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Vacuum line stalling engine when connected to nvld

2483 Views 48 Replies 5 Participants Last post by  Bob Lincoln
Does anyone know why when I connect the 2 vacuum lines 1 from plenum the other on to of throttle body the engine cuts off on idle.
Do these lines go to a vacuum pump? Defective?
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Discussion Starter · #21 ·
It is difficult to envision the dislodged. vacuum hoses on your vehicle without an image. If you can take a picture and post that would be helpful. Otherwise find the underhood vacuum diagram and connect lines as shown.

From a view into the engine compartment all you will see is the purge valve under the brake booster. There will be a vacuum hose from the purge valve that connects to a line under the body that runs to the vapor canister mounted on the fuel tank. The purge valve will have another port with a vacuum line that attaches somewhere on the intake plenum.

Follow the larger hose from the brake booster to the intake system. At the intake is there an open port with no vacuum hose attached? If YES this port with missing hose should have to be connected to the purge valve.

This connected vacuum line should agree with the underhood diagram. If the engine stalls at idle with this configuration, it is possible that the purge valve is stuck open. With a stuck open valve the engine is drawing in rich fuel vapors and the overly rich air-fuel ratio is causing engine stall. Just a guess on my part.
Here the diagram attached
 

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Discussion Starter · #22 ·
Start engine and let it idle. Remove vacuum hose connected to vapor canister port on purge solenoid valve. Apply piece of paper to uncovered port on valve. There should be no vacuum at port trying to attract paper with engine idling. If vacuum is found, the purge valve is leaking and needs to be replaced. See attached image.

View attachment 89141
Ok thanks, I put another used purge valve and it's going the same, I'll buy a new one
 

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1966 Crown Coupe, 2016 200 S AWD, 1962 Lark Daytona V8.
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It may not need a purge valve. I've had purge valves stuck open because a piece of charcoal from the charcoal canister got sucked up into it. Can you blow through the valve?
If the canister is loaded with raw fuel, it can allow for a rich mixture. Do you smell a strong odor of fuel?
Either condition may or may not cause a stall. Always diagnose first.
 

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Discussion Starter · #24 ·
It may not need a purge valve. I've had purge valves stuck open because a piece of charcoal from the charcoal canister got sucked up into it. Can you blow through the valve?
If the canister is loaded with raw fuel, it can allow for a rich mixture. Do you smell a strong odor of fuel?
Either condition may or may not cause a stall. Always diagnose first.
Cannot blow through the tube, this tube goes to the valve below the brake booster, in a real awkward place, I guess this is the canister. The purge valve on the throttle body is ok, since I changed that already
 

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The canister is in the back on the fuel tank.
Automotive design Motor vehicle Automotive exterior Font Engineering


There is no purge valve on the throttle body.
Gesture Font Auto part Automotive exterior Engineering


A service manual for this car would help & maybe pay for itself:
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. . . .Cannot blow through the tube, this tube goes to the valve below the brake booster, in a real awkward place, I guess this is the canister. The purge valve on the throttle body is ok, since I changed that already . . . .
As ImperialCrown stated in post #26 the device with vacuum hose below the power brake booster is the purge valve. It is not the vapor canister which is located at the rear alongside the fuel tank. Please post a picture of the attachment of the vacuum hose at the throttle body and the device you changed at the throttle body.

. . . .I also came across a relay,/fuse yellow and orange in color, 3, pins that fell off and I cannot find where that plugs into, wondering if that had something to do with it . . .
Please post a picture of this "relay / fuse yellow and orange in color 3 pins that fell off ". Identify any wire colors attached including secondary tracer color wire.
 

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Discussion Starter · #27 ·
As ImperialCrown stated in post #26 the device with vacuum hose below the power brake booster is the purge valve. It is not the vapor canister which is located at the rear alongside the fuel tank. Please post a picture of the attachment of the vacuum hose at the throttle body and the device you changed at the throttle body.



Please post a picture of this "relay / fuse yellow and orange in color 3 pins that fell off ". Identify any wire colors attached including secondary tracer color wire.
I changed the purge valve below the booster, it's still doing that, does the ac lines have anything you do with this. Ok had found a couple of loose ac pipes
 

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Discussion Starter · #28 ·
As ImperialCrown stated we need to know specific make, model, year and engine configuarion, 4 cylinger, V6, V8, and some images of the vacuum lines in question to make a reasonable, accurate diagnosis.

Now if you wanted a "wild guess" I would say one of the suspect vacuum lines might be connected to the EGR valve. Fully activated EGR (exhaust gas recirculation) will stall an engine and stop it from idling. But again just a guess. Give more detailed information as requested.
The 2003 does not justice egr valve
Ok thanks, I put another used purge valve and it's going the same, I'll buy a new one
Are you talking about purge valve in the fuel tank or below the brake booster
 

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Discussion Starter · #29 ·
I give up, all the vacuum lines are connected correctly, no kinks or tears, installed new nvld valve and engine still stalling, even changed purge valve on throttle body.

Could it be the other valve on the tank, Is there a relay or fuse somewhere that can be causing this, did the ac lines have something to do with these vacuum lines. Any ideas, thanks
 

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If you block the end of the hose with your finger, does it stall? Or only when plugged in to the purge valve?
If the charcoal canister is flooded with liquid gasoline, it may stall the engine by being too rich. It is supposed to store fuel vapor only.
If you install the hose onto the valve slowly, allowing it to stumble & recover, but not stall out, can the hose be installed all the way with the engine still running?
 
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. . .I give up, all the vacuum lines are connected correctly, no kinks or tears, installed new nvld valve and engine still stalling, even changed purge valve on throttle body. . . .
The purge valve is NOT located on the throttle body. What device have you changed on the throttle body? Have you changed the throttle position sensor? Idle air control? See attached image.
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. . . .did the ac lines have something to do with these vacuum lines. . . . .
Air conditioning refrigerant lines would not cause this issue.

. . . If the charcoal canister is flooded with liquid gasoline, it may stall the engine by being too rich. It is supposed to store fuel vapor only. . . . .
I would think that even if the vapor canister is flooded with liquid fuel and the purge valve is sealing correctly, no liquid and / or vapor should be entering the induction system through the purge valve???

Have you check the PCV (positive crankcase ventilation valve)? If it is stuck open it would allow excess air and crankcase vapors to enter the induction system and cause a stall at idle. Remove the hose at the PCV valve and seal the end. Does the engine continue to stall? Remove the PCV valve from the camshaft cover. You should be able to shake and hear it rattle. If no noise or movement detected it is stuck and needs replacement. See attached image.
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Discussion Starter · #32 ·
The purge valve is NOT located on the throttle body. What device have you changed on the throttle body? Have you changed the throttle position sensor? Idle air control? See attached image.
View attachment 89212



Air conditioning refrigerant lines would not cause this issue.



I would think that even if the vapor canister is flooded with liquid fuel and the purge valve is sealing correctly, no liquid and / or vapor should be entering the induction system through the purge valve???

Have you check the PCV (positive crankcase ventilation valve)? If it is stuck open it would allow excess air and crankcase vapors to enter the induction system and cause a stall at idle. Remove the hose at the PCV valve and seal the end. Does the engine continue to stall? Remove the PCV valve from the camshaft cover. You should be able to shake and hear it rattle. If no noise or movement detected it is stuck and needs replacement. See attached image.
View attachment 89211
I changed the throttle position sensor
 

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Discussion Starter · #33 ·
Start engine and let it idle. Remove vacuum hose connected to vapor canister port on purge solenoid valve. Apply piece of paper to uncovered port on valve. There should be no vacuum at port trying to attract paper with engine idling. If vacuum is found, the purge valve is leaking and needs to be replaced. See attached image.

View attachment 89141
When u say purge valve leaking, r u referring to the one at the back on has tank or the one below the brake booster, nvld valve?
 

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There is only one purge valve. It is the one under the brake booster.
(an undercar image looking up at it):



The NVLD is at the rear of the car on the fuel tank next to the canister.
 

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Discussion Starter · #35 ·
There is only one purge valve. It is the one under the brake booster.
(an undercar image looking up at it):



The NVLD is at the rear of the car on the fuel tank next to the canister.
Thanks so I changed the purge valve, do I think it could be the nvld then. Also do u recognize this fuse/relay it feel off somewhere from engine compartment
 

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. . . .I changed the throttle position sensor . . . ..
You probably installed the TPS / throttle position sensor incorrectly. There are plastic lugs in the TPS which must be mated properly to adjoining lugs on the throttle blade shaft. If not mated properly a rotating throttle blade shaft will not advance the TPS and cause a varying TPS signal to be sent to the PCM. An accurate TPS signal is necessary to allow the engine to run properly.

Review this video which shows how to replace a TPS. Video is for a V6 engine but the technique for proper installation is identical for a 4 cylinder engine. Pay particular attention to the video starting at time interval 2:50. It shows the lugs on the TPS which mate with lugs on the throttle blade shaft.

 

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Discussion Starter · #37 ·
As ImperialCrown stated in post #26 the device with vacuum hose below the power brake booster is the purge valve. It is not the vapor canister which is located at the rear alongside the fuel tank. Please post a picture of the attachment of the vacuum hose at the throttle body and the device you changed at the throttle body.



Please post a picture of this "relay / fuse yellow and orange in color 3 pins that fell off ". Identify any wire colors attached including secondary tracer color wire.
Here is the picture, has 3 pins
 

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. . . Here is the picture, has 3 pins . . . .
I believe the image shows a 40 amp cartiridge fuse used in the PDC / power distribution center or fuse box in the vehicle. Orange is the convention color used for 40 amp. The PDC is located under and to rear of air filter plenum box. Is number 40 printed somewhere on the fuse?

Remove the lid and see if a cartridge fuse is missing. There is a provision for holding a spare fuse in the fuse box. See attached image for identification of components in PDC.

Schematic Parallel Font Rectangle Technical drawing
 

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Discussion Starter · #39 ·
I believe the image shows a 40 amp cartiridge fuse used in the PDC / power distribution center or fuse box in the vehicle. Orange is the convention color used for 40 amp. The PDC is located under and to rear of air filter plenum box. Is number 40 printed somewhere on the fuse?

Remove the lid and see if a cartridge fuse is missing. There is a provision for holding a spare fuse in the fuse box. See attached image for identification of components in PDC.

View attachment 89241
This is a different fuse, but I looked in the fuse box there's a fuse missing that's 40amp, days for abs pump, could this be the booster not sucking in air.
The weired thing is this fuse has 3 make pins and it fits on a plug that's connects on the valve cover to the ignition coil but theres an electrical 3 pins plug that goes there already, but ironic that it will fit there too
 

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. . . This is a different fuse, but I looked in the fuse box there's a fuse missing that's 40amp, days for abs pump, could this be the booster not sucking in air. . . .
I do not understand what you mean by "booster not sucking in air". ABS is acronym for antilock braking system. The ABS is fuse protected. This fuse would not have any affect on the purge valve. This fuse has no affect on the power brake booster.

Go back to post #37 and follow the detail about correct installation of the throttle position sensor. If not installed correctly this could very well be the source of your engine stall issue.
 
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