Ford 300 6-Cylinder hot dying issues and won't crank over.

[svk]

90' F-150 with fuel injected 300 six.

Engine runs great but will occasionally die when hot (usually when idling in gear). Sometimes it starts right up and other times it will barely crank over (vapor lock??) unless you put a surge charger on it. Otherwise just it cool for an hour and it starts right up.

I have read this is an occasional issue with these engines but nobody has mentioned how to remedy it.

It is not a starter issue or bad ground issue. Cranks fine otherwise. Something is causing the engine to die when hot and then the engine is not wanting to turn over.

Thoughts?

 

[cookies]

need a scan tool to check temp sensor readings, any codes? have you checked for vacuum leaks? fuel pressure with engine fully warmed up? distributor cap show carbon tracking or button damage?

 

[Mad Professor]

By turn over you mean start? Or the engine won't crank with the starter?

 

[svk]

By turn over you mean start? Or the engine won't crank with the starter?

Starter will barely turn over the engine like it has a dead battery but it doesnt... mrooooh, rohhhh, rohhhh

 

[svk]

need a scan tool to check temp sensor readings, any codes? have you checked for vacuum leaks? fuel pressure with engine fully warmed up? distributor cap show carbon tracking or button damage?

Brand new distributor cap and rotor.

Haven't checked for vacuum leaks but the thing runs like a top except for the occasional issue.

Before it dies it detonates/diesels for a bit. If you are really paying attention, usually you can get on the gas and rev out of it but occasionally it is dead.

I need to find a shop that can scan that year of car. My usual shop doesn't have the right tool. Maybe the parts store can?

 

[SS396driver]

Sounds like you have a few issues . The starter is most likely heat soaked causing it to pull huge amount of amps . Check the cable from the solenoid in the engine bay. Make sure all connections are clean and tight . They can cause both problems low voltage to the distributor when hot .

 

[wildwes]

I had a 95 with a 302 in it, other than the not wanting to turn over part it was doing much the same as yours. It gradually got worse, started doing it sometimes going down the road. I replaced the fuel pressure regulator, coil, ignition module, and some other things, it finally ended up being that the hall pickup in the distributor was going bad. A new distributor fixed the issue

 

[cookies]

I had a 95 with a 302 in it, other than the not wanting to turn over part it was doing much the same as yours. It gradually got worse, started doing it sometimes going down the road. I replaced the fuel pressure regulator, coil, ignition module, and some other things, it finally ended up being that the hall pickup in the distributor was going bad. A new distributor fixed the issue

I was thinking timing falling apart after heating up after his second round of clues, spark/ignition module failing or even the distributor bearing/bushing or gear worn .

 

[promechanic]

The ignition modules are really common failures on that era of Fords when. The usual complaint is dying when hot, then restarting after cooking down. They can throw the timing off, which can cause the starter to crank against the engine trying to fire too early (sounds like a dead battery or bad connection). I haven't worked on one in years, but we used to keep several modules on hand in the shop.

 

[Modifiedmark]

The ignition modules are really common failures on that era of Fords when. The usual complaint is dying when hot, then restarting after cooking down. They can throw the timing off, which can cause the starter to crank against the engine trying to fire too early (sounds like a dead battery or bad connection). I haven't worked on one in years, but we used to keep several modules on hand in the shop.

This right here! I still have the stubby little tool for removing those screws that hold that module on to the side of the distributor. I had a lot of Fords from that era, never had a whole lot of trouble but had to replace a couple of those.

 

[Jed1124]

Starter will barely turn over the engine like it has a dead battery but it doesnt... mrooooh, rohhhh, rohhhh

My 94 with the same motor and manual transmission does the same slow cranking thing every once in a while when it gets hot. Thought my battery was getting tired.
Following.

 

[northmanlogging]

starter, they are known to get hot and not co-operate, check alll connections especially the grounds, if that don't solve it, than the starter might be worn just enough to cause issues.
while your at it check the battery, hot batteries push less amps, a weak battery will have less amps to push anyways.
If it wasn't a cranking issue but rather a refusal to start issue then it could be the temp sensor they go bad and tell the engine its cold flooding it kinda... but honestly is sounds like typical heat soak on the starter.
worst absolute worst case is that you have failing rings/bearings or not enough oil to keep things lubed, but that tends to be a short lived issue before kaboom rattle rattle knockity knock wheezzzzz

 

[svk]

Sounds like you have a few issues . The starter is most likely heat soaked causing it to pull huge amount of amps . Check the cable from the solenoid in the engine bay. Make sure all connections are clean and tight . They can cause both problems low voltage to the distributor when hot .

All cables are new (positive to solenoid, solenoid to starter, and ground cable to both starter and frame) and the grounds are very clean. This has slow cranking issues in general before we fixed this.

 

[svk]

This went bad last summer, and the hot dying issue started sometime after we had the new one in… Wondering if this is a faulty piece? This is not the actual unit I bought, just a picture of what it is.

 

[svk]

starter, they are known to get hot and not co-operate, check alll connections especially the grounds, if that don't solve it, than the starter might be worn just enough to cause issues.
while your at it check the battery, hot batteries push less amps, a weak battery will have less amps to push anyways.
If it wasn't a cranking issue but rather a refusal to start issue then it could be the temp sensor they go bad and tell the engine its cold flooding it kinda... but honestly is sounds like typical heat soak on the starter.
worst absolute worst case is that you have failing rings/bearings or not enough oil to keep things lubed, but that tends to be a short lived issue before kaboom rattle rattle knockity knock wheezzzzz

I understand what you’re saying, but the starter is not causing the engine to die when it’s hot.

 

[Modifiedmark]

This went bad last summer, and the hot dying issue started sometime after we had the new one in… Wondering if this is a faulty piece? This is not the actual unit I bought, just a picture of what it is.
View attachment 1093191

I would say there is a good chance you got a bad one. That's how they acted when I had them go bad. I remember trying to figure out what the hell was causing my Lincoln to just randomly die then later start when it cooled off.

 

[northmanlogging]

I understand what you’re saying, but the starter is not causing the engine to die when it’s hot.

to be fair you mostly focused on it being hard to crank after hot...
probably the temp sending unit then. fairly common on early fuel injected engines to have it fail and send goofy fuel numbers

 

[svk]

Just ordered the code reader for fords of that era. Being we have three of them and picking up a 4th soon, it will come in handy. Will know for sure then whats up. I am betting it is the module like you guys said.

 

[lone wolf]

Sounds like you have a few issues . The starter is most likely heat soaked causing it to pull huge amount of amps . Check the cable from the solenoid in the engine bay. Make sure all connections are clean and tight . They can cause both problems low voltage to the distributor when hot .

I had a problem like that it was the ground wire it was rotten inside, and you couldn't tell until it was cut. Use a volt meter and figure out if your cables are losing voltage at the starter end .

 

[svk]

I had a problem like that it was the ground wire it was rotten inside, and you couldn't tell until it was cut. Use a volt meter and figure out if your cables are losing voltage at the starter end .

Yes sir-that family of trucks is notorious for having bad grounds… This one previously had a bad ground at the battery to frame and my other one had a bad ground at the starter.