fuel smell from under hood

[kickass audio]

Hey GMT members, as usual I have another fun one. For the past 2 days my truck has been smelling of gasoline in the cabin. The exhaust smells like normal and there is pressure that builds up if I were to cover the exhaust with my hand for a second or 2 and then release it so it doesn't seem to be a cracked or broken exhaust. I opened my hood and checked for smell and with the engine off I couldn't really smell anything from either side. With the engine running I can smell gas on the passenger side, it is really strong if I get into the passenger wheel well.

I checked the sending and return fuel line that attaches on the drivers side of the engine at the top and they look fine. I couldn't really follow the line though that well to see if it has a leak on any other part of the line. I did not check the fuel trim on a scan tool to see if it is doing anything with my engine but will check this out tonight when I get out of work. The truck runs perfect at idle, WOT and normal cruise speeds of 30-65mph.

Can anyone give some insight on what to look for when I dig into it tonight? I might not be able to do it all tonight with it being in the single digits but I can try.

edit: I did check the gas cap and it is on tight. This did start happening after I fueled up on the 31st but I have a half tank of gas. I will check my fuel regulator tonight when I get home too. It starts just fine too and has no long crank time so I am thinking the fuel regulator is okay.

 

[The_Roadie]

FPR diaphragm can fail with a pinhole and still be functional. Smell its resonator hose.

 

[kickass audio]

FPR diaphragm can fail with a pinhole and still be functional. Smell its resonator hose.

The resonator hose you mean the vacuum line that goes to my air intake?

 

[The_Roadie]

This one:

View attachment 31860

 

[kickass audio]

Okay Roadie that is the line I was thinking of. I can't believe how much the regulator costs on rock auto. I am going to my sisters boyfriends house tomorrow for some more help as he was a mechanic for a few years and has tons of tools to test line pressure and things like that. I think it might be my regulator because the smell is strong on the passenger side. I did smell a weird odor near the top by where the regulator sits but it smelled like melting plastic. I will see what I find out tonight by checking that fuel regulator and then check the fuel trim to see what it looks like. Will the fuel trim make any difference if the engine is hot or cold or should it be around the same range for both under good conditions?

 

[kickass audio]

update: I checked the resonator hose as Roadie suggested and I smell gas directly in that area. I pulled the hose and smelled and it is a little stronger of a smell in that hose. I had noticed on the one fuel hose that it looks like it leaked at one point in time because there is a drip mark on it. It didn't look fresh but my truck was off for 5 hours now. I started it up and the odor got really strong when the engine was running but it was a cold start too not hot. Before I turned the engine on I turned the key to run and off 3 times and no fuel came out of any of the connectors down there by the regulator. It seems like the regulator is bad?

I looked at the exhaust and see no drip marks. I parked my truck on snow and there are no drip marks on the ground or in the snow from fuel. I can't smell any gas under the truck, only within the engine. Its hard to pinpoint when its running though because of the rush from the fan spinning the air around, when its running it smells strong towards the passenger side.

Would I hear the puffs of air if my exhaust manifold was cracked/leaking? I hear no air hissing or anything like that when its running and the pressure builds up real well in the exhaust when I cover it.

 

[The_Roadie]

The regulator has a diaphragm in it to separate fuel from the hose. It shouldn't smell like fuel in the hose. $70 on Ebay. If you need one, the price is sort of irrelevant. Think of how much cheaper it is than a new car's payment.

 

[kickass audio]

If it catches fire its insured for it. hahahaa. Well I checked the fuel trim and short term was ranging from .8-4.3 the highest I saw it was when I gave it gas it would go up 19 both positive and negative. I also noticed this time when I ran the engine it had a hissing noise, not like a vacuum leak or hose leak but almost like listening to water run through a partially opened faucet. It was hard to detect where it was from but it was around the area of the regulator. I wiggled the lines and nothing came out and there was nothing in the vacuum line of the fuel regulator. The smell of gas around the regulator isn't as strong as it was earlier today before I played with wiggling the hoses and removing the vacuum line. I didn't have any burst of gas fumes in my truck at all while driving. Maybe its a fluke? Idk.

Has anyone heard of the fuel lines making sound like water coming through a faucet? It did it at idle and at 4k rpm.

 

[kickass audio]

Okay so its cold again and it smells a little once again. Yet when I give it gas it has 0 dripping, running, not a single bit of gas. I had tried sucking on the vacuum hose and it is still bone dry and taking the hose off has no fuel deposited in the opening port on the regulator. I think I am just going to replace the damn thing and hope that is my problem and not the fuel rail or something like that.

Do I have to remove the whole rail to get that damn thing replaced or can I just disconnect the fuel line, vacuum line and unbolt the star bolt holding it on and pull it out and replace it. It is hard to see if there is another screw for the fuel pressure regulator behind the intake manifold. I found all the instructions on the service manual both on here and the one we can download but all it says is to disconnect the harness, take off the intake resonator, disconnect return fuel line, disconnect vacuum line and remove the FPR. It looks like on rock auto's pics that it just gets pushed straight down so if I remove that star screw and the lines it should pull straight out, is this right? Also on rock auto it doesn't show the little line that bends into the FPR, do they come with it just not show it in the pic or do I need to take that little pipe off the old FPR and put it on the new one? And when I mean pull straight off I mean that you pull it towards the drivers side and pull it upwards. Just wanted to make sure I know what I am getting into and if anyone had their FPR come with that little metal tube on the end where it goes to the return line.

Thanks again guys!

 

[Matt]

Funny, I'm going to have to replace mine too. I'm getting the fuel smell and I checked the vacuum hose...it stinks of petrol.

From what I can see, it's a straight forward job, shouldn't take more than about 20 minutes to remove and replace the regulator. Just remove the lines, take out the star screw and replace...lube the new O ring with some engine oil. You may need to take the intake resonator off but that's a trivial thing to do.

Matt

 

[kickass audio]

I see in the manual that you need to remove the resonator but I don't see why, its right there to get to. I just was wondering about the return fuel line on if you just remove the disconnect where it goes from the rubber line to the quick connect that goes to the metal line that connects to the FPR or if you can just undo the star screw, pull the FPR out with the hose attached and then disconnect it from the FPR.

Like what im questioning is in the video:

http://www.youtube.com/watch?feature=player_detailpage&v=yG0y3bqaV7E#t=392

Right at that clip where he is prying off the fuel line from the regulator is what im wondering if I can remove that after I pull the regulator out or if you look at that metal pipe there is a quick disconnect at the end of the line like 3 inches away, if I disconnect that first, pull the FPR and disconnect the metal fuel tube like shown in the video.

 

[CaptainXL]

Make sure to pull the fuel pump relay while running so you minimize fuel spray when disconnecting. I would replace it when engine is cold to reduce chance of any fire. Have extinguisher standing by.

 

[kickass audio]

Make sure to pull the fuel pump relay while running so you minimize fuel spray when disconnecting. I would replace it when engine is cold to reduce chance of any fire. Have extinguisher standing by.

I was thinking that since the FPR works open when you give it throttle I was thinking to go WOT and then pull the relay. Would that work okay? I figured at idle it would only clear the main fuel line not the return line. And who needs a fire extinguisher when you have fire insurance :wootwoot: hahahahaa.

 

[Matt]

This is a good video of someone changing the FPR in an 04 TB.

[video=youtube_share;oa3E7ClI3Bw]http://youtu.be/oa3E7ClI3Bw[/video]

 

[kickass audio]

Let it be known that I hate you. I tried to lookup envoy and trailblazer fuel pressure regulator and had 0 videos or anything showing how it was done, only the service manual showing the whole rail dis-assembly process of removing the intake manifold and everything which I know is unnecessary for the FPR. Thank you so much for finding that video!!!

 

[kickass audio]

That vid helped but it doesn't show if there is a locking ring on the part where the return fuel line comes into the FPR. It seems like he said it just sits in there which seems pretty damn stupid. Thats all i need to know is if there is a locking ring that keeps the fuel line locked into the pressure regulator.

 

[CaptainXL]

On those double lock connectors you actually don't need to take off the grey piece. Just slide it back a bit and press to release. The grey piece is really just a safeguard. Not a redundant connection. I believe ASTM and SAE mandate them to comply with NHTSA requirements.

Colorful commentary in the video BTW.

 

[kickass audio]

On those double lock connectors you actually don't need to take off the grey piece. Just slide it back a bit and press to release. The grey piece is really just a safeguard. Not a redundant connection. I believe ASTM and SAE mandate them to comply with NHTSA requirements.

Colorful commentary in the video BTW.

Haha on the commentary. I thought the same thing. What do you mean the double lock connector? Are you talking about the line that goes to the fuel rail and to the throttle body? I don't plan to disconnect them. I have plenty of safe guards to prevent the truck from starting when the hood is open. I mean the locking connector where the metal hose goes into the bottom of the fuel pressure regulator. Look at the vid when he removes the regulator from on the engine, see the metal hose just sitting in the opening? That is what I want to know if there is a lock to hold it on or not.

 

[CaptainXL]

I want to know if there is a lock to hold it on or not.

It looks like the FPR just slides out after removing the two torx head bolts.

 

[kickass audio]

That's what it seems like to me, just wanted to make sure. Seems like a pretty dumb idea having the return fuel line just slide into the FPR with no lock on it but thats GM for ya....

 

[kickass audio]

since it was holding off on the rain and snow today I decided to tackle the FPR replacement. It took maybe 10-15 minutes. First I started the truck and removed the relay that operates the fuel pump and let the truck stall out from losing fuel. Then I removed the resonator just before the throttle body and then loosen up that plastic wire container that goes across the front of the engine by piston 1 which I broke off 2 of the 3 retaining clips that hold it down to the top of the engine. Then I used little torx screwdriver tips on a rachet to undo the two torx screws that hold the FPR and return fuel line in place. Take off the vacuum line on the FPR. The part that was the real pain was to get the FPR out of the fuel rail. I had used a flat head screw driver to pry underneath the arm that attaches to the regulator where the bolt passes through but after 2 pry's it bent that arm a lot so I then took the screwdriver underneath the regulator on the top and bottom to wiggle it lose and as soon as I started to see the blue o-ring where it goes into the rail I shoved an old towel underneath the regulator to absorb the fuel that was about to come out. I recommend putting something over your drive belt because I had a little bit of gas spray on it from the pressure in the rail but it isn't anything to worry about. Give the regulator a good tug and it will come off from the rail and then you just pull the regulator straight off the return fuel line. Before you reinstall the new regulator make sure the rubber o-ring is not stuck on the return fuel line and if it is remove it. My regulator I purchased was the ac-delco so it came with a new o-ring for the return line, I can't speak on the other manufacturers but i would assume they come with one too. I took some oil off my dipstick and put it on both o-rings and first attached the FPR to the return fuel line then set the FPR in the fuel rail. Bolt up the two retaining arms for the fuel line and regulator and test it. I tested it first by putting the fuel pump relay back in and turning the truck to ON but not actually start, I did this 4 times to pressurize the fuel system and inspect for any leaks or sprays of fuel to which I found none. I then started the truck up and let it warm up a little all the while checking for leaks with none found. I revved the engine to the rev limit of around 4k and still no leaks. I shut down the engine and reattached the resonator and did another test still with no leaks.

One thing to note is that i do know you aren't supposed to run the engine without the filter and entire air intake system attached but I did it just for a few seconds to get a better look at the regulator and fuel rail for leaks.

My old FPR was very rusted on the bottom half of it where it goes into the fuel rail so I am suspecting this is where it was leaking. I didn't see any rust on the inside of the rail, regulator or fuel lines. There was no debris in the filter of the regulator. The only thing I found was a little bit of varnishing in the fuel rail where the main fuel line goes into it but it was so minimal I wouldn't worry about it. It was a very very light brown, almost like a caramel color on it but it was just on the outside of where the line comes into the fuel rail so I am not concerning myself with it. I do run techtron2 fuel cleaner in my truck 3 times a year so it shouldn't be a problem.

Thanks again guys for all your help!! Lets see if it still smells when it gets cold outside. It was 35 degrees when I did this and I didn't have any gas smell after it was replaced and had a slight smell before it was removed so I think you were right in replacing it.:wootwoot:

 

[Matt]

I did mine yesterday too. Although I didn't remove the fuse or run the pump down, I just opened the fuel filler cap to relieve the pressure...no fuel leak or spray at all.

I use an upholstery tool to lift that wire tray so I didn't break any clips, it also came in handy when I removed the FPR itself. Maybe I was fortunate, but I didn't have any issues with the steel fuel line.

All in all, it took about the same amount of time as you.

 

[kickass audio]

The only reason I ran the truck dry like that is to let out some pressure on the fuel rail so when I pulled it out it wouldn't spray fuel everywhere from the back pressure. I saw a few people use a panel removal tool but I don't have one so it wasn't an option for me. As for breaking those retaining clips I had the middle one broken when I tried to move it out of the way for my spark plug. It sits down securely though so I am not worried with replacing it.

My fuel line was in great shape, some rust on the outside of the line but nothing bad. I was shocked at how the rubber part of the fuel lines moved, I figured they would be hard with it being so cold