lynchsg
Member
No, spray it down the carb while holding open with your fingerg the choke butterfly and opening the throttle linkage by hand.
Bronco Not Starting (Firing)
- Thread starter lucky7_1080
- Start date
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wyo58
Member
Usually a good place to start on float level is perpendicular to the top plate base. Could you see where all the fuel was coming from in the carb?
wyo58
Member
Sorry parallel!
lynchsg
Member
Holding the top plate and float assembly upside down (with the needle and seat in a closed position).
lynchsg
Member
The fact that you originally got the engine to run back awhile ago and then had these issues leads me down the carb path.
Plug wires could be damaged removing them (or changed) or put in the wrong places when changing plugs also.
Plug wires could be damaged removing them (or changed) or put in the wrong places when changing plugs also.
lynchsg
Member
"(or changed)" meaning put in the wrong places (rotor cap or spark plug location).
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lucky7_1080
New member
****UPDATED****
Hi folks.
So I pulled the carb open this morning, drained the bowl, tested the needle, seat, checked float for air tight, check float level (it's raising just just a hair under parallel with the top of the bowl), drained the intake and let the gas evaporate.
I then crimped the fuel line prior to the pump, pulled the fuel hose of the inlet on the front of the carb (so no fuel is going to carb). Cranked over once to see if it would fire, it did not. Sprayed some starer fluid in the carb, cranked and couldn't get it to fire.
One other thing to note: when I hold the key over and crank the engine for an extended period (5 seconds plus), no fire whatsoever. When I do a good quick crank (~1 second) and let off, you can hear an extremely muffled and weak firing, every third crank or so.
At this point, I'm at a loss. All of the ignition components have been confirmed (save rotor position, i.e. timing). Carb is fully rebuilt and working well. What would you all do as next step? Compression test, pull the front end off and swap gears?
L7
Hi folks.
So I pulled the carb open this morning, drained the bowl, tested the needle, seat, checked float for air tight, check float level (it's raising just just a hair under parallel with the top of the bowl), drained the intake and let the gas evaporate.
I then crimped the fuel line prior to the pump, pulled the fuel hose of the inlet on the front of the carb (so no fuel is going to carb). Cranked over once to see if it would fire, it did not. Sprayed some starer fluid in the carb, cranked and couldn't get it to fire.
One other thing to note: when I hold the key over and crank the engine for an extended period (5 seconds plus), no fire whatsoever. When I do a good quick crank (~1 second) and let off, you can hear an extremely muffled and weak firing, every third crank or so.
At this point, I'm at a loss. All of the ignition components have been confirmed (save rotor position, i.e. timing). Carb is fully rebuilt and working well. What would you all do as next step? Compression test, pull the front end off and swap gears?
L7
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wyo58
Member
Two things to check: Like Lynch said did you pull the wires off of the cap and maybe placed them back in the wrong place? If not then you will have to find top dead center of #1 cylinder and check where the rotor is pointing in relation to the distributor cap. If it is off then it is quite possible that the timing chain has slipped.
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lucky7_1080
New member
I never pulled any wires off of the cap, and made sure that all wires were placed properly back on the appropriate plugs. I just triple checked as the only thing that could have happened is the harness “flipped over” while I was replacing the plugs. Everything is back in place in the right spot.
I’d love some additional guidance on how to get the engine to TDC on cylinder 1 to confirm that the rotor is pointing to that cylinder. Once the engine is in the right position, would I mark the outside of the distributor cap to confirm its right on.
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lucky7_1080
New member
@Motech Any thoughts on next steps?
lynchsg
Member
By yourself (that's what I do), put, I think, a 15/16" socket on the crankshaft pulley nut and use a ratchet or breaker bar to turn the engine (Trans in neutral) to the TDC (top dead center) mark on the crankshaft pulley mark and the timing pointer.
The rotor (cap off) should be on the #1 position spark plug location of the distributer cap terminal going to #1 spark plug (fwd right side viewed from cab).
If it is 180° out on the distributor, then turn crankshaft another 360°. (Crankshaft turns twice to the camshaft and distributor on a 4 cycle engine.) I have to leave for a couple of hours and will look to see what others say.
It may be just moving the distributor a little to get timing better...
The rotor (cap off) should be on the #1 position spark plug location of the distributer cap terminal going to #1 spark plug (fwd right side viewed from cab).
If it is 180° out on the distributor, then turn crankshaft another 360°. (Crankshaft turns twice to the camshaft and distributor on a 4 cycle engine.) I have to leave for a couple of hours and will look to see what others say.
It may be just moving the distributor a little to get timing better...
lynchsg
Member
Again, you had it running enough to move it before this issue, correct?
Hopefully nother moved, i.e. timing chain jumped or crank pulley spun.
Did you put new gas in the tank. I don't remember if you said you did earlier in this string of posts?? I thought you said it had rained a lot.
Not starting on starting fluid is a question. 3-5 second spray with choke butterfly and throttle wide open, then close throttle and try starting engine as usually done.
Better with 2 people because as you try starting it in the cab, another person can spray a little more in while you crank the engine.
Hopefully nother moved, i.e. timing chain jumped or crank pulley spun.
Did you put new gas in the tank. I don't remember if you said you did earlier in this string of posts?? I thought you said it had rained a lot.
Not starting on starting fluid is a question. 3-5 second spray with choke butterfly and throttle wide open, then close throttle and try starting engine as usually done.
Better with 2 people because as you try starting it in the cab, another person can spray a little more in while you crank the engine.
Motech
Well-known member
Just triple check your float adjustment. Be sure you're not crossing your float LEVEL adjustment (critical) with your float DROP adjustment (non-critical)
Also make sure the needle is sealing well against the seat, and that the brass seat section is torqued well I'm the bowl with a good seal at the round washer gasket.
And then, when reassembled, open the choke valve but NOT the throttle and watch down the carburetor throat during initial float fill-up cranking to see where all that fuel is coming from.
Hint:
If you don't have a remote starter switch you're using on the solenoid relay to crank the engine over without key on, then pull coil wire from cap, ground it to engine and have a helper crank it with key while you peer into carb.
Use a bright light too. The source of that much fuel should be easy to spot.
Also make sure the needle is sealing well against the seat, and that the brass seat section is torqued well I'm the bowl with a good seal at the round washer gasket.
And then, when reassembled, open the choke valve but NOT the throttle and watch down the carburetor throat during initial float fill-up cranking to see where all that fuel is coming from.
Hint:
If you don't have a remote starter switch you're using on the solenoid relay to crank the engine over without key on, then pull coil wire from cap, ground it to engine and have a helper crank it with key while you peer into carb.
Use a bright light too. The source of that much fuel should be easy to spot.
This part caught my attention. I wonder if the battery voltage is too low, or starter drawing too much and not leaving enough voltage for the ignition module to fire.
Wasn't there something in these related to only firing when letting off the key, from start to run cycle? Hmmm, can't remember.
Anyway, You pinched the fuel line. Then if you are holding the choke open, and holding the pedal to the floor that should clear the flooded condition after just a few revolutions.
But I still kinda think you are losing spark. It won't fire on starting fluid. In won't fire when clearing the flood.
It should be backfiring through the intake or exhaust or spitting or popping or something and the only time you got something was with a quick once second spin.
I would leave the fuel line pinched and focus on trying to get it to start on Starting fluid. They should always run, or pop on starting fluid. Once you have achieved that you know the cylinders are dry and ready for fuel. Then un pinch the fuel line and try it.
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lucky7_1080
New member
@Tiha Thanks. Check my voltage testing here at the ignition coil:
(Battery is at 12v, due to cranking, have on tender now and bringing it back up to 14v)
+ and - connectors attached to coil: 5.6v across the coil, 6.5v from positive side of coil to block or battery.
+ connection removed from coil: 11.6v from connector to negative side of coil, and same at block and negative side of battery.
In short: Should I be reading battery voltage across the coil, or is there meant to be resistance?
What should voltage be across the coil when cranking?
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lucky7_1080
New member
@lynchsg
Ok. Dug into this a bit more and found some wierdness. First, I pulled this firing order diagram for reference for the 400:
Couple things right off the bat: the wires are in the correct order but my number one starts at the number eight position as per the above diagram. I recognize that this is not the correct position, however this is how the truck has been running.
I then popped it into neutral and pulled it up to TDC. I pulled the cap off and checked the rotor position and it was sitting around the 6th cylinder per the diagram above. Then I rotated the crank another 360 and the rotor is lining up with my number one cylinder (even though in wrong position).
Couple things here:
1) The rotor didn’t rotate 180, more like 270.
2) While I was manually cranking the crank bolt, the passenger side of the engine would audibly pop (soft) after I’d cranked the it.
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lucky7_1080
New member
@Tiha Thanks. I had my wife crank it over just now with fuel line disconnected, fuel line crimped etc. I was able to get it to fire with starting fluid but couldn’t keep it running. It was still struggling to fire and run at full RPMs. This is what I experienced when the initial issue presented itself. Given the rotor button position, concerned that this in fact may be a timing issue.
lynchsg
Member
With the key is in the Run position, the positive side of the coil needs to see as close to battery voltage (12.5V) as possible. Mine drops to 11.6V. Which would be the same on the negative side of the coil. A resistor in the ignition prevents a large voltage drop to the coil from the starter voltage draw during cranking. When the key returns to Run, that resistor circuit is removed.
As far as the voltage across the coil, I am not sure what it should be. I don't have a remote starter, am by myself and can't see my voltmeter from the cab when cranking.
Someone else know???
As far as the voltage across the coil, I am not sure what it should be. I don't have a remote starter, am by myself and can't see my voltmeter from the cab when cranking.
Someone else know???
lynchsg
Member
The distributor rotor should turn once for every 2 turns of the crank.
A pop followed by a hiss is compression in the cylinders during rotation of the crank.
Rotor not in sync with the crank rotation and a pop heard while rotating only once is not good! Timing chain or distributor drive gears (cam or distributor) are possibly bad?
A pop followed by a hiss is compression in the cylinders during rotation of the crank.
Rotor not in sync with the crank rotation and a pop heard while rotating only once is not good! Timing chain or distributor drive gears (cam or distributor) are possibly bad?
#1 wire position can be anywhere. The manual shows a factory location, but like you did, you popped the cap at TDC and it was at 1 or 6. So that should be fine.
But you said it rotates like 270 degrees?
Might want to rotate the engine a few times with the cap off. Make sure the rotor doesn't skip, or ends in the same place. If it keeps moving your timing chain is jumping.
The coil is marked with a + and -, or pos and neg. Or even batt. and ground.
Positive side or + side should have 12 volts. The negative side should pulse or flash when using a test light.
Testing across the terminals is only good with an ohm meter for a resistance reading
But you said it rotates like 270 degrees?
Might want to rotate the engine a few times with the cap off. Make sure the rotor doesn't skip, or ends in the same place. If it keeps moving your timing chain is jumping.
The coil is marked with a + and -, or pos and neg. Or even batt. and ground.
Positive side or + side should have 12 volts. The negative side should pulse or flash when using a test light.
Testing across the terminals is only good with an ohm meter for a resistance reading
