Boost troubles
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Joined: Jun 2007
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Boost troubles
New to the forum, and only owned the 7.3 for a few months, so please forgive any "stupid questions"...
Towed a couple of atv's on an aluminum trailer on about a 200 mile trip last fall and averaged 10 mpg; no nuts at all on the top end. Local power stroke guru tested and replaced fuel lift pump, citing that as the problem. Minor improvement in drivability, but didn't do any more towing at the time. Fast forward to last week, as part of the upgrade process finally had some guages installed to go with the chip/intake/exhaust, and lo and behold, I'm making about 14psi at WOT, about 2 cruising down the highway at 70. Seems to run well in town, but get her on the highway and the power disappears. Have pretty much checked over a lot of things I could glean from you guys' posts...MAP sensor, up tubes, replaced fuel filter (gunked up), cleaned screen (REALLY gunked up) etc, to no avail. Possibly still a fuel pressure problem? I'm going to pulling about a 9k load around this summer and afraid to see what'll happen. At least I can keep an eye on my tranny temp and EGT's now, though.
Towed a couple of atv's on an aluminum trailer on about a 200 mile trip last fall and averaged 10 mpg; no nuts at all on the top end. Local power stroke guru tested and replaced fuel lift pump, citing that as the problem. Minor improvement in drivability, but didn't do any more towing at the time. Fast forward to last week, as part of the upgrade process finally had some guages installed to go with the chip/intake/exhaust, and lo and behold, I'm making about 14psi at WOT, about 2 cruising down the highway at 70. Seems to run well in town, but get her on the highway and the power disappears. Have pretty much checked over a lot of things I could glean from you guys' posts...MAP sensor, up tubes, replaced fuel filter (gunked up), cleaned screen (REALLY gunked up) etc, to no avail. Possibly still a fuel pressure problem? I'm going to pulling about a 9k load around this summer and afraid to see what'll happen. At least I can keep an eye on my tranny temp and EGT's now, though.
Tuned
Joined: Oct 2006
Posts: 358
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From: Broken Arrow, Oklahoma
a stock PSD should be pushing around 16psi at wot around 3200 rpm. I would start by checking you EBPV(exhaust back pressure valve) its located on the outlet side of your turbo just before the turbo connects to the down pipe. Sometimes these are known to stick such thus restricting you exhaust flow. Kinda makes a hissing sound out the exhaust when shut. You can check it by unhooking the wires that are on the cold side of your turbo right under the outlet neck on the cold side of the turbo. If no change and your still getting a hissing sound you can unhook the bar on the EBPV and wire it open.
Far as fuel pressure somewhere around 45-70 is normal. this can be checked with a tire guage very messy on the shrader valve(looks like tire valve stem) that is next to your fuel filter. A better way of checking this is to get a liquid filled guage and take the shrader valve out and screw the guage in. But dont leave the guage hooked up because the fuel pressure pulses with the pump very quickly and it will kill most guages.
Im sure some of the other guys will chime in also with some possiblities.
Far as fuel pressure somewhere around 45-70 is normal. this can be checked with a tire guage very messy on the shrader valve(looks like tire valve stem) that is next to your fuel filter. A better way of checking this is to get a liquid filled guage and take the shrader valve out and screw the guage in. But dont leave the guage hooked up because the fuel pressure pulses with the pump very quickly and it will kill most guages.
Im sure some of the other guys will chime in also with some possiblities.
Post Fiend
Joined: Oct 2003
Posts: 5,903
Likes: 1
From: MICHIGAN
If you find the EBPV OK then check the rubber boots for leaks, you may be loosing boost. Check the MAP sensor line too. I use a little soapy water in a spray bottle.
Remove the cold side boot from the turbo and look closly at the turbo blades. They should be sharp and straight. If you haven't replaced the stock air filter and housing, this is good time to do it. The stock housings may leak dirt and dust the turbo, that's why I suggest you look at the turbo blades.
Remove the cold side boot from the turbo and look closly at the turbo blades. They should be sharp and straight. If you haven't replaced the stock air filter and housing, this is good time to do it. The stock housings may leak dirt and dust the turbo, that's why I suggest you look at the turbo blades.
Senior User
Joined: Oct 2006
Posts: 332
Likes: 0
From: Emmett, ID
I don't mean to Hijack, But I just have to say between Tim and Cuda Jim you guys really step up to the plate! I rarely have to post anything because YOU GUYS ROCK! It seems I can always find the answers in the search, or just by watching your replies!
Ok, I guess we can include Rubberduck!
Ok, I guess we can include Rubberduck!
Post Fiend
Joined: Oct 2003
Posts: 5,903
Likes: 1
From: MICHIGAN
Originally Posted by mcdavidson
I don't mean to Hijack, But I just have to say between Tim and Cuda Jim you guys really step up to the plate! I rarely have to post anything because YOU GUYS ROCK! It seems I can always find the answers in the search, or just by watching your replies!
Ok, I guess we can include Rubberduck!
Ok, I guess we can include Rubberduck!
