I've been trying to get my truck started for a while but haven't had too much luck. I get over 12 volts on my battery but while cranking the max i ever see is around 10 volts or so and I get a thick orangeish yellow spark at all spark plugs.

Anyone know what to do for this problem? I've been searching the threads and have been trying everything but nothing seems to work. I've got brand new grounds from the battery to the block, block to frame, and block to firewall/cab. This truck is gonna drive me crazy any replies are much appreciated!

Truck is a 1977 f-150 ranger with a 351m.

 

If you have spark at all it should try to run. could be the coil, seems like the ecm is always suspect but I don't see how it would cause weak spark.

Will it try to go if you give it a shot of starting fluid ? even lame spark will suffice on starting fluid. it also indicates if you have a fuel delivery problem or not.

 

Even on starting fluid it doesn't even try to run. Even though I don't use a whole lot of that stuff because I read on one of the threads that it can burn valves.

​​​​And I don't think it's fuel delivery either because I can see gas coming from the carb and if I pour too much then my spark plugs are wet when I pull them. It makes no sense why it doesn't at least fire up for a couple seconds

 

How old is the gasoline? Stale fuel won't help. Orange spark though, is no bueno. Fuel fouled plugs won't help either, maybe spin the engine over with the plugs removed, try fresh plugs.

 

Try some basic checks.
Are your plug wires in proper sequence?
plug boots fully seated?
Cap and rotor in good shape?
Distributor tightened down?
Tires inflated? (from Cheech and Chong)

 

Brand new gasoline less than a week old. I can spin the engine without the plugs and get some new ones and see if that helps

 

Yessir brand New plug wires in correct firing order, plug boots seated with dielectric grease on them, cap and rotor are good, distributor clamped down. Haven't even thought about tire pressure maybe that's my problem!

 

I little humor when dealing with these trucks and the current state of affairs in the world/nation is always useful.

 

When you get the plugs, (cleaning them with a wire brush would no doubt be OK), get that battery checked. Dropping to
10V?? Is the motor turning over fast? that's another battery test. If the motor is turning over fast, and you have spark at
all plugs,do a compression check. 100lbs in each Cyl. (not a great number) will be enough to start it.

 

Plugs, wires , firing order, compression those are all important but they're not causing your problem. if they were it would still do something you have a basic failure somewhere.

Starting fluid won't hurt anything just don't load it up with half a can. a 3 second burst is plenty. to test for fuel you can just dump some gas in it if you'd rather, give it a splash and see if it tries.

how many volts are you getting to the coil ? and then check it again while cranking. if that's good I'd look at the coil next. all assuming fuel doesn't make it sputter.

 

Im not too sure if the motor is turning fast enough or not. it seems good to me but I'm new to all this
I've got around 115 in nearly all cylinders with #3 being pretty low at 100

Yeah i set my battery to charge for a couple hours last night and it measured around 13.2 volts and when I slapped it in my truck and cranked it over I was only getting 10.3 or something like that at the max

 

This morning when the battery was fully charged up and around 13 volts. In "run" on the ignition switch I get battery voltage and while cranking I get around 10.3 or so at the max. Any way to check the coil and see if it's bad? You are right, gas or starting fluid doesn't do anything for this engine

 

I'm sorry you're still having trouble CanOfBeans, but why start a completely new thread when you have literally three months worth of questions-n-answers going on over there?
You've been discussing a no-start issue for awhile now in the other thread and I see no reason to make us start all over again with all the same questions that may already have been asked. With no quick access to some of the clues and things you've already tried.
Just narrowing it down to a voltage thing does not justify a new discussion when it's really still the same no-start problem.

And yes, the 10v seems low, but it's not out of line for a reading you get during cranking. Where are you measuring the voltage, and have you tested your meter on other known good older vehicles to see how they react? Won't likely be the same if you're testing a Honda with a 4-cyl engine of course, but any older V8 should give you the desired voltage readings during START.

Generally though, if your engine is being turned over normally by the starter then you have sufficient voltage to create a spark.
You say you're not sure if it's turning over quickly or not, but if you know the normal sound of a starter motor spinning an engine, you can tell if it's slower or not.

Did you measure the ohms on the distributor's Purple and Green (or Orange?) wires? Should fall well between 400 and 800 ohms.
You can test the relative health of a coil by itself not only with ohms, but by disconnecting it from the electrical system and using a jumper wire to apply 12v to the positive side and another jumper wire to manually open and close (ground and release) the negative side.
With the coil wire lying near grounded metal, you should get a big fat healthy spark jumping from the coil wire each time you remove the ground wire.
If it does this consistently, the coil is fine.

Paul

 

And just what were the circumstances under which it first refused to start? Did you do some work on it, or were you driving it and it died? Or had it been sitting for decades?
I'm sure these must have been asked in your other thread, but I don't remember even though the last few questions were as recently as this weekend if I remember?

Good luck.

Paul

 

So then it has to be spark if fuel won't do anything. if you have fuel and good spark any engine should do something when you crank it .

I assume you have the stock durashart ignition ? I suspect the coil or the ecm. I've never tried to test either I just replace them.

I would think 10v would be enough to fire things up but I'm not sure of that. Mopar electronic ignition runs on 8V . if you want to eliminate that possibility you could run a test jump wire to the input side of the coil from the battery or solenoid.