My classic Mustang won't start/run

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172
Location
Georgia
I took my 69 Mach 1 Mustang for one of its periodic rides last Sunday. After 4-5 miles, while running at hwy speeds, the engine gradually lost power and died, necessitating a coast to the side of the hwy. Ended up towed back to my garage. Of note, essentially the same thing happened a few mos. ago. That time, after sitting for an hour or so, the car did start and I was able to drive it back home. It was a hot day, and I thought maybe it was vapor lock. So I put an insulating wrap around the stock metal fuel line from the fuel pump to the carb. Obviously, that did not fix the problem. Additional info: stroked 464 CI CJ motor, stock Holley carb that was rebuilt by Year one,aluminum intake, stock Carter mechanical fuel pump. Car had never done this before recently. ?sound like a fuel issue? could it be a dying/dead fuel pump? Other thoughts? All help appreciated as I figure out whether to try to tackle this myself or have it towed to a mechanic Thanks!
 

OVERKILL

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46,056
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Ontario, Canada
If it is still doing it, check the fuel level in the carb by pulling one of the sight plugs. If there's little to no fuel in there, well, you know you have a fuel delivery problem. Probably the pump or a plugged pick-up.
 

OVERKILL

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Originally Posted By: Merkava_4
^ It's a mechanical fuel pump driven off the camshaft. No fuel pump in the tank.
I am aware of that. They still fail. And there is still a pick-up in the tank that can get plugged. Most recently we had a similar issue with my dad's Glastron which has a GM I4 in it. Fuel pump started to go out, similar symptoms to the OP, then the pump completely failed. We replaced it with an electric unit.
 
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17,501
Location
Clovis, CA
Originally Posted By: OVERKILL
I am aware of that. They still fail. And there is still a pick-up in the tank that can get plugged.
There's no fuel pick-up in the tank. There's a supply hose and a return hose, both are attached to the outside of the tank.
 
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17,501
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Clovis, CA
Those mechanical fuel pumps have a weep hole like a water pump. As long as it's not leaking, it's working. There should be an inline fuel filter between the fuel pump and the carburetor. If it was a FoMoCo carburetor, it would have a screw-in filter, but since it's a Holley, it'll need an inline filter. On those old Fords, when the alternator quits generating current, the engine will run off the battery until it quits.
 
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3,558
Location
SE Pa
Just one question: After it dies, does it even attempt to start (even momentarily) if you immediately start cranking it?
 
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7,116
Location
MIchigan
Originally Posted By: mechjames
Did you check for spark when it died out? Possibly your ignition module / coil is overheating and then it works again when it cools down.
This^^^^
 
Messages
25,952
Location
MA, Mittelfranken.de
This sounds like a typical old school oil filled coil problem. I have also seen the coil HT wire cause similar problems. These kinds of problems show up more in the heat. What kind of ignition system is in this? Still running points and condenser?
 
Messages
3,558
Location
SE Pa
Originally Posted By: Trav
This sounds like a typical old school oil filled coil problem. I have also seen the coil HT wire cause similar problems. These kinds of problems show up more in the heat. What kind of ignition system is in this? Still running points and condenser?
That was on my radar, too. Need to know how the restart attempts play out, though. I've had coils from those fade out at higher temps, especially the way they were mounted. When they go under, you get a dead cranking condition. Half the time when they leak, it's the seal under the HV socket. If he's lucky, it's a screw on HV terminal and the seal can be replaced. More often with a failing condenser, they are worst when the engine is cold. The heat actually helps dry them out when the seals go on them and they take on moisture. When points go, they go. I've never encountered points that were all that temp sensitive.
 

OVERKILL

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Originally Posted By: Merkava_4
Originally Posted By: OVERKILL
I am aware of that. They still fail. And there is still a pick-up in the tank that can get plugged.
There's no fuel pick-up in the tank. There's a supply hose and a return hose, both are attached to the outside of the tank.
It has a pick-up: And I believe it is returnless. The later ones (like my '87) with electric pumps had a return. Here's a link to the procedure for replacing the sending unit (which has the pick-up as part of it) and I don't see a return line: http://www.mustangandfords.com/how-to/engine/mump-0606-ford-mustang-fuel-sending-unit/
 

OVERKILL

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Originally Posted By: Merkava_4
Those mechanical fuel pumps have a weep hole like a water pump. As long as it's not leaking, it's working.
I've had several fail and never weep.
 

OVERKILL

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Messages
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Originally Posted By: Trav
This sounds like a typical old school oil filled coil problem. I have also seen the coil HT wire cause similar problems. These kinds of problems show up more in the heat. What kind of ignition system is in this? Still running points and condenser?
Definitely could be this as well. I'd check the float bowls first since they are the easiest thing to check and if they are fine, go with Trav's suggestion next.
 
Messages
25,952
Location
MA, Mittelfranken.de
Originally Posted By: Volvohead
Originally Posted By: Trav
This sounds like a typical old school oil filled coil problem. I have also seen the coil HT wire cause similar problems. These kinds of problems show up more in the heat. What kind of ignition system is in this? Still running points and condenser?
That was on my radar, too. Need to know how the restart attempts play out, though. I've had coils from those fade out at higher temps, especially the way they were mounted. When they go under, you get a dead cranking condition. Half the time when they leak, it's the seal under the HV socket. If he's lucky, it's a screw on HV terminal and the seal can be replaced. More often with a failing condenser, they are worst when the engine is cold. The heat actually helps dry them out when the seals go on them and they take on moisture. When points go, they go. I've never encountered points that were all that temp sensitive.
I haven't seen any heat related issues with points either. I am just going through a thought process. Points condenser ignition with an HEI aftermarket coil, compatibility issue and so on. Just thinking out loud. Edit: Checking the fuel is first priority then spark then spark at the right time in the right place.
 
Last edited:
Messages
8,859
Location
Texas
Originally Posted By: Merkava_4
Originally Posted By: OVERKILL
I am aware of that. They still fail. And there is still a pick-up in the tank that can get plugged.
There's no fuel pick-up in the tank. There's a supply hose and a return hose, both are attached to the outside of the tank.
Seriously?? Have you ever actually WORKED on a car of 1969 vintage??? Of COURSE there's a pickup in the tank!!! The fuel doesn't just voluntarily JUMP from the bottom of the tank up to that "supply hose" fitting on the top/side of the tank, after all! On Fords of that vintage its almost identical to Mopars of the same era- the sending unit floats interchange even though the calibration is different on the sender proper. The "sock" strainer on the pickup tube can get clogged, and often does on vehicles that sit a lot. You get at it by removing the pickup/sending unit as an assembly. But FIRST, I would check the fuel pump and in-line fuel filter to make sure those aren't clogged, check the carb to make sure the inlet needle valves aren't sticking, etc. And speaking of...
Originally Posted By: Merkava_4
Those mechanical fuel pumps have a weep hole like a water pump. As long as it's not leaking, it's working.
That's false. They can fail and not pump OR weep. They can fail and weep, but still pump. Or they can fail and pump and leak fuel into the crankcase instead of out the weep hole. Many options there, and only one case involves leaking and not working.
 
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