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Posted: 4/11/2014 10:09:46 PM EDT
Thanks for stopping by.
Here's a brief run down of a problem that has me stumped. I have a 1979 Bronco, 400ci with a C6. It's a pretty stock engine, only mods are a Edelbrock manifold/1406 carb. The truck has been running great for the past 6-9 months. Took her out today to the car wash, cleaned it up. Fired the truck up, drove off no problems...about 1/4mi down the road something starts acting up. The engine stuttered and lost power. I coasted into a parking lot and tried to re-fire it...nothing...hrmm. Pulled it aside and let it sit. Tried to fire it again, it acted like the carb was flooded..okay, let it sit a few min more. Tried to fire it up again...nada...no joy. After repeated attempts to start the truck I got a very loud backfire...still wouldn't start. I checked to see if I was getting spark off the #1 wire, good spark. I have a clear fuel filter, could see good fuel flow to the carb. I did notice a couple of times, the hot lead off of the battery that connects to the hot side of the starter relay had a wisp of smoke coming off of it...bad starter relay? I recently replaced the alternator, didn't replace the alternator regulator. It's the external type that mounts to the inner fender. Haven't replaced the ignition module aka brain...don't know how old it is. I'm stumped. The engine acts like it wants to fire but if I try too many times to start it, I get an awesome backfire. I thought that maybe it could have been that the timing chain snapped or the distributor took a dump. I took the dist cap off to see if the dist gear was turning..it moves. I have air/fuel/spark at the plugs...but not enough to fire the engine. Anyone have a clue as to what I should look at next? I had to have it towed home on a flatbed. To add insult to injury to tow truck driver winched my Bronco up too far on the bed, smashing the rear tire into the "roll bar" light mount of his truck...tacoing the tailgate to hell. What a shitty day. Thanks in advance.
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[#2]
Quoted: So it is cranking but not firing up correct? View Quote Yep. From what I've been finding on the google machine it seems like it's possibly a timing issue...backfiring...maybe the timing chain jumped a tooth? I know that these engines had some type of fiber-plastic timing gear. Maybe that's the culprit. When this occurred the engine was under 3/4 throttle. I was coming out of the car wash, lit up the rears a bit for my son and kept into the throttle while I drove down the road then *poof*, stuttered and died..won't re-start.
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[#3]
Sounds like timing to me. I would try turning the timing down a bit at a time and see if it helps. If that gear is the issue you should be able to tell before you mess around too much.
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[#4]
From a google sniff....
MOST COMMONLY THIS IS A FAULTY DIST PICK UP , OR IGNITION MODULE HERE ARE A FEW TESTS TO DO AND LET ME KNOW WHAT YOU FIND SO WE CAN PINPOINT THE CAUSE HERE ARE A FEW TESTS TO DO AND LET ME KNOW WHAT YOU FIND SO WE CAN PINPOINT THE CAUSE ests/Procedures:1. Check voltage on the Black/Light Green (BK/LG) wire of the ICM with the ignition switch in the Run position with the ICM and distributor connected. Voltage on this circuit should indicate less than 0.2 volts. 2. If voltage is high, supplement the circuit with a ground directly to battery negative and recheck for spark. 3. If the ground checks to be OK, verify battery voltage is present on the ICM Red (RD) wire (this circuit is generally the White/Light Blue (W/LB) wire on the harness side of the connection) with the key in the Run position. 4. Check for battery voltage on the ICM White (W) wire (this circuit is typically Red/Light Blue (R/LB) on the harness side of the connection) with the ignition key in the Crank position). 5. With the key in the Run position and the ICM connected, use a standard 12-volt test light to induce a battery voltage signal into the Orange (O) wire of the ICM creating an on/off signal. This should result in a coil trigger signal on the Dark Green/Yellow (DG/Y) wire which triggers the coil and creates spark. 6. Using the standard 12-volt test light, connect the test light between battery power and the DG/Y wire at the coil and at the ICM. The test light should glow with the key on. 7. If probing the OR wire with 12 volts through the test light does not result in a trigger signal on the DG/Y wire, the ICM is defective. 8. If a trigger signal can be produced and spark created when probing the O wire with the voltage signal, it suggests that the distributor pickup coil is weak. 9. If a trigger signal is produced on the DG/Y wire but no spark is present from the ignition coil, either the coil connection is faulty, or the coil is defective |
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[#5]
Thanks guys.
I didn't have time to break out the multi-meter to check electrics, it was dark by the time I got home I'll dive into it in the morning and see what I can find. *Fingers crossed* that it's something simple.. regulator/module,etc...but I'm thinking that it's a timing issue. If I have to R&R the distributor it'll be a large pain. The A/C compressor is mounted directly in front of the dist...sigh...add another hour to the process.
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[#6]
Take the dist cap off. Turn the motor backwards until the rotor moves.
Turn it forward until it moves again. It shouldn't turn very far. Maybe 10 degrees crank rotation. Turn it around to the timing mark. The rotor should be really close to the #1 wire in the cap. If not, turn it all the way around and check again. This will eliminate or confirm timing chain issues. |
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[#8]
Quoted:
Tried to fire it up again...nada...no joy. After repeated attempts to start the truck I got a very loud backfire...still wouldn't start. I checked to see if I was getting spark off the #1 wire, good spark. View Quote If you have spark, move on. If the spark were weak, I would suggest putting a fresh coil in it. The ignition (module, pickup, etc) typically either works or it does not with this era of Ford electronics. Odds are very good that your timing set is toast. Align the timing pointer with 10 degrees BTDC as marked on your dampener. Your rotor should either be pointed at the #1 cylinder or 180 degrees out depending if it is on the compression or exhaust stroke. This should take you less than 5 minutes and will definitively tell you if you need to start pulling the front of your engine apart. |
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[#9]
Quoted:
Take the dist cap off. Turn the motor backwards until the rotor moves. Turn it forward until it moves again. It shouldn't turn very far. Maybe 10 degrees crank rotation. Turn it around to the timing mark. The rotor should be really close to the #1 wire in the cap. If not, turn it all the way around and check again. This will eliminate or confirm timing chain issues. View Quote yep Check this before anything else. |
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[#10]
Pull the coil wire off the distributor cap and hold it close to the intake manifold, around .30" from it. Have someone crank it over. What color is the spark? Bright blue or orange/red color?
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[#11]
I had an issue with a Ford years ago that sounded a lot like the one
you are dealing with. My engine quit while driving down the road and then would crank without starting while every once in a while it would backfire while cranking. I had looked at the rotor while I cranked it and it turned. What I found was the drift pin that held the distributor gear to the distributor shaft had sheared. Friction allowed it to turn but it had slipped on the shaft and was out of time. I replaced the 10 cent pin and drove on. Just to be sure that this isn't the case just try to turn the rotor by hand. |
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[#12]
Quoted: Pull the coil wire off the distributor cap and hold it close to the intake manifold, around .30" from it. Have someone crank it over. What color is the spark? Bright blue or orange/red color? View Quote I had the coil wire off of the coil, had the wife crank the engine...lots of bright blue spark shooting out of the coil.
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[#13]
Quoted: I had an issue with a Ford years ago that sounded a lot like the one you are dealing with. My engine quit while driving down the road and then would crank without starting while every once in a while it would backfire while cranking. I had looked at the rotor while I cranked it and it turned. What I found was the drift pin that held the distributor gear to the distributor shaft had sheared. Friction allowed it to turn but it had slipped on the shaft and was out of time. I replaced the 10 cent pin and drove on. Just to be sure that this isn't the case just try to turn the rotor by hand. View Quote |
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[#14]
Quoted: Quoted: Take the dist cap off. Turn the motor backwards until the rotor moves. Turn it forward until it moves again. It shouldn't turn very far. Maybe 10 degrees crank rotation. Turn it around to the timing mark. The rotor should be really close to the #1 wire in the cap. If not, turn it all the way around and check again. This will eliminate or confirm timing chain issues. yep Check this before anything else. She said that the rotor would move pretty much as soon as I moved the breaker bar. I had the air cleaner off and happened to notice that the carb seemed like it wanted to back fire, but it would shoot a stream of fuel up out of it. The engine almost starts...like it's 99% of the way there...just won't catch and fire up.
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[#15]
Sounds like it's slow in time.
That's what it'll act like if it jumps time. Did you put it on the timing mark and check the location of the rotor? I bet it jumped a tooth on the top timing gear. |
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[#16]
I know the ignition control module like to go flaky after awhile.
Did you pressure wash the engine? |
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[#17]
sounds just like moisture in the cap to me, happened right after the car wash doesn't take much water in the cap to make the engine backfire and seem like its out of time should of been first thing checked if you haven't already.
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[#18]
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[#19]
Quoted:
sounds just like moisture in the cap to me, happened right after the car wash doesn't take much water in the cap to make the engine backfire and seem like its out of time should of been first thing checked if you haven't already. View Quote Spray the inside of the dizzy with WD40 then try to start it again. |
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[#20]
get a timing light and check the timing if you think it's the timing, simple, easy, effective
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[#21]
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[#22]
Best thing is to put a timing light on it and make sure it's 8-10 degrees advanced.
Also, grab the dizzy by the cap and give it a snug twist, if the dizzy or cap moves more than a hair that's an issue. Tighten the bolt at the base or re-bend the clips that hold the cap, depending on what is loose. Sounds liek you already pulled your plugs. Have you checked for a random vacuum leak or broken/worn hose? Vacuum leaks can affect timing IIRC (all my smog crap is long gone). Then I'd pull the timing cover off and check the marks and slack on the chain. BTW your motor had some significant timing retard cut into thestock cam in order for Ford to meet smog regulations, this can't be fixed without a cam change, but it can be compensated for. Also, the nylon timing teeth were a noise-reducing measure that only stock timing sets had. They are just caps and once they let go they will fall into the oil pan. Any 400 that still has them is well past time for a timing chain change. Use one of these if your cam is stock. BTW I have a 400 in my truck, but the gurus of all things 400 are these guys: http://www.ford-trucks.com/forums/forum54/ You can always PM me if you have questions though. Get the towing company to fix your tailgate. Once you get it fixed the next step is to pull off that Edelbrock and throw it in the trash . I had one on my 400 and replaced it with a Street Demon; the improvement was dramatic. The 400 is a great truck motor; don't let anyone tell you it's a boat anchor. ETA: GET THIS BOOK BEFORE YOU BREAK INTO THE MOTOR: http://www.amazon.com/How-Rebuild-Ford-V-8-Engines/dp/0895860368 |
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[#23]
Quoted:
Best thing is to put a timing light on it and make sure it's 8-10 degrees advanced. View Quote . He likely does not possess a timing light. If he takes the socket he already had on the crank and turns the engine over to align the pointer with the timing marks on the dampener, it will be immediately obvious if it jumped time or not based on the rotor position. |
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[#24]
As long as he remembers that the crank turns twice for every full revolution of the distributor.
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[#25]
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[#27]
Put the distributor back in for a moment and see if you can turn the oil pump drive shaft by turning the rotor. If not, the oil pump is seized.
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[#28]
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[#30]
Make sure you get that book for the engine before tear into it.
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[#31]
OP, did you get my last IM at about 4:30?
I don't know whats' up, my IMs are acting goofy. |
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[#32]
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