Twice in the last month, the 99 F150, won’t start. It’s a 4.6 L with 85 K on it. The engine cranks smoothly at normal speed but there is no hint of the engine firing. The battery is good and all the cabin electronics are acting correctly. After about ten minutes of cranking and resting, it suddenly starts and runs fine.

After the first time, I removed the air intake and cleaned the throttle plate throat and checked the various connectors. I didn’t really fine anything.
When it runs, it runs smoothly with no problems. But I was thirty miles from home in the dark when it decided not to start last night. Code reader did not find any codes.

Suggestions and advice on where to look would be appreciated.

Thanks in advance.

 

well first when the truck won't start, does the theft light blink rapidly when it's happening? if it does, do you have extra pats keys next to your truck key? does it happen with your spare key?

 

Try depressing the gas slightly. If it starts, your IAC (idle air control) is bad.

 

The engine is hard to start and will not idle unless propane is metered into the engine. The fuel pressure tests out good. There are no codes in the Powertrain Control Module (PCM).
Tests/Procedures: 1. Unplug the electrical connector from the Mass Air Flow (MAF) sensor. Check if the engine starts and stays running.

2. If the engine stays running with the MAF sensor disconnected, check for a large vacuum leak or a leak in the ductwork between the MAF sensor and the throttle body. Also check for a piece of trash or debris in the MAF sensor. If all is OK, replace the MAF sensor.
Potential Causes: Defective Mass Air Flow (MAF) Sensor
Dirty Mass Air Flow (MAF) Sensor — Debris in the MAF sensor.
Leaking Unmetered Air

Tech Tips: Failed MAF sensor Debris in the MAF sensor Large unmetered air leak

 

i have a 95 towncar with the same motor was doing the same thing it was the crankshaft position sensor try unplugging it and cleaning connections see if that is the problem

 

There is a Starter Relay mounted on the firewall same side as battery. Mine was having issues and would start intermittently. Got worse over time. A way to test, is when it is not starting lay a screwdriver shaft across the two contact bolts (holding onto the plastic insulated handle) and see if it starts.

 

there is no need to do this, the engine is cranking

 

@fordtech08

Dan, when my Expedition had this issue, it would crank and crank and crank but not turn over. Once I 'jumped' the relay it would start. I replaced the relay and have not had an issue since.

Don

 

ok then we have a conflict of word definitions to me when you say the truck cranks that means it's turning over, you had a no crank no start, not a crank no start

 

but glad you got it fixed

 

Well I fixed it. I traded it in on a 2010 F150.

I am aware of the starter relay trick. That has been a Ford feature since the 50's. But that was not the problem.

I found if I turned the key to ON and left it for about 20 seconds, it would always start, Walking through the shop manual diagnostics and talking to some other veterans says this is probably a fuel pump issue. That is very pricey.

It worked 99.99% of the time and waiting 10-20 seconds is not that big a deal, but I decided I didn't want to take the chance of being stranded.

This is Ford Truck month and there are some big package discounts. So I have a new XLT

I loved the 99 but this truck is that much better. I'm still learning the buttons.

Thanks to the forum for all your help and insight.