Cranks but won’t start

[Fbks_Cruiser]

350, HEI, edelbrock 1406.

Truck has always started easily. Press pedal once to set choke, crank a second or two and she fired right up. In colder weather 2 pedal pumps. Then Last week I had to crank for several seconds before it would start. But then it ran good, started fine and started fine the rest of that day.

Now today I jumped in the truck press pedal to set choke and crank away but it never fires. I press pedal again. Still cranks but no fire. Pedal full to floor no fire.
So I pull the air cleaner, open choke butterfly and work the throttle, see good fuel spray. I then check power at HEI 12.5 volts key on (12 gage wire from ign unfused). I do note that voltage drops to about 10v when cranking, too low?
I tried a ignition tester that goes inline between spark plug and wire, showed a flash as I cranked the engine so it appears I am getting fire to the plugs.

I had a spare ignition module and coil so I swapped em just to rule that out. Same symptoms.

If I hold pedal to floor and crank a long time I get occasional pop out the exhaust, so I am thinking timing is goofed up? But how? It ran great when I parked it last week.

Ideas?

[ncpetersc]

Originally Posted by Fbks_Cruiser

350, HEI, edelbrock 1406.

Truck has always started easily. Press pedal once to set choke, crank a second or two and she fired right up. In colder weather 2 pedal pumps. Then Last week I had to crank for several seconds before it would start. But then it ran good, started fine and started fine the rest of that day.

Now today I jumped in the truck press pedal to set choke and crank away but it never fires. I press pedal again. Still cranks but no fire. Pedal full to floor no fire.
So I pull the air cleaner, open choke butterfly and work the throttle, see good fuel spray. I then check power at HEI 12.5 volts key on (12 gage wire from ign unfused). I do note that voltage drops to about 10v when cranking, too low?
I tried a ignition tester that goes inline between spark plug and wire, showed a flash as I cranked the engine so it appears I am getting fire to the plugs.

I had a spare ignition module and coil so I swapped em just to rule that out. Same symptoms.

If I hold pedal to floor and crank a long time I get occasional pop out the exhaust, so I am thinking timing is goofed up? But how? It ran great when I parked it last week.

Ideas?

Dumb thought I'm sure, but did distributor loosen up?

[Fbks_Cruiser]

Not dumb. I checked to make sure it was still tight. Mechanical advance is free (not bound and spring right back when moved by hand).

[Fbks_Cruiser]

I’m kinda wondering about fuel even tough I saw it spray when moving throttle.

I don’t have a helper right now but think I might disconnect fuel line at carb and run it to a container and crank for a few seconds and see how much gas I get.

['68OrangeSunshine]

Look inside the cap for traces of High Voltage arcing and pitting on the cap contacts and rotor. While I've gone thru similar gripes
on the distributor on my '71 GMC Jimmy's 350, and replaced each component ala-carte, I've found a fresh [US-made if available] whole HEI distributor is cheaper to replace.

[A buddy of mine had an FJ40 with a 327.]

[Getter-Done]

Originally Posted by Fbks_Cruiser

350, HEI

If I hold pedal to floor and crank a long time I get occasional pop out the exhaust, so I am thinking timing is goofed up? But how? It ran great when I parked it last week.

Ideas?

Do you have a compression tester?
Doesn't take long to do.
That would narrow things down.
Compression test good (ok now what).
Compression test bad (Ah-Ha).

[Fbks_Cruiser]

Didn’t see any tracks inside the distributor cap and the contacts look good. Cap, rotor, wires, plugs new about 2000 miles ago.

I can get compression checked once I have a helper!

Just sold the FJ40 to my friend. Had it for 20 years and had done a complete mechanical rebuild but never got into fixing all the rust and other body repairs. Friend is gonna finish it.

[AussieinNC]

Are you sure you have spark ?

Sounds like a loss of spark...

Go back to basics...

Remove Cyl 1 spark plug
Bring cyl 1 uo to tdc on compression
Hint: (put your thumb over the plug hole to feel pressure build up)
Set the balancer timing mark to 12 BTDC
Loosen the distributor
Put cyl 1 plug back on the wire and ground the body of the plug
Turn on ign but dont turn to Start
Turn the distributor body backwards about an inch, then forward until you here the spark plug fire...lock distributor down.
Turn off ignition.

Replace the plug and wire
Check firing order 18436572

Now start the engine...

Obviously if you cant get spark this way, you will need to figure out where the issue is...

Start with supplying 12V direct to Batt terminal ...on HEI...have seen those original wires crap out so many times...
Also have seen timing chains wear so much they jump a tooth and give similar symptons...

Let us know how you go

[Grumpy old man]

"Also have seen timing chains wear so much they jump a tooth and give similar symptons..."

^ Bingo , I'll bet a donut this is what happened .

Post a picture of the engine ,Pictures always help .

[billthompson]

have you checked the ignition switch?

[Fbks_Cruiser]

It runs!

Not 100% sure what the problem was but I think these threads are more useful if not left hanging without resolution.

I am leaning towards bad ignition module. When it first would not start I verified fuel delivery and 12 v at the distributor in both run and start key positions. So that left spark. Knowing that I had replaced the cap, rotor, plugs and wires just 2000 miles ago I figured they were pretty good and likely wouldn’t cause it to not fire at all. So since I had to go to the parts store anyway, I pulled the ignition module to test it and also buy one of those ignition test lights. The old module tested okay. Hmmm. But I put in the new one anyway. Along with a spare coil I had.
Here on reassembly is what got me. This time around when I pulled the wires off of the distributor cap I didn’t pay as much attention to where the number 1 plug wire was beforehand. So on reassembly I put number 1 wire on the post pointing at cylinder 1. Then the rest in correct firing order. I put in the ignition test light on plug 1 and tried to start. I was getting a flash so knew I was getting spark. But it still wouldn’t fire, just the occasional pop from the exhaust.
Next step back to square one. I pulled plug 1 and had wife bump the starter until I was at TDC compression on #1. Then pulled the distributor cap and guess what? Rotor wasn’t pointing at cylinder 1! Apparently when the previous owner installed the HEI distributor he got it a couple teeth off. Rotor was pointing towards the post just counter clockwise. ( for cylinder#2). So I moved all the wires counter clockwise one post while maintaining correct firing order. Touched the key and she fired right up before the engine even cranked a full revolution!
Took it out for a test drive and ran great...... for about 5 minutes. Then it just stopped running. Not like no gas, it didn’t sputter and die, it just quit. I turned the key and it started up again. It did that 2 more times then ran great for an hour. WTH?... Ignition switch and wiring were replaced a few months (1000 miles ago). Even so while running I jiggled the key switch and wires and it all seems good.

This leads me to believe there is still something not quit right in the ignition system. Maybe a bad/intermittent connection to the pickup coil?

[geezer#99]

I’ve heard of intermittent problems like that caused by the coil ground.
Some info and a few other useful things here.
http://www.crankshaftcoalition.com/w...EI_distributor

[Fbks_Cruiser]

Thanks. I did check the ground strap in the distributor cap. But it may not be making as good of contact as it should. The coil mounting screw at the corner where the strap is felt like it was about to strip the plastic before it really snugged down. I may see if I can replace with a slightly bigger screw or else I will need a new cap.

[billthompson]

one thing you could try is ‘hot wiring’ it. run a lenth of wire from your battery + directly to your hei red terminal. this bypasses the key and all the wiring. once installed start as normal but this time the only thing the key does is crank it. the temp wire will be what keeps it running. if it runs you know its in the key or wiring. if you continue to have the problem you know its in the
distribtor.

['68OrangeSunshine]

The white grease is important. It is NOT the same dielectric you smear on all the plugwire contacts. It's a heat sink grease, it insulates the base of the module. Not sure we covered that earlier?
Also you might have to reset the distributor on #1 @ TDC and reset plug wires off the cap correspondingly. Otherwise your valves are out of phase by a couple of distributor teeth.

[Fbks_Cruiser]

Yes I used heat sink paste under the ignition module (not dielectric).

I verified that with the plug wires moved as I described base timing is again at 12* just as I had it before the no start issue.

Having looks through this:
http://www.crankshaftcoalition.com/w...EI_distributor

I now am wondering if my intermittent problem may be the wires to the pickup coil being flakey.

Rather than continuing to through parts at this old distributor that I don’t know the history of, maybe I would be better getting a new one.

[Steeveedee]

There is a resistance check for diagnosing the pickup in the link Geezer#99 posted. If you don't have an ohmmeter you can just leave the truck running and cycle the vacuum advance to see if that causes it to run poorly and/or quit. I will say though that I've only ever replaced one pickup on a GM vehicle Vs hundreds of rotors and a handful of modules.

[Fbks_Cruiser]

Okay. I think I am zeroing in on the intermittent stall problem. I just replaced the distributor cap due to the nearly stripped hole where the screw goes through the coil and clamps against the ground strap. So I feel that is good.

I also tested the pickup coil as described here and other places:
http://www.crankshaftcoalition.com/w...EI_distributor

I had about 900 ohms across the leads and no short to body which sounds good but as soon as I wiggled the wires resistance changed a bunch. Then just leaving the meter probes connected I moved the vacuum advance by hand and the resistance also changed. Sounds like flakey wires to pickup coil.

I won’t be able to do any more with it for a while but I’ll let you know how it turns out.

[Steeveedee]

Looks like that is a problem. It's fun to replace- you have to take the drive shaft out of the distributor. While you're in there, clean up any excessive gap per section 10 of that link.