Need advice/not getting gas

I have an 86 f150 5.0 that I recently changed a lot of things to fix a skip and stall issue. The distributor turned out to fix the lifelong stalling problem and skip went away and was ok for a short bit but now it runs for 5 min and warms up good then it starts to pop skip and barely run. I rev it and it does worse. It never cuts off but after its warm it runs really bad. I switch tanks back and forth then it gets better sometimes and it runs perfect. I cranked it Saturday and it ran fine after switching tanks 3 times and drove 5 miles all was good. I cut it off and it wont crank without starter fluid. It can run fine then wont crank when I cut it off. It has to sit for an hour or 2 before cranking on it own. This happens 50% of the time. Other times it cranks fine. Every time I crank it its runs smooth until it warms up then it goes to running horribly. Not sure what's going on. Fuel filter was changed 3 years ago but it hasnt been driven much in 3 years.

I really know nothing about the 5.0 but heat soak issues are often electronic

I would disconnect the vacuum line to the EGR and plug it and see if that changes anything when it gets warmed up.

I would want to determine if it is a spark or fuel problem.  Check to see if you have good, hot spark when it won't start.  You probably as you said it will start with ether, but ether is easier to light off than gas, so see if you have a blue to white spark.  Not yellow or red.

If you have good spark then it is probably fuel, and from what you've said it may well be.  But, Dane is suggesting the EGR valve may be stuck open, which puts exhaust gas in at idle, and that may cause it to stall.  And while I agree pulling the hose off won't hurt, many EGR valves are so badly coked up that they can't possibly close.  If that is the case you won't be able to tell by pulling the hose as it won't change anything.

Anyway, try several things and let us know.

First off, let's be clear about terminology.
"Crank" is the act of the starter turning the engine.  Years ago (before electric starters) you had to go stand in front of the vehicle and insert a crank handle into a sprag clutch at the front of the engine.
Just like those guys pulling propellers over, it was done by hand.

Catch, and run are where the engine takes over from the starter's cranking and can power itself.

If changing the distributor and tfi module cured your stalling, did you use the correct amount of thermal paste on installation?

If you think it is a fuel issue, maybe you should set up a fuel pressure gauge where you can monitor it as the engine warms up?
Maybe duct tape it to the windshield wiper arm or something?

I bought the distributor and it had the tfi module on it. I didnt take it off assuming it was already fixed like it should be.

It runs bad 50% of the time and then it's fine other times and runs good. Almost always it will not run good 3 or 4 minutes after its started and idles down. It didnt do this until I replaced distributor but it didnt do it the first couple times after it was replaced. Now its every time but eventually works itself out.

Thanks for the info Gary.

One of the problems I have seen with the 1985/86 5.0L EFI systems is the single ground connection for the entire system. It is near the battery negative post and is an open to the elements 1/4" blade connector. Since it is right at the battery the fumes given off in charging corrode it resulting in a bad ground. I would cut the connector off, put a solid ground lug on it and get another cable and run it from the block to the fender bolts and also ground the harness there.

Second item, both my son and I have had bad issues with non-Motorcraft replacement electronic (sensors, modules) on these systems, Behind your battery is a bank of solenoids and two of them are for the EGR valve, these are a vacuum and a vent solenoid, if these are "chattering" then you will need to check the voltage on the throttle position sensor it is supposed to be set to 1.0 +/- .2 volts, if it is too high the EGR will be trying to open at idle, the only adjustment is the idle speed screw and if it will not come down to the proper voltage, there used to be a bypass kit from Ford for these problems.

But you're saying it won't start without a shot of ether?
And that sometimes it needs to cool down an hour (or more) before it will restart?

While it does make sense that having the EGR open at idle will cause stumbling and stalling, it doesn't explain those symptoms.

What codes is it throwing now?


http://forum.garysgaragemahal.com/New-member-with-idle-issues-tp81318p82221.html

Three months ago you told us you replaced the grounds.
You also said (on the 13th) that you had replaced the TFI.
And then on the 20th state that you replaced the distributor, "solving" your problem.
SO.... this makes me think that you have that little screwdriver and changed one at a time.

And this is why I ask about using paste..... when it seems like a heat soak problem.

Correct, I did change the TFI module and then when i replaced the distributor it came with a TFI on it when I bought it and was already screwed onto it so I kept that one on it. I didnt take it off to see if it had the paste on it assuming it was good to go. The only time it wont start is when it has been running for a while and it can be running fine when i cut it off then wont start. This past weekend i tried ether and it did not start unlike other times. Usually it will help.
I will check for codes hopefully today.

Ah, okay.
Yes, if It came as an assembly there should be thermal paste behind the TFI.

So now, with a replaced distributor (and everything else from your December thread) the truck will not restart when warm.
I would definitely check codes, and consider a shim under the EGR, something like this, depending on what the codes were telling me.

Have you checked for bad caps in your ECM?

Intermittent problems are way more difficult than simply having the truck die.

I have changed out the ecm when it was not starting (with one from the junk yard) and it still didnt start. It sometimes will start after its warm and sometimes not. The long it runs the more likely it wont start especially like when it's been driven and not just idling.  What is the shim under the EGR?

You can buy a cover like I showed, or you can use a feeler gauge, shim stock or even a slip of tin can to block off the EGR where it bolts to the plate.

I didn't ask if you had swapped for a junked one, I asked if you had looked for signs of deteriorated caps.
Capacitors go bad just sitting on the shelf.
35 years is a long time for anything filled with electrolyte.

I'm trying to reason out what is getting heat soaked.
So many parts have already been shotgunned at it, it is hard to keep track.

But if it doesn't want to start, you might do best by asking it why it doesn't want to start.

Let me chime in again. You need to do some basic diagnostics and not just throw parts at it.

First item, you should be able to hear the high pressure fuel pump when the key is turned to run, it will power on for a short time then off again this is to pressurize the fuel rails on the engine. If this is happening hot or cold then that part is working correctly.

Now, when it will not start hot, try several cycles of the key and listen for a slight change in tone of the HP pump, you should hear it change to a slightly deeper tone as the pressure in the system comes up. Once you hear that, try a hot start, if it now starts fairly normally your problem is fuel pressure leakdown.

If that isn't the problem, then it on to the ignition system. Remove the coil wire from the distributor cap and place it near (1/4") a piece of metal on the engine and either have someone watch it or them crank the truck and you watch. You should have a nice blue or yellow/blue spark. If it is orange or no spark, close the gap up to 1/8" and try, if you now get a weak spark, replace the coil.

If both these tests yield satisfactory results, see if the injectors are triggering, they are wired in two groups of 4, the 4 end ones (1458) and the 4 center ones (2367), you should be able to feel the "click" of the solenoid in the injector. If not, then either the ECM is bad, or (more likely) there is a wiring problem. These 1985-86 EFI trucks have some of the crappiest wiring I have seen since the old rubber and cloth wiring in the 50s.

Good luck with it!

Bill,
Micah's first post stated (in part)

"So far here's some things that have been done recently.
Intake and valve cover gaskets
Idle air control valve
Thermostat
PCV valve
Throttle position sensor
MAP sensor
Fuel pressure regulator
Swapped out a computer from junk yard
Harmonic balancer
New belts and hoses
Spark plugs and wires
02 sensor
Fuel relay
Oil sending unit
Water pump
Fuel filter is relatively new
Solenoid
Starter

Motor was rebuilt 20 years ago and has low miles on it since rebuilt.
No vacuum leaks
Fuel pressure is good"

I'm not sure what "fuel pressure is good" really means..
But stated new FPR and relay.
This is why I suggested real time monitoring.

Heat soak doesn't come to mind causing a pump problem, but as you said you can have all the fuel in the world, if the injectors don't open you'll have no joy.
He states new grounds and a new distributor/TFI.
So again new parts, but not the problem.

But if the ECM is getting a signal from the PIP the pump relay should continue on the clock.
And the injectors -should- fire.
A noid light is cheap.
You can also pull the spout and see if the noid light starts working with the computer out of the picture.

I'm not exactly sure where to be looking for deteriorated caps. I've learned alot through this process but still have a ways to go and I'm not sure what I'm looking for on the caps.
Also, do I remove the EGR, place a plate between it and put it back and start it to see if it does it still? I can always just get an Egr and replace it if I have to and return if it's not the issue. Actually we may have a spare that was a trial and error in the past trying to fix an issue. Thanks for your expertise in this.

Coincidentally or not it has gotten better when I switched tanks back and forth. Could it be the fuel tank switch valve?

Could be the pump in the one tank that doesn’t work good.

Edit: on the tank that it doesn’t run right, with the engine running take the gas cap off that tank and try and listen to the pump. It should be continuous and smooth.

Before my pump went bad in my rear tank I could hear it not operating as it should.

That might well be the problem, Dane.

But like Bill said, do some diagnostics.
Since the truck is doing its own diagnostics -constantly- the first thing I'd do is pull codes.

Even if the pumps are good and the valve is bad, what matters is pressure in the rail.
That's why there's a Schrader valve.
If you have a fuel pressure gauge stuck in front of your face you can see if the fuel pressure is low or non-existent, while you're driving or when it won't restart.

If the injectors aren't cycling it doesn't matter if there's fuel.
Again, a flashing light makes it pretty obvious if the computer is grounding the injector or not.

It's been three months now, hundreds of dollars in parts even before then, and the truck still won't start when heat soaked. (It seems)