truck runs for fifteen minutes then dies and won't start for at least twenty minutes. I think I have pulled my hair and teeth out trying to figure this out!!

75

Asked by Feb 01, 2013 at 01:07 AM about the 1973 Ford F-100

Question type: Maintenance & Repair

73 f100390 c.i; Replaced timing chain,distributor,plugs, new cap, pertronix ignitor, fuel filter, gas tank, Compression is 120 7 cylinders 140 on 1. Checked and adjusted floats and cleaned, carburator!

29 Answers

90,065

I want to see a picture of your bald dome and wide open smile.

73---eh? pollution control device is chokin' ya- EGR comes to mind. This nasty device pumps exhaust fumes into the intake upon deceleration. If it sticks, the motor cannot breathe a correct air/fuel ratio. Clean or replace your EGR. This will fix your hair/teeth.

1 out of 1 people think this is helpful.
7,915

Some 73's have electronic ignition. If yours is one of them, then the answer is simple. You need a new electronic ignition control module. You probably have the 2 wire one, and they are readily available new just about anywhere you care to name. What you describe is very typical of these failing.

1 out of 1 people think this is helpful.

Yeah Michael Ford did away with breaker points in the distributor right about then. I have to say ditto on your answer ..unless the heat shield is gone and it is vapor locking when up to operating temp, but that usually happens only after you shut it off, then it has to cool, but will still run for longer than 20 minutes

2 out of 2 people think this is helpful.
75

Well I believe this isn't the original motor, there is no egr system, and as for thee eec system this is a factor either because when i bought the truck the charcoal canister wasn't hooked up. I replaced the distributor with a reman one replaced the point with a pertronix ignitor, I,m going to start it now and let it run, I was thinking maybe valve seals extinguishing the spark. When i bought the truck there were two fuel filter on it fuel of sediment, is it possible there could be an issue with the carb? Oh it's a edelbrock 1406 4 barrel! Thanks guys

1 out of 1 people think this is helpful.

Woah, even a '73 has an EGR, or Exhaust Gas Recirculation. If not somebody took it off, and that's not good, and obviously somebody has screwed around with the emissions systems if the charcoal canister is disabled. It needs to be purged, if it is simply unhooked at one end it could be full of liquid gasoline not just fumes in the charcoal, the vapors every time you put gas in, especially if you try to top it off after the nozzle clicks off, have collected to the point of saturation

1 out of 1 people think this is helpful.

Let's say you live in a State, one of the few that don't have emissions laws such as Wyoming, and you don't need all that crap anyway. Then get rid of it entirely, not just pull off some hoses. You need PCV, that is not emissions but keeps the air clean in the crankcase. Different animal alltogether .....and for the valve seals to leak so badly to kill the spark, well that needs attention asap if that is what is happening. That's a LOT of oil to do that. What did the old spark plugs look like when you changed them, and how old were they?

1 out of 1 people think this is helpful.
75

They werent to bad a few looked fouled one or two and one of them had some build up on it looked like little rock or possible the sediment from the tank, according to the previous owner six months to a year old. It still has the pvc just no egr anywhere. The truck ran fine on the way down then started running like crap That's when i replaced the timing chain and plugs, ran good for a week then just stalled one night took and hour trip to get home instead of the normal ten minutes. Notice i was getting fuel, do to a clogged fuel filter. It doesn't smoke so i really didn't think the seal but now i am here and stabbing in the dark cuz i am not familiar with pre fuel injection cars. So this is becoming a valuable lesson. Give Me a 96 and up Mustang Or a 99 and up Lightning and i would be Great. Yeah I'm a new age ford guy soon to be all ages once I figure this damn thing out!

1 out of 1 people think this is helpful.

When you changed the timing chain, it's real easy to time, but you can have it off one cog and it will still run

75

I am real meticulous when doing timing, i must have pulled it off like ten times trying to get both marks on point because it kept going on cog off. I have considered that as an option but just ruling out any other possiblity before i rip it apart to check the the marks again. I just readjusted my A/F screws as per manifacture recommends and have it running since 10:53 it s still running but the point of stall time is approaching.

Oh, man, don't go to all that tearing it apart yet again, if you say you were meticulous then you were and it's right as is. You must me somewhere East 'cause it's 8:19 here Central Calif

Then..you had the distributor out. Have that off one notch and it will still be able ti time it but will have to turn distributor all the way one way or the other, too advanced or retarded ... also Luis it happens all the time that guys say pvc, it's a much more common acronym for pipe I do it too, PCV Positive Crankcase Ventilation ....and just another shot of chain

5,975

You are experiencing "VAPOR LOCK". The 2 fuel filters explains it. The fuel is boiling when the engine reaches operating temperature. You need to isolate the fuel lines from the hot intake manifold, raise them up & away from everything and install a one inch phenolic gasket/spacer between the carb and the intake manifold and that should solve your problem. Those big block fords can run very hot and give off a lot of excess heat. I know, I've got a 390 in my '69. I installed the spacer and now the fuel stays cool and no vapor lock. The older carbureted high compression engines were known for that, especially in warm weather. Good Luck, Kenny/MrBlueOval

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7,020

I was going to ask about that but we did not yet hear if he lost spark or fuel. That is really hot really soon. how about sampling the fuel and putting it in a jar to separate too. He could have one of them star trek amoeba's in the tank made of water alcohol or some other contaminating liquid. we have a chimp in our neighborhood that siphons your gas and then pees in it. paraquat or something.

Could be many things. Start with cheapest and most likely. Original voltage regulator was mechanical and prone to problems when hot. I would replace as a matter of course. To trouble shoot hit it with freon and see if it runs after cooling. If that doesn't work let me know.

10

did you check your fuel lines at the back of the tank sometimes they collapse

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31,585

This is a 2 year old thread.... Just saying.

7,020

He never responded to the info when it was current. A rig like that can heat up parts idling and shut off because of electrical. His changes to it or his original. Resistor wire, dura spark, or his aftermarket ideas combining with them. If you were at this thread looking for new ideas for your older truck, providing readings and test results with a new question is best. But answer people with data about tests run. Keep your teeth hair,etc.

31,585

I like it when the original posters tell us what the problem was when it is fixed, but that happens not nearly often enough.

7,020

If you were having the same issue today, the way luis described it then, you would want to tell your fuel volume test amount, as well as fuel pressure. you could clean your pump valves with carb spray to see if it repeats in short order from contaminated fuel. Many folks have elected to go with electric low pressure pumps. hope this helps a future reader.

7,020

Thks bob.

This happened on my Ford Mustang and boyfriend's Ford Explorer. After stations trying all mechanic's ideas from everywhere in both cases years apart the fuel pump was getting intermittent power to the fuel pump and was a wiring isdue. Need to run a bypass wire from firewall under hood to dash area. On my Mustang they also put it on a kill switch.

5,975

This didn't happen like your cars did. if you read the posting, This happen to a 1973 Ford pickup truck with a 390 engine which was NEVER fuel-Injected. This engine would have a carburetor and a mechanical fuel pump mounted on the front drivers side of the engine that runs off of a lever going to the camshaft's eccentric that's inside the engine front timing cover, not an electric fuel pump in the gas tank like your fuel injected Mustang and BF's Explorer so that wouldn't be the problem here plus this is almost a 3 year old posting dating back to Feb of 2013 and I'm hoping Luis solved the problem by now but at least you tried to help. Kenny/MrBlueOval

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Mr. Blue Oval, hope you may help. I have a '76 Bronco, 302 , 4b carb. MSD ignition system installed, has electric fuel pump with filter , vehicle has the two fuel tanks. Problem : cold start fine- will drive 10 , 20,30 minutes somewhere, turn key off, come back to vehicle 10 minutes later or about. This happens more than 50% of the time --- Engine will start, shut down 20-30 seconds. Try starting immediately again, it will just crank, wont start up. I'll wait 5-10 minutes, it will start & shut down in 30 seconds....and so on & so on. It shuts down as if key turned off. Things checked-- pulled fuel line off carb, it's squirting fuel. Did not check pressure with gauge. New plugs, wires, cap. , checked fuel lines from tank to carb - integrity ok. Fuse panel - says painless wiring and only fuse associated that I can tell is "ignition" which is good (continuity) , wires at ignition, where key goes all connected and look ok. Everyone says- it's either fuel problem or ignition problem, I say thanks. Any info, leads in narrowing to area to focus would be so very helpful. Trial & error is so very frustrating. G.C.

5,975

It sounds like a fuel problem with the fuel burning up or percolating before entering the cylinders. Try mounting a phenolic (did I spell that right?) carb spacer between the carb and the intake manifold raising the carb up away from the heat of the engine. A one inch spacer should do the job but 2 inch high spacers are also available. Racers, street rodders, and anyone who wants to maximize an engine's performance, rely on Phenolic Carburetor spacers. The advanced phenolic laminate transfers approximately ten times less heat to the carburetor resulting in cooler denser fuel/air mixtures. The fuel could be percolating inside the carb once the engine warms up starving the engine of power. The colder the fuel the better the engine will run. If the fuel is burning before it gets inside the cylinders the engine is not going to run. It will start but shut off right away like what yours is doing. A carb spacer between the carb and manifold should solve that problem but no guarantee without actually being there to see what is happening but this is the most likely problem. You can also try raising the fuel line up and away from the hot engine if it's laying on the intake manifold or replace the steel or neoprene fuel line with aluminum fuel line that dissipates heat faster. If you are running a 190 degree thermostat, try running a 165 degree one instead to lower engine temperatures. Anything that will lower the temperature of the carb or the fuel in the carb will keep that fuel cooler. They even make what they call a fuel can that cools the fuel before it reaches the carb. Good luck and keep us informed. Kenny/MrBlueOval

5,975

One other thing I just thought of is check where that MSD ignition box is located. make sure that is not in harms way and located away from the hot engine, preferably up on the firewall in a corner or on a fenderwell where it can be kept cool. Excessive engine heat can play havoc on ignition boxes, ignition modules and carburetors too. I don't know if you live in a very warm climate like Florida or Arizona but that could be half your problem also. An electric cooling fan thermostatically controlled mounted in front of the radiator could pull in cooler air and bring engine compartment temps down drastically especially when idling at stoplights or stop and go traffic in 90 degree or above outside temps. The excessive engine compartment heat can cause vapor lock like what I talked about above. Excessive heat is your engines worst enemy. Kenny/MrBlueOval

i have a 69 ford f1oo i think it has a 360 in it ause on the door it has a y and thats 360 but looking at the engines in it it has number on front 14 over 352 all the probles that u talked a about i have and more some crazy person took key out its not charging right and u have to touch start wire to battery but it runns great when its runing and how to hook up temp wire plz need help i live in lubbock tx

I am having same type of problem with my 87 f150 -- but sometimes it runs fine -- then after a week of it being fine I will be driving and the power begins to diminish and I hear a faint whirhing - then it dies -- after a half an hour of being stuck somewhere it starts up like a new truck -- its driving me nuts.

10

Kenny/MrBlueOval, I have a 79 Bronco with a big block 460, mechanical fuel pump, Holley 750. It runs for 15 to 30 minutes then dies. Your vapor lock theory sounds like it could very possibly be my problem. But can you answer this for me? I have a pressure gauge at the carburetor that reads 6 to 7 psi. After it idles or you drive it for 15 to 30 minutes, pressure goes to 0 psi and then the engine will die. If it is a vapor lock issue would this cause pressure to go down to 0? And just so you are aware, the fuel pump is brand new and the fuel is brand new, I just replaced them and the problem is still exists.

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