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Evap code

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I had the same problem, it is most likely a little pipe above your gas tank that is leaking slowly.
The DSM's have little plastic covers on three pipes there for the fuel, but since the car is so small they are put close together causing them to rub alot and brakes the plastic pieces causing the pipe to leak.
It's not a MAJOR issue but you'll probably want to get it fixed.
To do so you have to remove the gas tank to access the pipes, seal the leaking one up, and replace the plastic piece.
 
First off you don't have to drop our tank to get to the area you are talking about. There is an access panel underneath the rear seats. That will give you acess to 2 fuel lines. A send and return. Chances are you've got a leak somewhere in the fuel system. Are you also throwing a code for running too rich or too lean, as well. And none of that area is plastic.
 
First off you don't have to drop our tank to get to the area you are talking about. There is an access panel underneath the rear seats. That will give you acess to 2 fuel lines. A send and return. Chances are you've got a leak somewhere in the fuel system. Are you also throwing a code for running too rich or too lean, as well. And none of that area is plastic.

This p1494 code is for
"Leak detection pump switch or mechinical failure"

I had this same thing happen on my old 99 GS The Leak detection monitor was bad and also the vent valve on top of the fuel tank was bad. The Leak detection pump I got to from the underneath of the car, BUT I DID have to drop the tank a little to get to the VENT VALVE on the top of the tank. It was NOT accessible through either hole under the backseat. Its a little plastic check valve vent, that is supposed to let air IN the tank, but not OUT of the tank. Well this valve gets gummed up and stays stuck open, allowing air IN and Fumes OUT.

The EVAP system check engine light DOES NOT mean there is a FUEL leak. It means there is a Fuel VAPOR leak.

The job of the evap system is to collect extra fumes off the fuel tank while the car sits. Just like if you left the CAP off a 2 gallon gas can. It will slowly vaporize (evaporate) and go into the atmosphere.:notgood: The Evap system will take these fumes and store them In a Charcoal canister until the engine is started. Then the vacuum from the engine will suck the fumes out of the Charcoal Canister and burn them off through the combustion process.

So basically you have a Fuel Vapor Leak somewhere in the Evap system. The proper way to test is with a 500 dollar smoke machine that will fill your Gas tank with Smoke/ dye. Then using an Ultraviolet light you will see the smoke dye coming out of your leak.

I'm willing to bet you need a new Leak detection pump. And maybe a Vent Valve too.
 
Last time I checked the P1495 code was for the LDP going bad or a circuit malfunction, not anything of a vapor leak. If he had a leak it would be anything from the check valve to the gas cap going bad, but that would flag a code such as PO455, PO442 (True PITA). OP: what you need to do is test the LDP to see if it's still good with an ohm meter, if it's good check the circuit connections/clean harness. You should test around ~10-40 ohms (solenoid). If it's reading anything significantly over that replace it, don't go off looking for EVAP leaks, ect. There a little pricy depending on what place you order from: $100-200, so shop around. 96-98: In the front next to the charcoal canister. 98-99 - In the back near the fuel tank. Should be an easy fix.

FWIW, I Hook up an air compressor (low psi) to mine and listen for hisses around the tank and fuel lines (EVAP wise). A lot of people simply ignore it in states without emissions......I cut the cord to my CEL because it was getting on my nerves. I'm thinking about using it for something else (maybe an output for something involving a pic16fXXX, or smaller).:aha:
 
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Last time I checked the P1495 code was for the LDP going bad or a circuit malfunction, not anything of a vapor leak. If he had a leak it would be anything from the check valve to the gas cap going bad, but that would flag a code such as PO455, PO442 (True PITA). OP: what you need to do is test the LDP to see if it's still good with an ohm meter, if it's good check the circuit connections/clean harness. You should test around ~10-40 ohms (solenoid). If it's reading anything significantly over that replace it, don't go off looking for EVAP leaks, ect. There a little pricy depending on what place you order from: $100-200, so shop around. 96-98: In the front next to the charcoal canister. 98-99 - In the back near the fuel tank. Should be an easy fix.

FWIW, I Hook up an air compressor (low psi) to mine and listen for hisses around the tank and fuel lines (EVAP wise). A lot of people simply ignore it in states without emissions......I cut the cord to my CEL because it was getting on my nerves. I'm thinking about using it for something else (maybe an output for something involving a pic16fXXX, or smaller).:aha:

LOL thats what I said...the code was for a Leak detection pump. I was just stating that on my 99 NT I had a bad LDP AND also a bad Vent valve. After all The LDP is a small air pump. It pressurizes the EVAP & fuel system to make sure there are no leaks. This ensures that no harmfull vapors are escaping to the atmosphere.
So.... it's a pump... and it is used by the PCM to detect leaks...... hence the name Leak Detection Pump. So you wouldn't KNOW if anything was leaking or NOT Cause the pump is not working.

I was just informing people what an evap system does. Someone was talking about fuel leaks so I wanted to clarify that the evap system is for Fuel Vapors, not RAW fuel...GET IT? :thumb:
 
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Eh...I understand what you were trying to explain throughout the post (with was fine), but this paragraph is what got me....
So basically you have a Fuel Vapor Leak somewhere in the Evap system. The proper way to test is with a 500 dollar smoke machine that will fill your Gas tank with Smoke/ dye. Then using an Ultraviolet light you will see the smoke dye coming out of your leak.
Make sure when you're "speaking" you address who your talking to weather it be DELTA or the OP, so people like I/OP don't get it confused. The OP's short answer was how to test one; the OP doesn't need to replace things/check for leaks, ect until they fix the pump/pump circuit. Besides the question on how to test one/where to find it/how much one was remained unanswered, so I answered it, GET IT? I go by "IF IT AINT BROKE DON'T FIX IT" hence test it before replacing.

LOL thats what I said...the code was for a Leak detection pump.

Now I may be blind, but I didn't see where you showed the OP how to test the pump.:D

Not everyone has access to $500 smoke machines, there's easier ways to test.
 
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Right I understand what you're saying...It is still good to check the part to make sure it is bad. That makes sense. I just look at it like, the pump is either broke or unplugged if the CEL came on. It's not like this unit is repairable or you can buy parts for it.

The Computer is telling you what's wrong with the car. I was just giving the guy my 2 cents because I have had this exact same problem in my GS 420a.
I got the same code, then I went under the car looked at the pump....It Looked OK. Hoses tight/ no damage. So I ordered a New LDP. Installed it, then the Engine light went OFF. 2 weeks later the CEL came back on...But now it was a different code...It was the code for Small leak detected. So I Changed the vent valve and the light stayed off for good!

The Guy at the dealer told me that the pump burns out when there is a Air LEAK in the tank. That causes the Leak Detection Pump to run for long periods of time and heat up.

That is the only reason I suspect a Vapor leak as well as the pump.
 
I'm willing to bet you need a new Leak detection pump. And maybe a Vent Valve too.

Thanks! Tow things, were is the leak detection pump and what does it look like(size, shape anything to help find it)?

I hit a bump yesterday and the light went off while driving and stayed off all day, today, its back on again. does that info help with diagnostic? I'm planning on working on the car this Sunday.
 
http://www.dsmtuners.com/forums/articles-engine-fuel/100294-2gnt-engine-bay-tutorial.html
That might help, the LDP gets move around a lot depending on year models.

The LDP can fail, you can have vacuum lines (interpret that as a line, similar to vacuum, used for whatever reason) that are split, or you can have the roll-over valve on the top of the fuel tank that has broken. You frequently can't see it until you lower the rear of the tank and try and move the fitting. THEN you see that it's broken.

Also, I recently had to replace the PCM on one after replacing all of the above mentioned components with no success. I ran through the tests two or three times and while I did have multiple problems the final fix for it all was the PCM. That did fix the problem and he hasn't been back since for the CEL (though tomorrow I'm doing a timing belt w/ UDP on it).

Additionally... the system in question deals with vapor fuel. Adding compressed air (ie a shitton-o-oxygen) in to a small space isn't exactly the best of test methods. I would discourage anyone from doing this as it could create a more flamable situation than you might think.

I would spend quite a bit of time with a flashlight and mirror checked for split lines and such first. If all else fails call around and see if you can find a repair shop that has an Evaporative emissions leak detection machine. It introduces an inert smoke to aid in the tech looking for the leak and many of those same machines can pressurize the system with nitrogen post-repair to verify the repair (or pre-repair to make sure the leak is going to show up when checked with smoke).

Be safe, don't blow yourself up unless you can take Rosane Barr (sp?) with you when you explode.
 
This p1494 code is for
"Leak detection pump switch or mechinical failure"

I had this same thing happen on my old 99 GS The Leak detection monitor was bad and also the vent valve on top of the fuel tank was bad. The Leak detection pump I got to from the underneath of the car, BUT I DID have to drop the tank a little to get to the VENT VALVE on the top of the tank. It was NOT accessible through either hole under the backseat. Its a little plastic check valve vent, that is supposed to let air IN the tank, but not OUT of the tank. Well this valve gets gummed up and stays stuck open, allowing air IN and Fumes OUT.

The EVAP system check engine light DOES NOT mean there is a FUEL leak. It means there is a Fuel VAPOR leak.

The job of the evap system is to collect extra fumes off the fuel tank while the car sits. Just like if you left the CAP off a 2 gallon gas can. It will slowly vaporize (evaporate) and go into the atmosphere.:notgood: The Evap system will take these fumes and store them In a Charcoal canister until the engine is started. Then the vacuum from the engine will suck the fumes out of the Charcoal Canister and burn them off through the combustion process.

So basically you have a Fuel Vapor Leak somewhere in the Evap system. The proper way to test is with a 500 dollar smoke machine that will fill your Gas tank with Smoke/ dye. Then using an Ultraviolet light you will see the smoke dye coming out of your leak.

I'm willing to bet you need a new Leak detection pump. And maybe a Vent Valve too.

If you want to be proper, Fuel is anything that can be used as a cumbustible in addition to air. So if it's gasoline or gasoline vapor, it's still fuel. If it's a piece of 2x4 or a oil soaked rag, it's still fuel. Not sure why you went through all the trouble to explain how an EVAP system works cause that wasn't gonna fix his problem. Telling him the parts and giving him reference pics would have been more helpful. That's why I asked if there were and ADDTITIONAL codes being thrown that might be able to point him in the direction of the leak. And I never said what kind of leak because some fuel systems have a vaccum reference for the FPR: Like our early 95-96 fuel systems and anyone with an aftermarket FPR. seeing as how the OP never filled out his info, one can only assume. :notgood:


+1 to Doug for advocating not blowing yourself up!
 
If you want to be proper, Fuel is anything that can be used as a cumbustible in addition to air. So if it's gasoline or gasoline vapor, it's still fuel. If it's a piece of 2x4 or a oil soaked rag, it's still fuel. Not sure why you went through all the trouble to explain how an EVAP system works cause that wasn't gonna fix his problem. Telling him the parts and giving him reference pics would have been more helpful. That's why I asked if there were and ADDTITIONAL codes being thrown that might be able to point him in the direction of the leak. And I never said what kind of leak because some fuel systems have a vaccum reference for the FPR: Like our early 95-96 fuel systems and anyone with an aftermarket FPR. seeing as how the OP never filled out his info, one can only assume. :notgood:


+1 to Doug for advocating not blowing yourself up!

While you're right about what a fuel is it's more important to keep in mind how the liquid fuel and vapor fuel are dealt with. The liquid is used for the combustion process. The vapor fuel is not as far as the ultimate operation of the combustion process goes. The vapors ARE routed back in to the engine when certain components are commanded to operate and as such small changes to the fuel trim strategy is required. But the EVAP system in question is used to capture vapors that would have otherwise, on old vehicles or those with failing Emissions components, been dumped in to the atmosphere. The fuel vapors are not captured, compressed back in to liquid and then reintroduced in to the fuel tank. So it's important to isolate the two types of fuel being brought up here. Liquid for combustion vs Vapor for reducing unburned emissions output.

In your early post you refer to two liquid lines under the rear seat for the fuel system. Both of these are not related to evaporative emissions. The component that is being referred to by Jeff is referred to on many vehicles as a "roll-over valve". It's simply a valve that flows constantly when in the upright position and when flipped upside down the flow stops. Most of the time where the nipple meets the body of the valve the weight of the hose OR the positioning against the body will force the nipple/hose downward. After a while it breaks thus causing the evap leak.

But regardless of how the car is failing it doesn't seem like all of our assistance was enough to justify some updates by the OP.
 
While you're right about what a fuel is it's more important to keep in mind how the liquid fuel and vapor fuel are dealt with. The liquid is used for the combustion process. The vapor fuel is not as far as the ultimate operation of the combustion process goes. The vapors ARE routed back in to the engine when certain components are commanded to operate and as such small changes to the fuel trim strategy is required. But the EVAP system in question is used to capture vapors that would have otherwise, on old vehicles or those with failing Emissions components, been dumped in to the atmosphere. The fuel vapors are not captured, compressed back in to liquid and then reintroduced in to the fuel tank. So it's important to isolate the two types of fuel being brought up here. Liquid for combustion vs Vapor for reducing unburned emissions output.

In your early post you refer to two liquid lines under the rear seat for the fuel system. Both of these are not related to evaporative emissions. The component that is being referred to by Jeff is referred to on many vehicles as a "roll-over valve". It's simply a valve that flows constantly when in the upright position and when flipped upside down the flow stops. Most of the time where the nipple meets the body of the valve the weight of the hose OR the positioning against the body will force the nipple/hose downward. After a while it breaks thus causing the evap leak.

But regardless of how the car is failing it doesn't seem like all of our assistance was enough to justify some updates by the OP.


After doing some research myself, I studied the evap system more carefully figured out it's inner workings and what not. I'm always learning something new everyday. Now I just need to learn the Brake booster system and the transmission. I was just giving him a hard time with the fuel definition. I fully understand the system and how fuel vapors apply as compared to FUEL. At least now I do.
 
This p1494 code is for
"Leak detection pump switch or mechinical failure"

I had this same thing happen on my old 99 GS The Leak detection monitor was bad and also the vent valve on top of the fuel tank was bad. The Leak detection pump I got to from the underneath of the car, BUT I DID have to drop the tank a little to get to the VENT VALVE on the top of the tank. It was NOT accessible through either hole under the backseat. Its a little plastic check valve vent, that is supposed to let air IN the tank, but not OUT of the tank. Well this valve gets gummed up and stays stuck open, allowing air IN and Fumes OUT.

The EVAP system check engine light DOES NOT mean there is a FUEL leak. It means there is a Fuel VAPOR leak.

The job of the evap system is to collect extra fumes off the fuel tank while the car sits. Just like if you left the CAP off a 2 gallon gas can. It will slowly vaporize (evaporate) and go into the atmosphere.:notgood: The Evap system will take these fumes and store them In a Charcoal canister until the engine is started. Then the vacuum from the engine will suck the fumes out of the Charcoal Canister and burn them off through the combustion process.

So basically you have a Fuel Vapor Leak somewhere in the Evap system. The proper way to test is with a 500 dollar smoke machine that will fill your Gas tank with Smoke/ dye. Then using an Ultraviolet light you will see the smoke dye coming out of your leak.

I'm willing to bet you need a new Leak detection pump. And maybe a Vent Valve too.
i was wondering if a bad fuel pressure regulator would have to do anything wit setting off p1494 engine code :confused:? thanks
 
My problem with this code started over two years ago. It started coming on and it would go off randomly when I was driving but in the past 6 months it has been stuck ON. Now, I replaced the LDP and that did nothing for my problem. The car DID also throw a "running lean" code once but amidst trying to pass inspection I just cleared it and never saw it throw the lean code again. Months later that P1494 is not on CONSTANTLY. I'll clear it and about 45 miles later... there it is. I suppose I should drop my tank and check those vacuum lines but that just seems like an awful lot of trouble.
 
Not sure why you went through all the trouble to explain how an EVAP system works cause that wasn't gonna fix his problem. Telling him the parts and giving him reference pics would have been more helpful. :notgood:

Because You told the guy he had a LEAK in his fuel system. The EVAP system and Fuel system are 2 different things. The Evap system deals with the VAPORS of GASOLINE in the fuel tank. The fuel system carries the Liquid Gasoline. By telling him he had a LEAK in a fuel line is Total MISINFORMATION. That would NEVER cause the LDP to throw a code. The LDP is detecting VAPOR leaks in the evap system. It does NOT detect leaks in the liquid fuel system. So by Me EXPLAINING how the system works I am helping the guy understand what to look for and how to Properly diagnose the Evap system. The LDP is part of the EVAP system.


I told him to check/replace the LEAK DETECTION PUMP and Or Check valves on top of the Gas tank. Im not going outside and dropping my fuel tank so I can take pics of these valves for the guy....BUT trust me The valves are there. If they are leaking, then the LDP will see that and throw a code.




My problem with this code started over two years ago. It started coming on and it would go off randomly when I was driving but in the past 6 months it has been stuck ON. Now, I replaced the LDP and that did nothing for my problem. The car DID also throw a "running lean" code once but amidst trying to pass inspection I just cleared it and never saw it throw the lean code again. Months later that P1494 is not on CONSTANTLY. I'll clear it and about 45 miles later... there it is. I suppose I should drop my tank and check those vacuum lines but that just seems like an awful lot of trouble.

Drop your tank and replace the $15 dollar vent valve (check valve) on the top of the gas tank. You can NOT access it through the holes under the back seat. You have to lower the tank.


Drive your car around till your almost out of gas. Then its Much easier to manage!
 
From reading the link that Doug99rs kindly supplied, I read that filling the gas tank while the car is running can also cause this. I left my car running and about 1/4 tank later I get the check engine lite and the P1494 code. Could this have caused it quarter tank later?
 
Chances are that it did not. Most of the Leak Detection related tests, which include those resulting in a "Leak" code and those resulting in a component related code, require a test to run twice and fail both times before it will turn on the light. Some tests may be checked immediately, like when checking to see if the Purge solenoid and LDP pump are pluggedin, but if the problem was created by refilling, it would result in a "Leak" type of code. All of these leak codes that I've addressed required multiple drive cycles in order to set.

Refueling with the car running, no other problems being active, would result in a leak type of failure code. That's ONE drive cycle. You'd then have to shut the car off, restart and drive it again, the test run and FAIL a second time in order for the light to come on.

I would recomend double checking your gas cap since you just filled up not too long ago but would suspect that you have other issues like many of the components already mentioned in this thread.
Doug
 
I would recomend double checking your gas cap since you just filled up not too long ago but would suspect that you have other issues like many of the components already mentioned in this thread.
Doug
Bingo.

First impulse as well (when I read his post). Not that Doug needed any support, but I have seen this multiple times on various vehicles.

MB
 
thanks doug, i have checked the gas cap yesterday but it still on today. i was just asking that question for an idea that maybe it was the problem. everything else i will look at later today well at least try to. bullettdsm nice whp
 
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