Starting problems (1 Viewer)

[FJmaine]

Looking for some help diagnosing a starting issue. I have a 1974 FJ40 with a F.5 motor. Everything looks to be original/ stock. The last time it was registered was 2004. I have the motor spinning freely, starter is strong, plugs are getting spark (using a known good distributor with Pertronix unit), plug gaps have been checked. The issue we are having is it just won't fire. Fuel pump is moving gas, we are getting great suction through the carb, but even using starting fluid sprayed into the carb, we can't get it to catch.

things we have done:
-Marvel mystery oil in all cylinders to help free them up
-Got the motor turning with the starter
-Removed all plugs, cleaned, set gap
-Verify we are getting spark at each plug
-Pulled carb to get everything moving on it
-Sprayed carb cleaner through jets to make sure fuel would pass through
-Made sure all vacuum ports were sealed
-Set distributor based on FSM

We have tried running with starting fluid and gas through the pump, but we cannot get it to catch. Any ideas of what could be causing the issue? My next step at this point is pull the carb and rebuild it, but I feel like we should have caught with starting fluid sprayed direct into the carb.


@JRhino, @Travis Kinney feel free to add any details I may have missed.

 

[Malleus]

If you're sure you're getting fuel to the carburetor, you aren't getting a hot enough spark. Check the coil and igniter. I had no luck with a new Pertronix ingiter; my OEM ingniter needed to be rebuilt, because it wasn't passing enough juice to the plugs.

You have to have the trinity to get an engine to run: fuel, fire and air, and they have to be in the right proportions.

 

[FJmaine]

I'm using a Pertronix unit coupled with the flamethrower coil that they recommend with the unit. I was using this exact setup in my '76 before I switched to an HEI unit.

Is there a way to verify the spark is "hot" enough?

 

[Malleus]

Use a multimeter and the service manual or specs from Pertronix. You may get some help from their tech support.

 

[Malleus]

FWIW, I'm not the best source for support for Pertronix; I gave up on them when I tested the same setup you described, it checked out, according to their published specs, and still didn't work. I don't have any patience for them.

 

[73FJ40]

Run a jumper wire directly from + battery to + coil.

Bypasses all voltage losses through the ignition system

 

[Grayscale]

Check continuity (ohms) between distributor's breaker plate and engine ground.

 

[vfrer]

Are you certain you were at TDC on No. 1 cylinder compression stroke when you set the distributor? Could be 180 out.

 

[FJmaine]

Are you certain you were at TDC on No. 1 cylinder compression stroke when you set the distributor? Could be 180 out.

Verified that both lifers were loose meaning the valves were closed. I would think that even at 180 out, I would have some kind of backfire.

 

[pb4ugo]

Well with an electronic distributor you wont be able to complete #3 in the directions, because there are no points to adjust to. You might try rotating the dist at different locations or turn it while cranking it over to get it to fire. Has this engine run in the past with the petronics installed? Are you currently getting these below freezing temps? You might want to check the plugs and see if they are wet from trying to start it. Its easy to flood an engine in the cold. Most folk revert to Either or pouring gas down the carb, when it's usually the last thing you should do. If the plugs are wet, then pull them all and open the throttle wide open and crank to dry out the cylinders and dry the plugs.

 

[igotta40]

Got compression?

 

[45Dougal]

It will normally 'diesel' on starter spray, so if you don't get a single pop then I'd be guessing compression - maybe valve timing, or stuck valves? - rusty?

 

[JRhino]

It will normally 'diesel' on starter spray, so if you don't get a single pop then I'd be guessing compression - maybe valve timing, or stuck valves? - rusty?

Been working on this with @FJmaine; it has 125psi compression in each cylinder, which tells me the valves are cycling. We have had it diesel along but never backfire, which makes me think timing is right, but maybe this points us to a weak spark issue?

 

[sggoat]

just to confirm--when the timing is at ~7 deg tdc,(vlv springs loose on #1 and6) where is the dizzy rotor pointing?(rotor should be pointing sorta at #4 plug)
Seems the lower compression #s are well below spec,but certainly not low enough to cause what you are seeing--think this may indeed point to a spark issue--pb4ugo has some good suggestions--

 

[FJmaine]

The image below shows how it was set up.

I haven't had a chance to get back on this project this week. Maybe Sunday...

 

[Pighead]

here's mine at TDC

 

[45Dougal]

Maybe worth disconnecting, cleaning, and reseating the ignition switch connector.
Or try bump starting it and see if you get the same

 

[65swb45]

The image below shows how it was set up.
View attachment 3822604

I haven't had a chance to get back on this project this week. Maybe Sunday...

You can't experiment with advancing the timing with the diaphragm jammed up against the oil filter. Clock the whole dizzy over a tooth clockwise and try again.