Coughing bucking bronco

[tedhas7]

I have a 1977 bronco with the 302 ford. When I bought the bronco it had a fitech with a fuel comand center and after numerous issues, i finally got rid of the fitech, the fuel command center and when back to a carburator.Since it had a 4 barrel intake ( an edlebrock intake) for the fitech, i went back with a edlebrock 4 barrel performer carb. Other than that the bronco is original. when I had the fitech woes, i put new electronic ignition module, new coil, new switch, new battery, pretty much all new electric componentry. I have not tuned it up, but it does not have stock distributor cap or rotor or wires nor plugs. The bronco only has 57000 original miles. The bronco was bought for my daughter.

After we put the carb and got it set and got it running it ran great. It took a little bit to get electric choke right, but it was running good. But then a couple of times as I drove it it acted like the power was cut to it then picked back up, did they several times and then ran fine. I drove several times over the next few days and it did not do it, but then did it again. It never died but just felt like it was losing power, then picked back up, did that several times and then ran fine

So my daughter is driving it tonight and of course I am out of time, and it does the same thing to her and then quits. She can't get it started again. My neighbor and my wife go to get it, and they can't get it started after trying several times, but my neighbor shifts it to neutral and trys to start it and it doesn't start at first but after a few tries starts, He turns it off and then moves it to park and it starts. So my wife gets in it to drive it home and it starts the losing power then picks back up on her as she starts up a hill heading home. It never dies just acts like it but then runs fine the rest of the way home.

last week when i was home, i pulled off distributor cap and there was a build up of corrision on the inside of the contacts of cap, the wires looked old and the rotor looke worn so I bought new cap, rotor plugs and wires to change out this week end, but I don't think the symptoms i have seen would have anything to do with those things. I did notice the star wheel at the bottom of the distributor that rotates with the electric pick up was rusty. i planned to sand the contacts when I tuned it up.

So the question is, any idea based on what i told you, what could be the issue with it that I need to fix to keep it from stranding my daughter on the side of the road as it did tonight. What would cause this lost of power, then pick up, lose power, pick back up, do this 3 or 4 times in a few seconds and then run fine or quit and then not start- The coughing and quiting seem to somehow be related. Electronic ignition pick up? Neutral safety switch? Distributor? Any suggestions and how I can check it would be great or what to fix on it. thanks for any suggestion

 

[tedhas7]

BTW it is an automatic and has had the fuel tank replaced.

 

[B RON CO]

Hi, if it won't start you need a spark tester on a spark plug wire.
Low fuel pressure, clogged fuel filter or stuck float could also cause be the problem.
Good luck

 

[surfer-b]

77 with that low of miles I bet the timing chain and gear have never been changed if not it will have a plastic coated cam gear, I would bet you that gear is missing teeth and causing you problems. Remove the dizzy cap, place a socket on the harmonic balancer bolt, the crank, rotate clockwise then counter clockwise notice the amount of delay it takes for the rotor button to respond, sometimes its really noticeable, sometimes it takes a few rotations to get it to hit the part that is missing teeth. along with that it also sounds if it needs a good tune-up

 

[.94 OR]

To follow up on surfer-b's comment, rotate the engine by hand watching the timing marks. Rotate all the way through them stopping on a larger mark. Now reverse rotation and start turning while watching the rotor. When the rotor just starts to turn count how many degrees of crank rotation it took to activate the rotor. I was told no more than 7° of crank rotation before the timing gears and chain need replaced.

 

[71broncman]

What fuel pump are you running with the carb? Edelbrock carburetors don't like any more than 6 PSI. If you're still running the high pressure pump from the Fitech without a regulator it can cause flooding, which may be the cause of the symptoms. A tune up, checking or changing fuel filter, fuel pressure test while running, and cleaning inside the distributor would be a good place to start.
Mark.

 

[blubuckaroo]

Any carb out-of-the-box will need some tuning to get it right. Edelbrocks have their own set of issues to deal with though.
Mine would hesitate after going over a speed bump. I ended up lowering the fuel level a bit, and also added a fuel pressure regulator.
Edelbrock floats have a short fulcrum point so they put less pressure on the needle valves. This can cause the float bowl to overfill when you hit a bump.
Edelbrock makes spring-loaded needle valves listed as "off road" needles. I've tried them, but they didn't help my situation.
I think your best first move should be to get the Edelbrock book out and lower the fuel level a bit. It's pretty easy on these carbs.

Also, Edelbrock sells a tuning kit for each model carb they make. It has a variety of jets, metering rods, and metering rod step-up springs.
It's a good investment!

 

[DirtDonk]

...The coughing and quitting seem to somehow be related. Electronic ignition pick up? Neutral safety switch? Distributor? Any suggestions and how I can check it would be great or what to fix on it. thanks for any suggestion

It's not a neutral safety switch issue. This only keeps the starter from cranking.
When you say it's not starting though, is it always cranking, and just won't fire? Or have there been times when it won't even crank?

Regarding the distributor, even though I'm not sure it can cause any trouble, it's still not a bad idea to clean off that rust.
You can check the condition of the trigger mechanism with an ohm-meter checking between the purple and orange wires at the connector. Should read between 400 and 800 ohms. If it's anywhere outside of that range, or even if it's close to the limits, I'd replace it.
And frankly, with the number of units I've seen break a wire inside after many years of service, it would not be out of line to replace it if there is any doubt.
Jiggle the wires while testing and watch your readings. If it's not fully broken to where you can see a wire ready to fall off, this jiggling may at least show up on the meter.

So that's a start anyway. Good luck!

Paul

 

[tedhas7]

Thanks for all the suggestions. A few things to clarify. The entire fitech system and command center was removed and I went back to the stock fuel pump, one just like the one that came on the bronco. Fuel doesn't seem to be the problem. The two times it would not start, the first time it had set for a week and was cold and would not start. Took the breather off and there was gas getting into the carb. It turned over but did not appear to be getting fire. I check all the plug wires and wiggled each one including the coil wire and then it started, but did the routine of almost dying and then picking back up and almost dying (coughing and loss of power) and then ran perfect for about a 15 mile drive. Two nights ago when I was out of town it died on my daughter. My neighbor went to get it and who is a very good mechanic said he thought that fuel was fine, he said it was not firing and he did basically the same thing I did only got in it and shifted the transmission between N and P and then tried it several times and it started. It was hot at that point. My wife started driving it home. It coughed as she climbed a small hill, then picked up and ran perfect the rest of the way home. 2 times I have went out started it right up, left the house,drove a half a mile, it started the coughing almost dying and then picked back up and ran perfect for again a 5 mile drive. These two times were days apart and it was driven between then and started and ran perfect. It seems like an electrical problem where it is just not firing. According to the records I got from the previous owner, ( I am second owner and owned it for about 8 months) the timing gear and chain was replaced about 10 years ago and he said he changed it just because and that he did not really need to just thought he should due to the age, He said when he changed it, the one that was in it was just fine, but he changed it anyway. So i am doubting anything to do with the timing but will check it this weekend.

Plan on a tune up this weekend. Will check as you describe this weekend Paul. I have messed with Edlebrocks on and off so it just doesn't seem to be carb, it almost like a total loss of power due to electrical but it comes right back and runs fine till it does it the next time. If i can find one locally, i will check then change the pick up. Could it be a coil? The coil was replaced but with a one from ORileys? How about the horseshoe connection to the coils. Every seen those go bad and cause something like this. I am grasping at straws, but don't want it to leave my 16 year daughter stranded on side of road at night anymore

Thanks for your suggestions and anymore will be greatly appreciated

 

[DirtDonk]

Not wild straws it turns out. Literally anything could be the culprit at this point. Yes the horseshoe connectors get old. Both the plastic part and the wires with their connectors. If they're original, they're over 40 years old and spent that time in a harsh environment under the hood.

If you have a tachometer you would know for sure. If you're driving along and the engine coughs or dies, if it's fuel the tach would continue to read engine rpm while you're pulling over. If it's electrical the tach plummets to zero immediately.

It could actually be the new parts too unfortunately. Throwing parts at a problem no longer guarantees success in narrowing down the suspects. It simply throws more suspect parts at the problem and sometimes we end up with multiple problems.
Makes it harder to track down stuff than it did 30, or even 20 years ago.

But a loose or corroded wire is high on the list.
A couple of things to do though when it does it the next time (hopefully there is no next time, but we have to work with that for now) you can disconnect a couple of things that sometimes fail and kill an ignition and running engine.
Disconnect the small Brown wire on the starter relay/solenoid's "I" terminal.
Disconnect the radio noise suppressor connected to the coil's + positive terminal. There will be a Red w/green wire at that terminal, with perhaps a second Red w/green wire running down to a small capacitor/condenser thingy.
And third, if your (sorry, your daughters!) Bronco does happen to have a tachometer, disconnect the tach wire from the - negative terminal of the coil.
These three items can mess with a running engine's ignition system.

But a tune-up isn't a bad idea if it's been awhile. If everything was new or only the 8mo old that you've had it, this would not be an issue usually.
But if it's last tune-up was a long time before you bought it and it sat for awhile as well, no telling what's going on.

You will still need to check the ohms of your distributor's magnetic pickup (stator) to be sure it's not failing, and that should maybe be the first next thing you do. But any of the other things can be part of it. Including the bad wiring somewhere.

Ignore the starter and neutral safety system for now, but that Brown "I" wire is directly connected to the ignition coil and is not completely necessary for the engine to run. Same for the radio noise suppressor and tach. Leaving them disconnected for now then may be it's own test.

Paul

 

[tedhas7]

Just an update. Today I tuned it up, new wires, plugs, distributor, rotor. I also change the horseshoe clamp on the coil. It would not start. Went through coil checks, coil was bad. Got new coil at Orileys. While there picked up new pick up unit as I thought I would follow dirtdonks advice and clean up rust on star wheel in distributor so while in there replaced pick up unit. Wouldn't start. Checked coil. Appeared to be good. No fire. Started checking electronic ignition module. Did not appear to be functioning. Back to orileys and got a new one. Put it in. Would not start. No Fire. Got old pick up unit. Cleaned it up. Took new pick up unit out. Put in old pick up unit. Put all togather. Tapped switch-started right up. Drove back to oriley to return pick up unit. No problems. My daughter took me to get yogart in it tonight. No problems No coughing or bucking-We will see, but appears to be running smoother and quieter. We will see!

 

[DirtDonk]

Yikes. Oops, I mean great!;D Haha!

Definitely glad it didn't give you any trouble, but the fix sure seems inconsistent.
So like you say... We will see.

Crossing fingers it doesn't come back though.

Paul

 

[.94 OR]

I hope you got it figured out.

I had an '86 F150 that had something similar. The coil was mounted out on the front of the engine and when it was raining hard and I followed someone on the highway the fan would pull moisture in on the coil and it would short out from the primary. I would let it sit for a while then it would fire up and down the road I would go. Did this several times and the Ford shop couldn't figure it out. Finally did it to me one night so I had the hood up and I could see the sparks coming off the coil. It turned out the insulation on the coil protecting the output where the wire connects was broken and allowing it to arc to the mount when wet.

 

[bladesnbroncos]

Hopefully it is fixed. If not one thing i would do is go through the grounding system and clean all of the grounds. My uncle had an rv that had a lot of the same issues as your bronco. Turned out the bolt holding the ground wire to the engine block was too long and the ground would go in and out of contact.