Not staying running
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Not staying running
I have a 1983 Ford F250 with the 7.5L 4bbl. I recently rebuilt it and it was running fine until the other day. It stalled and no it will start for a few seconds and then just quit. I checked the fuel bowl and It doesnt seem like its filling up correctly. Could this cause the sudden shut off? I have taken it apart and rechecked the level and its still not working. I am getting fuel to the carb. I checked by turning it over and filling up a bottle. What other causes should I be looking at if it doesnt want to stay running? Thanks for any input.
Treedoctor
Treedoctor
pedant
Joined: Jan 2008
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From: EXTREME southwest CT
The first thing to check for is spark.
The Duraspark II modules get overheated and fail.
Sometimes it will restart when the module cools down, sometimes not.
This is the aluminum box about 5" square on the drivers side inner fender.
It will have two plugs, one red and white, the other orange, purple, green and black.
The Duraspark II modules get overheated and fail.
Sometimes it will restart when the module cools down, sometimes not.
This is the aluminum box about 5" square on the drivers side inner fender.
It will have two plugs, one red and white, the other orange, purple, green and black.
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From: Virginia
What could also be happening; The fuel pump is running while you are cranking, but not when the engine is running. If you have electric fuel pumps(most of the 460's do) they are controlled by a relay that is controlled by a oil pressure switch. So when the engine quits, you lose oil pressure and that turns off the fuel pumps, in case you are in a accident and leave the key in run but the engine stalls.
But this system doesn't work well when starting the engine, so they added a wire to the starter relay that bypasses all this and sends power directly to the pumps when cranking. This fills the carb enough to get the engine running and to build oil pressure, so then when you let off the key the relay kicks in and sends power to the pumps.
If you want to check this theory, look over at the starter relay. On the large terminal that goes down to the starter, see if you have smaller wire on there too, going from memory I want to say it's blue or violet. If you take this wire off and put it directly on the + of the battery, will the truck stay running?
But this system doesn't work well when starting the engine, so they added a wire to the starter relay that bypasses all this and sends power directly to the pumps when cranking. This fills the carb enough to get the engine running and to build oil pressure, so then when you let off the key the relay kicks in and sends power to the pumps.
If you want to check this theory, look over at the starter relay. On the large terminal that goes down to the starter, see if you have smaller wire on there too, going from memory I want to say it's blue or violet. If you take this wire off and put it directly on the + of the battery, will the truck stay running?
pedant
Joined: Jan 2008
Posts: 23,576
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From: EXTREME southwest CT
Dave is likely right, the symptoms fit.
This could be down to a bad oil pressure switch, inertia switch that needs resetting or simply a faulty fuel pump relay.
I don't have schematics detailing the 1983 fuel pump wiring.
Bill K (Subford) likely does.
This could be down to a bad oil pressure switch, inertia switch that needs resetting or simply a faulty fuel pump relay.
I don't have schematics detailing the 1983 fuel pump wiring.
Bill K (Subford) likely does.
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There is a blue wire on the starter relay, but its not on the big terminal going to the starter, its on a post by itself right next to the starter wire. Should I try attaching this wire to the positive terminal?
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pedant
Joined: Jan 2008
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From: EXTREME southwest CT
There should be a blue/red wire coming from the ignition switch going to the small 'S' post.
That wire tells the solenoid to close and crank the starter.
If it is on the 'I' post, then that is the one!
That wire tells the solenoid to close and crank the starter.
If it is on the 'I' post, then that is the one!
pedant
Joined: Jan 2008
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From: EXTREME southwest CT
Unfortunately there are MANY iterations of the 460 "Hot Fuel Handling" system.
Some early ones get power from the starter solenoid.
Later ones pick it up from somewhere in the harness.
Edit to add, I sent a PM requesting a schematic if available.
Some early ones get power from the starter solenoid.
Later ones pick it up from somewhere in the harness.
Edit to add, I sent a PM requesting a schematic if available.
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Freshman User
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So Dave, I put the blue wire directly to the positive feed and presto, a continuously running truck. So it must be the solenoid that is bad because when I put a tester to that specific post I was getting nothing. Is this correct. And thanks a million for that suggestion. I would have never figured that one out on my own. Thanks Again!!!!
TreeDoctor (Back in Business)
TreeDoctor (Back in Business)
pedant
Joined: Jan 2008
Posts: 23,576
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From: EXTREME southwest CT
No
The 'I' terminal of the solenoid is powered only while cranking.
This is used for ignition retard and/or powering the fuel pumps (only in the 'hot fuel handling' 460)
Your problem is either the fuse, the oil pressure cutoff, the relay, the inertia switch, or its fusible link.
The 'I' terminal of the solenoid is powered only while cranking.
This is used for ignition retard and/or powering the fuel pumps (only in the 'hot fuel handling' 460)
Your problem is either the fuse, the oil pressure cutoff, the relay, the inertia switch, or its fusible link.
pedant
Joined: Jan 2008
Posts: 23,576
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From: EXTREME southwest CT
Follow the first diagram...
Start simple, with the fuse in the upper left. This is located in the main fuse panel.
If good, check for power at the Oil Pressure cutoff Switch (back of engine near the EGR)
Disconnect and jumper the OPS plug.
if the relay clicks and the pumps run it is the OPS.
If the relay clicks and the pumps don't run, check for power going to the inertia switch in the cab.
(usually by the passengers legs- could be kick panel or on the side of transmission hump)
If no power to the inertia switch, replace the 20Ga blue fusible link.
If yes, try resetting the button on the inertia switch.
If there is power leaving the inertia switch by the yellow wire,
Check the cutoff relay on the drivers side of the engine compartment.
Start simple, with the fuse in the upper left. This is located in the main fuse panel.
If good, check for power at the Oil Pressure cutoff Switch (back of engine near the EGR)
Disconnect and jumper the OPS plug.
if the relay clicks and the pumps run it is the OPS.
If the relay clicks and the pumps don't run, check for power going to the inertia switch in the cab.
(usually by the passengers legs- could be kick panel or on the side of transmission hump)
If no power to the inertia switch, replace the 20Ga blue fusible link.
If yes, try resetting the button on the inertia switch.
If there is power leaving the inertia switch by the yellow wire,
Check the cutoff relay on the drivers side of the engine compartment.