'92 5.0 Cranks but won't start...
02-01-2015, 08:14 PM
#1
'92 5.0 Cranks but won't start...
Hello.
First post here, but I've had experience with these trucks for a few years on different models.
So far, I've isolated the problem to being a positive ground.
The ICM is good, because I have fuel pressure when I turn the ignition to the run position at the shrader valve on the driver's side rail. When the engine cranks, I get spark when I disconnect a wire from the plug, or even at the coil, so I know the relays are good.
I've checked every single fuse and pulled and tripped each relay with test jump leads and a multimeter and all are good.
I have 12 volts at the feed/ common color on the injectors in run and start positions on the ignition switch as well.
It does not respond to extra strength starting fluid shot down the barrels with the throttle plates open.
I didn't understand why it was not responding to starting fluid with spark showing at the coil and wires, so I went ahead and pulled a spark plug to see if it was showing mechanical damage.
What I discovered was that the spark plug has good kernel, but only when the housing/ threads are not touching a ground source. When the plug is grounded like it should be, I have absolutely no spark.
This tells me that the thing has a positive ground somewhere, that is not blowing a single fuse. I've checked the Inertia switch, even though it just shuts the fuel off and it is in the correct, down position.
When I put the multimeter on the pos and neg terminals of the battery cables, with the ignition coil feed plug disconnected and positive cable disconnected from the battery, I show no continuity in off and solid contact between pos and neg in both run and start positions.
The owner of this truck said that it happened after he had a blowout, which could mean something or nothing. My first thought was the inertia switch or something fuel related, but I've got solid fuel.
I can't check timing, because I only get signal on the light, when I disconnect the wire or plug and break the ground from the engine.
Is there a common problem on these trucks that can cause a solid grounded positive that does not blow fuses or relays?
Any info is greatly appreciated.
Dave
First post here, but I've had experience with these trucks for a few years on different models.
So far, I've isolated the problem to being a positive ground.
The ICM is good, because I have fuel pressure when I turn the ignition to the run position at the shrader valve on the driver's side rail. When the engine cranks, I get spark when I disconnect a wire from the plug, or even at the coil, so I know the relays are good.
I've checked every single fuse and pulled and tripped each relay with test jump leads and a multimeter and all are good.
I have 12 volts at the feed/ common color on the injectors in run and start positions on the ignition switch as well.
It does not respond to extra strength starting fluid shot down the barrels with the throttle plates open.
I didn't understand why it was not responding to starting fluid with spark showing at the coil and wires, so I went ahead and pulled a spark plug to see if it was showing mechanical damage.
What I discovered was that the spark plug has good kernel, but only when the housing/ threads are not touching a ground source. When the plug is grounded like it should be, I have absolutely no spark.
This tells me that the thing has a positive ground somewhere, that is not blowing a single fuse. I've checked the Inertia switch, even though it just shuts the fuel off and it is in the correct, down position.
When I put the multimeter on the pos and neg terminals of the battery cables, with the ignition coil feed plug disconnected and positive cable disconnected from the battery, I show no continuity in off and solid contact between pos and neg in both run and start positions.
The owner of this truck said that it happened after he had a blowout, which could mean something or nothing. My first thought was the inertia switch or something fuel related, but I've got solid fuel.
I can't check timing, because I only get signal on the light, when I disconnect the wire or plug and break the ground from the engine.
Is there a common problem on these trucks that can cause a solid grounded positive that does not blow fuses or relays?
Any info is greatly appreciated.
Dave
02-01-2015, 08:36 PM
#2
Does the neutral safety allow the starter to run?
If it does, I suppose this could be the problem.
Edit:
Just tried starting it in gear. It cuts power to the starter. Tried staring it in neutral, does the same thing as in park/ cranks and no ignition.
If it does, I suppose this could be the problem.
Edit:
Just tried starting it in gear. It cuts power to the starter. Tried staring it in neutral, does the same thing as in park/ cranks and no ignition.
Last edited by DaveBonds; 02-01-2015 at 08:46 PM.
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DaveBonds (02-02-2015)
02-02-2015, 07:15 PM
#4
Ok, so if I have this right,
The PIP on the distributor sends separate signals to the ICM and fuel injection, under start mode and then the fuel injection computer runs both once it starts?
I thought perhaps they were tied together all the time, but as I'm reading this and flipping through some ICM articles, the fuel system is apart from the ICM and the ignition is only controlled by the fuel injection computer, once it starts. I think that's what confused me.
It looks like the ICM's job is to open and close the coil. I get coil sparking, when the coil wire is disconnected from the coil or distributor. It will find a ground and I get a good kernel. The only time I do not see spark is when everything is connected, all the way to the plug and the plug is either contacting ground/ or threaded into place in the head.
I've seen this problem on motorcycles when spark plugs go solid contact between the insulated positive electrode and the ground electrode/ housing. It will throw a spark in the gap when it is not contacting anything and simply act as one wire/ complete circuit when its grounded and no energy is expelled at the gap, since it is technically closed against a ground source at that point.
I'll check the plugs with my multimeter and work my way back through the feed wire and trigger wire on the coil, back through the feed wire on the distributor and see how far back this goes.
Thanks for the heads up.
The PIP on the distributor sends separate signals to the ICM and fuel injection, under start mode and then the fuel injection computer runs both once it starts?
I thought perhaps they were tied together all the time, but as I'm reading this and flipping through some ICM articles, the fuel system is apart from the ICM and the ignition is only controlled by the fuel injection computer, once it starts. I think that's what confused me.
It looks like the ICM's job is to open and close the coil. I get coil sparking, when the coil wire is disconnected from the coil or distributor. It will find a ground and I get a good kernel. The only time I do not see spark is when everything is connected, all the way to the plug and the plug is either contacting ground/ or threaded into place in the head.
I've seen this problem on motorcycles when spark plugs go solid contact between the insulated positive electrode and the ground electrode/ housing. It will throw a spark in the gap when it is not contacting anything and simply act as one wire/ complete circuit when its grounded and no energy is expelled at the gap, since it is technically closed against a ground source at that point.
I'll check the plugs with my multimeter and work my way back through the feed wire and trigger wire on the coil, back through the feed wire on the distributor and see how far back this goes.
Thanks for the heads up.
02-02-2015, 08:05 PM
#6
Try some new plugs, maybe.
Your post has me a little confused.
If you have power to the wires and all the way to the plug, how can the plug fire if it's not grounded ? That's a positive charge coming through the wire, you shouldn't be able to get a spark unless the spark has a way to return to ground.
Am I missing something here ?
Anyway, if you did actually have a spark, starting fluid should have done something, the only thing I figured I'd throw out there is that having pressure at the schrader valve is not the same thing as having enough pressure. If you didn't use a gauge to check it, you should. If you did, and you're looking at around 40 psi, then I'd go to the electrical (ignition). ICM, PIP or coil (presuming your cap, rotor and wires are good.
Your post has me a little confused.
If you have power to the wires and all the way to the plug, how can the plug fire if it's not grounded ? That's a positive charge coming through the wire, you shouldn't be able to get a spark unless the spark has a way to return to ground.
Am I missing something here ?
Anyway, if you did actually have a spark, starting fluid should have done something, the only thing I figured I'd throw out there is that having pressure at the schrader valve is not the same thing as having enough pressure. If you didn't use a gauge to check it, you should. If you did, and you're looking at around 40 psi, then I'd go to the electrical (ignition). ICM, PIP or coil (presuming your cap, rotor and wires are good.
02-09-2015, 08:35 PM
#7
Ok, so I think I've corrected SOME of the issue here.
The PIP signal was there, but something in the original distributor was sending positive and negative electrode charge through the spark end of the ignition system, without ground.
This is why none of the fuses or relays were bad and I was getting spark, when I shouldn't have. I was seeing positive and negative charge trying to discharge somewhere, with the plug just hanging.
I have replaced the distributor and the spark kernel is there and bright, when the plug is grounded against the engine or car, somewhere and I get nothing when its just hanging. So, the spark is doing what it should, now. That changed and is corrected, as best I can tell.
I have not checked fuel pressure, but this is still not responding to extra strength starting fluid.
I can smell fuel from the exhaust and I just put 2 1/2 gallons into the front tank. the tank switch is set to front and that was what was there, when I checked the valve without a gauge.
If I can get one over here, I will do that, next, but the fact that this is not responding to starter fluid and I have now confirmed spark, leads me to believe that this was a spark issue and is now a timing issue.
I replaced the timing chain, because it was worn out and I set the gears dot to dot. The double roller had the option of going 0° +4° and for some reason -4° with three different crank gear keyways.
With it in mind that I didn't want to try and get anything else out of this engine, I opted for 0°, just to keep everything the same.
When I pulled the distributor out, I put the rotor back into place where it was. I pulled the #1 plug out and cranked the engine with my finger over the plug hole to feel compression, to confirm that it was coming up on TDC compression cycle, to have the rotor at the #1 plug wire terminal on the cap, when I manually cranked it the rest of the way to 0° on the balancer. My timing light shows it at around 10° advanced from the faint timing marks that it does have. I masked a stripe at zero and hit it with some neon orange paint so I could see it and set my timing light to zero advance, to watch the balancer's advance mark.
I toyed with the distributor, back and fourth across about -25° to +25° at the pointed end of the sheet metal timing marker that has the ring on it, while cranking the engine.
I was able to get it to kick a few times, on its own, without starting fluid, as I cranked it, while hitting it with the timing light.
I don't hear any oddities in compression, when it cranks. It sounds like it did before. I have not checked leakdown or overall compression, yet, but I'm about to.
I took a picture of the gear positions on the timing set, before I put the cover on, so I could look at them later on and keep peace of mind. They are dead on.
Am I missing something? I don't think its fuel related, because it would have responded to starter fluid and it is trying to run every so often, when its been cranking for a few revolutions with breaks in between, to let the starter cool.
I have the battery on a charger.
The firing order that I am following is 1-5-4-2-6-3-7-8. 1-2-3-4 on the right (vehicle's right), from the front and 5-6-7-8 on the left (vehicle's left), from the front. #1 position at the back of the cap, just left (vehicle's left) of center.
This was the order that the original cap was also in.
I still think I messed up the timing, but my timing light, wire locations, compression cycle coming up when the #1 plug is out, in accordance with the rotor position coming up to #1 on the cap all tell me its not timing?
I'm still convinced I messed something up or I am missing something.
The PIP signal was there, but something in the original distributor was sending positive and negative electrode charge through the spark end of the ignition system, without ground.
This is why none of the fuses or relays were bad and I was getting spark, when I shouldn't have. I was seeing positive and negative charge trying to discharge somewhere, with the plug just hanging.
I have replaced the distributor and the spark kernel is there and bright, when the plug is grounded against the engine or car, somewhere and I get nothing when its just hanging. So, the spark is doing what it should, now. That changed and is corrected, as best I can tell.
I have not checked fuel pressure, but this is still not responding to extra strength starting fluid.
I can smell fuel from the exhaust and I just put 2 1/2 gallons into the front tank. the tank switch is set to front and that was what was there, when I checked the valve without a gauge.
If I can get one over here, I will do that, next, but the fact that this is not responding to starter fluid and I have now confirmed spark, leads me to believe that this was a spark issue and is now a timing issue.
I replaced the timing chain, because it was worn out and I set the gears dot to dot. The double roller had the option of going 0° +4° and for some reason -4° with three different crank gear keyways.
With it in mind that I didn't want to try and get anything else out of this engine, I opted for 0°, just to keep everything the same.
When I pulled the distributor out, I put the rotor back into place where it was. I pulled the #1 plug out and cranked the engine with my finger over the plug hole to feel compression, to confirm that it was coming up on TDC compression cycle, to have the rotor at the #1 plug wire terminal on the cap, when I manually cranked it the rest of the way to 0° on the balancer. My timing light shows it at around 10° advanced from the faint timing marks that it does have. I masked a stripe at zero and hit it with some neon orange paint so I could see it and set my timing light to zero advance, to watch the balancer's advance mark.
I toyed with the distributor, back and fourth across about -25° to +25° at the pointed end of the sheet metal timing marker that has the ring on it, while cranking the engine.
I was able to get it to kick a few times, on its own, without starting fluid, as I cranked it, while hitting it with the timing light.
I don't hear any oddities in compression, when it cranks. It sounds like it did before. I have not checked leakdown or overall compression, yet, but I'm about to.
I took a picture of the gear positions on the timing set, before I put the cover on, so I could look at them later on and keep peace of mind. They are dead on.
Am I missing something? I don't think its fuel related, because it would have responded to starter fluid and it is trying to run every so often, when its been cranking for a few revolutions with breaks in between, to let the starter cool.
I have the battery on a charger.
The firing order that I am following is 1-5-4-2-6-3-7-8. 1-2-3-4 on the right (vehicle's right), from the front and 5-6-7-8 on the left (vehicle's left), from the front. #1 position at the back of the cap, just left (vehicle's left) of center.
This was the order that the original cap was also in.
I still think I messed up the timing, but my timing light, wire locations, compression cycle coming up when the #1 plug is out, in accordance with the rotor position coming up to #1 on the cap all tell me its not timing?
I'm still convinced I messed something up or I am missing something.
Last edited by DaveBonds; 02-09-2015 at 08:40 PM.
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02-09-2015, 08:44 PM
#8
Compression stroke, up to 10 degrees before TDC, the dist. rotor should be pointing exactly at #1 on the cap.
One of the bumps on the distributor shaft should be at the signal pickup on the PIP.
That should be close enough to run.
Remove the SPOUT plug (near the brake booster) to set timing with a light. 10 degrees BTDC. Reinsert SPOUT plug.
Note ; make sure you are using the correct timing marks and the correct timing positioner.
One of the bumps on the distributor shaft should be at the signal pickup on the PIP.
That should be close enough to run.
Remove the SPOUT plug (near the brake booster) to set timing with a light. 10 degrees BTDC. Reinsert SPOUT plug.
Note ; make sure you are using the correct timing marks and the correct timing positioner.
02-09-2015, 08:54 PM
#10
Ok, so a plug needs to be disconnected in order to time this thing. I think that's the missing link. I'm guessing that the computer is adjusting it, when I don't want it to?
I do have the timing light inductive pickup on the wire that is going from the terminal on the cap at the rear, just to the left, which I've looked up online and have determined to be #1. I chased the wire to the front, passenger side plug and followed the diagram for the rest. That makes me confident that I did the right thing.
I'm betting my ignition/PIP for fuel is WAY off, because I didn't know about the diagnostic/ spout plug to be disconnected.
I will give that a try and re-time it accordingly. The timing arrow on the sheet metal timing marker is what I'm trying to set to 10°, correct? I'm not sure what the ring is for, that is counter-clockwise, on it, but I'm aiming for the metal point at the most clockwise part of the timing marker that is bolted to the timing cover and the back of the exhaust pump bracket.
I've got my advance on my light set to zero, but I'm tempted to set it to ten, because the marks are very faint, except for the zero mark on the balancer. The 10° marks almost look like zero, with the tiny slashes, but I determined where zero was, based on the incriments from 30° and 20° marks that are easier to read, to make sure that I didn't accidentally mark one of the 10° + or - as zero with my orange paint line.
I do have the timing light inductive pickup on the wire that is going from the terminal on the cap at the rear, just to the left, which I've looked up online and have determined to be #1. I chased the wire to the front, passenger side plug and followed the diagram for the rest. That makes me confident that I did the right thing.
I'm betting my ignition/PIP for fuel is WAY off, because I didn't know about the diagnostic/ spout plug to be disconnected.
I will give that a try and re-time it accordingly. The timing arrow on the sheet metal timing marker is what I'm trying to set to 10°, correct? I'm not sure what the ring is for, that is counter-clockwise, on it, but I'm aiming for the metal point at the most clockwise part of the timing marker that is bolted to the timing cover and the back of the exhaust pump bracket.
I've got my advance on my light set to zero, but I'm tempted to set it to ten, because the marks are very faint, except for the zero mark on the balancer. The 10° marks almost look like zero, with the tiny slashes, but I determined where zero was, based on the incriments from 30° and 20° marks that are easier to read, to make sure that I didn't accidentally mark one of the 10° + or - as zero with my orange paint line.