69 Impala with 350 idles but dies while driving - Impala Tech
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post #1 of 7 (permalink) Old 11-03-2013, 08:48 AM Thread Starter
 
 
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Question 69 Impala with 350 idles but dies while driving

I am glad I found this forum and was able to join it. I have a problem that I hope someone here can help me with. It has drove me nuts for a few months now, any help would be great! Here is my problem. I have a 69 Impala with a 350 engine. It starts and Idles good but when I drive it for about 15 to 20 min. It starts to spudder and the engine will sometimes die as if it is running out of gas. When it dies it will start right back up, and if I can get pulled over and sit with it in neutral a min. or so it smooths back out and runs for a few more miles and repeats the issue. I have replaced the plugwires, plugs, distr. cap, rotary, coil, I have rebuilt the carb (Rochester quadra jet 4MV ), repaced the fuel filer, fuelpump, replaced. vacuum lines, I even changed the thermestat but I still have the issue, IM STUMPED! Any Sugestions? I have also checked the timing and checked for signs of a blown head gasket. Timing looked good and I found no oil in the water, no water in the oil, no coolent comming out of the tailpipe. I would realy like to get this car back on the road I miss her! I have noiticed that the flap on the passenger side exaust manifold has a broke thermastat spring and im not sure if the down position is open or closed, or if this could be the problem. I have tried it in the up position and it did'nt seem to help.

Last edited by tatman6; 11-03-2013 at 09:38 AM. Reason: More info on things I have tried.
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post #2 of 7 (permalink) Old 11-03-2013, 09:55 AM
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Welcome to the Team Von!

There is one more filter you have not looked at and it is probably clogged. That is the sock on the pick-up inside the fuel tank. You will have to drop the tank to get to it. So go ahead and run the tank down to empty.

I suspect you will find the inside the tank is going to be a rusted mess with scale and sludge clogging your fuel pick-up. You will probably need a replacement tank; and because of alcohol in current gas, it will need to be made of stainless steel to prevent rusting. SS tanks are available in the aftermarket, but they cost more than a stock galvanized steel tank.

Big Dave
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post #3 of 7 (permalink) Old 11-03-2013, 10:18 AM Thread Starter
 
 
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Thank you for responding. I was planning to do that anyway ,Becouse I need to replace the sending unit. Just thought it may be something else becouse it did fine up untill a few months ago and it has seemed to have got worse over that time and it has plenty of power until the problem acts up. I have had more then a few old cars and never ran into this problem before. Plenty of other problems but not this one. Thanks
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post #4 of 7 (permalink) Old 11-03-2013, 07:27 PM
 
 
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not only the sock filter but you could also have a pin hole in the fuel line, and you did say you rebuild the carburator did you set the floats correctly?
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post #5 of 7 (permalink) Old 11-04-2013, 08:58 AM Thread Starter
 
 
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I have checked the float and it was set correctly. I also replaced the short rubber line that comes from the main fuel line to the pump. I have'nt found any leaks or crimps in the metal lines coming from the tank or the pump. I do thank you for your sugestion.
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post #6 of 7 (permalink) Old 11-04-2013, 10:34 AM
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Quote:
Originally Posted by tatman6 View Post
I have checked the float and it was set correctly. I also replaced the short rubber line that comes from the main fuel line to the pump. I have'nt found any leaks or crimps in the metal lines coming from the tank or the pump. I do thank you for your sugestion.
Alcohol in the fuel is acidic. It attacks the mild steel zinc clad fuel lines to cause them to rust from the inside out (just like in the tank). It will clog up very quickly because the interior diameter is so small. The alcohol also attacks the natural rubber hose (which was used back in the day since we didn't have the knowledge of plastics that we have today). There is another rubber hose on top of the tank that connects the fuel line to the tank. If it rots it becomes porous allowing the fuel pump to suck air right through the line. Alcohol also suck moisture right out of the air and when you have an aqueous acidic solution and ferrous metal you get instant corrosion. that is why new cars that are designed to run on alcohol in the gas have stainless steel tanks and fuel lines and the rubber hoses are all Teflon plastic lined. The seals and gaskets are all made of a plastic that is rubbery but impervious to chemical attack. Even the pot metal that the carburetors are cast out of is prone to corrosion (that white gummy sludge in the fuel bowl) because they are not protected from the alcohol (fuel injectors are all made of high density plastic or anodized aluminum).

Your car was designed back in 1956 and built in 1961 decades before President Jimmy Carter first proposed gasohol as a means of breaking our dependence to OPEC countries for oil. Just like with modern motor oil, you can not use it in your car's engine because it is formulated for a motor with roller tappets, not flat tappets. Your cars static compression is far too high to run on todays regular grade gas. Back in 1961 "Regular" gas was 94 octane and premium was rated at over 100 octane. You can not find those octane numbers at the pump any more.

A lot of the problems you are encountering are not your fault in terms of abuse but a problem in that time has moved on and left the requirements of these old cars behind. You will have to upgrade more than your brakes if you want to make this car a driver as it was designed and built in a bygone age for products no longer available at your corner "Service Station" where the attendant rushed out at the clang of the bell to wash your car's windows, pump high octane leaded fuel for you, and checked your API SAE 30 weight SD rated motor oil.

Big Dave
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post #7 of 7 (permalink) Old 11-04-2013, 12:29 PM Thread Starter
 
 
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Hello again Big Dave and thank you for posting on this again. I agree with you completely exept for my car being built in 1961, its a 1969 Impala but the rest of your post is indeed a fact. I sure do miss the old regular gas along with the price I use to pay for it. I do intend to change the fuel lines with stianless ones at taxtime along with the tank if I can afford it. Its like all older cars, A on going project! I would still take old tech over new tech any day, the old cars are more staight foward with no computers or a hundred sencers just to get them to run and I think the older ones had style to them. Thanks again Big Dave for your post it is vary informative. I dont know if it is available every where but the Shell station near my house has Alcohol free gas now and this is what I have been using in my 69 it cost a little more but I thought it would be worth it.
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