Please help!

[lvmymopar]

I have a 66 coronet 440 with a 440 motor. The other day I was out for a drive and the car started acting like it was out of gas. Hesitating, missing, etc. I had a 1/2 tank and it has been running fine. I drive it several times a week so it does not sit. We changed the fuel filter, fuel pump, and sprayed carb. cleaner in the carb and put carb cleaner in the gas tank. When you sit and let it idle it runs fine. It seems to be getting plenty of gas to the carb. Only hesitates when you are driving. Any ideas on what it could be or any troubleshooting things we can do? It was all of a sudden thing. Been running great until then. We havent done anything to it recently except change plugs and plug wires about a month ago. Did a lube job also. Car ran great after the plug job. My husband thinks something is in the carb plugging it up maybe? He doesnt know much about edelbrock carbs. He has a chevy and has a holley carb. Flustrated!!!

 

[GORDIE MACLENNAN]

had same type of problem with 69 GTX I had. Ended up with crud in the gas tank or could be pickup tube on sending unit. Car runs fine at idle, but when you start to run it out, gas gets pulled to carb faster, and any crud in a tank that old may get sucked to pickup tube and restrict flow. When your idling enough gas can get by so it runs just fine. When you shut the car off, their is no longer pull of gas to the carb, so what may be restricting the flow settles back to bottom of tank

 

[moparker]

Married a chevy guy is the main problem. LOL

 

[66 Charger]

Check the obvious first...Are the plug wires fully on and or melted anywhere?

 

[daredevil]

Eddie carbs are simple. take the top off and check for water or crud in the float bowl. Also check for cracked or broken vacumn lines. when you move them around they break from being brittle.

 

[lvmymopar]

We will check the carb. We will also check plugs and wires to make sure that is okay. I also heard that you can check the fuel flow by taking the line off of the carb and turn car over to see the gas flow. If there is good flow it has to be a vacuum leak or carb problem or dirty? I sure dont want to take it to the shop.

 

[lvmymopar]

Is there a way to check the carb to see if that is the problem?

 

[lvmymopar]

We did some more checking and think that Gordie is right. That sounds just like what is happening with our car. Runs great in idle but when we start to run the car in stumbles and acts like it is out of gas. Going to take of gas tank this Friday and clean it out. Do you just unhook it from the gas line underneath and take of the straps? Should we change the filter in there and clean out the pickup tube or replace that? We checked everything else and that is what we are left with. We didnt take the top of the carb of to check that but will if cleaning out the tank doesnt fix it. Or should we do that also? We dont know how long the car was sitting before we bought it.

 

[lvmymopar]

We also had an idea. A friend asked us if it was vapor locking. When I took of the gas cap to put carb. cleaner in the tank it had alot of pressure in it. Like a wooshing sound. Maybe the cap is not venting? Is that normal and can cause the problem?

 

[GORDIE MACLENNAN]

what your talking about doing, taking out the tank and cleaning it is the best idea. You will be surprised at the amount of crud in a tank that old. Actually it normally isn't that hard to take out the tank, especially if it's not rusty. Like you said, unhook the gas line and drop the straps. wi'll your at it, I brought mine to car wash or use pressure washer and spray out, then buy gas tank sealer that's sold at many restoration shops and slosh the tank per instructions. I recently took out sending unit out of my 64 chrysler because it didn't go above quarter tank. What a mess. Bought new one from Auto City Classics in Isanti, MN. Works great

 

[Meep-Meep]

Do you have points or electronic ignition?

 

[daredevil]

We also had an idea. A friend asked us if it was vapor locking. When I took of the gas cap to put carb. cleaner in the tank it had alot of pressure in it. Like a wooshing sound. Maybe the cap is not venting? Is that normal and can cause the problem?

try running it with the cap loose a 1/4 turn. i think my 66 net has a vented cap. Went out and checked and it says vented anti surge on my cap. i bet you are on to the problem.

 

[72 Charger SE]

Kind of similar to a problem I had with mine. Mine was a plugged filter on the pickup tube in the gas tank and ran okay most of the time, but after a 30 minute ride, it would sometimes act like it was out of gas. Engine never died, but wouldn't run above an idle until after I shut it off for a few minutes. I have a pressure gauge mounted at the carb, so it was a lot easier to diagnose the problem. When it would only run at idle, I was still getting fuel, but the pressure gauge showed 0 pressure.

Good luck with it, sounds like you are already on the right path to solving the problem.

 

[lvmymopar]

Yes it does have a vented gas cap. Ordered one from our local parts store. We live in a small town of 3000 and have to order everything. I think we are going to drop the tank Friday and clean it out and see if it is ok. If it's too bad I think it would be better to get a new tank. Hopefully just the cap.

 

[lvmymopar]

OK. I changed the cap and the car ran alot better for a little bit. After about 20 minutes in started doing the same thing. Ran good at idle but when I drove it it started surging and acting like it was running out of gas. So we checked the cap and it had a lot of air pressure again. So I guess it ran good until the pressure built back up again? So we are going to pull the tank and see what is going on. My question is how do you know know when the pickup filter is ok? Do you just clean it and put the sock back on it? And how do you know when you need a new filter? And do you have to buy the whole sending unit and replace the whole thing, or can you just buy the filter? Or do we not even mess with it and just get a new sending unit? Flustrated!!!! We have never pulled a tank before so any imput would be great. Thanks.

 

[old tired rebel]

I would put a new filter and a sock on. Also blow out the gas line with a air hose from the fuel pump too.

 

[fugly]

Did you try loosening the cap ( or temporarily removing it ) and redoing the drive test? If that works it may well be the tank vent line clogged up .

 

[Meep-Meep]

If you think running out of gas in the carb is responsible for your problem then you should be able to verify this by checking the carb for lack of fuel when it starts to act up.

When you say pressure I think you mean vacuum? If you hear a hiss sound as you open the gas cap then you are most likely letting air in to the tank. Pulling a vacuum on the tank would indicate the aforementioned clogged vent.

If you want to drop the tank it's no big deal. It helps if it's completely empty, not only to reduce the weight but to make it more stable because you won't have gas sloshing around as you're lowering it. Disconnect the lines, sending unit wire, filler neck and plug/cap off the fittings. Take a wire brush and some penetrating oil and clean the threads of the strap studs. These are usually covered in muck and that makes it harder to remove the nuts. The strap anchors are towards the front facing the rear axle and as soon as they are loose the tank will be ready to move. An impact and lots of oil on the threads makes the job palatable.

The fuel filler sock may be too brittle to reuse but I think you can get a new replacement by itself.

 

[lvmymopar]

Thanks everyone. We are going to drop the tank tomorrow. We went ahead and ordered a new sock anyway. Maybe get a new tank if it is too bad. We also had a new problem come up. We had a weak battery and tested the alternator. It is bad. But that is a easy fix. This maybe a dumb question, but would a bad alternator make it run like I have described previously?

 

[69 Runner]

There is also a vent tube at the front of the tank. Make sure it is clear