[Rabbit929]

1982 w150 360la carbed

So after all this work and she’s running good and strong, can pull 90mph with ease.
Drove 75 miles, another 75 mile back home, suddenly out of nowhere she stalls, exploded out the exhaust, returns to normal, then repeats about every 5 or so seconds.

My a/f gauge reads that there’s no fuel when this happens. What the hell?? She ran so good now THIS.
And I honestly have no idea why it would do this so consistently-intermittently like this. Thank god it did it before I was out of town again. I limped it home sending gunshots behind me when I needed to. I’be never seen anything like it.
Where do I start??

 

[Jeffy45]

Is there enough fuel in the tank

 

[Rabbit929]

Is there enough fuel in the tank

Plumb full. Maybe 4-5 gallons down.

I should also add, it will run good, then nothing, no fuel, no burn, nothing, then run good and pull back up normally, then BLANK. nothin again. About 5 second intervals. I'm at a loss.

 

[Jeffy45]

You still got a engine block mounted fuel pump?

 

[Rabbit929]

You still got a engine block mounted fuel pump?

Yes I do

 

[Jeffy45]

Fuel lines fuel filter fuel pump I'd start there. Especially if it's the original fuel pump.

 

[Jeffy45]

And if you're running all rubber hose from the fuel pump to the fuel tank instead of Hardline in the heat you could be collapsing it

 

[Rabbit929]

Just replaced fuel pump, same problem. Runs good, then stalls, hard lean, major exhaust backfire, then picks up again for a couple seconds.
Rinse and repeat.
It ran so good for 150 mile highway trip, suddenly get back home then this.

 

[dodge82273]

if it back fires from exhaust after it has stalled while driving , my guess is its lost spark , built up fuel in the exhaust, then gotten a spark igniting the unburnt fuel in the exhaust system ... as kids we'd switch off the key while driving in gear , then switch it back on so it would go BANG and scare the hell outta people ..... why the af meter reads no fuel ?  I have No clue .

 

[Jeffy45]

Yes reading full lean weird. I was going to say a coil getting hot and not firing but then he should be reading rich. no?

 

[modelcitizen]

1st thing comes to mind,pickup coil,ignition module,overheated/broken.ballast. Possible ignition coil failure.Intermittent loss of voltage to ignition system. All components easy enough to check.

Before you take anything apart,rig up a test light to ballast resistor input and drive til failure while observing test light.If it goes out,then you have an intermittent loss of voltage from ignition switch? Had this symptom in my Ramcharger switch was worn out,problem gone after replacing.
If test light doesn't go out when truck shuts down,switch test light to opposite side of ballast,drive to failure,if light remains on,supply of voltage to ignition system is good,goes out,close inspection of resistor block.

You can jump between terminals to prove out defective resistor,and drive it just long enough to determine problem is gone. I have done this to get home after a ballast failure. Like others i began to carry a spare resistor in glovebox and to date have never needed it-cheap insurance.

Check that ig module is grounded properly to firewall. Check ig coil not leaking oil,can be ohm tested. Pickup coil can be ohm tested and wire harness from dist to ig harness can be manipulated while ohmeter is hooked up. Any resistance change that happens while doing this would indicate an internal break in dist wire harness. Look over your work in/on distributor,seems to be last thing you did before problem appeared.

Can't explain AFR going completely lean while this is happening. Not sure where you're picking up power for that,an internal problem with AFR meter if wired into ignition system circuit could pull voltage low on ignition feed. Try disconnecting AFR meter and driving truck if none of previously mentioned has an effect. You will have heatedO2 sensor,inspect the wiring to/from  for chafing or melting on exhaust,disconnect it also,have seen fair number of oe and aftermarket O2 heaters short out causing CEL lights and driveability problems.
You can quickly eliminate wiring/ignition issues and move to fuel supply next as source for problem if nothing found at this point.

 

[dodge82273]

yeah , well .......  if it were no fuel , then what's exploding in the exhaust when it re-fires? air ... ? LOL 

 

[Jeffy45]

You funny

 

[KurtfromLaQuinta]

yeah , well ....... if it were no fuel , then what's exploding in the exhaust when it re-fires? air ... ? LOL

Nice deduction.

 

[dodge82273]

um just sayin ... reason it out ... has to be some fuel in there to go bang .....  that's with out an A/F meter telling me anything ...

 

[Jeffy45]

Yes sir

 

[Jeffy45]

Poorly terminated electrical connections

 

[moparmike72]

It wouldn't hurt to check out the inside of the distributor cap for cracks and carbon tracking.

 

[Rabbit929]

Sorry for late reply, long weekend. Took the bike to town for the week instead for the time being.

Haven’t got the chance to look at it yet, but there is a point that the a/f gauge won’t read how rich it is, so if it goes rich so hard it doesn’t burn, it will read lean.
After much pondering the side effects I’m pretty sure it’s ignition related. Sucks too, as all the components are new.
When some of this blood comes back into my alcohol system tomorrow I’ll have another looksy.

 

[Rabbit929]

So I got a chance to look at it, used a timing light on the coil wire and yup. It will idle good, but hold it at a steady reverse rpm, it loses spark intermittently.
Just sits there and -vroom.....vroom.....vroom-

Any ideas?