Hard Cold Start

AC932 · Nov 13, 2018

Stock 302 V8

Last week it took me ~15 minutes to start it up after sitting for ~5 days. Normally it fires up in an instant with a pump of the gas pedal after sitting for same amount of time. Strong crank, getting gas. Started to fire once, then twice, eventually started and ran smooth/normally. Sat overnight and started fine.

Started hardish today (~20 seconds) after sitting for 24 hours.

Under the distributor cap everything was coated with a thin layer of copper dust, so I wiped off the rotor and contacts. I'll see if that helps tomorrow

The plugs and wires were replaced 3 years and 25,000 miles ago. When running it doesn't feel down on power, and the fuel economy is slightly lower than during the summer (as it usually is at this time of year).

Any ideas?

DirtDonk · Nov 13, 2018

It does kind of sound like the kind of thing a weak spark can cause, so maybe you're on to something with the coating in the cap.
But frankly, 25,000 miles on an old engine like ours is a LONG time for spark plugs. I would seriously consider at least removing a couple of them for inspection. If they look even remotely fouled, clean or replace them.

What type of ignition are you running?

Paul

DirtDonk · Nov 13, 2018

Oh, and welcome to classicbroncos too by the way!
Good on you for driving your Bronco so much. Many of them no longer get driven as often, or for as many miles as they used to (I'm guilty too!) unfortunately.

Paul

Boss Hugg · Nov 14, 2018

How old is your battery. Sounds like the starter may be pulling voltage away from your ignition. Cold temps draw amperage down.

AC932 · Nov 14, 2018

First off, thanks for the responses! I went to start it up today after cleaning up the distributor and it fired right up, so that's nice. I'll see how it does after sitting for the rest of the week.

DirtDonk: I agree that 25,000 miles is a bit much for the plugs, I pulled a couple and they're pretty black, I'll see about replacing them this weekend. As for my ignition system, I have absolutely no idea. I assume it's more or less factory, but I'll take some pictures and post em this afternoon. (And yea, it's been my daily driver/road trip truck since I got it

)

Boss Hugg: I'm honestly not sure how old the battery is, it's the same one I got with the truck, so at least 4 years. That said, I did get it and the alternator tested last summer and they were both good, and it did end up starting fine today (was about 40 degrees F)

B RON CO · Nov 14, 2018

Hi, our Broncos came with a points and condenser or duraspark electronic ignition after about 1975.
The duraspark ignition is very good. It will have a control box mounted on the inner fender. The only ignition maintenance is cap, rotor, plugs and wires.
Early points and condenser systems needed yearly maintenance, @ 12,000 miles and the points were shot. Also the secondary voltage was less, so the spark plug gap needs to be smaller.
Many guys put in a Pertronix to replace the points and condenser.
You should also make sure the choke closes when cold, and fully opens when the engine warms up.
Your battery and charging system may be working, but I am not comfortable with a battery over 5 years. I live in the North East, and we may get snow tomorrow. Cold weather kills batteries.
So figure out which ignition you have, and probably tune it up and check the carb.
You can get a lot of help here, but I would suggest getting a Chilton's manual, so you can learn how to diagnose and repair most everything on your Bronco.
Good luck

68ford · Nov 14, 2018

Check you voltgae at the coil + post before and during cranking. It should be about 6 volts key on engine off. It should jump up to 11 to 12 when cranking. If not, you resistor bypass wire has an issue. This happened to me 20 yrs ago.

AC932 · Nov 15, 2018

Seems I've got a duraspark system with a replacement control box from NAPA. I'll be sure to change out those plugs this weekend, and I'll poke around the choke to make sure it's behaving. As for a manual, I've already got the Haynes one, which has been sorta hit and miss in my opinion.

If all of that don't solve it, I'll start doing voltage checks.

Thanks again for suggestions

jagbucket · Nov 17, 2018

Ive had the same kind of problem but in my case the holley leaked and it took some cranking to refill the float bowl .If it turns out not to be electrical, did you verify that after sitting you have fuel when hitting the accelerator pump? ,

DirtDonk · Nov 17, 2018

If you continue to have some issues, there are some other tests to perform that are quick and pretty easy for the most part.
An easy test of a Dura Spark distributor pickup coil is to separate the 3-wire connector and check with an ohm-meter between the Purple and the Orange wires (the black is a ground). You're looking for between 400 and 800 ohms resistance.
Any more or less than that, or even if you're near one of those limits, it's time to replace the stator/pickup coil/magnetic thingy inside the distributor.

This is not one of the normal symptoms of a bad distributor pickup however, as they usually give more trouble when hot than cold. But inconsistency is a common thread, so still worth a quick check in my book.

Paul

nvrstuk · Nov 17, 2018

I'm leaning toward gas supply to your carb...

-Before cranking, take the air filter off and crawl up with your head over the carb and move the accelerator and you should see gas squirt out of the pump nozzles in the carb...no fuel shooting out means your carb is OUT of fuel

-Before cranking, check the bowl level on your Holley simply by removing the float bowl screw.

- remove the fuel line and crank the engine and see if your mech fuel pump is up to snuff... when yours sits a while it could be your pump isn't picking up the fuel. have a can handy and be safe

All the electrical and fuel checks suggested so far are really basic. Give them a try and keep us posted.

AC932 · Nov 18, 2018

Well thanks again for all your suggestions, I'll keep 'em in mind if this happens again. Seems the issue was that dust in the distributor, haven't had an issue since cleaning that up. That said, I did replace the plugs (Autolite 45's gapped @ .044 per my EPA sticker, if you were wondering) and it definitely feels happier.

nvrstuk · Nov 18, 2018

Glad you're up and running... I suggested fuel delivery because I thought you'd already been running it since that was 11/14 and still having issues after wiping all the contaminants out of the distributor cap making me lean towards fuel...

Nice that it was any easy fix!

Hard Cold Start

AC932

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DirtDonk

Bronco Guru

DirtDonk

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Boss Hugg

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AC932

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B RON CO

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68ford

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AC932

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jagbucket

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DirtDonk

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nvrstuk

Just a Bronco driver for over 50 yrs!

AC932

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nvrstuk

Just a Bronco driver for over 50 yrs!

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