Car Bucks, Fuel Problem? - Team Camaro Tech
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post #1 of 10 (permalink) Old May 24th, 10, 10:07 AM Thread Starter
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Logan
 
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Car Bucks, Fuel Problem?

Hello, I have a 72 Camaro SS with a 350 and a Rochester quad carb. New HEI distributor on it too. Here is my problem that i cannot figure out...

When i am driving my car on the highway is runs fine going about 75 MPH for about 60 miles from when i start. after about 60 miles (sometimes 90 miles sometimes only 15 miles) when i am going up a little hill the car starts bucking and when i try to give it more gas it bucks harder. It acts like it is getting no fuel but i know the tank is full or at least has gas. I thought maybe it was bad gas, even though i have been using the same gas stations for 2 years, so i tried dry gas, no help.

Here are this weird things. The bucking only starts going up hill but once it starts it will do it whether on flat ground or going down hill. i pull over to a rest area or something and decided to change the fuel filter, not the one inside the carb. i clean it all out, there is nothing in it, and put it back together. Magic, the car works, until anywheres from 15-90 miles later, then it all starts over again.

Here is what i think it may be, one of these: fuel filter, fuel pump, sediment in the gas tank(even though there is nothing in the filter but cleaning it tends to temporarly fix it), fuel lines(maybe air is getting in?), or something is messed up inside my carb.

Does anyone have any ideas!?!?

Thanks in advance for all the help!!

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post #2 of 10 (permalink) Old May 24th, 10, 11:57 AM
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Vince
 
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Re: Car Bucks, Fuel Problem?

Nice car. I would say a filter somewhere is the culprit unless something is closing off the exhaust when going uphill and the car is choking.

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post #3 of 10 (permalink) Old May 24th, 10, 04:08 PM Thread Starter
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Logan
 
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Re: Car Bucks, Fuel Problem?

If that was the problem why would cleaning the one filter fix it temporarily? And if the problem was the exhaust closing off then why would it only do it after a bunch of miles.

Also, if i really hammer on it(really push it through all 4 gears), it chokes up at about 50 mph.

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post #4 of 10 (permalink) Old May 25th, 10, 04:07 AM
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Jim
 
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Re: Car Bucks, Fuel Problem?

sounds to me like it might be more of a carb problem...sitting for a few minutes while cleaning out a filter that's not dirty gives it time to "normalize".

But I'm not a carb guy...so wait for one of them to chime in

Jim
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post #5 of 10 (permalink) Old May 25th, 10, 08:16 AM Thread Starter
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Logan
 
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Re: Car Bucks, Fuel Problem?

Yeah, i was starting to think it has to be the carb too because with all the clues put together nothing else made sense. I don't know too much about what the problem in the carb could be though...

Anyone out there know about carbs well enough to give me an idea of what to look for before i just go head first tearing things apart? haha

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post #6 of 10 (permalink) Old May 25th, 10, 09:44 AM
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Re: Car Bucks, Fuel Problem?

I've heard mention that all this 'new' gas with ethanol in it can gum up a carb after a period of time.
I don't know how true that is, or whether hammering on the Go pedal helps clear this type of thing. Whens the last time the carb was gone thru?

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post #7 of 10 (permalink) Old May 25th, 10, 10:28 AM Thread Starter
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Logan
 
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Re: Car Bucks, Fuel Problem?

The top end was done about a year ago, new float jet and gaskets. Its been a while for a total job.

Hammering the go pedal doesn't clear things up, when the car is in gear it makes it worse and when the clutch is in it usually is fine.

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post #8 of 10 (permalink) Old May 26th, 10, 06:31 PM
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Re: Car Bucks, Fuel Problem?

Most likely a dirty filter or you have a bunch of debri in the tank that getting sucked up onto the pickup sock. One other thought - if this is a breaker point ignition, a bad condnesor will cause it to buck and fart under load. Typically though condensor problems I've seen had an effect at say 20 to 40 MPH, though I suppose higher speed issues aren't out of the question. Capacitors (a.k.a. condensors) are also affected by heat, so I suppose it could be a problem that gets worse the longer you drive it. Points and condensors are pretty easy to change, so keep it in mind if the other things don't check out.

Dave
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post #9 of 10 (permalink) Old May 27th, 10, 07:31 PM Thread Starter
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Logan
 
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Re: Car Bucks, Fuel Problem?

So i think the problem is fixed, i think there were 2 problems.

1. The fuel filter in the carb was pretty dirty
2. The float was set pretty low so it wasnt getting much gas before the jet was closed off

If the problem occours again ill be back
Thanks for all your help!!!

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post #10 of 10 (permalink) Old Jun 2nd, 10, 04:19 PM
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Charlie
 
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Re: Car Bucks, Fuel Problem?

I run a heavily modified QJet and I set my float to 1/4"-5/16" and she never runs out of fuel. The factory setting is for a completely bone stock engine.

Also, it's best to totally eliminate the filter in the carb and get an inline filter. The filters in the carb are restrictive.

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