318 Poly idling question

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70DartMike

70DartMike

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65 Power Wagon, unknown year of 318 Poly, but guessing around 65. New fuel pump, manual choke, still has points. Ran great with no problems up until a few days ago. Close the choke a bit, fire it up, idles good and strong for about 5 minutes, then stalls. Try to start it again, the starter cranks, but won't start. Then if I leave it alone for a while, go out to it again, same thing. It will start and run for 5 minutes, stall, etc etc.
Any ideas?
 
Sounds like the coil is on its way out. Could also be the fuel tank vent is plugged. Next time it stalls pop the air cleaner and look down the carb to see if you have fuel, if your getting fuel to the carb when it dies its definatly electrical.
 
adjust the valves...puhleezeeeee then tune it up them things will haul the load if ya just adjust the valves then tune them....sorry in bad mood tonight
 
Its a 65it dont have a vent on the tank.....just a vented cap.....coil don't have a on the way out mode...they just good or they ain't and from what he has said it runs then it wont restart when its hot....that is valves adjusted too tight.......and if i'm wrong...SO!!!!:angry7:
P.S. all polydomes have adjustable rocker arms a manual will tell ya the lash for them
daliant said:
Sounds like the coil is on its way out. Could also be the fuel tank vent is plugged. Next time it stalls pop the air cleaner and look down the carb to see if you have fuel, if your getting fuel to the carb when it dies its definatly electrical.
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waggin said:
Its a 65it dont have a vent on the tank.....just a vented cap
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You sure? I'm not. On pre-1970 (California) Pre-1971 (Federal/Canada) Mopar passenger cars, there's no vented fuel cap; they have fuel tank vents. I think, but am not certain, that the same is true for Mopar trucks.

coil don't have a on the way out mode...they just good or they ain't
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Nope. Coils can be failing, not just "good" or "dead". If one winding shorts to one adjacent winding, coil output drops a little. If two windings short to two adjacent windings, coil output drops a little more. If three windings...

he has said it runs then it wont restart when its hot....that is valves adjusted too tight
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Maybe. Could also be other factors. A failing coil is possible but I would say but not too likely in this case. Easy diagnostic is to get a hair dryer or incandescent droplight and use it to heat up the coil with the engine cold, before trying to start it. Once the coil's about as warm as it gets from 5 minutes of engine operation, try and start the truck. If no go, replace the coil.

Fuel supply problems within or outside the carburetor are more likely. Sounds to me as if there's trash in the fuel tank and/or in the fuel filter. Engine starts from cold, fuel flow pulls trash against screen on end of fuel pickup pipe in tank and/or against walls of fuel filter element. Eventually enough trash builds up to block flow. Engine stalls and won't restart. Fuel flow stops, trash is no longer forced against screen/element by flow, drifts away from screen/element. Engine will start again. Lather, rinse, repeat. Next time the engine stalls and won't restart, try filling up the carburetor bowl by spraying carb cleaner in through the angled bowl vent tube that protrudes into the carburetor throat. Give it a good long spray; you want the bowl up to its normal fuel level -- might take 30 seconds or more depending on what carburetor is installed. Then go hit the key. If the engine will start, you've got a fuel supply problem.
 
I had a 66 w200 power wagon, Vented cap. Used to pop off in the summer when id fill it up. Yeah the coil went out once on me in my 87. But it had MSD and i left the key on all day.

It sounds electrical though. If the valves are tight, does it just free spin or does it have compression when it turns over.
 
Not to diss ya....but and I use the term but loosely......adjust the valves before trying any weird science.......just makes good sense to start at the bottom and work your way to the top,with todays gas,yesterdays valve seats....dont ya think for a second that you should start with a simple valve adjustment?....actually do all that science stuff first.......ya still gotta adjust the valves and in reality....why do anything until the valve lash is set?????? I rest my case :stop:
P.S. sinking valves is common on older engines due to lack of lead in fuel,when a valve sinks...it makes the lash to tight which holds the valve open which causes the symptoms he described.I hate to be a jerk but the ignition system on a car that old is pretty much tried and true with 45 or so years of experience to its credit, the fact that it runs at all atests to its reliability and the fact that when it gets hot it don't run pretty much paints the picture that the valves need to be adjusted.......I could be wrong ya know......won't be the first time but (theres that word but again) still need the valves adjusted no matter what anyone says.............Wagg's
slantsixdan said:
You sure? I'm not. On pre-1970 (California) Pre-1971 (Federal/Canada) Mopar passenger cars, there's no vented fuel cap; they have fuel tank vents. I think, but am not certain, that the same is true for Mopar trucks.



Nope. Coils can be failing, not just "good" or "dead". If one winding shorts to one adjacent winding, coil output drops a little. If two windings short to two adjacent windings, coil output drops a little more. If three windings...



Maybe. Could also be other factors. A failing coil is possible but I would say but not too likely in this case. Easy diagnostic is to get a hair dryer or incandescent droplight and use it to heat up the coil with the engine cold, before trying to start it. Once the coil's about as warm as it gets from 5 minutes of engine operation, try and start the truck. If no go, replace the coil.

Fuel supply problems within or outside the carburetor are more likely. Sounds to me as if there's trash in the fuel tank and/or in the fuel filter. Engine starts from cold, fuel flow pulls trash against screen on end of fuel pickup pipe in tank and/or against walls of fuel filter element. Eventually enough trash builds up to block flow. Engine stalls and won't restart. Fuel flow stops, trash is no longer forced against screen/element by flow, drifts away from screen/element. Engine will start again. Lather, rinse, repeat. Next time the engine stalls and won't restart, try filling up the carburetor bowl by spraying carb cleaner in through the angled bowl vent tube that protrudes into the carburetor throat. Give it a good long spray; you want the bowl up to its normal fuel level -- might take 30 seconds or more depending on what carburetor is installed. Then go hit the key. If the engine will start, you've got a fuel supply problem.
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Oh yeah i forgot it would fire then die, I was just thinking of it heat soaking...
 
It will be 2 weeks until I get to work on it again, but could anyone point me in a good direction to adjust the valves? It will be my first time, but it will be a good thing to learn anyways.

Edit: I found a couple videos on youtube on how to adjust.
 
daliant said:
Sounds like the coil is on its way out. Could also be the fuel tank vent is plugged. Next time it stalls pop the air cleaner and look down the carb to see if you have fuel, if your getting fuel to the carb when it dies its definatly electrical.
Click to expand...

Good place to start.
 
Alright, here's an update to what's been done.

- I did a valve adjustment, and it now runs a lot smoother (when it runs..)

- It has a new fuel pump

- New fuel filter

- I changed the gas tank last night, the old one was full of buckshot and rocks.. I put in a tank that was totally clean

- I changed the coil to a known good one

It still is doing the same thing. Idle for roughly 2 - 3 minutes, then die. It will start up again, but die quickly. No sputtering while dying, it just quits on me. Could some crap have gotten past the filter and into my line between the fuel pickup and the fuel pump? The filter looked to be good, not punctured or rotten or anything. The filter is dry once the truck dies, and only gets a little bit of fuel in it when I pump the pedal before starting it.
 
Have you confirmed spark when it dies? The abruptness of how it seems it's sounding when it shuts off leads me to think it's losing spark. Running our of fuel would be some sputtering I suspect.
 
70DartMike said:
How should I confirm it when it dies? Get someone to pull the #1 plug wire as soon as it dies, and have me turn the key for a second?
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I'd check at the coil wire. So far as a coil "is either good or bad" Coils are FAMOUS for running when cold, failing when hot, so the comment the "coil is on it's way out" DOES HAVE some merit.

Condensers (the one in the distributor, remember?) can do the same thing.

Condensers can develop all kinds of irritating problems, cheapest thing to do is just replace them.
 
70DartMike said:
Alright, here's an update to what's been done.

- I did a valve adjustment, and it now runs a lot smoother (when it runs..)

- It has a new fuel pump

- New fuel filter

- I changed the gas tank last night, the old one was full of buckshot and rocks.. I put in a tank that was totally clean

- I changed the coil to a known good one

It still is doing the same thing. Idle for roughly 2 - 3 minutes, then die. It will start up again, but die quickly. No sputtering while dying, it just quits on me. Could some crap have gotten past the filter and into my line between the fuel pickup and the fuel pump? The filter looked to be good, not punctured or rotten or anything. The filter is dry once the truck dies, and only gets a little bit of fuel in it when I pump the pedal before starting it.
Click to expand...

Was I the only one that caught "filter is dry once the truck dies" here?

First of all I suggest you test it above idle. Start it and run it up above 1500 rpm and hold it and see if it dies. If so you know it's not dying at idle because of some problem in the idle circuit.

If it dies that way, then I would eliminate or confirm a fuel supply problem by running the engine from a separate gas can hooked to the fuel pump.
If it doesn't die then you've found the problem, if it does then you know it's more likely there's a spark problem.

I don't think 5 minutes is long enough to bring out a heat related spark issue, but to be sure I would obtain one of those inline spark testers that flashes with the engine running, and also i would check to make sure the coil isn't losing it's voltage supply somehow.

You'll get to the bottom of it. Just follow the trail and see what it "runs out of" when it dies.
 
Did you replace the rubber lines in the fuel system? and maybe some trash is in your carburetor?
 
Like said above, sounds like a condenser problem...... Won't hurt to do plugs, wires, cap, rotor, points, condenser anyway.......

I have even seen condensers run EXACTLY like a lean running out of fuel condition, strange strange things they are, always a mystery to me.
 
Figured out the problem.

Someone at some point put an electric fuel pump on the truck, and tucked it way up under the cab, so I didn't see it at all when looking around for a problem. I just bypassed the electric fuel pump, and all is good.

Now for replacing wheel cylinders..
 
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