Funny, was just looking at a hot wire thread! Ignition switch possible... but I don't like a shotgun approach as that already proved it didn't work. Download service schematic some you can determine where to check... if you don't have this knowledge, look for a good mech. It's not that hard though if you got some basic electrical skills/knowledge.
oh, put the old computer back in it too...
the old computer had to be turned in for the new one
Well let's assume the "new" one is good (I don't like to assume and the computer didn't fix it so the old one was not the cause and it definitely did work correctly for that vehicle prior). Proceed to schematics to get knowledge on where to check is the best advice I can give other that take to mech.
Been a mech for 40 plus years worked as a logger this has stumped me and this one you just can't put it on the computer. me and my other friend he is a cert. mech and we are puzzled
where would I find that
Ah, I'll look as sch and see if I can come up with some ideas and points to measure. That's for the past exp info, it will help! Give me a bit as I have a phone call scheduled at 4 but should have some suggestions by 6.
do you set up calls
No offense sir, but if you have been a mech for 40 and a ase mech is with you too and you don't know how to find the service manual...
Anyway, I'll post a link in a bit for it... got phone call now.
I'm his girlfriend Im doing this for him while he is working on sorry didn't know you were talking about the service manual.
Ah, gotta, sorry but I hope you see why I asked... anyway. Here's a link for Haynes I made, It will expire in 24 hours
https://drive.google.com/file/d/1IVOe9k6pc14n0V-82BvgquRfXEfV2Hca/view?usp=sharing
And here's a write up I promised.... not mine but better than I would have done in a short time. GL and pls keep us posted.
A.) MSD, Crane, or other ignition box if present - Bypass it and return to stock configuration if possible. Do this as a temporary measure to eliminate it as a possible problem source.
B.) PIP sensor in distributor. The PIP sensor supplies the timing pulse to trigger the TFI and injectors. A failing PIP sensor will sometimes let the engine start if the SPOUT is removed. See paragraph 5A – Using a noid light will tell if the PIP is working by flashing when the engine is cranking.
C.) TFI module: use a test light to check the TFI module. Place one lead of the test light on the red/green wire on the ignition coil connector and the other lead on the dark green/yellow wire on the ignition coil connector. If the TFI is working properly, the test light will flash when the engine is cranked using the ignition switch.
D.) Coil
E.) No EEC or computer power - EEC or computer relay failure
86-93 models only: EEC relay next to computer - look for 12 volts at the fuel injector red wires.
94-95 models only: EEC or PCM power relay in the constant control relay module. Look for 12 volts at the fuel injector red wires.
Both 86-93 and 94-95 models: No 12 volts with the ignition switch in the run position on the fuel injector red wires. The relay has failed or there is no power coming from the ignition switch. Make sure that there is 12 volts on the red/green wire on the coil before replacing the relay.
F.) No EEC or computer power - fuse or fuse link failure
86-93 models only: Fuse links in wiring harness - look for 12 volts at the fuel injector red wires. All the fuse links live in a bundle up near the starter solenoid. Look for a 20 gauge blue fuse link connected to 2 black/orange 14 gauge wires.
94-95 models only: 20 amp EEC fuse in the engine compartment fuse box. Look for 12 volts at the fuel injector red wires.
G.) Ignition switch - look for 12 volts at the ignition coil red/lt green wire. No 12 volts, blown fuse link or faulty ignition switch. Remove the plastic from around the ignition switch and look for 12 volts on the red/green wire on the ignition switch with it in the Run position. No 12 volts and the ignition switch is faulty. If 12 volts is present in the Run position at the ignition switch but not at the coil, then the fuse or fuse link is blown.
Note: fuses or fuse links blow for a reason. Don’t replace either a fuse or fuse link with one with a larger rating than stock. Doing so invites an electrical fire.
Ignition fuse links may be replaced with an inline fuse holder and 5 amp fuse for troubleshooting purposes.
94-95 models only: Check inside fuse panel for fuse #18 blown – 20 amp [fuse
H.) Missing or loose computer power ground. The computer has its own dedicated power ground that comes off the ground pigtail on the battery ground wire. Due to it's proximity to the battery, it may become corroded by acid fumes from the battery.
In 86-90 model cars, it is a black cylinder about 2 1/2" long by 1" diameter with a black/lt green wire.
In 91-95 model cars it is a black cylinder about 2 1/2" long by 1" diameter with a black/white wire.
You'll find it up next to the starter solenoid where the wire goes into the wiring harness
I.) Computer. Don’t replace the computer just because you don’t understand how it works. Computers seldom fail, it usually is a sensor or wiring problem that causes the problems.
J.) Bad or missing secondary power ground. It is located between the back of the intake manifold and the driver's side firewall. It supplies ground for the alternator, A/C compressor clutch and other electrical accessories such as the gauges.
K.) Engine fires briefly, but dies immediately when the key is released to the Run position. Crank the engine & when it fires off, pull the small push on connector (red/blue wire) off the starter relay (Looks like it is stuck on a screw). Hold the switch in the crank position: if it continues to run there is a problem with either the ignition switch or TFI module. Check for 12 volts at the red/green wire on the coil with the switch in the Run position. Good 12 volts, then replace the TFI.
See the Ignition switch wiring diagram for more information on the ignition wiring fuse link because it is the next thing to be tested. You will need a Multimeter or DVM and know how to use the Ohms function to check continuity between the red/green wire on the ignition coil and the red/green wire on the ignition switch. Make sure that the ignition switch is in the off position when you do the check. You should see less than 1 Ω (Ohm) between the red/green wire on the coil and the red/green wire on the ignition switch. More than 1 Ω means that the fuse link may have blown open and needs to be replaced. If you get 1 Ω or less means the fuse link is OK and the ignition switch is bad.
Inspect the connecdtor which goes to the distributor. The contacts inside degrade and cause bad connection. It is a known problem going on for years. Also this another trick to see if things are working...pull the dist - mark the rotor position. Ground the dist and then use a drill to turn the dist with ignition on with coil wire almost touching near a ground. Also ground dist as well. Lets see how long the spark shoots out while the drill is turning dist.....it should quit unless something has changed....but if never quits...suspect some wiring problem and if you have no spark at all..suspect some wiring that has disconected fully.
The module (PIP...profile ignition pickup acts a crankshaft or camshaft sensor in that it see rotation) inside the distributor, it tells the ignition control module (ICM) to send pulsed 12volts to the positive terminal on the coil.
ICM must have a good ground and have heat sink paste applied to its mounting surface to dissipate heat...very common cause of it to intermittently fail and eventually completely fail.
The way to check for that pulsed 12volts is by using a LED test light. Common test light won't work.
Considering all these parts have been thrown at...I'd suspect a bad wire or connection...probably a bad ground.
Let's try to help this guy out. After all, he's investing his time in helping someone who has a physical disability and probably can't wrench on the pickup himself.
There's enough of us "old codgers" here and if we all think real hard we can probably remember something about TFI ignition. Maybe if we "talk it through".
C'mon, this is 1989 technology, if we can't help him figure this out we might as well hang-up our shop overalls and take up bird watching.
So the guy disconnects the SPOUT (SPark OUTput) connection and the truck starts.
The 1989 302 ford uses a Hall effect gizmo in the distributor that acts like a camshaft sensor.
The computer uses it to determine the proper advance/retard of the timing.
So, without the SPOUT connection plugged in, the ignition timing is being determined by the PIP (Ignition Pick-up) signal being generated by the leading edge of the vane in the distributor's Hall effect contraption. He probably set it somewhere around 10° BTDC.
We can assume he got the got the leading edge of the Vane correctly positioned at the center point of the Hall effect stator when he put the new distributor in. (otherwise the truck wouldn't start using only the PIP signal) (which once again is generated by the leading edge of the vane that has to be properly timed in relationship to the center of the hall effect stator in the distributor)
The PIP signal is providing the ECM's reference for the engine's speed and position.
But when he plugs in the SPOUT and turns control of timing (spark advance/retard) to the computer, it doesn't work.
Once again, if memory serves me, the SPOUT signal is determined by the trailing edge of that vane.
This has me thinking that the SPOUT voltage is somehow being degraded.
If the leading edge of the vane is reporting the correct PIP timing, then the trailing edge of the vane should be determining the correct SPOUT.
So this has me thinking, "shorted/corroded wires in the circuit dragging the SPOUT voltage down."
I think at this point he should check voltages coming from the power relay to the TFI connection and the voltage between his "SPOUT out" from the computer to his TFI connection.
This is a 30 year old truck. My bet is that some wires /connections have either, through engine compartment heat (after 30 years) or just age, shedded their insulation and are being partially or completely grounded causing insufficient voltage.
Here’s a TFI Worksheet that provides step by step instructions to diagnose TFI voltages.
If anyone can provide the "pin voltages" of the relay that provides power it might be of help.
If I remember, back in the early 2000 years they were selling "pigtail" connections with that relay socket because there was a huge problem with the wiring shorting out.
Thank you very much It will run with the spout out then when you put it back in it dies but not all the time. Someone put a new crate engine about 4 years ago and it has done this since them my friend has said so do you think it could be one notch off the timing
I haven't given up on that 89 F150 you're working on.
If you have doubts about the timing being set correctly then definitely redo the timing.
I think the initial timing for that 302 is 10 to 14 degrees BTDC.
(check to be sure).
But as I work your problem over in my head I keep coming back to a failure in the PIP/SPOUT signals.
From your last post, I think you're saying that the truck doesn't consistently start with the SPOUT unplugged.
But it does sometimes.
So this has me thinking about a faulty Hall effect pickup in the distributor. (since I presume you've already looked carefully for damaged wires and connections, not only at the TFI module but tracing all the wires connected to that module to/from the computer and from the power relay )
But then, after re-examining your top post, you said that you replaced that pickup in the distributor.
So, you had to pull the distributor to do that.
Let's get back to basics.
You definitely have to redo the timing since you pulled the distributor and have a No Start condition.
But you say the thing has started on occasion (SPOUT unplugged) but not always.. So, that's perplexing.
If you've checked your wiring and connections to be sure everything is good,
and after you redo the timing, if the problem persists and I hate to be "hard headed", but this keeps coming back to a faulty Hall effect issue and at this point I'm still looking squarely at that Hall effect stator/pickup coil in the distributor.
Sounds like the Spout circuit may have a problem. The Yel-Lt Grn wire comes out of the Ignition Module and goes to the Spout connector. From the Spout connector it goes to Pin 36 of the ECM.
I would remove the ECM connector and the Ignition Module connector. Check continuity of the Yel-Lt Grn wire. Try wiggling the wiring harness while checking continuity watching for changes.
Check to see if the circuit is shorted to ground.
Check to see if the circuit is shorted to power.
Load the circuit. Put battery voltage to one end of the circuit and a sealed beam headlight to the other end and connect it to ground. The light should burn bright. Again, wiggle the harness and see it affects the test. HTH
