When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
1986 4speed manual. Have checked clutch interlock, previous owner has already bypassed clutch interlock. Next on my suspect list is Bosch relay on engine inner guard, 4 wires from ignition go there before heading across to engine. Any ideas or new advice would be greatly appreciated.
Starter isn't spinning? Did this pop up out of no where? Is this a daily driver or did it sit for awhile before it happened? Have you checked to make sure you've got signal from the ignition to the starter solenoid?
On one occasion a year ago it wouldnt start, I came back an hour later and it started. I had been driving it prior to both instances of no cranking. I plan to replace Bosch relay that maybe not working and hence not sending signal to starter solenoid. Thanks for your help.
Be warned, aftermarket starter solenoids are mostly garbage, dead out of the box. Big thread here talking about it. https://www.ford-trucks.com/forums/1...i-mean-it.html It could also be your key cylinder sticking or a worn or misaligned ignition switch as well as bad connections to the battery or starter ground. Use a multimeter or a test light to make sure you have power on the ignition wire when you turn the key.
Not trying to bust your butt, but it's best to keep everything in one thread, otherwise info can get overlooked.
And then you mention the "Bosch relay". Can you please post a picture? This is what comes to mind for a Bosch relay:
There's a similar version without the mounting tab on top, and is made to plug into a socket. As far as I know, Ford didn't use these either type of "Bosch" style relays on our trucks, especially in the starter control circuit. That makes me think you've got some kind of wiring modification. A picture or two would really help.
And then you mentioned "Bosch relay ... sending signal to starter solenoid". You totally lost me there. Please define "starter solenoid". Are you talking about the big relay inside the passenger fender, just aft of the battery? That is technically the starter relay, but is often (incorrectly) called the starter solenoid. Or are you talking about a conventional "starter solenoid" mounted on the side of the starter? Except for diesel models, Ford trucks of this era didn't have a solenoid on the starter itself. More than you ever wanted to know about the starter system here, including details of the somewhat confusing terminology:
For troubleshooting your no-crank condition, identify the small S terminal on the side of the big starter relay. (Remember, I'm talking about the unit just aft of the battery.) Normally, when you turn the key to Start, power is routed through the ignition switch to this S terminal. Without this signal, the starter relay won't close. Here are two easy tests to run before changing any parts:
1) Remove the wire from this small S terminal. Connect your voltmeter's red lead to this wire. Connect the voltmeter's black lead to the battery's (-) terminal. Turn the key to start and you should see battery voltage. If not, you need to troubleshoot why. This control circuit goes through the ignition switch and clutch interlock switch. Wiring diagram here, you're looking at wire 32 (red with light blue hash marks) at the starter relay:
2) With this wire still removed and the ignition switch off, make sure the transmission is in neutral and the parking brake is applied. For this test, the starter should engage, even though the engine won't start. Momentarily connect a short jumper wire from the battery's (+) terminal to the small S terminal on the side of the starter relay. This mimics the normal start signal via the ignition switch. If all is well, you should hear a big clunk from the starter relay and the starter should engage.
Please try these two simple tests and tell us what happens. The results will determine the next troubleshooting steps.
Oh, I almost forgot. Make sure your battery is fully charged before any electrical troubleshooting. Please don't skip this important step. I recommend charging the battery overnight on an automatic charger with at least a ten amp output. A trickle charger won't cut it.
Not trying to bust your butt, but it's best to keep everything in one thread, otherwise info can get overlooked.
And then you mention the "Bosch relay". Can you please post a picture? This is what comes to mind for a Bosch relay:
There's a similar version without the mounting tab on top, and is made to plug into a socket. As far as I know, Ford didn't use these either type of "Bosch" style relays on our trucks, especially in the starter control circuit. That makes me think you've got some kind of wiring modification. A picture or two would really help.
And then you mentioned "Bosch relay ... sending signal to starter solenoid". You totally lost me there. Please define "starter solenoid". Are you talking about the big relay inside the passenger fender, just aft of the battery? That is technically the starter relay, but is often (incorrectly) called the starter solenoid. Or are you talking about a conventional "starter solenoid" mounted on the side of the starter? Except for diesel models, Ford trucks of this era didn't have a solenoid on the starter itself. More than you ever wanted to know about the starter system here, including details of the somewhat confusing terminology:
For troubleshooting your no-crank condition, identify the small S terminal on the side of the big starter relay. (Remember, I'm talking about the unit just aft of the battery.) Normally, when you turn the key to Start, power is routed through the ignition switch to this S terminal. Without this signal, the starter relay won't close. Here are two easy tests to run before changing any parts:
1) Remove the wire from this small S terminal. Connect your voltmeter's red lead to this wire. Connect the voltmeter's black lead to the battery's (-) terminal. Turn the key to start and you should see battery voltage. If not, you need to troubleshoot why. This control circuit goes through the ignition switch and clutch interlock switch. Wiring diagram here, you're looking at wire 32 (red with light blue hash marks) at the starter relay:
2) With this wire still removed and the ignition switch off, make sure the transmission is in neutral and the parking brake is applied. For this test, the starter should engage, even though the engine won't start. Momentarily connect a short jumper wire from the battery's (+) terminal to the small S terminal on the side of the starter relay. This mimics the normal start signal via the ignition switch. If all is well, you should hear a big clunk from the starter relay and the starter should engage.
Please try these two simple tests and tell us what happens. The results will determine the next troubleshooting steps.
Oh, I almost forgot. Make sure your battery is fully charged before any electrical troubleshooting. Please don't skip this important step. I recommend charging the battery overnight on an automatic charger with at least a ten amp output. A trickle charger won't cut it.
Shoot, wish I had thought to say that,is it too late to change my answer?
Really appreciate all the helpful advice so far. Well after completing those 2 tests and tightening positive terminal on battery I have engine cranking!! But no start, no smell of fuel so maybe the engine isn't getting fuel? I can hear fuel pump priming. Front tank is on 1/4 rear tank empty
Really appreciate all the helpful advice so far. Well after completing those 2 tests and tightening positive terminal on battery I have engine cranking!! But no start, no smell of fuel so maybe the engine isn't getting fuel? I can hear fuel pump priming. Front tank is on 1/4 rear tank empty
Put a little fuel in the rear and try it again. When the fuel switching system fails it defaults to the rear tank. If it fires after you put a couple of gallons of fuel in the rear tank we'll know to troubleshoot the switching system. If it still doesn't fire we'll test other stuff.
Making progress! You've gone from a no-crank to a no-start. Still wondering about the mystery Bosch relay, though.
There's another quickie troubleshooting trick you can try, using a can of starting fluid. But first, raise your right hand and repeat the following:
I, (insert name) [really say your name, not just "insert name"], do solemnly swear I will follow these steps EXACTLY as written. If I disobey them, I shall be forced to listen to a Justin Bieber Christmas album on a continuous loop for the rest of my natural days.
1) Prepare a sturdy medium sized box, one with a hasp and padlock.
2) Spray a 3 second burst of starting fluid into the air cleaner inlet.
3) Working quickly, place the can into the box and lock it securely.
4) Throw the padlock key as far as you can, so it will take you at least 20 minutes to find it. Toss it in the grass, a gravel pit, the back of a passing truck, etc. Use your imagination and put some effort into it. Make us proud of you.
5) Still working quickly, try to start the truck. (This may be too late to mention now, but don't keep the truck key on the same keychain as the padlock key.)
6) If the engine starts, even if only briefly, then you know the ignition system is in reasonably good working order and the problem lies with the fuel delivery system (carb, fuel pump, filter, etc.)
7) If the engine never fires (or even coughs) on the starting fluid, then you know you've got an ignition problem.
The business with the locking box for the starting fluid? That's to keep you from trying more than a single 3-second blast. This is not a case of more is better. If the engine doesn't respond to that initial shot, then stop. Shift mental gears and troubleshoot the ignition system. More starting fluid is NOT the answer. Don't keep trying more and more. Unless you want to explode your muffler and/or oil pan...
Making progress! You've gone from a no-crank to a no-start. Still wondering about the mystery Bosch relay, though.
There's another quickie troubleshooting trick you can try, using a can of starting fluid. But first, raise your right hand and repeat the following:
I, (insert name) [really say your name, not just "insert name"], do solemnly swear I will follow these steps EXACTLY as written. If I disobey them, I shall be forced to listen to a Justin Bieber Christmas album on a continuous loop for the rest of my natural days.
1) Prepare a sturdy medium sized box, one with a hasp and padlock.
2) Spray a 3 second burst of starting fluid into the air cleaner inlet.
3) Working quickly, place the can into the box and lock it securely.
4) Throw the padlock key as far as you can, so it will take you at least 20 minutes to find it. Toss it in the grass, a gravel pit, the back of a passing truck, etc. Use your imagination and put some effort into it. Make us proud of you.
5) Still working quickly, try to start the truck. (This may be too late to mention now, but don't keep the truck key on the same keychain as the padlock key.)
6) If the engine starts, even if only briefly, then you know the ignition system is in reasonably good working order and the problem lies with the fuel delivery system (carb, fuel pump, filter, etc.)
7) If the engine never fires (or even coughs) on the starting fluid, then you know you've got an ignition problem.
The business with the locking box for the starting fluid? That's to keep you from trying more than a single 3-second blast. This is not a case of more is better. If the engine doesn't respond to that initial shot, then stop. Shift mental gears and troubleshoot the ignition system. More starting fluid is NOT the answer. Don't keep trying more and more. Unless you want to explode your muffler and/or oil pan...
I think you're over thinking it. I took the air inlet off my early 90's ranger today and dumped chainsaw gas all over the engine and down the throttlebody. After about the fifth crank(20-30s) she burst to life. Literally. Set the whole engine bay on fire. Purdy fireball though. Looks like I only lost one vacuum line, believe it or not.
Appreciate the entertaining and informative advice guys! Here is photo of the mysterious bosch relay that is located on drivers side inner fender. Will try and get out to truck today to try ether 3 second spray and throw away..
Here is photo of the mysterious bosch relay that is located on drivers side inner fender.
I'd be willing to bet your reputation that relay installation is an aftermarket or homebrew modification. If factory, the wiring would typically have one big connector with built-in sockets. Instead, you've got individual crimped terminals.
My best guess is it's part of the lighting circuit, either for the headlights or trailer/camper wiring. Put your finger on the relay and feel for a click while a helper turns on the lights. If a click is felt, the relay is energized with the lights. With the lights on, unplug any of those four terminals and the controlled circuit should go dead.
Well I put some fuel in rear tank, then sprayed ether into inlet manifold for 3 seconds. Then cranked her over. There was no start, no firing, no coughing. And no Justin bieber!! What's next? Obviously no spark...
