EVAP hose collapses

Tiny
CBRASSO
  • MEMBER
  • 2001 FORD F-150
  • 4.6L
  • V8
  • 2WD
  • AUTOMATIC
  • 185,000 MILES
Had a code P1401 so I replaced the EGR pressure sensor which cleared the light. Few days later I got a code P0401 for insufficient flow. The 2 hoses from the sensor had deteriorated and pieces clogged up the pipe they connect to. Cleaned that out and code cleared but now I have a noise like a howl in my air box area and the hose from the evap system to the back of throttle body collapses. Could it be the EGR valve itself? Let me add I’d removed EGR valve and the ports were completely clogged up solid and I did clean it all out. I have pictures below of before and after. Thanks
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Tuesday, January 14th, 2020 AT 5:16 AM

16 Replies

Tiny
BMDOUBLE
  • EXPERT
The hose at the rear of the throttle body is the PCV tube elbow and is extremely common to collapse over time just due to normal deterioration of the rubber from exposure to oil. The howl noise on these trucks is usually due to the idle air control valve sticking and will cause a droning noise, the PCV hose collapsed can intensify this noise also. Sometimes you can give the idle air control valve a tap with the handle of a screwdriver and the drone will disappear.
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Tuesday, January 14th, 2020 AT 9:08 AM
Tiny
CBRASSO
  • MEMBER
BMDOUBLE thanks for the reply but I m talking about this hose that s circled.
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Tuesday, January 14th, 2020 AT 2:01 PM
Tiny
BMDOUBLE
  • EXPERT
Oh okay, no problem! Yes that is the evap line and they collapse due to age and exposure to fuel vapors. I actually just replaced the one on my expedition, just carefully split the line with a razor blade at the green fitting and remove the fitting. Replace the line with fuel hose then retest to make sure that it doesn't collapse. If there is still an issue with the line collapsing, the canister could be restricted or the a restriction between the tank and the purge valve, but the canister is the prime suspect.
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+1
Tuesday, January 14th, 2020 AT 7:08 PM
Tiny
CBRASSO
  • MEMBER
Okay. I did replace it but with regular heater hose. I ll replace it with fuel line. And if still persists I ll do as you said and report back. Thanks again.
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Tuesday, January 14th, 2020 AT 7:56 PM
Tiny
KEN
  • ADMIN
BMDOUBLE is one of our best! Please let us know what happens.
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Saturday, January 18th, 2020 AT 3:26 PM
Tiny
CBRASSO
  • MEMBER
BMDOUBLE, the box next to the canister had no fresh air hose and had gotten clogged up with dirt. I blew it out with low pressure air and cleaned it out really good but the problem appeared again. I read that a faulty PCV valve would also cause this is it possible? Problem started after I changed hoses for EGR back pressure sensor and sensor and cleaned out the EGR passages. Any idea what could be happening?
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Sunday, January 19th, 2020 AT 12:14 AM
Tiny
KEN
  • ADMIN
Yes, a bad PCV valve can cause EGR issues. Here is the location so you can change it out. Also I have seen clogged catalytic converters cause this issue as well. Check out the diagrams (below). Please let us know what you find.
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Monday, January 20th, 2020 AT 10:13 AM
Tiny
BMDOUBLE
  • EXPERT
If the box next to the canister was clogged, then the canister itself could be clogged which is common on higher mileage vehicles. If the evap line is collapsing, it would be from a restriction on the evap side starting at the purge valve then the lines that go under the truck then to the canister itself. What you can do is verify that the purge valve is not clogged by grounding the lg/bk wire then disconnecting the white fitting at the valve to see if you can feel any vacuum there, if not then the valve has failed. The PCV should have nothing to do with this line being collapsed because it is parallel to this vacuum circuit, kind of like 2 straws in a drink.
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Monday, January 20th, 2020 AT 11:57 AM
Tiny
CBRASSO
  • MEMBER
Okay, I will do that this evening after work and respond back and let you guys know. Thanks
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Monday, January 20th, 2020 AT 12:38 PM
Tiny
CBRASSO
  • MEMBER
BMDOUBLE just to be sure. Exactly how would I ground out the lg/bk wire?
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Monday, January 20th, 2020 AT 12:45 PM
Tiny
BMDOUBLE
  • EXPERT
You back-probe the wire at the connector with a needle, or small wire as long as it fits into the connector and use a jumper wire straight to a clean piece of metal. If you have a hard time fitting something into the connector just take a razor blade and shave off a small piece of the wire's insulation then make contact with a jumper wire from there to ground, you should hear a click then a hiss from the vacuum being present now at the unhooked port of the purge valve.
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Monday, January 20th, 2020 AT 2:29 PM
Tiny
CBRASSO
  • MEMBER
Okay. I wasn t able to check last night but will ASAP and let you know the findings.
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Tuesday, January 21st, 2020 AT 5:46 AM
Tiny
BMDOUBLE
  • EXPERT
No problem! We're here for ya!
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Tuesday, January 21st, 2020 AT 7:43 AM
Tiny
CBRASSO
  • MEMBER
Bmdouble, I did as you stated above and I do have vacuum and the motor surges. So I take it the purge valve is okay?
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Sunday, January 26th, 2020 AT 9:24 AM
Tiny
BMDOUBLE
  • EXPERT
Yes, that verifies that the purge valve is good, but verifies also that there is a restriction more than likely inside of the canister, that would be the only explanation for the vacuum line to collapse, kind of like the straw inside of an extra thick milkshake scenario.
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Sunday, January 26th, 2020 AT 3:39 PM
Tiny
CBRASSO
  • MEMBER
Okay, when I removed the canister to check the vent solenoid which clicked when connected directly to 12v when I blew into the hose air came out the other one. So I d assume the restriction is between there and the purge valve.
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Sunday, January 26th, 2020 AT 8:24 PM

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