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gas fumes

 
lmd500
I love my Chevy Chevette!
Posts: 2
Joined: 01/13
Posted: 01/08/13 02:39 PM

Strong gas fumes under hood. Absolutely no signs of fuel leakage. 1968 el camino 327. anyone have a suggestion?  

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pepsi1
I mow my lawn and find Chevys
Posts: 1718
Joined: 09/11
Posted: 01/08/13 03:04 PM

Imd500 welcome to CHP.

If the smell is after you have run the engine for awhile,I.E. running errands and then you get the strong gas smell. You didn't mention a 2bbl or 4bbl carb.

Remove the top of the air cleaner. If there is a haze or smoke the carb is leaking internally and its time for a rebuild.

If its not that then there maybe a pin hole in a fuel line where you can't see it. Then you need to become an investigator.

Let us know what you find.

Bob  

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idrivejunk
I mow my lawn and find Chevys
Posts: 5119
Joined: 12/09
Posted: 01/08/13 05:29 PM

Was the car equipped with E.E.C. (evaporative emission control) and if so is it still in place and working, with the stock air cleaner intact? If not, and an open element air cleaner has been added, that may be the problem. In enclosed storage, its very noticeable. Did the smell just start, and wasn't there before? Some fuel pumps have a "weep hole" so gas can escape if the diaphragm is punctured or split, and that makes a leak possibly only when its running. If the engine is really clean, a small gas leak can be hard to spot like Bob mentioned. Or an internal carb leak (dripping into intake manifold after shutdown). Which carb is on it?  
idrivejunk

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pepsi1
I mow my lawn and find Chevys
Posts: 1718
Joined: 09/11
Posted: 01/08/13 07:03 PM

Is it a California car?

Matt your right. Some of those engines had them hidden. Usually up in a wheel well. If it was full of gas over the last 45 years it could out gas at the least resistence. That could be the carb, or a vent valve somewhere.

Bob  

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pepsi1
I mow my lawn and find Chevys
Posts: 1718
Joined: 09/11
Posted: 01/08/13 07:18 PM

I just ran really quick through the Elky sites. Some guys have a vented gas cap and some guys didn't. The EEC system according to the data there was. Some units had them some didn't.
  I remember I bought a used 79 Z28 and when I opened the gas cap it would suck air in. The system never vented. It had the wrong gas cap. The cap the was on it was a locking cap. Back then people did steal the gas from your car. The woman I bought the Z from had that cap put on.

If you can try just cracking the gas cap. Then see if the smell goes away. Or gets better.

Bob  

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waynep71222
I have an SS396 tatoo
Posts: 448
Joined: 03/12
Posted: 01/08/13 07:58 PM

look carefully at the FUEL PUMP... and the BLOCK areas..

there is a vent hole in the side of the fuel pump housing above the diaphragm...

when the fuel pump diaphragm fails.. the fuel pushes out that hole and sprays the block.. its NOT always visible...     start and run the engine for a minute...  shut it off and wait a minute.. have somebody else start the engine while you shine a BRIGHT light at the top of the fuel pump.. in line with the mounting bolts...   is there a SPRAY of gasoline coming out????  bet there is...

a few tricks for changing the fuel pumps on chevy v8 motors..

set the crank damper mark to TDC....  pull the distributer cap.. is it pointing at the Number one wire or the number 6 wire...  if its pointing at the Number one wire you can continue..

if the rotor is pointing toward the #6 spark plug wire position. turn the crank one more turn...

the eccentric lobe on the cam shaft is in the proper location when the #1 piston is ready to fire at TDC...

~~~~~~~~~~~~~~~~~

glue the fuel pump gasket to the face of the new fuel pump...

disconnect the battery...    

pull the engine oil dipstick...

slip the engine oil dipstick straight down through the fuel pump plate opening..  i am talking straight down..  so the dip stick is touching the top of the outside of the oval hole..  and the inside of the bottom side of the opening.. wiggle it to get the dipstick tip in front of the push rod..

now that the fuel pump gasket is almost hard glued to the pump.. slip the pump up and push the lever in to touch the dipstick.. this will shove the pushrod up allowing you to drop the pump into place without ANY FUSS OR CUSSING..    

now you can just easily extract the dipstick and bolt the pump up...

this is so easy its crazy..

the reason to disconnect the battery.. is you can do this with the dipstick shoved down behind the alternator..  so you really don't want a short happening there..

you don't have to grease the pump pushrod.. you don't have to put marks on it to hold it up.. yo don't have to take the bolts out of the front of the block..  and you don't have to fight it anymore.. unless you are working by the hour ... and want to extend the job to fatten the paycheck..

if you don't believe me about the dipstick .. try it..   you will like it..

perhaps one of the engine builders on this forum will have one on a stand and photograph what i am talking about..


this is a different type of pump.. but a similar fuel leak.. in slow motion...


http://www.youtube.com/watch?v=6Mlwpp_lHrE  

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BuzzLOL
I have an SS396 tatoo
Posts: 380
Joined: 12/10
Posted: 01/08/13 10:43 PM

. My Monte did that last summer... no leak when sitting, but when I drove it the gas was spraying out in a fine mist onto the hot engine and evaporating and giving about 1 MPG... couldn't figure out why I was running out of gas every few miles...  

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lmd500
I love my Chevy Chevette!
Posts: 2
Joined: 01/13
Posted: 01/09/13 10:41 AM

thanks for the post. new edelbroch 600 carb and new metal lines from pump to carb. no rubber lines. no smoke or haze from carb.  

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76Skylark
Big Block power for the win
Posts: 868
Joined: 12/11
Posted: 01/09/13 10:55 AM

another place to check.  the Hard line TO the pump from the Tank may have a rubber piece to allow Flex between engine and frame look around the Frame cross member Backside and Pass. side of car  

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