I have owned my 1994 F150 4.9l I6 for about 4 months now, and put about 1,200 miles on it. About a month ago my truck wouldn't start, tried to figure out why, ended up being a bad battery. Replaced that and it ran good for the last month.

Two days ago I go to turn on my truck and what do you know? Doesn't want to turn on. I try and turn it on the next day and after about 15 seconds on the starter it almost started, was running at about 300RPM all bogged down and wouldn't respond to the throttle. Turned it of and tried it again and after about 10 seconds it barely started, but I kept with the throttle and then it ran completely fine until I got home and parked it. Then it wouldn't start again. At first I thought it had something to do with the fuel, like a bad pump, but I sprayed starter fluid in the intake and again it didn't start. So now I believe it has to do with the spark, but I don't know exactly what. Is there any tests I can do to help troubleshoot this down to one thing?

Sorry for being so verbose, but I am at my wits end. Thank you so much in advance.

 

Get a spark tester for a couple bucks at the parts store and use that to check and see if you got good spark.

Check your contacts on the distributor cap as well as the rotor. Could be oxidized or something.

Playing with the throttle is probably coincidence. Holding the pedal down actually shuts off the injectors in these trucks.

 

My 1st guess- ignition module? But have it tested before you buy one. Check for voltage at coil and at starter relay. AND MOST IMPORTANT make sure you have a good battery before doing electrical tests

 

Ill look into both of those things right now, thanks!

Instead of a spark tester cant you just touch the spark plug to some metal part of the engine?

 

A tester is better, but, i always stuck a 5/16x1-1/2" bolt in the plug boot and layed it against something that it can arc to (valvecover for example)

 

I tried one spark plug, and i got a blue spark. Should I try the rest?

 

Naw, not unless you think one of the plug wires is broken. If youre getting spark to one, you know you coil is ok. How did the plug that you took out look?

 

It looked fine to me. So now I am utterly confused. If starter fluid doesn't do anything and I am getting a spark, what is going on?

 

Fuel pump. Can you hear the relay turning on?

 

When I turn my key i hear a sort of buzz I guess for about 2 seconds. But it would start with starter fluid if it was the pump right?

 

K check for fuel pressure at the fuel rail( bike valve near injectors)

 

OOOHKaaay. Take the distributor cap off and have somebody crank the engine over while you watch the rotor button. If it doesnt turn when engine is cranking that will indicate a broken camgear

 

The OP stated he has spark.

 

Ill do this in the morning when I can get to the store and pick up a pressure tester. Besides this could there be anything else wrong?

 

I-6/4.9 engine, right? They have a fiber camgear that sometimes breaks. that is why you check for rotor button movement when cranking the engine. If thats not it maybe timing has slipped off somehow?