72 280SE 4.5 Engine Won't Start

It has been few days now trying to get car to start and it is very frustrating. Checked everything I know and it still wouldn’t. I checked the following:

1- plugs are definitely getting fuel. Pulled several plugs out and all were wet.
2- Measured ignition coil primary and secondary coils for resistance. Got 0.45 ohms and 10K ohms respectively. Ignition coil is fine.
3- Checked transistorized switching unit. Got about 5 volts at primary coil end when points were closed and 0 volts when points were opened.
4- Replaced distributor rotor.
5- Checked resistance of electrical lead going from coil to distributor and measured high as expected about 10k ohms.
6- Did not check for spark but I am sure I am getting spark because engine is turning and sounds like it is firing in there but doesn’t want to keep going.
7- Checked all of the hoses and connections.
8- I don’t think it is the timing
9- Choke is fine and am getting plenty of air.

If I am getting all of the three ingredients (fuel, air, and spark) why isn’t the engine running. Could anything else be bad?

Please help.

[ctaylor738]

I think you should check for a good hot spark by holding a lead 3/8 of an inch from ground and cranking the engine. If you get a good bluish-white spark, check the timing.

If the timing is on, then I would check fuel delivery. You might be getting fuel from the cold start valve, but not from the injection pump.

Did the car exhibit any symptoms before it started not starting? That could be a clue.

Chuck

[Mark DiSilvestro]

Sounds like too much fuel, Flooding.
Mark DiSilvestro

"Did the car exhibit any symptoms before it started not starting? That could be a clue."

Mustafa36

Tell us what happened, did the car run fine and then quit?
Also, if you did not check for spark at the plugs, Don't assume that it is there! Give us the low down and will give you the CURE
Regards,
Bryan

[cth350]

Two things strike me right off the bat,

1. Is 5v at the coil enough? Check the diagnostics on the igntion in the v8 manual (Channel1 just got them from me last night).

2. Your plugs shouldn't be wet.

If you pull the plugs to let things dry out AND disable the fuel delivery (disconnect the brain box or the fuel pump relay).

Your car should start and run on some ether for all of about 2 seconds. If it doesn't the problem is ignition, not fuel. (obviously, put the plugs back).

-CTH

The problem started a couple of weeks ago after I got the car ready to be painted. I removed the following items: Head lights, tail lights, fog lights, side lights, fuel vapor tank in trunk to gain access to the right hand side light, and fuel door along with the vacuum operated locking mechanism attached to fuel door. When I got done that day I drove the car few feet into the garage. The next day the car started very rough and was barely able to drive it more than 20 yards. That day I had the car towed to the paint shop. At the paint shop, they cleaned few spark plugs (owner told me they were fouled) and the car started right up but a little rough. The car started right up few times to move it around the shop except the last couple of times.

On a separate note, few days prior to taking them parts out to prepare car for painting, I adjust the timing because the car was running a little rough and hesitating. I set the time to 10BTDC with vacuum line removed. Reattached vacuum line and dropped RPM to 750 and the time was now at 2 BTDC (I’m not sure why but it should have been around 5ATDC or so). Regardless the car ran fine and very smooth.

CTH, the voltage as specified in the manual for the car is supposed to read 2.6-3.5 volts at coil when points are closed. Mine was a little high I know but I think it is OK.

Tonight I am going to check for spark. My coil resistance values tested fine but may be my coil is arching inside and not producing high enough voltage. This check tonight should give me a real indication if coil is working or not (I hope).

Any ideas out there what else to check for.

I will check back in the morning.

Out for now.