Hello,

I've got a fuel smell coming off my vehicle. There ARE NO CODES. The smell is not that strong. It is coming off the drivers side of the vehicle. The drivers side rear wheel well has the strongest scent of fuel fumes. IT just so happens that the fuel tank is right there. But again the smell isn't terrible.

I've looked the hole damn thing over looking for broken tubes. I can't see any further on top of the tank without dropping it. I was thinking, I 've got a paint can and air compressor. I could use low pressure (1 PSI) to generate smoke inside the fuel tank and see if it comes out of the top area where the fuel pump and some other things are.

Any DANGER in doing this? I was going to use smoke bombs (you know those little fire crackers things that emit smoke but no sparks) inside the paint can, but not sure if this is a bad idea or not. First of all I wonder if it would even generate enough smoke because it's such a big tank. Second of all, can anything be damaged by doing this?

Should I get the fuel level up to 85% before doing this? would that make it fill with smoke a heck uva lot quicker?

And again I don't have any codes. guessing before I would flood the fuel tank with smoke, I need to disconnect the evap line that runs to the vaper cannister so I would know if smoke has pretty much filled up the tank?

also WILL the EVAP Cannister ABSORB smoke from this smoke bomb?

 

You can buy a smoke machine for $45.00 with the fluid included.
https://www.walmart.com/ip/AutoLine-...hoClHcQAvD_BwE

Amazon has options around the same price too.

I'm sure you could sell the machine if you don't want to keep it.

I used a smoke machine to diagnose an intake leak a few years ago. The smoke was pretty impossible to see but it was UV reactive and I was able to find the residue around the leak with a UV flashlight.

 

Allright thanks Derrick, Seen you reply to a lot of my threads. Today went to refuel to get the tank up to 80% to began the test. The pump clicked off 6 or so times. No stored or pending codes. That was a little a scary. I am guessing charcoal cannister is partially clogged and about to get fully clogged. Vehicle sat for a long time. Is it normal for this problem to gradually get worse? I want to see if the cannister is clogged before anything

I guess to do that I should probably just simply try and see if I can blow through one of end and feel anything on the other end of the cannister? I am worried the cannister will catch smoke and not show anything. Before I spend even $45 on a new tool that i'll only use once.

Right now I am sitting on $10 worth of parts for my DIY tester. I might even be willing to burn that money just to give it a shot if I think I can learn just a little.

GOTTA Be real careful not to put too much compressed air in tank. That could be tricky to control.... ideas? also a little worried that a bunch of fumes can get whirled up just by disconnecting these lines.

 

The problem with your DIY set up is the HEAT and particulate matter the smoke will carry with it into the fuel system. I don’t know how hot a smoke bomb gets, but in a confined area (i.e. paint can) there’s no place for it to go, so the heat will be introduced into the fuel system. And it’s likely that some of the smaller particles coming off the smoke bomb will be carried into the fuel system as well.

The flash point of gasoline is -45*F so it wouldn’t take much heat and/or hot particles to ignite it.

As for pressure, the smoke machine I use at work produces about 10 PSI, which is enough to find any leak.

Get the cheap tester or go to a shop.

 

Ok guess I can just try blowing some smoke from a cigar into the charcoal cannister to see if air or smoke can get through. I think it's just clogged. I thought the pressure should be 1 or 2 PSI ?

I guess if above idea doesn't work I can go out and get a smoke machine. Guess I am returning this paint can then.

 

It is starting to sound like the canister is clogged instead of cracked. As it clogs the vapors can't escape fast enough through the canister while you pump fuel into the tank. That builds pressure in the tank which keeps the fuel from flowing freely and kicks off the pump.

As you pump liquid into any container it displaces an equal volume of air from the container. If you fill a jug, the air passes out through the same hole you're filling from. A car's filler system is designed so that the air and vapor can't vent through the filler neck and has to vent through the canister to be filtered. It's all designed so there's enough pressure to push air through the canister without triggering the pressure cutoff on the fuel filler.

That could explain the gas smell too since the vapor has to vent somewhere as the contents of the tank expand and contract with temperature changes. You normally don't smell it because it's caught by the canister and pumped back into the fuel system. The fuel heats up when the van is running so you might get more smell after starting it.

A crack in the canister, or anywhere in the system, should throw a code for the evap system not having proper pressure.

The canister can be damaged by someone regularly overfilling the tank.

 

I’ve safely pressurized the EVAP system up to 20 PSI using regulated compressed air, but in most situations, it’s not necessary to exceed 10 when searching for a leak.

To check canister flow, at least 10 PSI is necessary, because 1-2 PSI wouldn’t be enough for accurate results. The canister should be free flowing between all 3 ports. Regardless of which port is pressurized, from the other 2 you should get out what you put in. It helps to plug one with your finger to verify the individual compartments are clear.

For safety reasons, please don’t use smoke bombs/cigars/flame sources for testing.

 

I worked on it today. It was a pain figuring out how to get all the little different evap clips off. And also disconnecting the electrical from the vent solenoid, a new kind of connector that is harder to figure out. I was able to blow through all three ports of the charcoal cannister. I used a long line of clear tubing to do this. I was able to blow through the fuel tank input and feel the same out put and no blockage through the engine input (line that vacuums on charcoal cannister.) I was also able to blow through the port to vent solenoid. I just used my mouth to blow through the tube. Not sure how much PSI that is. I think it around 6 PSI for an average adult.

The problem was the damn vent solenoid. I was cussing like crazy. IT seems like air flow is coming out around the bottom but it's hard to tell. So I lit a smoke bomb, and stuck THAT up so the smoke would travel up the tube. That smoke has **** ton of dye in it, glad I didn't use that on the fuel tank... I then blew on it and a bunch of smoke see to WHOOSH out of the vent solenoid on all sides.

I then tested the vent solenoid by applying 12 volts to the SOLENOID . I heard a very strong audible click, however I am worried about it because I think maybe I wasn't suppose to do that. It seemed like it got weaker because I opened closed, open closed a few times. And each time it sounded weaker.... Guessing I damaged it. Did I damage it ? was I suppose to do that? LEt me know.

SO now it seems like THERE IS NO BLOCKAGE. What do I do now ? Guessing I'll start it up tommorow and see a code because I F'ed up that vent solenoid.

ALSO There IS ANOTHER EVAP line on top of the tank right there next to the CHarcoal cannister? where does that one line at the filler neck travel to? you know the little line right off the top of the filler little pipe?

Hey it also seemed like the my gas cap was loose, like the ratchet was NOT ratcheting down hard enough. Even though it clicked once, I could still move the gas cap around... Is this normal? I check another car and it was the same.

 

does anybody know if it were the case that the purge solenoid was bad, then the tank would not be able to vent fumes, causing a hard fill situation at the gas station just like a clogged charcoal cannister? Also do any of you guys know if it's a good idea to blast compress air through the evap line that goes from the gas tank to the charcoal cannister? I am starting to think there is a blockage in that line. The problem is it's very difficult to see. sEe I can smell fumes in the tank when I pop the gas cap, BUT when i pop the lines for all the evap hoses, no smell. I haven't even seen any charcoal pellets yet in the lines, but maybe somehow a line is clogged.

NO codes yet, btw, I can still smell fumes though a tad

Also if anybody could give me a lay out of how the all these hoses connect up would be wonderful. let me guess, the one evap line that goes to the charcoal cannister, it connects to the tank around the fuel pump? IT's already looking like I need to drop the tank instead of buying a smoke machine.

ALSo I read that the evap system is a really tough system for onboard diag to throw a CEL. IS THIS True? What I mean is it could be months of driving around with the problem until the computer spots it. Is this common? I just passed smog too, this is all mind boggling

If you read this post, please read my above post, because it wouldn't let me edit that post.

 

https://charm.li/Chevrolet/2013/Expr...m%20Diagnosis/

Give that a read and see if it helps. Do you have a code reader or more complete scam tool? Can you see if you have tests pending or codes pending? Sometimes it takes a while for them to set and depends on fill level of the tank among other things. Are all tests complete?