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Hey guys, read a few post and didn’t see any that fit what I’m encountering. When I start the car and let it idle you can smell gas fumes. Not like straight gas but like possibly running rich. I pulled it out of the drive turned around and backed it up into the carport and my shirt now has a slight smell of exhaust and or gas to it. It was probably 5min max of being around the car. Also, a buddy was over today and said it smelled rich. I don’t have the extra $$ right now for the AFR ratio gauge to see what it is exactly doing for that aspect.

I posted previously about a stumble with the carb where it was running lean and adjusted the 750 Holley double pumper to have a 50cc primary and 35 nozzle in both. I went larger and it didn’t like that so this is where I ended up.

Gotta get this figured out, the wife wont ride in it like this haha!

Open to any suggestions, thanks!
 

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The accelerator pump does not effect idle unless it is leaking internally. Your idle circuit may just need a slight adjustment you didn’t say what carb you have but they all have idle mixture adjustments...

generally turning the screw clockwise will lessen and therefore lean the idle mixture and turning CC will open and therefore richer the mixture.....

you can go back to your carb’s original idle setting procedure......

make sure floats are set to proper spec height first and you have to adjust the mixture and the throttle screw together to get it just right,...use small changes and test....

try one eight of a turn in on the mixture screws and the drive it,...even that change will show up on an AFR meter...
 

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I’ll try that tomorrow! I adjusted the floats when I had that carb apart. Did it where you flip them over and adjust them in line with the screws. I think I’m explain that correctly ha.
 

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Plug a vacuum gauge into manifold vacuum. Adjust the idle air/fuel mixture screws for max vacuum.

If ur having trouble with a starting point... screw all the air/fuel mixture screws all the way in and back about a turn and a half. Start there and make 1/4 turn adjustments at a time (both sides at the same time for each adjustment) while watching the vacuum gauge. Keep adjusting until the vacuum gauge levels off the highest vaccum.

As lemans guy said tightening the screw (screwing it in) will lean the mixture while loosening the screw (screwing it out) will richen the mixture.

As stated make sure your float levels are correct first. Take the sight plug out of the float bowl with the car off. You should be able to rock the car and have some fuel come out of the hole. If you take the sight screw out and fuel pours out you need to lower the float level. Do this with the primary and secondary float bowl. Remember, After an adjustment to the float you need to put the sight screw back in, start the car and run for a couple seconds. Then shut it down and check the the float level again to see the results.
 
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Keep in mind a camshaft with a lot of overlap can give you that raw gas smell out the exhaust because its blowing unburned fuel out the exhaust.
 

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I know you were changing your accelerator pump nozzles and pump. One thing that will drive you crazy with hard cold rich starts is a leaking accelerator pump check valve.

in the newer versions it is a small rubber umbrella looking valve, older ones had a ball bearing style....Have you changed that umbrella valve? They do go bad and don’t seal...

when that happens you get a hard cold start, and it is frustrating. Holley sells them on their web, or any vendor that sells Holley carb parts. If you take off the accelerator pump check it if it looks warped like it is not flat it is not sealing.

that will make you rich at idle also.........
 

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Discussion Starter #9
I haven’t changed that but I remember seeing it when I was changing the parts. The car does sit for a few days and fires up fine but then will die with out a little throttle at first. After that it starts and idles fine.

I started it yesterday and being the coldest day since Ive owned it, about 60 outside, it really didn’t wanna stay running. Had to work the gas for a minute or so. Would the check valve be related to this or the fact that it is a manual choke version with the choke just wide open since the manual choke linkage isn’t setup?
 

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Also, I remember seeing a video from Holley on setting the mixture screws and they said to have it in drive while making the adjustments. Is this required or can you do it well enough in park? No big deal either way, just need to know so I can call a friend haha
 

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You need to have the choke properly adjusted for cold starts, it may not be closed enough during that initial 60 seconds which makes it richer.....your hitting the pedal squirts gas in and riches it, might need a slight more choke...

no set the idle in park or neutral, with wheels chocked and brake on.

First see what the RPM is at idle in drive, and at idle in park or neutral..

park or neutral will be higher, note the diference......

say it is 700 RPM in drive and 900 Rpm in park.......maybe you want 600 in drive.....

then drop that 900 Rpm to 800 Rpm.....then put it in drive is is 600? ....

adjust that way and you can dial it in much safer, and alone.....
 

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Discussion Starter #12
I’m gonna order a choke cable to help out with the cold starts. Unfortunately I don’t have a tach gauge yet either
 

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Also, I remember seeing a video from Holley on setting the mixture screws and they said to have it in drive while making the adjustments. Is this required or can you do it well enough in park? No big deal either way, just need to know so I can call a friend haha
You dont do it while you drive. But you want to do it when the car is fully warmed up. Thats why they probably mention driving it. The mixture screws are your idle circuit and dont effect the primary, secondary or accelerator circuits.
 

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Hey guys, read a few post and didn’t see any that fit what I’m encountering. When I start the car and let it idle you can smell gas fumes. Not like straight gas but like possibly running rich. I pulled it out of the drive turned around and backed it up into the carport and my shirt now has a slight smell of exhaust and or gas to it. It was probably 5min max of being around the car. Also, a buddy was over today and said it smelled rich. I don’t have the extra $$ right now for the AFR ratio gauge to see what it is exactly doing for that aspect.

I posted previously about a stumble with the carb where it was running lean and adjusted the 750 Holley double pumper to have a 50cc primary and 35 nozzle in both. I went larger and it didn’t like that so this is where I ended up.

Gotta get this figured out, the wife wont ride in it like this haha!

Open to any suggestions, thanks!
Another idea might be to check your choke pull off. If the pull off is not pulling off enough, the choke flap will cause a very rich mixture. I had this problem once, and the exhaust was a very white color and I could smell a great deal of gas Until it warmed up and went off choke. With the Quadra jet it was simply bending a tang, and I got it back to the right opening and solved the problem. Just a thought.
 
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