This is, unfortunately, a pathetic "I can't get my truck started, and its sitting in the shed, 12 miles out of town" story:

I've got a 1974 F100 farm truck w/ 302 V8.
Recently it wouldn't turn over,
and there was a clicking sound coming from the voltage regulator.

I put in a new voltage regulator.
Now its turning over just fine, but it won't catch.

I do a total tune-up (it was about time anyway):
new plugs, plug wires, coil, distributor parts, etc.
Now its still turning over good, but still won't catch.
It's getting gas, and I checked for fire at a couple of spark plugs on either side, and it is sparking........but, if I would have to guess, I would say that the spark looks pretty small??????
Anyway, as I said, it turns over just fine, but never catches even the tiniest bit.

My brother tells me, the only thing left that could possibly be the problem is my timing gear jumped, and I'll have to replace it.
I could probably do that, but I sure would like to be sure that that was the problem before diving into it.

I greatly appreciate any advice.---Aqualgirl

 

Hmm.... It is a 74 F-100 with a 302.....Hmm... If you could give more info about what you mean when you say it wont catch, do you mean that it starts hard.. Like it cranks over for a while before it starts? That could be caused my late timing, or too far advanced timing... Also it is very unlikely that you jumped time, especially if it is a chain(unless you look at the timing gear and it is very worn)... Another thing, are you electronic or points?

 

I am ssuming you have checked all fluids, belts, radiator hoses, wiring, firing order and routing of the sparkplug wires, points gap, condensor, spark plugs and their spark gap before you have been trying to start this engine.

Before you go through all of the trouble of checking the timing do this. Remove the air filter housing from the carburetor and check and tighten the carb to manifold nuts. With the key off and in your pocket you or someone with a flashlight or good eyes look down the throat of the carburetor and manually work the carburetor linkage to activate the accelerator pump and see if any gas is squirted into the carburetor's throat. If you don't see any gas then it is a good chance the carb isn't getting any gas. If it is then check all of the vacuum hoses for cracks and especially the PCV valve. If you didn't change it during this tune up then please do. After doing this one final check then literally pour a couple of bottle caps of gas down the throat of the carb with the key off. Now put the air filter housing back on. Try and start it now and see what the results are.
If it still doesn't start then you should check for proper timing on the harmonic balancer and number one piston at top dead center on a compression stroke. On the balancer there are timing marks and there is a timing pointer on the front cover. Pull the number one spark plug out (it is the first spark plug at the right front of the engine or passenger side whichever you want to call it). Place a piece of paper over the spark plug hole. You will need to turn the engine over clockwise with a flex handle and socket by hand until you can see the marks and align the 0 mark with the edge of the pointer. The reason for the paper on the hole is that when the piston is coming up on the compression stroke to top dead center it will blow the paper off of the hole. That way you will know that you have the engine in the proper position for checking the timing. If the paper doesn't blow off of the hole even when the piston is at top dead center then you need to rotate the crankshaft one more revolution to align the 0 mark on the harmonic balancer to the timing pointer.
If your timing set is timed the rotor inside of the distributor will be pointing at the number one post of the cap. Before you remove the cap mark the side of the distributor at the number one post location for a reference. You will be able to see very easily if everything is in time. If your engine is off a bit on the timing and is getting gas and spark it would at least backfire or cough through the carburetor. I'll bet you have more wrong than just timing.

 

Try This,

Pull out all of your spark Plugs.


Crank over engine without pulgs in it ...


Then Put them back in and try to start it up again..



This may work for U ..

Try it




F100 farm truck owner LOL

Im not sure why this works but it blows out all of gas inside of block which could cause her not to start....

 

What about the Brain box?

 

I second the brain box idea. They're cheap enough to replace, especially if you go aftermarket. I got mine for about $12. I also keep 2 spares in the truck.

Kevin K.

 

To me it just sounds like your not geting spark when you need it... Or like RHunt said your not geting gas when you have spark... Timing is really easy to check and I dont see why you cant do that befor you start replacing more things... And turning the engine over with no plugs works only if you have flooded the engine, it clears out all of the gas. Good luck.

 

Thank you all, for all your help and information.

Let me first reply to all the questions:

As I said before, I'm getting gas, no problem: strong visible streams into each of the two throats.

There's (new) old-fashioned breaker points in the distributor, set at .4mm.

New spark plugs are gapped at .7mm

Although you all may be LOL, I'd swear there was never no brain box in a 1974 F100??????????

As I said originally, I'm getting spark at all spark plugs; but the spark seems weak, and the engine has never started since I put in the new voltage regulator. It turns over strong, but never catches for even a second. By that I mean, I guess, that it never starts, never starts hard, never starts and then dies, it just never (catches) starts at all.

So, although I'm just an Aquagirl, I'd like to follow RHunt64's instructions and check that my timing is in alignment, especially since Racerdave says its so easy. But I'm still not quite sure exactly how to go about it. I can barely see the broad harmonic balancer disk, behind the double crank shaft pulley, and below the water pump, and there I can barely, barely see the indicator arrow, off on the top left side of the harmonic balancer. What is not becoming immediately clear is:

First, what is the usual stuff that ought to be taken off in order to be able to see the hash marks on the harmonic balancer?

Secondly, what's a flex handle and where do I go with it? Breaker bar and socket? I'm assuming that there is something inside the front crank shaft pulley that I should be able to grab onto, and thereby turn the engine?

Then, I have heard people say they stick a screwdriver into the #1 sparkplug hole. And then??? Everything should happen simultaneously, top dead center, with the rotor contact on the #1 spark plug contact? I guess I'll cross that bridge if I get to it.

Thanks again--------Aquagirl

 

Okay water girl,


Each Piston reaches TDC TWICE in a revolution

Once to compress the air/fuel mixture just before the power stroke
&
Once again when it is pushing the exhaust gases out of the cylinder ,just before the Intake stroke.


Try this.

First you may have to crawl under the truck to clean off the timing mark.Once it is clean take some White-out (liquid paper) and paint it on the timing mark.

Now you have a very visible mark to see.

Next, A flex handle is like a power bar.
Long handle that holds sockets.
You might need an short extension as well.

Place the socket with power bar onto the crankshaft bolt and turn it until the timing mark aligns with the other mark.
Stop.
Look under the dizzy cap to see if the rotor is pointing toward Number one sparkplug wire.
If it is 180* off move it one more rev until it does.

Now a thing to notice while you have the socket on the crank bolt.

How many degrees does the power bar move to make the rotor turn each direction?

We are going to check for SLOP in the timing chain & gears.
This slop is a result of a wornout chain & gear set usually on a high-miler engine.This slop can contribute to a skipped Timng chain thus throwing your timing out.

To do this Turn the crank until the dist. rotor starts moving.<>STOP<>

Now while turning the crank bolt the OTHER direction<> Observe how many degrees of a circle does the bar move until the dist rotor starts turning the other way.It should hardly move a bit without turning the rotor.

 

try using starting fluid.

 

Mil1ion hit it on the head, thats along the same lines I was thinking. You also said that when you replaced the voltage regulator the engine does not start anymore? Did it useto start befor you replaced the Voltage regulator? If it did then there is your problem.

I had no idea where my harmonic ballancer was when I first got my truck because there was about 1/4" of grease and road grime on it, so the easy'st way to find it is get underneath (right below your fan) and start cleaning off the pulleys, it is alomst touching your oil pan if I remember right, also I found that white is not as easy to see in a bright white timing lite as black is.... I used a black permenant marker to mark TDC (top dead center) I put 3 small dots along the line, and then I put a straight line across 10deg BTD (befor top dead). Also people stick there thumb or a piece of paper in the spark plug hole, I take off my cap and line up TDC and make sure my rotor is on #1 and then turn it over again untill its almost on TDC and stick a socket extention in the hole (fits perfect) and go untill it stops moving out and you have TDC(it will only work like thisif you know your harmonic ballancer is not off)

 

Million, Racerdave, thanks for the tips!

OK, I got down under the fan and can turn the crank with my 1/2 inch drive and an extension. I marked the TC with white-out, and turned the crank until the indicator was on my white mark. Now the rotor was almost, but not quite right on the #1 contact.

By the way, my harmonic balancer is callibrated like this:

ATC 10 ///////// TC ///////// 10 ///////// 20 BTC

So the rotor was almost perfectly aligned, but not quite.

Then, following Million's instructions, I checked for slop. With my brother looking at the rotor, no more than a 1/16 of a (counter-clockwise) turn on the crank was necessary for the rotor to turn.

So I'm beginning to think that my timing (although it may be a little off) is not the problem, as RHunt64 suggested. That is, I'm not thinking my timing chain has jumped and needs to be changed.

???

 

U may have a brain box My 75 F-100 has one it controls your ignition system.......That may be the problem....

You may have flooded your engine block with gasoline....and I had this happen to me before the vehicle will not start(at all even if it sits over night or a few days)...You must pull out all plugs turn her over(to blow out all of the gas)

then put then back in and start it up .....

It works and its free and easy to do.......


Besides U keep trying to start it which keeps it flooded out......

 

As Racerdave asked, did it start before volt reg. went out?..I would try another new volt reg. first..

 

This brain box (Ignition Modulator)that people keep mentioning are not on Trucks with Standard Ignition or POINTS distributors.

Aquagirl.

Time to check the state of the ignition system.

You need a test light hooked to the +terminal of the coil.

If you had a dwell meter or a test Tachometer you could check the - terminal of the coil.

I think you need to verify one thing at a time.


Fuel , You state you have fuel delivery.
That leaves that out of the equation then.

Next is Spark & when it gets there.

Has anyone verified the S/P wires are in the correct firing order?
Remember the rotor turns counter-clockwise.

Engine

Right side
|_ 1 2 3 4
| 5 6 7 8
Left side

Now,
Put a test light on the + terminal of the coil and turn the key to RUN.

Does the test light... light up ?

Now turn the key to start and see if the test light stays lit when cranking ?

If so, we move to the secondary circuit >

Check the NEG terminal of the coil while cranking the starter.

What is the points gap in *thousands of an inch* instead of mm ?

.014

Has anyone checked the resisitance of the primary & secondary circuits of the coil ?

Have you checked for spark coming out of the spark plug wires to ground?


You probably know this stuff but havea look at this anyway.

Click Me to Read about Ignition & Timing

I have to go now,

I'll be back !

Time 10:41 pm