Engine shutting down

[fj40z]

I have a '79 40 with a desmogged 2F that has up until recently ran very well. Now after running it about 20 minutes or so on the road it starts to sparatically shut down, almost like a fluttering or a bad miss. It kind of seems like it happens more often when I will be going up hill or incline but is not limited to that. My first inclination was the fuel filter so I changed that and thought I had fixed it, but it reared its ugly head again a couple of weeks later. Another thing is that it never did this until a couple of weeks after running some STP fuel treatment in with my gas, that wouldnt have anything to do with it would it? Any ideas on this matter would be appreciated,
Thanks

 

[Pin_Head]

Now after running it about 20 minutes or so on the road it starts to sparatically shut down, almost like a fluttering or a bad miss. It kind of seems like it happens more often when I will be going up hill or incline but is not limited to that. My first inclination was the fuel filter so I changed that and thought I had fixed it, but it reared its ugly head again a couple of weeks later.

As you guessed with the filter change, it is a fuel delivery problem.

You may have more dirt and/or rust in the tank than a new filter can handle. Remove the line at the filter and measure how long it takes for a cup of gas to run out. Then blow compressed air back in to the tank and repeat the test. If blowing it out increases the flow, you have junk in your tank.

If no junk in the tank, remove the gas line at the carb and measure how much time it takes to pump a cup of gas. It should pump a cup in less than 1 minute of cranking with the ignition HV wire disconnected. If the pump isn't putting out, you may need a new one, but they usually leak when they fail.

 

[Colorado Boy-74-FJ40]

Debris in the fuel tank?

 

[fj40z]

I have a feeling that it is probably junk coming from the tank and clogging everything up. I asked a mechanic and he said its possible that I was losing fire or spark somewhere like a bad plug wire or distributor cap, would this be a possibility?

 

[Colorado Boy-74-FJ40]

easy to check

I have a feeling that it is probably junk coming from the tank and clogging everything up. I asked a mechanic and he said its possible that I was losing fire or spark somewhere like a bad plug wire or distributor cap, would this be a possibility?

Checking the plug wires and popping off the dizzy cap are pretty easy to do to either confirm or exclude your mechanics theory. I dont think he's right. I believe you have gunk in the tank. Especially when you say it happened on an uphill angle. The tank draws from the rear. it makes the most sense. It's not hard to pull out the front seats and remove the tank. Took me about half an hour.