So my 78 F250 won’t start. The alt and regulator are factory style, new ~10 yrs ago. Batt is yellow top Optima ~3-4 yrs old. Truck sits a lot so batt dies occasionally. Hook up batt charger and usually truck fires up fine. Just replaced fuel tank, put batt charger on and it fired right up. Unhooked batt charger and it died immediately. Rehooked up batt charger and it won’t fire. Won’t even spit and sputter. Haven’t had time to mess with it, but I think voltmeter showed 14 last time it ran. Truck spins motor plenty fast with batt charger and smells like gas. Ignition is MSD 6AL box and Blaster 2 coil. My original thought is batt doesn’t have enough amps to fire ignition, so bad. I have a brand new alt, regulator and batt in garage for truck off another project. I was gonna replace batt, then alt, then regulator if required. But now I’m worried ign box is bad. I know you can test these, but I’d like suggestions please. I’ve had an MSD box go bad on me a few years ago, replaced box and no more problems till now.

 

It's true that Optima batteries are different internally than a standard car battery but it works essentially the same.
Anytime a battery drops below 10v for extended periods of time it receives damage. The coating on the inner plates begins to flake off reducing its ability to put out power. You would still see 11-12.6v fully charged because that in no way reduces its ability to store electricity (until there is no more coating anyway). But with the reduced surface area of the inner plates, the amperage drastically reduces.
Optima Blue Tops have thicker coatings with less surface area - Can take more damage from power loss, but has less amperage as a result. Good for applications with power usage without constant charging. RVs, Boats, etc.
Optima Red Tops have a thin coating with a lot of surface area - Easily damaged by power loss, but have excellent amperage readings. Good for applications that require a lot of power but also is constantly charged or charged immediately after usage. Starting an engine, high power audio equipment, welders, etc
Optima Yellow Tops are a best of both worlds solution, meaning they are like a standard car battery, but with the resilience of a dry cell. Winches, offroad lights, cars that sit, etc.
If yours sits for a long time I'd go with a yellow top and a lever style battery disconnect on the ground side. Disconnect it while it sits. No power loss.
Also with Optimas, always check the date of manufacture before purchase. They tend to sit on shelves for a VERY long time due to their price tag. A 2yr old battery can actually be 5yrs old. My local Advance Auto store has a blue top on it's shelf from 2015.

If the engine can not run without the charger then the alt isn't producing enough power to keep the truck running. I can disconnect my battery while the trucks running and then drive around town with ZERO issues. I've done it to win bets several times. I would take the alternator to your favorite parts store and have it tested. If it comes back okay then replace the regulator. Personally, if I had any doubts I'd replace them both.

Since you have all the parts, replace them all at once. Might seem like a waste but it's not IMHO. A bad starter kills a battery, a bad battery kills an alternator, a bad alternator kills a battery, a bad battery kills a starter. They are all dependent on another. I worked at Autozone for a time I can tell you that the three typically fail together if one of them fails and is ignored.

The smell of gas could be because you kept trying to start the truck without spark and flooded the cylinders. Take out a spark plug and check them for fouling. OR it could be a carb float issue, the bowls could be over filling.

I have no experience with MSD personally but if you're worried about it firing or not, take out off a plug lead, shove a screwdriver in it and hold the screwdriver close to the engine block while starting the truck. A spark should jump from the screwdriver to the block. Poor man's test, my favorite way to do it.
Another way is to pull the spark plug as well. Plug it into the lead and touch the threads to the block. The spark plug should spark when you try to start it.
If the smell of gas is strong though I'd set up a small fan to blow on the engine beforehand. Wouldn't want fumes to ignite.

Other than that check the basics. Look down the carb, pump accelerator, does gas pump into the carb?
Yes? Then you have fuel. Don't go off, "I smell the gas" it could be dumping out on the ground and that's why you smell it. Make sure it's getting in the engine.
No? Disconnect fuel filter that's before the carb at it's inlet, turn the engine over, does gas come out? Yes? Then filter is clogged, replace. I've seen clogged filters build pressure and leak at the inlet. Smells like gas and makes you think it's getting gas, but it's not.
No gas came out? Possibly a bad pump. Disconnect inlet from the pump. attach a hose and put in a container of gas. Turn the engine over, is the gas coming from the outlet? No? replace the pump.
Gas does come out? Possibly a clogged fuel line. Could just be your out of gas (happened to me, was having a bad day). Could be that your fuel pickup rusted in the tank and fell off (also happened once, VERY bad day).

 

Wow, lots of info, thanks.
The batt was a blue top, not yellow top, and I had a spare one. Took alt off and had it checked. It was good, so reinstalled it. Put on new voltage regulator just cause. Still nothing. So either MSD or fuel pump is bad. I guess all that rust could of gotten pump, but I would of thought prefilter would saved it. Waiting for assistance to check pump and then I’ll check MSD if necessary. Oh yeah, truck is aftermarket efi, so needs like 42-45 psi to fire injectors. No fuel leaks, it’s on a concrete pad.

 

You need to test for spark. You can pull a spark plug wire and spark plug, then plug the spark plug back into the wire, and ground the spark plug to the engine. Turn the key to "Run," and jumper the starter from under the hood via the "S" post on the relay/solenoid. If the spark plug doesn't spark, disconnect and try again just to be sure.

Ignition problems could be the pick up in the distributor or the control box or the coil. You can test the coil with an ohm meter.

If the truck is making spark, then you'll want to check for fuel. First make sure the pump is coming on and making pressure.
If fuel pressure is OK, then you're going to need to test the EFI system. I don't know how this is done. Hope you still have the instructions... But I can't imagine they'd sell an EFI system without provisions for a system test, like OBD1 and OBD2 systems do.

 

Yellow tops are deep cycle batteries so running them dead shouldn't damage them....


Just a tidbit....

 

Sounds like what I've been through recently with my '78. First up the battery should read 12.5v or more when standing. Anything less than this and its too discharged and may be damaged. Ideally you will see about 12.7v~13.0v at rest.

Prop your hood open and connect a multimeter to the battery. Place it so you can see the reading while the engine is cranking. Watch the reading as you crank - you will ideally see 11v or more. 12v is the ideal scenario. Anything under 11v and the EFI will have trouble. 10v or less and even points will have trouble firing the engine.

Doesn't have to be a $50 multimeter either, anything will work so long as it gives anything close to accurate readings. I have a few cheap dollar store ones so I can keep one in my go-bag, one in the car and another in the shed.

- boingk

 

I have a multimeter and even a spark tester. I’m going to hopefully test both later. I will also test for fuel and pressure if I have time. Definitely in the next day or two.

 

This right here. Each will affect the other over time. Short trips tends to leave a battery slightly undercharged. Over time the battery sulfates over into permanent reduction in capacity. A fully charged battery has a higher internal resistance, but a weak battery makes everything run hot. Now you can measure voltage all day, but it is current that makes things happen. And to transfer current we need clean, tight connections of adequate size. A brandy new alternator will be crippled trying to supply current through old corroded battery cables and ground connections. The battery will never quite get there. Replace all of the cables if they are original to the truck. Pay particular attention to the terminals that attaches to the block, frame and firewall. Grind down to bright shiny bare metal and tighten securely. Coat with grease or vaseline to exclude road brine and moisture.

 

I’ve replaced all the cables with heavier ones and even added additional grounds. Of course it was years ago, so I’ll recheck them

 

Ah, well no matter then. You're tracking. Grounds and connections are a maintenance item though. Very often overlooked. Even invisible corrosion is enough to interfere with current transfer. Once it becomes visible (like the blue powdery residue on battery terminals) then it has usually failed altogether. Lots of people ignore their electrical system, unless and until it won't start. Not FTE members, natch. Cables will get hot when loose or corroded, easy check. Another is to to turn headlights on during cranking. They will dim some, but not much, when everything is in good shape.

 

As an afterthought to the true solutions described above, if the truck sits a bit, buy a battery disconnect. There are a few different styles, but a basic one can be had for $15 or less. I put one on my truck because it also sits a lot during my different project phases and gets driven in between projects for fun. I've never had an issue charging, and nothing in my truck requires memory power (still running stock ford am/fm **** radio). Mine connects between the negative terminal and ground cable. Throw a lever to connect/disconnect.

 

Got a little work done tonight. My cousin helped me, truck has fuel, but spark only happens when cranking begins and then nothing. Truck cranks fine, but no continuous spark. So I guess switch? But truck cranks fine. Can you test just ignition circuit?

 

Two tests:

1. Ohm out the stator (AKA pick-up coil). Disconnect the three prong terminal form/at the distributor. Measure the resistance between the ORANGE and PURPLE wires (making sure the spade terminals are clean and un-boogered). You want to see between 400 and 700 ohms. Any more/less, replace the stator. The BLACK wire is a distributor ground and should not show any reading...or a very minute reading in ohms or a good continuity check to ground.

2. Key ON engine OFF....measure the voltage between the BATT (+) terminal on the coil and a good clean ground. You want to see 6 - 9 VDC. This is the ballast resistor wire....if it's shorted or open, the vehicle won't stay running. This circuit is bypassed in START...allowing the full battery voltage (momentarily) to the coil.

 

Break in the pink resistor wire then? That's no bueno. I tracked down the cause of an engine fire to that wire being replaced with a standard wire in my 79. 6v systems do not like 12v.

 

Yes, indeed that would do it...unfortunate . Hope not too much damage was done?

If that ballast resistor wire goes too long without being fixed/replaced it could also be the cause of the coil goin' south. They get fried if ran on 12 VDC for too long as the OEM coils (as well as most after market ones) were meant to run on 9 VDC....or less.