Fuel 90 5.0 LX air buildup in fuel tank

dwb

Member
Oct 9, 2017
48
1
8
34
#1
Hey all

Is it normal when removing the gas cap for the tank to hissssss at you!? Relieving pressure ?

Could this cause low fuel pressure ?

Edit.. should also mention, I took out the smog pump ? Issue ?
 
  • Sponsors (?)

96pushrod

Active Member
May 15, 2018
209
110
53
26
Savannah
#2
I’m pretty sure there’s a charcoal canister in the engine bay that helps vent the pressure. There should be a line from the tank running to it. It’s actuated by a solenoid to feed excess pressure into the intake.

Maybe it’s missing or solenoids bad? I’m not too sure how often they give out.
 

jrichker

StangNet's favorite TOOL
SN Certified Technician
Mar 10, 2000
26,508
2,336
224
72
Dublin GA
#3
Some bonehead probably removed the carbon canister and capped off the vent line. The carbon canister has ZERO effect on performance. Its purpose is to vent the fuel tank and keep the vapor from polluting the air.

Code 85 CANP solenoid - The Carbon Canister solenoid is inoperative or missing.

Revised 11 –Jan_2015 to add warning about vacuum leaks due to deteriorated hose or missing caps on vacuum lines when the solenoid is removed.

Check vacuum lines for leaks and cracks. Check electrical wiring for loose connections, damaged wiring and insulation. Check solenoid valve operation by grounding the gray/yellow wire to the solenoid and blowing through it.
The computer provides the ground for the solenoid. The red wire to the solenoid is always energized any time the ignition switch is in the run position.

If you disconnected the carbon canister and failed to properly cap the vacuum line coming from under the upper intake manifold, you will have problems. You will also have problems if the remaining hose coming from under the upper intake manifold or caps for the vacuum line are sucking air.

Charcoal canister plumbing - one 3/8" tube from the bottom of the upper manifold to the rubber hose. Rubber hose connects to one side of the canister solenoid valve. Other side of the solenoid valve connects to one side of the canister. The other side of the canister connects to a rubber hose that connects to a line that goes all the way back to the gas tank. There is an electrical connector coming from the passenger side injector harness near #1 injector that plugs into the canister solenoid valve. It's purpose is to vent the gas tank. The solenoid valve opens at cruse to provide some extra fuel. The canister is normally mounted on the passenger side frame rail near the smog pump pulley.

Connecting the gas tank vent line directly to the intake manifold will result in fuel vapor being constantly sucked into the intake manifold. There is unmetered fuel that the computer cannot adjust for. The result is poor idle and poor fuel economy.



It does not weigh but a pound or so and helps richen up the cruse mixture. It draws no HP & keeps the car from smelling like gasoline in a closed garage. So with all these good things and no bad ones, why not hook it up & use it?


The purge valve solenoid connector is a dangling wire that is near the ECT sensor and oil filler on the passenger side rocker cover. The actual solenoid valve is down next to the carbon canister. There is about 12"-16" of wire that runs parallel to the canister vent hose that comes off the bottom side of the upper intake manifold. That hose connects one port of the solenoid valve; the other port connects to the carbon canister.

The purge valve solenoid should be available at your local auto parts store.

Purge valve solenoid:



The carbon canister is normally mounted on the passenger side frame rail near the smog pump pulley.
Carbon Canister:
903_AIRTEX%20_pct_2F%20WELLS_7310014_1.jpg
 

Boostedpimp

10 Year Member
May 8, 2003
656
141
74
NJ
#4
Couldn't you just purchase a vented fuel cap to replace what you have now.
 

dwb

Member
Oct 9, 2017
48
1
8
34
#5
Thanks for the replies and suggestions.

The charcoal canister is there. I have an Edelbrock Performer RPM 2 intake, I removed the plumbing to heater core as it is cracked and I don’t need heat. The vaccume tube is connected to the throttle body.. is that okay? Or where should I route it?

I noticed I only have the canister purge solinoid plugged in. But the engine coolant temp sensor is not as it would have plugged into that metal piping that would run into the heater core.
 

Attachments

Dan02gt

5 Year Member
Mar 2, 2003
478
194
83
39
Greenville, NC
#6
That's odd the canister purge is connected to the PCV port on the throttle body. That port is before the throttle blade and doesn't provide vacuum. The canister purge should going into intake where that little plug is to the right of the EGR spacer. Do you have a PCV system?
 

Mustang5L5

SN Certified Technician
Feb 18, 2001
28,946
5,838
224
Massachusetts
#7
That's not where that vac line should be routed to. It should run to the manifold itself and there's a port on the front of the stock intake where it ran to. Unsure if your manifold has an identical port.

In the picture below, it would be the vac line running to the 12 o'clock positon at the top of the photo.
manifold_upper_underside-sized-jpg.jpg


The throttle body port vac line should connect to the oil fill port
sr-75mm-egrspacer-8693-02.jpg


You need the ECT hooked up. Without it, i'm surprised your car isn't running pig rich. Find a threaded bushing to install in the port where the heater pipe was located so you can thread the ECT into that port. You need the end of the sensor to see coolant flow to be accurate.

You should really run codes to see if the canister purge solenoid is faulty. You'll get a code 85 if it is.

The evap tube from the gas tank runs to the front of the car, into the charcoal canister and has a solenoid controlling when it can be vented into the manifold. If the line got pinched anywhere, (usually at the fuel tank when doing an R&R) then it could be blocked downstream and allowing pressure to build. The solenoid could also be junk as well, or the canister is clogged.
 

dwb

Member
Oct 9, 2017
48
1
8
34
#8
Hey thanks for the info.
I run KOEO codes but only get 15 & 51.

51 would be that sensor not plugged in.

In the photo of the intake manifold I have marked up what’s plugged.

The left plugged hole would be where that coolant tube running to the heater core would plug in, then the sensor would be on that rail as well...

- I will get that sensor plugged into that hole.

The bottom right hole that is plugged.. looks like that should be the coolant tempature sender.
Not sure why I blocked that or where else the sender is plugged in.


I also don’t have the stock filler neck with that vaccume connection. So should I just plug that PCV port on the throttle body ? (Yes i have a pcv system, plugged in the back of the lower intake then up to the upper intake)

Can i plug the canister purge vaccume onto one of the connections on the EGR spacer or one of fhe plugged holes on the heck of the upper intake right after the EGR spacer?
 

Attachments

Last edited:

Mustang5L5

SN Certified Technician
Feb 18, 2001
28,946
5,838
224
Massachusetts
#9
Just cap that port on the TB then. You want to run that charcoal canister vac line to a dedicated vac port in case fuel gets drawn up the vac line.

Bottom right port is the temp sensor for the gauge in the cluster. Single wire hookup, and that's the only function of that sender. The coolant temp sensor in the tube is for the ECU, so you want to get it installed in that left port.

Code 15....you have a chip I assume?
 

dwb

Member
Oct 9, 2017
48
1
8
34
#11
Of course the stock ECT sensor off the rail would not fit in the Edelbrock manifold... gonna need to figure out an adaptor that will still get that sensor end to dip in the coolant.

- edit: doesn’t fit there because that hole is for that metal coolant tube to screw in

Should I just hook that tube up and cycle the hose back to each other as it can’t plug into the heater core?

Does the EGR spacer need coolant? (Disconnected the EGR, and blocked it off)




Oh and i do have the bottom right port hooked up for the temp sensor already. Second guessed myself when I was circling holes. (Don’t we all when 2 are in front of us.. ha)
 
Last edited:

Boostedpimp

10 Year Member
May 8, 2003
656
141
74
NJ
#12
Of course the stock ECT sensor off the rail would not fit in the Edelbrock manifold... gonna need to figure out an adaptor that will still get that sensor end to dip in the coolant.

- edit: doesn’t fit there because that hole is for that metal coolant tube to screw in

Should I just hook that tube up and cycle the hose back to each other as it can’t plug into the heater core?)

easiest thing would be to install the metal heater tube again and just loop the two lines in the back together since your not running a heater core or if you want to get ride of that mess you would have to find a reducer to fill that whole from the heater tube that you cant thread the sensor into. If not then verify what size the opening is on your intake for that heater tube. I believe this one has worked in the past. You just have to have the top tapped for the sensor to screw into. https://www.cjponyparts.com/5-8-hea...ign=shopping?gclid=CKyD1P3znr0CFTBgMgodTXcAEw
 

Attachments

dwb

Member
Oct 9, 2017
48
1
8
34
#13
Thanks boost.
I actually like the height of that setup for the rail clearence and plugging in the sensor.
 

Mustang5L5

SN Certified Technician
Feb 18, 2001
28,946
5,838
224
Massachusetts
#14
You want a bushing
$_35.jpg


problem with bushings is they place the ECT away from the main flow of coolant, so your readings may or may not be 10% accurate.

I believe the ECT is a 3/8" NPT, but unsure what size the port is in the manifold. You'd have to see how far into the coolant flow the ect actually sticks.

Or put the stock pipe back in and loop the coolant lines at the end
 

dwb

Member
Oct 9, 2017
48
1
8
34
#16
Hey

If I hook the coolant rail back up that runs to the heater core, and hook up the coolant line to the EGR spacer on the front, where does the hose connect too that runs on the back side of the EGR spacer ?
 

dwb

Member
Oct 9, 2017
48
1
8
34
#17
Should I run coolant through the EGR spacer? Won’t it heat up the spacer more than cool it down?
 

dwb

Member
Oct 9, 2017
48
1
8
34
#19
Okay, will skip it. Egr is off. Have the delete sensor to clear code
 

dwb

Member
Oct 9, 2017
48
1
8
34
#20
Would the charcoal canister vaccume be too much vaccume here ?
BB3806A4-03E7-4484-8C9C-0C7A0D508C05.jpeg
 

Similar threads