Randomly shuts off

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DartVadar

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I've had the problem twice now, and I don't really know what to do about it. This has happened twice now. The first time it happened was last year just before I put the car away for the winter.

I was driving it, everything was running perfectly and then the AFR gauge would slowly lean out and then it would die. It won't start, and doesn't get fuel. I had to get it towed him that night, as soon as I got home it fired right up like nothing was wrong.

The same thing happened last night, ran perfectly fine for a half hour of spirited driving then died, so it happened in a parking lot so I just left it there and went for dinner. As I got back it started right up like nothing was wrong.

What would be causing this? Vapour lock maybe? Had lots of gas in the tank both times, new sender, clean tank, new lines. It's a Holley mechanical fuel pump, fuel lines routed away from heat as much as possible and there is a wooden spacer under the carb to help with heat. My only thoughts are that its the winter gas we have here, it never happened all summer even after an hour driving in 30 degree c days.
 
That sounds typical of a plugging fuel system.
I know you mentioned all the new stuff and clean tank, but that AFR gauge is screaming at you that the problem is a lack of fuel.
 
Have you recently replaced the gas cap, it may need to be vented, or check the tank vent isn't plugged.

Next time it happens, loosen the gas cap, to let some air in, and see if it'll go.

cheers
 
Why would it run fine otherwise? I thought that before though and cleaned everything, and the fuel filter was nice and clean too. dropped the tank and cleaned everything so there isn't anything in the tank.

Yep new cap and vent is working as it should.
 
Maybe it is fuel boiling, aka vapor lock, does it just quit? My 340 dart boiled the fuel on a long drive last summer, is started wanting to quit every time I let off the gas. I have an electric fuel pump though, it never quit but acts like it is starved for fuel. I let it cool off and it was fine until it heated back up. I think my car did it because of some crappy fuel I put in on the way home. That is the only time I had any problems like that. I had a slant 6 aspen that used to do the same thing, that had a stock mechanical pump, would fire right up after it cooled down.
 
Why would it run fine otherwise? I thought that before though and cleaned everything, and the fuel filter was nice and clean too. dropped the tank and cleaned everything so there isn't anything in the tank.

Yep new cap and vent is working as it should.

It takes awhile sometimes for the garbage in a fuel filter (or sock) to build up on the filter element surface enough to slow the fuel gpm enough so the available volume can't keep up with the demand.
Stopping, or sitting lets that stuff drop away and it starts all over again next time it's run.

If it were my car I would recheck the filter points and then check the pump volume.
If that didn't solve it and I was absolutely sure of the supply I would put a new pump on it and see what it does.

Also keep in mind that an air leak on the vacuum side of the line can do the same thing by sucking air bubbles instead of fuel. (rubber hoses and the like)
 
I've had the problem twice.

So what is it we are working on?

1928 Hemi Farmall?

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1939 Flying Pancake?

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Have you recently replaced the gas cap, it may need to be vented, or check the tank vent isn't plugged.

Next time it happens, loosen the gas cap, to let some air in, and see if it'll go.

cheers
None of these Mopars use a "vented" cap. The later ones using the evap emission controls use "pressure vacuum" caps, but those are not meant for an "operational" vent.

However it certainly could be that the system has a problem with the vent IE plugged

Rubber connector hose tank to supply tube? Rubber connector hose tube to pump?

pickup plugged in the tank?

OR EVEN JUST as simple as a defective pump. "New" parts don't mean "good" parts

There's a procedure in the service manuals for checking the pump, pressure and vacuum, as well as estimating flow.
 
To clarify, it was running perfectly fine, and then the AFR gauge went instantly lean and it shut off. I put in all new fuel lines, fuel sender, steam cleaned tank, fuel pump, fuel filter etc, so everything fuel wise is brand new and it ran all last summer without an issue. So I don't think it's a clog in the line. Also I have a fuel pressure gauge on and at idle it's making about 6 PSI. When it died yesterday the carb was empty, when it works I checked the float levels and everything carb wise is perfect. But yes the lines are all rubber hoses from tank to supply line and supply line to fuel pump.

So what is it we are working on?

1928 Hemi Farmall?

01.gif


1939 Flying Pancake?

http://www.weirdworm.com/img/misc/5-weird-airplanes/vought-v-173.jpg[/kimg][/quote]

LOL its a 73 dart swinger with a 360 I built last year, headers, Holley 650, aluminum heads etc. All the emissions controls were disabled, and it has a vented cap. The same fuel pump has been used for the past two years, but its possible that's the problem. I have a manual so ill diagnose that in the next few days.


[quote="AJ/FormS, post: 1971170187"]I hope it's not a solid lifter cam with the lash set too tight..........................[/quote]

It's a solid roller, but I've adjusted the lash not too long ago, and its right where it should be. Lunati wants 16 thou intake and exhaust hot, so that's what it's set to.
 
To clarify, it was running perfectly fine, and then the AFR gauge went instantly lean and it shut off. I put in all new fuel lines, fuel sender, steam cleaned tank, fuel pump, fuel filter etc, so everything fuel wise is brand new and it ran all last summer without an issue. So I don't think it's a clog in the line. Also I have a fuel pressure gauge on and at idle it's making about 6 PSI. When it died yesterday the carb was empty, when it works I checked the float levels and everything carb wise is perfect. But yes the lines are all rubber hoses from tank to supply line and supply line to fuel pump.



LOL its a 73 dart swinger with a 360 I built last year, headers, Holley 650, aluminum heads etc. All the emissions controls were disabled, and it has a vented cap. The same fuel pump has been used for the past two years, but its possible that's the problem. I have a manual so ill diagnose that in the next few days.




It's a solid roller, but I've adjusted the lash not too long ago, and its right where it should be. Lunati wants 16 thou intake and exhaust hot, so that's what it's set to.

If the carb is empty the fuel is going out the vents, or it has an internal leak that only happens in the perfect storm..
A long, long long time ago (probably about 1984 or 85) Holley sent out some power valves that would lose tension when hot and they would open up. Is it going rich right before it gets lean? Those P V's were a nightmare for a while.

You need to figure out where the fuel is going. It is either out the vent , through the power valve or you have a fuel pump that is leaking internally when everything is just right.
 
If the carb is empty the fuel is going out the vents, or it has an internal leak that only happens in the perfect storm..
A long, long long time ago (probably about 1984 or 85) Holley sent out some power valves that would lose tension when hot and they would open up. Is it going rich right before it gets lean? Those P V's were a nightmare for a while.

You need to figure out where the fuel is going. It is either out the vent , through the power valve or you have a fuel pump that is leaking internally when everything is just right.

I was assuming the carb goes empty when the fuel stops pumping and the engine is using up the fuel that is left in the carb. The AFR is exactly where it always is, doesn't get rich or anything. It just goes lean and the engine starts to stumble, it all happens within about 10 seconds.

When it happened last year I thought the pump went bad and was pumping into the crankcase like you said, so I changed the oil, but there wasn't any gas in it.

Im pretty sure its fuel pump back, because I brought some tools last night and when it died I undid the fuel line that goes to the carb and tried to syphon some fuel, nothing came out. Then I just waited about half an hour and it fired up perfectly.
 
Since this is in a 73, it could very well be a vent problem. Read your shop manual, the fuel section on tanks, and the emissions section in the back about the evap system. These changed over the years, so make sure yours "as built" matches what is in the manual

"Very first" thing I would try, is a drive with the gas cap loose or removed

What is the situation with the front 1/4 vent tube, IE is the carbon can stuff still hooked up?
 
Since this is in a 73, it could very well be a vent problem. Read your shop manual, the fuel section on tanks, and the emissions section in the back about the evap system. These changed over the years, so make sure yours "as built" matches what is in the manual

"Very first" thing I would try, is a drive with the gas cap loose or removed

What is the situation with the front 1/4 vent tube, IE is the carbon can stuff still hooked up?

I kept everything te same besides the emissions stuff. I took out the charcoal canister, plugged the vent line under the hood and added a vented gas cap. So technically I've only been driving it with a vented cap, and it still had this problem.

Not really sure if that's the correct way to do it though...lol It was all messed with when I got the car so I just didn't bother putting it all back together.
 
My old Coronet did the same thing. It was the ignition module (Orange Box). It would over heat and the board would separate and loose connection internally. Cool down and the car would start again. Remember your gauge is a lagging indicator of what has happened.

Also possible the front float is sticking.
 
"IF" it's ignition it's a crap shoot when heating.

Could be coil heating up and quitting.......used to be very VERY common

Could be the ECU

Could even be the dist.

Here's what I'd try. Try to get it to quit, but be prepared to do some testing so you can "jump out" and get right with it.

When it quits, leave the key "in run" and immediately check the coil plus and neg posts. You should have say, 6V or so on the pos, and very low on neg, 2V or less.

If the coil PLUS is high, the coil is not drawing current........bad ECU

If the coil NEG is also way higher than a couple volts, same thing as above.

If the coil POS is below 6V you may have a power problem. Check the ballast "key" side you should "same as battery."

Next, pull the distributor harness connector. Take up the engine side, and tap the bare end of the connector to ground. Should make a spark each time. No spark.....coil or ECU, assuming you have power at the ballast

If the above checks out, "try" a coil if you have a spare, and you should have, anyhow. Does not have to be the exact right coil.

This might also be the distributor pickup, but that would be rare.
 
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