Engine won't crank
 

I have a 1994 F150 with 190,000 miles. Every two weeks I have to jump start or charge the battery. Something is draining the battery. Today, battery is replaced with Red Top Optima and all lights are on. Try to start and now can't hear the fuel injector on. I kept the ignition on and took out the connector of the relay located at the passenger side engine compartment and with a flat screwdriver I tap it and and it starts. Let it start for a few and stop the truck. Restart and still no fuel noise and engine don't crank. What should I replace first, second, third?

I'd return that POS battery ASAP. A MotorCraft is a MUCH better battery, has the same warranty, is easier to exchange if there's a problem, has more CCA, & more reserve minutes. See if the MotorCraft or Ford websites have an offer right now - if they do, your local Ford parts guy should match it, and it's usually $80.

But what do you mean "all lights are on"? The headlights, parking lights, courtesy lights, & dash lights stay on when you turn them off, take the key out, & close the doors?What do you mean you can't hear the fuel injector? You can't hear them whether it's running or not. Do you mean the pump? They're pretty difficult to hear, too.So the engine will start & run when you crank it by bridging the starter relay, but when you use the key, it only cranks but never fires or runs?You don't necessarily need to replace anything, but if you do, replace the bad part first, and there won't be a 2nd or 3rd. It only takes a little diagnostic time to find the problem. Just remember that we can't see or hear your truck, so you have to tell us EXACTLY what it's doing, or NOT doing.

When you turn the key to RUN, do you hear the relays in the fuse block under the hood click? The EEC PWR should click once; the FP relay should click on, then ~1 sec later click off. Click this diagram:

https://www.supermotors.net/getfile/...fuses94gas.jpg

When I click the key switch, I would hear the fuel pump buzz sound, click again then the engine will crank and run. When I have a bad battery, I hear the fuel pump buzz sound, the engine will try to crank or make a clicking noise.

Problem now is I have no buzz sound, no click noise, and no crank. Bridging the starter relay will fire and run the truck. Not sure what part I should change first, the starter relay, ignition switch, etc. Thanks

The solenoid (relay) mounted on the inner fender is probably the easiest and cheapest to replace.
If "thumping" on it has worked in the past, it's coming up on near dead, if it is not already.
While doing all of that, check all the wires for proper contact & serviceability. Ensure your alternator is functioning properly by removing the positive battery cable with the engine running. If it quits right away, you have an unhappy alternator. The alternator should produce enough juice to keep the engine running.
Ford trucks like large batteries. I recently replaced mine with a monster from Interstate.
Good luck.

You SHOULDN'T replace parts first. You should diagnose the problem first, and replace ONE part last. Replacing a part is the END of the repair process; not the beginning.

So the ONLY thing you changed from the no-start to now was the battery, right? Does the dash/radio come on when you turn the key to RUN?

if you pull the battery cable with the engine running, it makes the alternator think that the battery is dead and charges at 100%. this in turn will caus a voltage sike, putting 18 volts to the pcm, frying it or something in it. also, this will put an ungodly strain on the alt. someone told me to try that one time and had to buy a battery, alternator, and computer. asked a friend at al white for about it, and he sowed me a service bulletin about this and it is a big no-no! if you want to check your alt. use a voltmeter or load tester like shops do. they are not exspensive.

yes the radio comes on and dash lights area on.

Sounds reasonable. Thanks for the tip.

no problem. just thought id throw that out there so nobody would make the same mistake i did. ive heard of people getting away with trying that, but all it takes is once and your screwed.:wave:;)

Then the battery is probably OK. Use the schematic in the top center of this diagram to trace the circuit from the ig.sw. to the starter relay.

https://www.supermotors.net/getfile/...erexploded.jpg

With the key in START, the LG/R wire should apply 12V to the relay's small stud.

It is the starter i just replaced mine, click when turning the key.. new starter was 99 bucks and 10 minutes

I would look at the "ground" wire to the block(either the battery end or the block end). sounds as if the ground is not making a good and tight connection.PS there are 2 ground wires,1 for radio ect. the other for the stater circuit.

There are 3 grounds (body, frame, block), but they all come together at the battery post. The positive is different for his '89, but the negative is just like view B of this diagram:

https://www.supermotors.net/getfile/...rtwire9296.jpg . https://www.supermotors.net/getfile/...nebay93rhf.jpg