1997 F150 4.6 v8 Engine was rebuilt by local shop (my father had this done. about two years ago, I got truck from him.)
Ran GREAT for a year, now, it runs great. IF it starts. For over a year now. Randomly will not start. Cranks, No start. It is either a fuel issue or short somewhere. I believe.
At one time it sat for 3 months without starting. Had it towed to mechanic I know and trust. Rolled it of tow truck, It started.
He said low fuel pressure. NO codes by the way. Replace fuel pump (motor craft pump and crank sensor. )
1650.00 bucks. Had him do it.
Ran great for two months. Then, crank, no start for over a week, no start. Towed back to mechanic. It started. He kept it, every time they got in it, it started. Finally after 3 months of trying daily it did not start.
They pushed it in shop to test out. It started. I said screw it. will pull engine, trans and put them in a 65 short bed I am rebuilding. But I love this truck. I want to keep it. So, I got in, started it and
I brought it home. Ran great, killed it. It would not start for two weeks. I put another heavier ground wire on it. From frame to engine, Fired it up and it ran for a year.
Then a month ago. It would not start. Sat for two weeks not starting. Then magically, It starts, ran GREAT for another two weeks. Now, It just cranks, will not start. If I spray starting fluid it tries, which leads me to believe fuel delivery. Spark is there. I do not hear the fuel pump kick in now. Surely it's not the fuel pump again I hope.
I have checked fuse and relay. They appear to be fine.
I thought maybe it's the fuel pump driver module. But apparently, this truck does not have one. It does have what is called a Fuel Injection Control Module. (FICM)
$368.00 bucks for a rebuilt one. I was gonna test it for power. Can't find it.
However, when I google that it comes up as an ignition control module, Which is NOT the same thing. I cannot find a location on the FICM.
I am at the end of my rope. I got this truck from my father and LOVE it. But I cannot justify putting up with this any longer. About time to scrap it and move the engine to the 65.
YOU are the man. Please help! LOL Tell me you have seen it.
Throw me a bone please.
go to the FAQ and click on 'why doesn't my car start'. Watch the videos there.
These intermittent issues are almost always electrical. You should hear the fuel pump kick on for a few seconds when you turn the key on. Get a helper, pull off the gas cap, listen at the fuel fill for the fuel pump when your assistant switches the key to ON. (during the NO START condition).
Is the fuel pump running for a few seconds?
If it isn't then this may just be a failing fuel pump relay or faulty (intermittent) relay wiring.
It's time to stop "scratching your head" and figure out what's going on here.
So spend a few bucks. You can buy a Noid Light set, Fuel Pressure Gauge, an HEI ignition spark tester, and a 12 volt test light for under $100 bucks from Amazon or Harbor Freight.
(There are youtubes on how to use all these things and it's very easy)
They're good enough. You aren't a professional mechanic who will use these tools everyday and they'll be fine for diagnosing this problem.
Don't let this stuff overwhelm you. Take it one step at a time. It isn't rocket science.
So during a NO START you'd want to connect your $20 Amazon/Harbor Freight Fuel Pressure Gauge to the Schrader valve on your fuel rail. You need to remove "No or Inadequate fuel pressure" from your troubleshooting.
See if you have sufficient fuel pressure. Between about 30 psi and 40 psi. (if it gets much over 60 psi the computer will shut the injectors down. (In that case you'd inspect the vacuum line to the FPR (Fuel Pressure Regulator) and if it's good, replace the fuel pressure regulator).
If you don't have fuel pressure the first place to look is at the fuel pump relay socket.
All this HAS to be done during the "No Start" condition.
You can simply "swap" relays with another relay in the engine compartment fuse box to see if it's a "lazy" relay to rule out a faulty relay.
If that doesn't work you have to entertain the possibility of: "what if" there's a wiring issue with the fuel pump relay socket?
So 1st you need to determine if the fuel pump relay is getting power during the "NO START" condition.
At this point we aren't concerned about the "coil side" of the relay.
We want to know if the fuel pump will run without the relay in the equation.
So let's look at the relay's socket.
You need to have Battery Voltage (around 12 volts + or -) at socket #30 of the relay socket.
Socket #87 goes to the fuel pump.
So use that $10 Amazon/Harbor Freight 12 volt test light to test the fuel pump relay socket at Socket Pin #30.
If you have 12 volts there then jump (using the little piece of wire) relay sockets #30 and #87.
That will take the relay's coil power (and the computer's ground) out of the equation and provide battery voltage to your fuel pump.
Does the fuel pump run? Is there fuel pressure at the fuel rail now?
If there isn't then it's a wiring issue between the relay and the fuel pump or a failing fuel pump. If the fuel pump runs (AND you confirmed that the relay is good) then it's an issue with the fuel pump's relay's coil circuit.
Let's look at it.
So socket 86 gets power (ignition ON) and socket 85 is controlled by the computer (PCM) (Ground) to energize the fuel pump's relay coil which closes the internal switch between relay pins #'s 30 and 87, That sends power to your fuel pump and also let's your PCM know the fuel pump is getting power from the relay.
You want to see (using your test light) if there's power (Key ON) at relay socket 86 and you want to see Ground at relay socket 85 for a few seconds after the Key is switched to the ON position. That will tell you that the relay's coil is getting power AND the computer (PCM) is in control of the relay. (providing Ground to energize the relay's coil).
If all this checks out OK and I just wasted 2 minutes of your life that you'll never get back it's time to test the "Battery Voltage" and the PCM's "ground pulse" to the injectors. Use that $15 Amazon/Harbor Freight Noid Light kit. (Watch youtubes on how to do that).
Don't be lazy. Test all 8 injectors.
If all this tests OK then use that HEI spark tester to be sure that you're getting adequate spark to each cylinder.
Be aware that "spark" isn't sufficient spark. The HEI spark tester will let you know that you have "sufficient" spark.
Again, don't be lazy. Test all 8 cylinders
When truck fails to start, check voltage at fuel pump relay while cranking. You should see 12 volts.
There have been times various legs of the ignition switch will drop to voltage below threshold needed to start the vehicle or run some of the accessories. This happens when the contacts wear thin.
I hope you find this helpful.
First let me say THANKS for the replies. I will read and follow up on these.
Okay. update, I went out today with my computer and seperate blue tooth OBDII reader. NO CODES again. Has not started for two weeks now.
Put the reader in. Tried to start. Just cranked, no start.
Turned on Torque App and turned on all 12 readings that this thing will make. Once it got connected. It started.
Ran it for a while, to charge battery. Pulled the OBD, no start. Put it back in. No start. Connected Torque program. It started.
Had to leave for a while, Come home. It starts now. Without the OBD.
Something about the sensors being engaged. Got it starting, I guess.
Am gonna hook up the computer this weekend, and try to get some better readings. Using Forscan.
The whole time. I have had fuel pressure. I have spark. I have checked and replaced the relay. Fuel pump replaced.
I have come to the conclusion, that somewhere. There is a short, either is a wire, or a sensor.