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Does my 1996 have a Leak Detection Pump?
Topic Started: Nov 13 2014, 04:54 PM (1,053 Views)
GoingGranola
Advanced Member
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I see that it has a Tank Pressure Control Valve and a Tank Pressure Control Solenoid Vacuum Valve but was wondering if these do the same thing as a leak detection pump. Do the hose from the engine provide vacuum to the Tank pressure control valve? I am guessing these two things function as a check for the EVAP system cause im getting codes related to the EVAP system. I just wanted to check cause I thought the EVAP check system was implemented in 1998.

This is my Vacuum Hose Routing Diagram:

http://imgur.com/rf6XOnt

I am having trouble codes of:

P1410 - Fuel Tank Pressure Control System Malfunction
P0136 - HO2S 2 Circuit Malfunction
P0455 - EVAP System Malfunction, Large Leak Detected
P0440 - EVAP System Malfunction/Gross Leak Detected

I am wondering if these codes mean for certain one failure or if there are multiple causes for these codes to go off because the P0136 print out from autozone says its the Oxygen sensor or fuel pressure. I checked the heater element and that it is getting 12V so idk. If the Fuel Tank pressure control system is malfunctioning wouldnt that cause the P0455 and P0440 to go off? jw
Edited by GoingGranola, Nov 13 2014, 04:57 PM.
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Woodie
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Normally when confronted by multiple error codes, I rush straight to a bad ground. This is an exception to that rule, as the O2 sensor code is for low voltage, the opposite of what a bad ground would cause. I'm thinking you have a bad second O2 sensor, or a bad connection going to it. All of the fuel system codes could be caused by a leak. Bad gas cap, or more likely, rusted out filler neck. Do you ever smell gas right after a fillup?

I don't think we have a leak detection pump, that's a much newer invention.
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GoingGranola
Advanced Member
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wait for real? so there is no way the car checks for a leak in the EVAP system? I though the "Tank Pressure Control Solenoid Vacuum Valve" and the "Tank Pressure Control Valve" work to monitor the EVAP system. or do you know what these two things do?
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Old Man


check your fill tube and its associated smaller tube that runs beside it. They rust out and/or their connecting rubber hoses crack and you lose vacumn in your fuel system and your "tank pressure" goes to hell. Also check the rubber o ring in the gas cap
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GoingGranola
Advanced Member
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so around the filler tube there is rust so idk if the cap is sealing the tube completely. I can take a picture in a bit.
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Old Man


GoingGranola
Nov 14 2014, 08:24 PM
so around the filler tube there is rust so idk if the cap is sealing the tube completely. I can take a picture in a bit.
Not THERE. crawl underneath and look at where it hooks to the gas tank, hooks to the rubber, hooks to the small tube.

Look at this post:
http://geometroforum.com/single/?p=605312&t=4664556
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vr4


Nvld is a Chrysler thing. We don't have one in any year or engine option.

As for evap emissions (I would have to refer to the wiring diagrams to verify) but we have purge solenoid, vent solenoid, charcoal canister, ftp sensor.

Basically it wants to see a certain vacuum on the ftp at x time. If not there pops code based on readings. Honestly I haven't dealt with evap issues on these as they're not very common. My 96 was tripping a code but I quit driving it at the same time so I never diagnosed it.
Edited by vr4, Nov 15 2014, 02:01 AM.
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GoingGranola
Advanced Member
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Old man: I looked at the filler tube which is metal but it looks good. This is the gas cap area I was talking about http://imgur.com/JtLUbm2
does the gas cap make a flush seal with the filler tube? I was going to light a cigar and blow smoke through the filler tube to check for leaks.

vr4: thanks for posting. I'm still confused on what the "Tank Pressure Control Solenoid Vacuum Valve" and the "Tank Pressure Control Valve" do. They are on my vacuum diagram in my first post in this thread. The intake from the gas tank and to the canister goes through the tank pressure control valve so idk if this system shuts on and off the evap to the canister. Any info much thanks
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Silver2K


The FSM has a section on the EVAP system. It is hard to find cuz the index sucks. I have a 95 FSM. The EVAP is in section 6E2-C3-1, under driveability and emissions. Has theory of operation and trouble shooting. I would recommend you ask on line if someone has the 96 FSM. There may be permanent links on this site to some FSMs. The 95 FSM may apply but I don't have a way to capture it. And I don't have a lot of time right now. If you can't get someone to provide the section, I'll see what I can do tomorrow.

Paraphrasing from the FSM: The TPCV is a mechanical device that opens when the pressure in the gas tank exceeds some threshold and allows vapors to enter EVAP canister. If the engine is running & there are < 8 gallons in the tank the TPCSVV is turned on and vacuum (from the throttle body) is applied to the TPCV which opens it (regardless of fuel tank pressure), allowing gas vapor to vent to the EVAP canister. Basically, if the car is off the TPCV will allow vapors to vent to the canister. If the car is on, the TPCSVV forces the TPCV open to allow vapors to the canister.

The oruge valve allows vapors from the canister to the throttle body when the car is on.
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Silver2K


As far as the O2S it is not uncommon for the heater to die. So you should check the resistance of the heater element, make sure it is not open. As someone else mentioned, you may have bad grounds. I got the O2S code twice in a 2 month period. I found a broken ground wire that ran from the throttle body into some cable bundle. Once I repaired the ground wire the O2S error never returned.
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GoingGranola
Advanced Member
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That helps so much. I though flying spaghetti monster but field service manual sounds better. I checked both 02 sensors for 12v going to the circuit and a continuety check for the filements. They might not be functioning properly though idk I'm going to fix the Evap codes and see if the 02 ones go away. Thanks for your time and imf oration. It helped alot oh! Do you know anything about the surge tank in the diagram mine are hooked up funky.
Edited by GoingGranola, Nov 15 2014, 03:22 PM.
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Silver2K


My 95 FSM does not show a surge tank. I did a Google search and found the following GMF link with pics. Good luck. You should try to get someone to send you the info of the EVAP section from the 96 FSM. If you are near a good library, you might find the FSM there. For example the LA central library has every year FSM for the Metro.

http://geometroforum.com/topic/5262195/1/
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dayle1960
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Fastest Hampster EVER

On another note, one which might or might not help, but I pulled the EFE heater out of my TB to only find that it was gummed up with oily residue. Be careful when you pull it because the gaskets are quite fragile and you might need to reuse them. Will this help you situation? Probably not, but it is something to look into.

Also that filler neck needs to be addressed. Find a replacement or you might have rusty particles flaking off and falling down into the fuel tank. If that happens then your fuel pump sock might become full of debris and cause a fuel flow problem. Plus, change out the fuel filter. It is amazing how plugged they become.

Seeing how you live in Chicago, prevention of rust problems is at a heightened concern when dealing with a Metro. Please check your horn frames. Dig into them with a screwdriver. Be vigorous with your probing.

Hope you find your gremlin.

Terry
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