Fuel Issue
#1
Good evening. My daughter and I had just left the house in our 69 Mach 1 428 CJ. On the way to a car show of all things...All was well until about 10 miles down the road. Car stalled, had to pull it to curb. Would try and try to turn over, not getting fuel. Would only stay alive with quick rapid depression of accelerator. Had towed back to house. need to consider fuel filter, fuel pump, vapor lock etc. I am a newbie, wanting to start with fuel filter, but want to be sure exactly where it is on the engine. Does someone have a photo to share locating fuel filter? Any other thoughts appreciated.
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#2
If it's supposed to be an "original or original restored" car the fuel is typically:
1) Inside the fuel inlet of the carb.
2) If not it might be external and threaded in to the carb inlet.

Otherwise:
3) If not in any of the above locations, a previous might have installed a fuel filter in the fuel line between the fuel pump and the carb.
4) Lastly, it's possible a previous owner installed an earlier style fuel pump with an integral canister type fuel filter.  That is an obvious fairly large cannister on the bottom side of the fuel pump.

If the fuel filter ends up being inside the carb inlet, it should have a light (weak) override spring behind it. So if the filter plugs the spring will allow the fuel pressure to move the filter and bypass it so the carb still gets fuel.

There is also a stock screen type filter inside the tank.  The fuel gauge sending unit needs to be removed to get to it.  Drain the fuel from the tank first.

If a previous owner installed a simple parts store filter between the tank and pump, it's not supposed to be there.  Mechanical fuel pumps cannot pull fuel through a filter very well.  Plus, I'd seriously wonder if the tank is clean.  If you want a filter between the tank and pump it should be a 100 micron filter so it flows easily and merely stops large particles from getting to the fuel pump.  But, that is what the factory screen filter inside the tank does so no need for a second unless the tank is dirty inside or the factory screen is missing.  Also, you can only find 100 micron fuel filters in a performance type from places like Summit Racing or Jegs and still need the finer (40 micron) filter somewhere between the pump and carb.

You mentioned possible vapor lock.  How hot was the ambient temp when the engine stopped running?  How hot was the engine?  That's a big motor in a small engine compartment, cooling is always an issue.

Stock type fuel pumps do not fail very often but, don't rule it out.  Also check the oil to be certain the fuel pump did leak fuel into the oil.  That is one way (although rare) that they fail.
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#3
(08-31-2021, 01:58 AM)1969_Mach1 Wrote: If it's supposed to be an "original or original restored" car the fuel is typically:
1) Inside the fuel inlet of the carb.
2) If not it might be external and threaded in to the carb inlet.

Otherwise:
3) If not in any of the above locations, a previous might have installed a fuel filter in the fuel line between the fuel pump and the carb.
4) Lastly, it's possible a previous owner installed an earlier style fuel pump with an integral canister type fuel filter.  That is an obvious fairly large cannister on the bottom side of the fuel pump.

If the fuel filter ends up being inside the carb inlet, it should have a light (weak) override spring behind it. So if the filter plugs the spring will allow the fuel pressure to move the filter and bypass it so the carb still gets fuel.

There is also a stock screen type filter inside the tank.  The fuel gauge sending unit needs to be removed to get to it.  Drain the fuel from the tank first.

If a previous owner installed a simple parts store filter between the tank and pump, it's not supposed to be there.  Mechanical fuel pumps cannot pull fuel through a filter very well.  Plus, I'd seriously wonder if the tank is clean.  If you want a filter between the tank and pump it should be a 100 micron filter so it flows easily and merely stops large particles from getting to the fuel pump.  But, that is what the factory screen filter inside the tank does so no need for a second unless the tank is dirty inside or the factory screen is missing.  Also, you can only find 100 micron fuel filters in a performance type from places like Summit Racing or Jegs and still need the finer (40 micron) filter somewhere between the pump and carb.

You mentioned possible vapor lock.  How hot was the ambient temp when the engine stopped running?  How hot was the engine?  That's a big motor in a small engine compartment, cooling is always an issue.

Stock type fuel pumps do not fail very often but, don't rule it out.  Also check the oil to be certain the fuel pump did leak fuel into the oil.  That is one way (although rare) that they fail.

Thanks for the great response. I'll continue to investigate
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