chiuchimu
10+ Year Contributor
- 94
- 3
- Jun 25, 2008
-
Sylmar,
California
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just code 1494
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.
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).
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.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.
thats what I said...the code was for a Leak detection pump.
I'm willing to bet you need a new Leak detection pump. And maybe a Vent Valve too.
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. 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.
+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.
i was wondering if a bad fuel pressure regulator would have to do anything wit setting off p1494 engine code ? thanksThis 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. 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.
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.
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.
Bingo.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