hear thier own voice, " I'm not putting that McDonald's french fry oil bio-diesel in my pick up truck. Bla bla bla... "

What about the fuel tank? Is this an aft. axle tank? Has the liner come apart or is the inside of the tank all rusty?