All Small Six 250 Won't Stay Running

[Aeroneous]

Looking for a little guidance on troubleshooting steps for the 250 in my 1974 Maverick. I've been slowly redoing the interior on the car, usually starting it and letting it run every couple of months. Recently I put the interior back together and was planning to sell it. Got the car fired up and it was running perfectly. Topped off the coolant in the radiator, then took it to the car wash. I got a temp light on the way and the overflow hose on the radiator was steaming when I got there. Only ran it for about a minute after the temp light had come on. Washed the car and immediately afterwards it would not stay running without giving it some throttle.

I limped it home and started trying to figure out the issue (no temp light or overheating on the way back). Used a compressor to blow out all the spark plug wires, around the outside of the spark plugs, and inside the distributor. It ran perfectly again for about 10-15 seconds and then died. It is back to dying instantly after trying to start and you have to hold down the throttle to keep it going.

In the recent past I have replaced:
- Fuel pump (mechanical)
- Fuel filter
- Fuel line coming out of the gas tank that was deteriorating (this was shortly before the drive to the car wash)
- Spark plugs and wires
- Carburetor, tuned with a vacuum gauge
- Battery

If anyone has any thoughts on what the issue might be or recommendations for troubleshooting steps, please share them.

 

[B RON CO]

Hi, did you check for spark? What ignition system do you have, original points and condenser, or something else? Good luck

 

[DON]

Anytime I hear about a car or motorcycle sitting, then it doesn’t run good, I think fuel problem. Were you using ethanol free gas? That is the only thing I know that saves fuel systems when setting

 

[Frank]

Verify that the heat or anything else did not dislodge or rupture a vacuum line. Check for vacuum leaks, including the PCV system.

 

[Aeroneous]

Hi, did you check for spark? What ignition system do you have, original points and condenser, or something else? Good luck

I just used a spark tester to check for spark on all six cylinders and each one had spark. It's the original points and condenser.

Anytime I hear about a car or motorcycle sitting, then it doesn’t run good, I think fuel problem. Were you using ethanol free gas? That is the only thing I know that saves fuel systems when setting

I was not using ethanol free gas, but in this case the gas tank had emptied out pretty well because of the deteriorated line and I put probably three gallons of fresh premium gas in. At the advice of a family friend, I tried shooting some carb cleaner directly into the carb while keeping it running. They told me to check to see if the RPMs increased after doing that, and they did. The car also ran smoother when I did that as well. When I'm holding the throttle down a bit to keep it running, it runs a little rough.

Verify that the heat or anything else did not dislodge or rupture a vacuum line. Check for vacuum leaks, including the PCV system.

I checked all the vacuum lines I could find and they were all visibly in good shape. I could try replacing them all - I'm guessing it wouldn't cost much to buy fresh tubing.

 

[Frank]

I just used a spark tester to check for spark on all six cylinders and each one had spark. It's the original points and condenser.

I was not using ethanol free gas, but in this case the gas tank had emptied out pretty well because of the deteriorated line and I put probably three gallons of fresh premium gas in. At the advice of a family friend, I tried shooting some carb cleaner directly into the carb while keeping it running. They told me to check to see if the RPMs increased after doing that, and they did. The car also ran smoother when I did that as well. When I'm holding the throttle down a bit to keep it running, it runs a little rough.

I checked all the vacuum lines I could find and they were all visibly in good shape. I could try replacing them all - I'm guessing it wouldn't cost much to buy fresh tubing.

Good analysis. If the engine picked up rpm with the spray, then it's lean. Which is what the symptom sounded like from the start. Next time it's running, pull the PCV valve out of the valve cover and block it off with your thumb. Engine should pick up some rpm regardless, since it's lean already. If it smooths out completely, clean the valve before replacing it. Along with fuel pumps and other overseas new parts, PCV valves are often not calibrated correctly.
Use brake-clean or carb cleaner, race the engine a bit and spray shots of cleaner into the PCV. A good shot, but not enough to stall. Right after a shot, put your thumb on/off the end of the PCV valve several times. Repeat the process. Blocking the end of the valve forces the internal valve into full travel, and with the help of the spray, 95% of the time they will de gunk and return to correct operation.

 

[Aeroneous]

Good analysis. If the engine picked up rpm with the spray, then it's lean. Which is what the symptom sounded like from the start. Next time it's running, pull the PCV valve out of the valve cover and block it off with your thumb. Engine should pick up some rpm regardless, since it's lean already. If it smooths out completely, clean the valve before replacing it. Along with fuel pumps and other overseas new parts, PCV valves are often not calibrated correctly.
Use brake-clean or carb cleaner, race the engine a bit and spray shots of cleaner into the PCV. A good shot, but not enough to stall. Right after a shot, put your thumb on/off the end of the PCV valve several times. Repeat the process. Blocking the end of the valve forces the internal valve into full travel, and with the help of the spray, 95% of the time they will de gunk and return to correct operation.

Thanks for continuing to help out. My wife blocked off the PCV with her thumb while I had it running. It might have very slightly picked up some RPM, but didn't run anywhere near as smooth as when we shot the cleaner straight into the carb. We tried shooting cleaner into the PCV and blocking it with a thumb a few times. Each time, the RPMs picked up a bit temporarily. No noticeable long term change, though.

I've ordered a new PCV and grommets for the heck of it since they're dirt cheap.

Since that line coming out of the gas tank was deteriorating, is it possible that some debris is lodged in the hard fuel lines, fuel pump, or in the jet on the carb? Just wondering if I shouldn't be shifting my focus to something like looking for a blockage somewhere.

 

[Frank]

Thanks for continuing to help out. My wife blocked off the PCV with her thumb while I had it running. It might have very slightly picked up some RPM, but didn't run anywhere near as smooth as when we shot the cleaner straight into the carb. We tried shooting cleaner into the PCV and blocking it with a thumb a few times. Each time, the RPMs picked up a bit temporarily. No noticeable long term change, though.

I've ordered a new PCV and grommets for the heck of it since they're dirt cheap.

Since that line coming out of the gas tank was deteriorating, is it possible that some debris is lodged in the hard fuel lines, fuel pump, or in the jet on the carb? Just wondering if I shouldn't be shifting my focus to something like looking for a blockage somewhere.

Ok, PCV is checked off the list. . One element of good trouble shooting an engine issue like this is making one change at the time.
Fuel blockage- this would affect periods of high fuel demand. However, clean fuel is important. . . How old is the fuel?
Just reread the initial symptoms. Did you determine why it overheated? Since then, has it used any coolant? Need to determine if the head gasket may be playing a part. The overheating has to be considered a clue since- it's running fine, overheat, now not running fine. . Was that car wash trip the first time driving it in a while?

 

[Aeroneous]

Ok, PCV is checked off the list. . One element of good trouble shooting an engine issue like this is making one change at the time.
Fuel blockage- this would affect periods of high fuel demand. However, clean fuel is important. . . How old is the fuel?
Just reread the initial symptoms. Did you determine why it overheated? Since then, has it used any coolant? Need to determine if the head gasket may be playing a part. The overheating has to be considered a clue since- it's running fine, overheat, now not running fine. . Was that car wash trip the first time driving it in a while?

The fuel is new. The tank had basically drained out because of that deteriorated line and I put about 3 gallons in right before driving it.

I did not figure out for sure what caused it to overheat. The car had been started several times over the previous year, but the drive to the car wash was its first time driving in that long. Since it had sat so long, I also changed the oil and topped off the coolant in the radiator before that drive. Previously you couldn't really see where the coolant was at. It took about 1/3-1/2 a gallon to top it off. Now it's back down where I can't really see it again, but I had assumed that was because it boiled off. There was a lot of steam coming out of the overflow tube when I stopped at the car wash.

A family member that grew up on this generation of vehicle suggested that I should have "burped" the radiator after filling it by holding one of the hoses shut for a bit to build up pressure, and that it may have been a one time thing because of some pressure issue from not doing that. This was a new concept for me, but if that's really a thing then it might be the simplest explanation.

 

[Frank]

The fuel is new. The tank had basically drained out because of that deteriorated line and I put about 3 gallons in right before driving it.

I did not figure out for sure what caused it to overheat. The car had been started several times over the previous year, but the drive to the car wash was its first time driving in that long. Since it had sat so long, I also changed the oil and topped off the coolant in the radiator before that drive. Previously you couldn't really see where the coolant was at. It took about 1/3-1/2 a gallon to top it off. Now it's back down where I can't really see it again, but I had assumed that was because it boiled off. There was a lot of steam coming out of the overflow tube when I stopped at the car wash.

A family member that grew up on this generation of vehicle suggested that I should have "burped" the radiator after filling it by holding one of the hoses shut for a bit to build up pressure, and that it may have been a one time thing because of some pressure issue from not doing that. This was a new concept for me, but if that's really a thing then it might be the simplest explanation.

Sounds pretty normal. Overheat was probably the thermostat stuck because it had been shut for an extended time. For future reference, when running an engine that's out of service, they need to run until the thermostat is fully open. (And not idling either.) More harm than good can occur by a long season of starting an out of service engine, idling it a few minutes and shutting off.
This may not assist the immediate issue, but is good preventive assurance- replace the thermostat and fuel filter.
The t'stat working correctly can be judged by starting cold, as engine heats, feel the upper radiator hose. It should remain mostly cold, then heat up quickly as t'stat temp is reached. If it passes this test no need to change it now.
Fuel filter now, highly recommended.

 

[Aeroneous]

Sounds pretty normal. Overheat was probably the thermostat stuck because it had been shut for an extended time. For future reference, when running an engine that's out of service, they need to run until the thermostat is fully open. (And not idling either.) More harm than good can occur by a long season of starting an out of service engine, idling it a few minutes and shutting off.
This may not assist the immediate issue, but is good preventive assurance- replace the thermostat and fuel filter.
The t'stat working correctly can be judged by starting cold, as engine heats, feel the upper radiator hose. It should remain mostly cold, then heat up quickly as t'stat temp is reached. If it passes this test no need to change it now.
Fuel filter now, highly recommended.

I have replaced the fuel filter since this issue started happening. Pretty much at the same time I first created this thread. Happy to try another one as they're only about $5 and are super easy to replace, but I'm guessing that's probably not the problem.

I'll pick up a new thermostat to be safe - pretty cheap and easy to swap.

Very good info about starting and only idling, I had no idea. I thought I was actually helping things by running it lightly every now and then, so I will change that up going forward. Thank you!

Going back to the fuel option, you don't think some kind of partial obstruction could be causing the issues? Yes it keeps running under throttle, but it also runs rough when I do that.

 

[Frank]

I have replaced the fuel filter since this issue started happening. Pretty much at the same time I first created this thread. Happy to try another one as they're only about $5 and are super easy to replace, but I'm guessing that's probably not the problem.

I'll pick up a new thermostat to be safe - pretty cheap and easy to swap.

Very good info about starting and only idling, I had no idea. I thought I was actually helping things by running it lightly every now and then, so I will change that up going forward. Thank you!

Going back to the fuel option, you don't think some kind of partial obstruction could be causing the issues? Yes it keeps running under throttle, but it also runs rough when I do that.

Fuel filter- check.

Thermostat, not hotter than 180*. If you just ask for one you're going to get 195*.

I don't think the symptoms are consistent with restricted fuel flow. A better symptom would be noticeable or complete cutting-out of the engine under load, only recovering when you let off. A fuel restriction severe enough to affect idle would not be able to accelerate with load. Weak fuel pressure may be playing a role here though.

It's time to visit the ignition system at this point.

Everyone has their own method of running an out-of-service engine, I'm sure. Mine may not be the best. I came up with it over time, observing various methods of diesel engine off-season engine running at the dock. (Former commercial fisherman). An idling engine is not good for it, gas or diesel. The RPM is below dynamic balance, and it never warms up internally (especially diesels). Rings can gum up and stick, and carbon builds up on valves, etc on all of them with excessive idling. Older gas engines with worn valve guides and two-cycle diesels, oil is drawn into the combustion chambers too, compounding the accumulation of unburnt carbons. I will leave an engine off up to 6 months without running it. When running one, get the RPM to 1800 or so shortly after start up and set it there. Then watch the temp gauge or use the "feel the radiator hose" method to observe the thermostat opening up. 5 minutes or so of running after the t'stat is open is sufficient. This assures there is circulation of the coolant and exercising of the thermostat. Before the t'stat opens there is very little flow of coolant on automotive engines.

 

[Aeroneous]

Fuel filter- check.

Thermostat, not hotter than 180*. If you just ask for one you're going to get 195*.

I don't think the symptoms are consistent with restricted fuel flow. A better symptom would be noticeable or complete cutting-out of the engine under load, only recovering when you let off. A fuel restriction severe enough to affect idle would not be able to accelerate with load. Weak fuel pressure may be playing a role here though.

It's time to visit the ignition system at this point.

Everyone has their own method of running an out-of-service engine, I'm sure. Mine may not be the best. I came up with it over time, observing various methods of diesel engine off-season engine running at the dock. (Former commercial fisherman). An idling engine is not good for it, gas or diesel. The RPM is below dynamic balance, and it never warms up internally (especially diesels). Rings can gum up and stick, and carbon builds up on valves, etc on all of them with excessive idling. Older gas engines with worn valve guides and two-cycle diesels, oil is drawn into the combustion chambers too, compounding the accumulation of unburnt carbons. I will leave an engine off up to 6 months without running it. When running one, get the RPM to 1800 or so shortly after start up and set it there. Then watch the temp gauge or use the "feel the radiator hose" method to observe the thermostat opening up. 5 minutes or so of running after the t'stat is open is sufficient. This assures there is circulation of the coolant and exercising of the thermostat. Before the t'stat opens there is very little flow of coolant on automotive engines.

Your fuel explanation makes a lot of sense. Thank you.

Should I look at replacing the distributor, then? The spark plugs and wires were replaced within the last year. Doing the distributor intimidates me a bit because I've never done timing work before. Although I purchased this as a way to learn more about working on engines, so if that's what's needed so be it.

 

[Aeroneous]

Was just looking over everything again. Is this a possible clue? I noticed a little bit of fuel pooling up here on the carb when I looked at it this morning.

EDIT: Another possible clue? I let it run a little while this morning with some light throttle applied to keep it going. After several minutes I gave it some higher RPM revs. It has now developed a backfire/popping sound when letting off the pedal after revving it that it never had before.

 

[Frank]

Your fuel explanation makes a lot of sense. Thank you.

Should I look at replacing the distributor, then? The spark plugs and wires were replaced within the last year. Doing the distributor intimidates me a bit because I've never done timing work before. Although I purchased this as a way to learn more about working on engines, so if that's what's needed so be it.

Not necessary to change the distributor. Need to tune up what's inside. Is it points? Not sure if '74 was points or electronic.

Was just looking over everything again. Is this a possible clue? I noticed a little bit of fuel pooling up here on the carb when I looked at it this morning.

EDIT: Another possible clue? I let it run a little while this morning with some light throttle applied to keep it going. After several minutes I gave it some higher RPM revs. It has now developed a backfire/popping sound when letting off the pedal after revving it that it never had before.

No that fuel there is probably not directly related. The popping during decel indicates a lean condition, or possibly ignition miss. Was it smooth when you had it revved up, or misfiring some?

 

[Aeroneous]

Not necessary to change the distributor. Need to tune up what's inside. Is it points? Not sure if '74 was points or electronic.

No that fuel there is probably not directly related. The popping during decel indicates a lean condition, or possibly ignition miss. Was it smooth when you had it revved up, or misfiring some?

It was misfiring some.

It is a points type distributor. Maybe replace the cap, rotor, and condenser?

 

[Frank]

It was misfiring some.

It is a points type distributor. Maybe replace the cap, rotor, and condenser?

No sir. The points need to be addressed first. Don't change the condenser. You need to get a set of points for it, we'll walk you through swapping them out. Or if you know a trusted friend or mechanic to do it. This is 100% what needs to be done next before any other changes are made. It's not hard! I understand the intimidation factor of the unknown. Odds are good that a points tune up will cure the 'ol gal.

 

[Aeroneous]

No sir. The points need to be addressed first. Don't change the condenser. You need to get a set of points for it, we'll walk you through swapping them out. Or if you know a trusted friend or mechanic to do it. This is 100% what needs to be done next before any other changes are made. It's not hard! I understand the intimidation factor of the unknown. Odds are good that a points tune up will cure the 'ol gal.

Are the items shown in these screenshots the right kinds of parts? Looked on some of the usual retail auto parts store websites and I wasn't sure if I was finding the right stuff.

 

[Frank]

https://www.oreillyauto.com/detail/c/blue-streak/standard-blue-streak-contact-point-set/std2/fd8081/v/a/15188/automotive-car-1974-ford-maverick?q=ignitin+points

 

[Aeroneous]

https://www.oreillyauto.com/detail/c/blue-streak/standard-blue-streak-contact-point-set/std2/fd8081/v/a/15188/automotive-car-1974-ford-maverick?q=ignitin+points

Ordered and will pick it up tomorrow. Thank you!

I'll go find some YouTube videos or articles on how to replace the points.