Starting Problem

[Archrms]

Recently changed the plugs with the exact brand and heat range. The original plugs were heavily fouled by either oil or rich carb setting, however, the engine ran fine. I had a friend look at carbs (dual quads), and he said both primary fuel bowls were set too high and the secondaries were too low. He then proceeded to adjust the floats in both carbs. It was late when we finished, and it rained the next day, so today was the first day to fire it up and take a ride. It fired up on the first try, and idled roughly for a minute or so (no choke). It then quit and would not restart.

I checked all the plugs and cleaned them to be sure they weren't the issue, (they were still cleaner than the ones I took out originally). It won't catch completely, and occassionally has a small backfire through the carb with some flame if I keep cranking it and pump the pedal.

Nothing was changed but the plugs and the float levels, and now it will not start. The plugs are exactly the same, so they should not be the problem. Is there anything that I am missing and should be checking? Could changing the float levels cause this severe of a problem? It ran better with the fouled plugs.

[patrickt]

... if you still have the old fouled plugs, then stick them back in and just see if that makes a difference. It probably was the float adjustment, or maybe you damaged the plug wires in the process, but there's always the slim chance that the "identical plugs" are counterfeit knock-offs. I doubt that's the case, but putting the old ones back in would clear that possibility up. If the problem is still there with the old plugs back in then it was either the float adjustment or you damaged the wires pulling them off.

EDIT -- Educational NGK video on counterfeit spark plugs http://www.youtube.com/watch?v=b0sB81hI6AI

[Rick Parker]

Check the carbs (primary bowls) and be sure they have fuel. Check accelerator pump nozzels and be sure fuel comes out when throttle is opened. It is possible the float level is too low. Another long shot that if metering plates or blocks were removed that the incorrect gaskets were used between them and the main body. This asumes you have spark.

[Barnsnake]

It's quite possible you have an ignition problem that coincidentally appeared after you worked on the carbs. Check the distributor for condensation and look at the contacts for the rotor. If you have a timing light, see if the spark is steady and on-time. If it seems to fire or pop just as you release the key, suspect the ignition switch.

[PANAVIA]

If no POP (trying to fire)--no E juice, or no Gas.

I would hit it with starter fluid and see if it pops. if it does then its fuel, if not then it is spark related.

someone trip a hidden kill switch and not tell anyone >?

V+ to the + coil (or V+ to the MSD box) during cranking AND run of the ign switch is key to POPing, and running.

--Steve

[undy]

Make sure you didn't cross any plug wires when you changed the plugs..

[Bryan Wilson]

I had the exact same problem, would run rough then backfire through carb and stop. After swearing the problem was the carb I brought a new one and the problem was still there. Eventually got a new ignition coil and problem solved.
Try a new coil.
Cheers,
Bryan

[Archrms]

Patrickt - I will re-install the old plugs just to eliminate that possibility today.

Rick - The bowls have fuel, and there must be spark as per the backfire/flame.

Jim - The distributor cap and contacts look good. I will try to get an extra pair of hands to bump the engine to check the timing, and will pay attention to what happens when I release the ignition key.

Bryan - Is there a way to test the coil to see if it is the problem?

Thanks for all the input and suggestions guys. I plan on working on it some more this afternoon, and will check the wires and firing order again.

Ron

[Bryan Wilson]

Originally Posted by Archrms

Bryan - Is there a way to test the coil to see if it is the problem?
Ron

I was looking at things like carb. leads, dist. cap, stuck valves etc. and my son kept saying it's the coil and no I don't know how to test it. So to shut him up I put on another coil and then had to endure the "I told you so's".
Cheers,
Bryan

[Archrms]

I'd be willing to endure that just to get it running again

[cobred]

How did your friend adjust the float levels? This should be done with the engine running. I heard of a similar problem once when too much anti sieze was used on the plug threads, did not give a good ground to the plugs.

[SuperHart]

My first guess would be to agree with undy that you accidentally crossed plug wires. It's a simple matter to check that out. The symptom you describe is commonly caused by crossing wires.

[Archrms]

I re-checked the wires and firing order, and all is correct. I also checked the wired with a timing light, and all seemed to be getting a signal from the distributor.

He set the float levels by bumping the engine, it was not running.

I replaced the coil and re-installed the original plugs (just to be sure), both with no results.

The thing that bothers me the most is that the car started on the first try (which it rarely does after sitting for a few days), and ran for a few minutes before stalling, and now it won't restart. If something was wrong from the begining, the car should not have started in the first place. Battery is now dead from all the cranking and is being recharged. There has to be something that is being overlooked, but I can't seem to find it.

[VINCENT RUDI]

do you have a points distibutor, if so they may need to be reset or change its also possible your battery is low and not prviding proper voltage for spark.

[Barry_R]

When I get a customer with one of these - and it does happen - I have a procedure I follow just to get back to "square one".

Remove all the plugs and wires. I pull them right off of the car.

Diasable the coil, and crank the motor over a bunch of times (+/-20 rotations) with the plugs out to clear any liquid fuel. I've seen spouts of fuel spew from the cylinders.

Walk away for an hour to let things dry out.

Come back, install clean fresh plugs, and install the wires one at a time in the proper firing order - 15426378. Leave number one plug out - lay it up on the intake with the wire attached.

Check the float level - it might not be perfect without the engine running but it will be darned close and more than good enough to start and run fine. It should be at the lower edge of the threads.
No fuel = no start. Pouring out = no start.

Rotate the engine by hand until you are 20 degrees before top center checking to hear/feel compression on number one cylinder. You can reset it correctly later but this will start the engine.

Turn the key on but don't crank it. Loosen the distributor and rotate it back and forth watching for spark from that plug laying on the intake. "Catch" the right position as it just sparks and tighten the distributor.

Install the plug. Hit the gas twice, maybe three times and start the thing up. You will never know exactly which item was off/wrong - but you won't really care either.

[Archrms]

Barry,

I followed your procedure and hit a snag when I had the key "on", but could not get a spark by rotating the distributor. If I cranked the motor with the key I would get a spark, but could not do it by rotating the distributor cap by hand.

I have already replaced the coil, so this doesn't leave many possible culprits left. Could the module inside the distributor be bad and causing these problems?

[RAO-3]

Just a thought - did you check to be sure you didn't damage any of the wires when you were changing out the plugs?

Ray

[Archrms]

I went through everything again this morning after thinking about this all night. I double checked everything again, when I noticed that the front carb fuel bowl level was lower than it should be. While trying to adjust it, it started leaking from the screw, even after I locked it back down. Took carb off and pulled bowl off. Sure enough the float tang was bent. I bent it back in place, eyeballed an approximate float level, and reinstalled carb. It fired up after a few tries. Went through and adjusted all float levels with car running. Still trying to clear my lungs from all of the exhaust in the garage , but it was worth it.

Hopefully this solved the problem. Thanks to all for your input and suggestion. I will keep you all posted on final outcome.

[patrickt]

Originally Posted by Archrms

I had a friend look at carbs ... then proceeded to adjust the floats in both carbs.

Good to hear it's fixed. Now don't let that friend near your Cobra again, except to test the temperature of your sidepipes with the back of his calf.

[Archrms]

Took the car out for a quick spin. Ran fine until I stopped at a light, then it ran rough and wanted to stall. Coaxed it home and stalled in the garage. Lots of fumes/smoke from pipes after stall.

Pulled air cleaners, and found fuel dumping into the front carb from the primaries. Cranked engine while trying to adjust float level. The more I adjust (lower) it keeps pouring out the sight hole. At least it stopped pouring into the intake from the carb primaries.

I'm thinking the needle is stuck open in the front carb primaries, which may have been the cause of the oroiginal problem. If ity was stuck open, and kept filling the bowl, my friend would have kept lowering the adjusting screw, whiich eventually bent the tang when it bottomed out.

I know the float was correct and the fuel level adjusted before taking it out for the ride. Therefore, the needle stuck open afterwards.

What do you think, and how do I fix it?