84 Ford dies when hot
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Cargo Master
Joined: Nov 2010
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84 Ford dies when hot
I haven't messed around with my 84 F250 too much so I don't really know what all it has under the hood. It starts up great and runs for a while and then it dies. I figure its either a blown head gasket, or vapor locking combined with old gasoline. Just curious as to what would cause it to shut down like that. Near as I can tell it dies and you can fire it right back up?
Cargo Master
Joined: Dec 2004
Posts: 3,362
Likes: 22
From: Florence, SC
Check your ignition module. When they first start to go bad, they will cut off when the engine is hot. When it cools back down, they often start working again. Could be other things too, of course, but that is where I would check first.
What engine do you have? Some ignition modules (Duraspark) have a square box mounted on the driver's side inner fender, while others models have a thinner one (TFI) mounted to the side of the distributor itself.
What engine do you have? Some ignition modules (Duraspark) have a square box mounted on the driver's side inner fender, while others models have a thinner one (TFI) mounted to the side of the distributor itself.
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Cargo Master
Joined: Nov 2010
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Its a 460 with BW 4spd. Its carbed but I have yet to do much investigation as to if its computer controlled, with electric in tank pump or a block mounted pump but we shall see. I will give you guys pictures and more info once I get home from college if its not 10 degrees out side hahaha.
Posting Guru
Joined: Jun 2005
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From: charlotte, nc
If your module is mounted on the side of the dizzy, and it overheats, I have seen people move the module to the fender. I dont know if that will be possible with your specific truck though.
It could also be vapor locking, my old 78 did this. I simply cut the steel line at the fuel pump, and ran rubber fuel line up to the Carb. It should already have a barbed fitting at the carb, IIRC, so you are good to go on that side. Either that, or change to an electric fuel pump i have heard will help, but have not tried it personally.
It could also be vapor locking, my old 78 did this. I simply cut the steel line at the fuel pump, and ran rubber fuel line up to the Carb. It should already have a barbed fitting at the carb, IIRC, so you are good to go on that side. Either that, or change to an electric fuel pump i have heard will help, but have not tried it personally.
Cargo Master
Joined: Dec 2004
Posts: 3,362
Likes: 22
From: Florence, SC
If you have the 460 engine, it will have the Duraspark ignition with no other computer controls. The module will be on the driver's side inner fender. Check the underside of it and see if the epoxy has melted. If it has, replace it with a MOTORCRAFT module. You can get one from a junkyard real cheap, and they will last a lot longer than any aftermarket unit.
I have heard of 460s having issues with vapor locking. I would look into that as well.
I have heard of 460s having issues with vapor locking. I would look into that as well.
pedant
Joined: Jan 2008
Posts: 23,576
Likes: 39
From: EXTREME southwest CT
I wouldn't expect vapor lock in winter.
If it is not the DSII module I would check the magnetic pickup in the distributor and the coil as well.
These ignition systems are usually trouble free unless the module has overheated.
How many miles are on your truck glovemeister?
If it is not the DSII module I would check the magnetic pickup in the distributor and the coil as well.
These ignition systems are usually trouble free unless the module has overheated.
How many miles are on your truck glovemeister?
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Cargo Master
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It says 28k miles, but the OO/PO said that is has rolled once. I plan to do a full tuneup here in the next few days when i return home.
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pedant
Joined: Jan 2008
Posts: 23,576
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From: EXTREME southwest CT
At least, my '87 has 350,000+.
When you're tuning it up check the timing chain for slop.
Makes a huge difference.
When you're tuning it up check the timing chain for slop.
Makes a huge difference.
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Cargo Master
Joined: Nov 2010
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Alright, I haven't been able to mess around under the hood today. Radio works and is crystal clear, both doors and locks work, turn signals and hazards work. All the lights, work. Interior seats functions still work great.
Alright, well I gave my pickup one or two pumps today and she started right up first crank. I let it idle, which seemed high for a couple of minutes. I tried to knock it down but it didn't appear to reduce the idle speed. I again tried to knock it down and it didn't work. I then ran it for another couple minutes and shut it down, I noticed that some dieseling occured. I actually noted this on my old camaro and never knew what it was called until I searched this forum.
Well, from what I can determine I need to go ahead and adjust the high idle screw? While I am in there should I check anything else?
Alright, well I gave my pickup one or two pumps today and she started right up first crank. I let it idle, which seemed high for a couple of minutes. I tried to knock it down but it didn't appear to reduce the idle speed. I again tried to knock it down and it didn't work. I then ran it for another couple minutes and shut it down, I noticed that some dieseling occured. I actually noted this on my old camaro and never knew what it was called until I searched this forum.
Well, from what I can determine I need to go ahead and adjust the high idle screw? While I am in there should I check anything else?
Tuned
Joined: Sep 2010
Posts: 481
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From: Rockford, MI
Dies when hot
I am wondering if you have a fuel pump issue-I got a free pickup and it would run good cold but die hot...new fuel pump and its golden. You may also go through the diagnostics on your coil and/or your distributor pickup stator, as they are affected by heat...The DSII unit is not usually heat failure prone as it is on the fender.
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Cargo Master
Joined: Nov 2010
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I am going to run through all that when I get a chance, but from what I understand I need to figure out the ds2 module as if it doesn't have enough heat space with washers it starts to over heat and will melt.
Moderator
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From: Denver Metro Area, CO
I let it idle, which seemed high for a couple of minutes. I tried to knock it down but it didn't appear to reduce the idle speed. I again tried to knock it down and it didn't work. I then ran it for another couple minutes and shut it down, I noticed that some dieseling occured.
Well, from what I can determine I need to go ahead and adjust the high idle screw?
Well, from what I can determine I need to go ahead and adjust the high idle screw?
I wouldn't adjust the high idle speed just yet, it's likely doing its job just fine, it looks to
me like your choke isn't shutting off properly after the engine warms up.
After sitting overnight, remove the air cleaner assembly and plug any open vacuum lines.
Open the throttle fully with your hand, the choke plate should fully (or mostly) close.
Start the engine and let it warm up, after a while use your hand to try to kick the idle
down, watch the choke plate as you do that, it should begin opening up and the idle
speed should drop (I know, yours doesn't).
I'm guessing you have/had an electrical- and temperature-assisted automatic choke....
Does your carb have a black plastic wart on the side of it with a wire connected to it
(similar to this)?
Do you have a small metal tube connecting the choke & exhaust manifold (similar to this
tube covered in a white sleeve)?
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Cargo Master
Joined: Nov 2010
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I believe you are correct on both counts ct. I noticed today, that I ran it for pry 30 minutes before it wanted to die. I gave it gas and it seemed to keep on trucking, I did this a couple times just to see if it worked appear to for a short while. Then I shut her down. I noted that when I held the choke plate closed the truck would wanna die. Lastly, when I assumed it was warmed up the choke plate was forming a t almost. As in, you have the choke plate housing making the horizontal portion and the choke plate was vertical or straight up. This seems opposite of what one would think?
Moderator
Joined: Nov 2007
Posts: 22,415
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From: Denver Metro Area, CO
Pictures are most helpful. *hint* *hint* 
When the engine is cold, the choke plate should close, this lets less air in which means a
richer fuel <-> air mixture.
As it warms up, that plate opens, allowing more air in (which means a leaner mixture) and
should be fully vertical (no air restriction at all) when it's fully warmed up.
Along the way and at the same time, the high idle is supposed to get lower until such time
as it's using its curb idle adjustment.
These changes won't really happen by themselves, they'll occur as the throttle is kicked or
otherwise activated and released.
When the engine is cold, the choke plate should close, this lets less air in which means a
richer fuel <-> air mixture.
As it warms up, that plate opens, allowing more air in (which means a leaner mixture) and
should be fully vertical (no air restriction at all) when it's fully warmed up.
Along the way and at the same time, the high idle is supposed to get lower until such time
as it's using its curb idle adjustment.
These changes won't really happen by themselves, they'll occur as the throttle is kicked or
otherwise activated and released.