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GAS CAP CEL... Can I just disconnect anything?

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EclipseTrbo420A

15+ Year Contributor
3,427
38
Jan 23, 2004
WhiteOak/PGH, Pennsylvania
I have tried some different things new cap re set system, nothing is working. Is there just something I can unhook...maybe a wire near the cap? This is killing me, I need to get inspected. Any suggestions on what to check/lookfor or at. Thanks
 
Sorry I sould have said more. I didnt touch any part of the charcoal canister or the fuel stuff. To my knowledge its all hooked up as it should be. I took out link and put in a 96 ECU and there was no light, then I got a 98GSX ecu and the first time I fired it up it came on and has not gone off since. I hold pressure in my AFPR gauge for a good 40 mins after I shut off, and I also get the "Hiss" when I open the gas cap. I am lost...could it be the ECU? Everything else works fine, and if it is JUST the ECU what can I do to fix it. Maybe a trick signal like the fake 02 sensors. Thanks for the help.
 
Matt, I suck at wiring so can't help you there. However, it sounds like you have too much pressure in the tank, follow the relief hose from the tank all the way to the canister and make sure there are no kinks, then pull the hose off the canister and let it VTA and see if problem persists. Have you tried resetting the ECU?
 
Ohh I thought pressure was good in the system? and yes I re set and it just comes right back. I will check out all that stuff around the canister but Im wondering if it IS just the ECU I will also test it inplace of another.
 
Do you think it might be a problem with the EVAP purge solenoid? According to my Chilton's you can measure resistance accross the terminals. Normal values should be 34-44 ohms at room temperature. It also shows a way to use a vacuum pump to test it while battery voltage is being applied. Just a thought.

What code are you throwing? I have a P0455--EVAP leak. But I haven't had time to look into it at all yet.
 
This may help you. It's right out of the '99 factory Mitsu Eclipse Service Manual for P0455.
 

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Make sure your gas tank is sealed where the fuel pump assy is. I have replaced many of o-ring type gasket there, even on stock 2G DSM's. But if your getting a loud hiss from the gas cap area after removing the cap, after driving awhile, I'd the system is more than likely sealed and your dealing with a electronic malfution and damn evap systems are so sensitive.


The only wire I see you can do anything with is the P/S pressure wire you could ground it all the all time but your idle may not be the same and I'm not sure if it will affect your A/C or not.

I mean you could try it and I'd say maybe after driving it for maybe two days and the light doesn't return you may of found a way thru.

later
Douglas
 
Make sure your gas tank is sealed where the fuel pump assy is. I have replaced many of o-ring type gasket there, even on stock 2G DSM's. But if your getting a loud hiss from the gas cap area after removing the cap, after driving awhile, I'd the system is more than likely sealed and your dealing with a electronic malfution and damn evap systems are so sensitive.


The only wire I see you can do anything with is the P/S pressure wire you could ground it all the all time but your idle may not be the same and I'm not sure if it will affect your A/C or not.

I mean you could try it and I'd say maybe after driving it for maybe two days and the light doesn't return you may of found a way thru.

later
Douglas
Im going to look over everything...well try...that was in that diagram above. I get about 24 MPG mix city/highway dirving, not alot off boost. Would this have an effect on that? also would grounding out that p/s pressure wire hurt anything? I dont have A/C anymore.
 
OK I snooped around in there today for alittle...charcoal canister is all hooked up like it should be ( I cleaned it out around there anyway. ) I looked at my solenoids and they were ar cruddy in the connections, but I think its just that electrical gel for the connection to be made...either way they are all hooked up and I cleaned those too just to be safe.

I took the gas cap off and looked at the vent on there, I put a piece of bigger vac hose up against it and blew..It would not "vent", but I applied pressure with a small screw driver and it seemed to function properly. As for the filler vent neck, I dont even see how that could go bad...what could even happen there ? the hole seems to big and the tube to strong for something to go wrong. ss94s10, can you explain more about the grounding system you suggested ? Thanks

ALSO what was weird was, when I open the cap I got the hiss like normal, but then I put it back on....didnt start the car or anything then went to take it off again and it hissed alittle? THats weird anyone think of an explaination ?
 
Yea, its that single pin on top of your power steering pump, take you wire that goes to it. just wire it with some spare wire and a male bullet connector and also find a good bolt on the block to ground to.WARNING I think it may bump your idle up some.
 
Egad, put on a new gas cap and see what happens.

I did, I changed it and re set the ECU...nothing realy changed. I though that was it too:mad:

Alright also after snooping aroung in there and getting tangled up in all the vac Lines I started to RIP em out :coy: THen I check out the Taboo diagram and did it the right way and am done. One question The hard line comming from the fuel tank to the canister, after searching I hear I should let it alone, Plug it and put a pleather on it and run I line down under the car...which of those options is correct?

plug?
vent?
vent under car?
vent under car with an inline filter?

Also EGR, should I make a plate or just run and loop the 2 nipples and leave be? Thanks guys...Im also getting new soleniods to plug in to lose the CEL..that has to be it. Thanks

Also SS94S10 is this the wire you mean ground? Ill do it if none of these other solenoids cure the light.
 

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Matt, I just got a few feet of vacuum line and routed it back under the car leaving it vented so pressure doesn't build in the tank.
For the egr, I would just leave it on, but disconnected. I ran mine with no lines, and it ran perfect, but after a while I finally got a CEL. Some people don't. So I just hook up one line for the egr, solenoid, and throttle body for inspection time and leave everything else I removed off.
 
Matt, I just got a few feet of vacuum line and routed it back under the car leaving it vented so pressure doesn't build in the tank.
For the egr, I would just leave it on, but disconnected. I ran mine with no lines, and it ran perfect, but after a while I finally got a CEL. Some people don't. So I just hook up one line for the egr, solenoid, and throttle body for inspection time and leave everything else I removed off.

How did you run the egr Line? from what? theres 2 nipples how did you route them? THanks for the info. I figure I would just run it under the car so I just got that done.

I hope eveything turns out ok.

Also now that its just vented like that...I dont get the big HISS thats suposed to hapen right ?
 
Here's a quick pic. i couldn't get the camera back where the EGR is at so I'll explain that part.
The vacuum line that is going down from the T goes to the top nipple on the top of EGR valve more towards the front of the car.
The yellow striped vacuum line going from the bottom right of the solenoid goes on the bottom nipple of the EGR valve more towards the rear of the car.
Hope that helps.
 

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Where the other one go? NExt to the yellow and also did you notice anything different about your MPG? Did it change at all? I want to get my car running smooth. I hate the little noises and glitches. I might just put it all together, sell it and start over with a stock GSX and do what I tell eveyone else to do, hook up the suspension and leave the reat very close to stock that way you enhance the way the car feels and have sweet DD. Ill keep you guys posted. Thanks aain Erik.
 
Matt, I just got a few feet of vacuum line and routed it back under the car leaving it vented so pressure doesn't build in the tank.
For the egr, I would just leave it on, but disconnected. I ran mine with no lines, and it ran perfect, but after a while I finally got a CEL. Some people don't. So I just hook up one line for the egr, solenoid, and throttle body for inspection time and leave everything else I removed off.

You want a bit of pressure in the tank. That's WHY the gas cap should seal, and the other links in the system shouldn't leak. Why not just use the check valve to the canister on there. That way, the appropriate amount of pressure builds, but is released by the valve, as it is supposed to be, if the pressure becomes too great. You won't lose as much fuel to evaporation that way either... :thumb:
 
You want a bit of pressure in the tank. That's WHY the gas cap should seal, and the other links in the system shouldn't leak. Why not just use the check valve to the canister on there. That way, the appropriate amount of pressure builds, but is released by the valve, as it is supposed to be, if the pressure becomes too great. You won't lose as much fuel to evaporation that way either... :thumb:

Ahhh good Idea...Keep the gray check valve thanks.
 
Where the other one go? NExt to the yellow and also did you notice anything different about your MPG? Did it change at all?

The vacuum line next to the yellow one goes to the E port on the throttle body if you follow it around. MPG is the same.
 
You want a bit of pressure in the tank. That's WHY the gas cap should seal, and the other links in the system shouldn't leak. Why not just use the check valve to the canister on there. That way, the appropriate amount of pressure builds, but is released by the valve, as it is supposed to be, if the pressure becomes too great. You won't lose as much fuel to evaporation that way either... :thumb:

There is a pressure control valve located on the tank side. I don't believe you would need to have the one from the canister. I still build the usual mild pressure.
 
There is a pressure control valve located on the tank side. I don't believe you would need to have the one from the canister. I still build the usual mild pressure.

See not me I noticed I got no pressure any more I used to get a big HISSSSSSSSsssssss

Im gonna run the check and see if makes a difference. also getting a new cap not a Junk yard one. Thanks again guys Ill keep you posted
 
There is a pressure control valve located on the tank side. I don't believe you would need to have the one from the canister. I still build the usual mild pressure.

Are you talking on the tank side of the canister, or somewhere under the car. I was talking about the one between the canister and tank....? it's been off for a while now, so maybe I'm mistaking something, but the valve was on the tank side. Maybe we're saying the same thing. In any case: what it sounded like you were saying is leave an open tube from the gas tank to the atmosphere. Clearly, we're agreed that's not the way to do it. ;)
 
My car stopped building pressure on the gas tank. I don't know what's wrong as i didn't touch anthing.
 
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