1987 F150 5.0 liter NO start when hot, new ignition did not help, has fuel & spark..

[chubbygoatboy]

1987 F150, with the 5.0. I installed new coil, ignition module, and pickup. It will start cold, but will not start when hot. If it cools down for an hour or so, it will restart if you kind of pump the throttle, or hold it to the floor. I set the timing after pulling the dist. to replace the components. It has 35-40 psi fuel. It turns over fine, but will not fire. I checked with timing light, and it gets spark when it should, but will not fire. When you get it eventually started, it makes a throaty noise near the throttle body?? Any ideas?? THANKS

[chubbygoatboy]

Well, I answered my own question. Engine coolant temperature sensor. Replaced it, and now engine fires off no matter what the temp!! Hope this might help someone else!!

[chubbygoatboy]

I am curious if anyone knows why this is???? It is still starting just fine, at any temp.....

[unclebubbles]

The engine coolant temp sensor sends information to the computer about the ambient temperature during cold startup. After the engine starts, it keeps up with the coolant temp and helps control the spark and fuel delivery(the cps of the injectors depending on throttle opening). Other sensors also play a part in this, but this sensor provides fuel enrichment for cold starts(sorta like the choke on a carbed engine, and it also helps control the IAC valve). When this sensor goes bad, it can cause either an overly rich or an overly lean mixture during startup and normal (at operating temp) driving.

[chubbygoatboy]

thats kind of what I thought, that it contributed to those kinds of things, but I am having trouble understanding why it would cause a no start when warm??