1987 4.9 inline 6. I'm trying to determine if over the years the incorrect distrubutor has been installed on the truck. It currently has no vacuum on it. They sell it with or without. Ford dealer recommended I check here for help. If I can determine it's the proper one I am just going to do tune up (cap rotor)

The truck sounds great when running but warms up and stalls. Just got it yesterday for my son who is close to getting his license, we have few months to get truck

running perfect.

 

Need picture of the distributor...

My 1987, 4.9, has no vacuum advance on it. Only the grey TFI module on the side where the wires plug in.

 

A 1987 model year 4.9L F-series truck should be fuel injected, therefore no vacuum advance distributor. The timing is controlled by the computer.

 

I'm guessing yours looks just like this. And I would assume every single 87 that rolled off the line also looks like this then.

 

When the engine quits, does it act like someone cut the switch off, or stumbles, bogs down, or anything else? After stopping, does it start right back up? If so, does it start normally, or rough running?

If it doesn't start right up, how long before it does start, and how easy and smooth does it start?

 

Looks just like that....

I see your module has already been changed out with a Wells. That may be the problem, but need test to be sure.

 

I have limited testing so far. some off this was reported by seller.
my experience currently is that it starts easily idle just above 1000. Apply power and it stalls. After a few days and letting it idle I've been driving up and down the road without any issue. (I can't go far and get stranded at the moment)
The idle sitting in my driveway is now at 1500 so there's something that will need to be addressed also.
I have not got it warm enough to stall like the seller told me it would do.

I appreciate everyone's interest in helping. Thank you all.

 

Update. I got it to have the issue seller reported. It did not die but lost power under acceleration after driving it while warmed up. Seemed like it was running out of gas, but it would idle fine. Made it back into the driveway in second gear very little throttle. If I gave it gas it would bog out right away.

 

The high idle tells me you either have a bad vacuum leak, or someone has cranked the throttle body stop screw open to get the truck to stay running. Could also be the idle control valve stuck or holding open.

Lots of different things could be the problem, and will take a good bit of detective work on each system to hopefully find out what's wrong.

Start by renting a fuel pressure tester at AZ, Advance, or somewhere and test your fuel pressure at idle, with and without the vacuum hose hooked up to the fuel pressure regulator, located on the front passenger side of the valve cover. It is round, silver, with a vacuum hose ran to the top of it.

After that. test the TPS (throttle position sensor) for correct voltage, and a smooth sweep from idle to wide open. Get a vacuum gauge and see what vacuum you have at idle.

I would block off the EGR valve by unbolting it from the rear of the intake, use a piece of sheet metal, trace out and cut a piece of it to match the mating surface, and put it between the EGR and intake. I did mine years ago.

Check ALL vacuum lines for leaks. Remove and block off what lines you can for testing, especially the line going to the brake booster (a good source of vacuum leaks) and the cruise control. Also the line leading over to the heater box and vacuum reservoir built onto the side of the heater box. Look closely at the vacuum control unit below the passenger hood hinge. It has one white vacuum hose attached to it, That hose is bad to crumble and brake,

This is enough to start with. Let us know what you find, and if you need any help testing these things. There are many people much smarter with testing the 4.9 than I. Hopefully they will see this thread and help out.

 

That could be plugged cats. Checking your vacuum could tell you if that's the case. Have someone start the truck, and see if the vacuum drops while running.