Fuel starvation ??? - Team Camaro Tech
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post #1 of 7 (permalink) Old Sep 1st, 11, 02:54 AM Thread Starter
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Scott
 
Join Date: Aug 2011
Location: Amarillo, Texas
Posts: 52
Fuel starvation ???

I have recently install a 383 small block into my 69' camaro. It has a Holley 750 vac sec. That seems to be starving for fuel. When you put the pedal to the floor it will accelerate hard and gain about 40 mph before bogging down. It does this from 0-40, or 60-100mph does not matter. I installed a clear fuel filter and noticed the level begins to drop after 5-10min of normal driving to the point where it will eventually not have any fuel in the glass. I replaced the fuel sender and fuel line with a new larger line, insulated the line in the engine compartment, and installed a Holley 110gph mechanical fuel pump....no change! I was told by a couple of different people to use a "booster" pump, desperate I followed their advise and installed a Carter 72gph electric at the tank to push fuel to the mech pump. So far it seems to have completely fixed my problem the car is running great - the problem? Well I feel that these cars were designed to run on a mechanical pump and have for 40 + years. The car dynoed at 485hp it concerns me to have an electric pump indiscriminately sending fuel to the engine. Is this a common problem? Is this a good fix or could it lead to a crank case full of fuel? Anybody have another idea? I have noticedthat when you shut down the engine the vented fuel cap is really sucking wind...seems to really be pulling a vacuum ...maybe more than the relief at the cap can handle?
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post #2 of 7 (permalink) Old Sep 1st, 11, 03:37 AM
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Gene
 
Join Date: Jul 2010
Location: Smiths Grove Kentucky
Posts: 234
Re: Fuel starvation ???

I had not an exact but similar problem and after everything else checked the filter sock in the tank. It was split, frayed and would fold into the fuel outlet from the tank and cut off the fuel supply. I had trouble finding the problem and followed suggestions from Team members in solving the issue. It was intermittent at first then progressively worse until it would start and idle for just a few minutes or less, I had to be towed in.
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post #3 of 7 (permalink) Old Sep 1st, 11, 05:10 AM
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red
 
Join Date: Nov 2003
Location: OH
Posts: 918
Re: Fuel starvation ???

Did you use a light weight fuel pump rod?. What rpm are you running normally? Take the mech pump out if you eventially keep electric one.
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post #4 of 7 (permalink) Old Sep 1st, 11, 10:32 PM Thread Starter
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Scott
 
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Location: Amarillo, Texas
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Re: Fuel starvation ???

I had the problem before and after I installed a new, larger (3/8) fuel sending unit with the new and larger 3/8 fuel line. It has a standard fuel rod, but it moves freely. It happens in normal driving really only if you put it on the floor. It really seams that the mechanical is unable to pump enough fuel to keep the fuel bowl on the carburetor full. When I accelerate hard it's like it will run till the fuel bowl is empty then stumble until it begins to fill up again.
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post #5 of 7 (permalink) Old Sep 1st, 11, 10:38 PM Thread Starter
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Scott
 
Join Date: Aug 2011
Location: Amarillo, Texas
Posts: 52
Re: Fuel starvation ???

If I take the mechanical out, will the 72gph pump be enough?
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post #6 of 7 (permalink) Old Sep 4th, 11, 09:00 AM
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red
 
Join Date: Nov 2003
Location: OH
Posts: 918
Re: Fuel starvation ???

I think the fuel pump will be fine. Seems like you have tried everthing on the feed side. Lets look at the pressure side. Fuel filter restriction? Float level(both). Wondering if you could check fuel level at idle and rev to 3000 for awhile with veiwer open and see if stays there? I have a high flow filter with stainless steel replaceable element. i have a 375hp engine and drove 360 mile road trip last weekend with a stock mech pump with 3/8 fuel line. Running 3000 rpm for miles. No issues. Even with low fuel light flickers cuz tank low and still fine. I had the same setup with a electric pump back by the tank. I hooked it up to run when key in run postion. wire pushed on at fuse block just in case needed to unhook quickly. Did not have mech at time cuz i did not like duel pump setup. Safety?
When i desided to go back to stock with all metal lines in engine compartment and mech pump, i would run out of fuel. I could drive for miles but if you pushed it or went up a hill i would run out of fuel. Like on the verge of capacity. Replaced fuel pump and still had issue. What i had to do to solve problem, after time. 1) remove electric pump that i left inline,but not using. 2) remove filter i had on suction side of mech pump,paper stlye. 3) Replace fuel rod with lite weight one. 4)Put in high flow fuel filter,don't use paper style. Another note i made sure my power valves were correct size. i had to lower cuz vaccumme was low and could here valve fluttering. Possible drawing in fuel quicker than nessecary, therefore running rich and taking your fuel capacity level down?
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post #7 of 7 (permalink) Old Sep 6th, 11, 08:48 AM Thread Starter
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Scott
 
Join Date: Aug 2011
Location: Amarillo, Texas
Posts: 52
Re: Fuel starvation ???

Thank you for the ideas...I will get back to work on it and let you know how it goes!
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