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ChrisPatty

need a little help

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I have a nice little 73 Dodge Dart with a slant 6. Have been having some fuel problems with it. replaced just about everything except the fuel sending unit (looks good) and the steel lines (also good). The problem that I am still having is that there is no fuel at the filter/carb when it is ideling. I have been having this problem for about 3 months. Before that it ran like a dream. If I rev it up to around 3000 rpm the pump will kick in untill then I get nothing from the pump. Any ideas?

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I drove a slant-6 powered Mopar for several years... Have you replaced the fuel filter? When you say the sending unit looks good, have you pulled it out of the tank and checked the pick up tube screen for evidence of debris? Is it possible someone used gas tank sealer goop to fix a leak? That stuff has been known to disbond from tank surfaces and create fuel pick up havoc. There may be a fuel pump volume delivery spec for this car. You disconnect the fuel line at the carb, direct flow into a graduated contianer and should get 'x' ouces in 'y' seconds at a specified rpm. It sounds to me like a fuel pick up or filter problem.

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Yes to both. The filter has been replaced, and the sending unit has been completely removed from the tank and checked. The screen looks clean. it does have a cracked seam, though, could it be collapsing?

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Often this can be a gas cap vent problem. Run it without the gas cap to see if that makes any difference. I doubt the cracked seam would have the symptoms that you describe.

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Yes good point. I'm guessing in '73 the tank was still vented by the gas cap. Later systems vented through an added tube at the top of the tank which was plumbed to a charcoal filter (and the gas caps no longer had a vent holes).

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Replace all of the flexible lines if for no other reason to use new line that is less subject to colapsing internally from alchohol extended fuels. Also the rubber lines can be a source of air leaks. It sounds like it could be an intermittent air leak as the fuel pump will pull air easier than fuel. These lines are also known to turn to goo internally and plug themselves but still look good from the outside.

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Id like to see pics of the car, Ive had a 72, a 69 and a 66

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I tried and it still "runs out of gas" could I have gotten some bad gas or water in it somewhere? My '91 is acting like it is trying to run out of gas as well.

Edited by ChrisPatty (see edit history)

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If you suspect bad gas throw in a couple bottles of 'dry gas' (which is mostly alcohol). Unlike gasoline, it mixes with water. However, a lot of places sell gas with 10% ethanol already in there. Have you tried the volume test? This engine has a mechanical fuel pump and it should deliver some amount of fuel while cranking the engine. I'm just not sure what the spec is. I don't imagine a fuel pump is very expensive for one of these. Probably worth a try.

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Just put a new one on. I know that it is possible to get a bad pump from the parts house, but what are the chances?

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Not very likely I agree. Perhaps it is a carburetor issue? Idle jet clogged? I think these were still very simple carbs in '73 and should be easy to rebuild.

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Try running a gravity feed gasoline container to carb temporarily. If it clears up, look in other places, if same problem, look into the carb for your problem. Be very careful with gasoline! Use your common sense when experimenting with gas.

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How could it be a carb problem if I'm not getting gas to the carb? I'll try though. The carb was rebuilt about 500 miles ago.

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Sorry Chris, I had to re-read your original post to straighten me out on the problem. I'm trying to figure this out. I suppose you could try a remote gas can to the PUMP intake to verify pump is doing it's thing. Use known good fuel in can if you think you may have gotten some bad gas. Place gas can lower than pump to check the holding action of the fuel pump's check valves. A collapsing screen on sending unit shouldn't be problem, fuel should still flow through it enough, if it's a clean tank. it's the pick-up tube you should worry about. I once had one that had a hole half way up in the pick-up tube. At a half tank of gas, I would "run out" of gas. Jack M made a good point of the older flex lines. It happens.

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Is there a filter at the carb inlet on those?

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Yes, it is less than 10 inches from the inlet of the carb. That hose has been changed as well.(both ends)

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I am talking of right at the carb where the line goes in. I dont remember if the S6 has one but they are small and I know trhat some carbs have one under the inlet fitting.

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Well, here's a quick update. We treated the gas, installed an assist pump, and she runs. But she still seem to vapor lock when she gets hot.

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The only thing I can add to this is to be certain that any fuel line near the heat of the engine or exhaust is steel or insulated.

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