84 F350 460

Was driving it the other day and it seemed fine for about 10-15 min but after that I could feel the engine struggling at idle. Low rpm, shuttering, rpm bouncing, etc. Next thing I knew it was stalling out at all stops. It would restart but I’d have to keep my foot on the gas to keep RPM up. If I didnt it would immediately stall out. Still ended up stalling out about 5 times on the way home and then finally it refused to start. Engine would barely turn over. Very slowly and lethargic... no chance of starting. Ended up leaving it on the side of the road and came back the next day. Fired right up but shortly down the road had the same issues. Luckily I got it home.

Recently i replaced the starter. Which I believe is unrelated bc I was having the same issue before replacing the starter. With that it was just spinning and wouldn’t turn the engine over. Replaced it and now it seems to be functioning fine.

Today I replaced the ignition module, ignition coil, and pcv valve. After doing that it seemed to fire quicker, however I could tell just by the idle that the issue is not resolved. Low idle, still struggling to stay running, shuttering, rpm jumping. I swear it almost sounded like half the engine wasn’t running. Even when I gave it gas it sounded very weak at higher rpms. Anyway, While it was running I played with distributor cap, plug wires, and coil wire. No change in how it idled. Also doubled checked that I had fuel with engine off. Gas def squirting 2 streams down throat of carb.

I was was planning on doing the ignition switch just bc but also was going to do distributor cap/rotor, wires, and plugs next. Hoping a good tune up does the trick. The battery is def good as well.

Any other thoughts?

 

fuel flow? But I don't think that would effect a slow start.

 

YUGE clue right there.

This sounds like your charging system is renting the farm with an option to buy. If not charging properly, the battery is being depleted while driving. That means a weak spark and rough running, followed by lethargic performance from the starter after stalling. If your truck has an electric fuel pump (in the tank?), fuel delivery will be poor, too.

After sitting overnight, a partially depleted battery will self-recover to some extent, often enough to spin the starter at a good clip.

From Troubleshooting 101: Always begin any electrical troubleshooting with a fully charged battery. Charge it overnight using an automatic charger with at least a ten amp output. If you try using a trickle charger, I shall track you down and taunt you with terrible squinty looks, and then you'll be sorry. Don't make me go there.

After the battery is fully charged (notice I said after), test the alternator output. I can find the proper test procedure, but basically you should see at least 13.5V at the battery while idling.

Don't load anything else into the parts catapult (Pull!) until you rule out a problem with the charging system. Your wallet will thank me.

 

I would do the tune up but ...... do just the plugs first and a compression test so we know if it doesn't have a dead hole.
I say just plugs first because if you do cap/rotor/wires/plugs and it now runs we may not know what the fix was.
Then think I would do the wires and see how it runs then cap/rotor.

Being a 350 I take it no cat in the exh system?
Truck sit for a spell? Maybe a plugged muffler from something the got in and made a home or I have seen the baffles break off and block the path of exh.
Dave ----

 

Official alternator test procedure in this thread:


https://www.ford-trucks.com/forums/1...lternator.html


If out of specs, note the comments about adding a ground wire to the voltage regulator base.

 

Thanks!! So do you think this could be a problem with the alternator? The battery isnt very old, less than a year for sure and hasn't be run all that much at all. I will prob still do the tune up bc it sure looks like it needs one.

 

I did not look over the test but not charging could be the ALT or REG as 1 will not work with out the other.
If the test is worth anything it should walk you thru how to tell what one is at fault.

As pointed out if there is no juice to make the IGN box & coil work it will lack power and run like crap.
Easy test is to put a meter across the battery and start it up, bring the RPM up to about 2500 and read the meter IIRC 13.5 to 14.5 is good 12.5 or below is not good as that is battery voltage.
Dave ----

 

It could be a problem with any part of the charging system, not just the alternator. It could be a bad regulator. It could be a loose connection. It could be all sorts of things. Don't just rush out to replace the alternator, as it's only one part of the charging system. Run the test linked above to rule out a problem with the complete charging system.



You might want to hold off on that for the time being. If the truck has run passably well for you recently, don't risk introducing more problems until you clear up the present whopper staring you in the face. If you translate the Latin in my signature, it means "As little as possible, for as long as it takes". I'd hate to see you fix the present rough running and stalling, only to inadvertently introduce a new fault that mimics old one. You wouldn't realize you had actually fixed something, and might continue trying to fix a fault that had already been corrected. One crisis at a time. I do not care to discuss how I learned this...

 

Here's what I'd do. Charge battery overnight and start her up. Measure voltage across batt. Should be like 13-14v. If lower suspect alternator. Pull positive terminal from battery while running, if it dies, then ALT is probably bad.

Next, check all ground wire connections. Your coil is probably good. I am betting on bad charging system or cap/rotor/plug wires first.

 

Unfortunately I don’t have a battery charger or a way to check voltage. Will try to see if I can borrow either or both from a friend.

2 questions thinking ahead.

When I search online for voltage regulator I see 2 options, mechanical or electronic. Which should I get? Care or recommend a brand?

If end up doing the alternator as well, what brand do you recommend? What does it mean when it says with or without plug? I took a peek at mine and it has 1 pully. Care to recommend a specific model?

Im new to all this and not sure what physical stores, online stores, and or brands are the best.

Appreciate the help.

 

I'd buy the alternator at a store with a good return policy such as NAPA or O'reillys or even auto zone. Unless I am missing something, your truck should have an internal voltage regulator built into the alternator so no need.

I would invest in a $20 volt/ohm meter if you plan to own this truck. Great around the house as well.

 

With a username as epic as JackieTreehorn, I'm loathe to second guess you, but no, please don't disconnect the battery with the engine running. Never on any vehicle equipped with an alternator or any electronic equipment. The voltage spikes this causes can wreak a lot of damage.

This was a valid troubleshooting technique on older vehicles, with a generator instead of an alternator, and the sum total of zero electronic bits. It's fine on a Studebaker or DeSoto, but generally not on anything newer than the mid 1960s.

Respectfully submitted.

 

Hmm I'll defer to you Karl. I figured the Duraspark was dumb enough not to care. I started doing that on my 225 valiant and all the way up to my 86 F-150 with smarty pants feedback carb but never anything newer.

 

I THINK I do have a voltage regulator next to the solenoid. Gotta double check.

 

You drive a thirty five (35) year old truck? You need a voltmeter. Before throwing more parts at your truck, invest in a decent midrange DVOM. They will test volts, DC and AC, ohms resistance, and current. They are needed around the household too, as somebody mentioned. Nod your head "yes".

Also a decent battery charger. The classic 2/4/6 amp automotive charger of the type that Sears and a gazillion other places used to sell is perfect. Good $4 yard sale find. Then you can tell when your battery is well and truly charged, with your new voltmeter. The alternator does not fully charge a battery, nor is it really designed to. If you drive to Montana or something like that, sure. A battery charger will easily pay for itself, by maximizing battery service life, and saving wear and tear on starter and alternator.