MBC1980 Posted March 10, 2021 Share Posted March 10, 2021 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. Link to comment Share on other sites More sharing options...
swampedout Posted March 10, 2021 Share Posted March 10, 2021 I really know nothing about the 5.0 but heat soak issues are often electronic Link to comment Share on other sites More sharing options...
grumpin Posted March 10, 2021 Share Posted March 10, 2021 I would disconnect the vacuum line to the EGR and plug it and see if that changes anything when it gets warmed up. Link to comment Share on other sites More sharing options...
Gary Lewis Posted March 10, 2021 Share Posted March 10, 2021 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. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted March 10, 2021 Share Posted March 10, 2021 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? Link to comment Share on other sites More sharing options...
MBC1980 Posted March 11, 2021 Author Share Posted March 11, 2021 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. Link to comment Share on other sites More sharing options...
MBC1980 Posted March 11, 2021 Author Share Posted March 11, 2021 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. Link to comment Share on other sites More sharing options...
MBC1980 Posted March 11, 2021 Author Share Posted March 11, 2021 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? Thanks for the info Gary. Link to comment Share on other sites More sharing options...
85lebaront2 Posted March 11, 2021 Share Posted March 11, 2021 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. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted March 11, 2021 Share Posted March 11, 2021 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. 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. Link to comment Share on other sites More sharing options...
Recommended Posts