Cobra cutting out

[rodneym]

The other day I took my son out for a 1/2 hour drive. Everything was fine. On the home stretch I decided to piss off some golfers so I gunned it pretty hard. The engine cut out 3 times. Not your typical hesitation, but on-off-on-off-on-off. Absolute silence between these split second 'offs'. Then it was fine, golfers pissed, mission accomplished.
Then yesterday I warm her up for 5 minutes, drive up to a stop light, press the clutch and the car dies. Crank it and nothing. Switched on and off the fuel pump switch a couple times like some WWII Ace about to crash land. I limp to the side of the road. Won't start. Engine looks good, still cold. I crank it again and viola! No problem for the 60 mile round trip.
My confidence is waning. I have a 5 year old Roush 402R/SPF. The installer took out the mechanical fuel pump and I can't find the electrical one. I presume it's by the tank. All I see is a braided line going from the carb and down through the tunnel.
My neighbor thinks it's the ignition, MSD/Fireball. Pump makes quite a loud noise when ignition is on. When I start, I usually turn the key on, let the pump work for a few secs, pump the gas and start. The installer also took off the choke for what that's worth.
Any ideas? Could fuel boil while engine is cold? Loose ground? How many ground connections are there?

[xlr8or]

I would look for a bad ground or loose connection. Check the MSD wiring on the ignition box. Also check the fuel level in the bowls it might be a sticky float or needle/seat is dirty.

[strictlypersonl]

Definitely electrical. A fuel problem wouldn't have your on/off symptom.

It could be in so many places in the ignition circuit, from the ignition switch to a bad distributor, and everything in between.

[Blittleton]

I would agree with the ignition module in the distributer. I have seen several fail with that same type of discription.

Bill

[Blas]

You said, "...Crank it and nothing..." Could you clarify that a little? Did it actually crank...or do nothing? If it didn't even turn over I would look at the battery ground first, then the ignition switch. If it turned over but did not fire, check the easy stuff first, power and ground on MSD box. The 2 wires on the coil, inside the distributor cap/center contact. Do this easy/cheap stuff first...then start spending $$$$..

[Fordzilla]

Sounds electrical. Hopefully you can find it relatively quickly as some times these things can drive you crazy!

[jhv48]

Definitely electrical.

Those golfer Gods can play dirty when pissed off!

Good luck.

[rodneym]

I should have clarified, it did crank. It was as if I had no gas. I spoke with a couple of local mechanic friends and they said loose ground or ignition. All connections looked good.
I showed off a bit for my friend, an old Corvette and Porsche guy. He loved it and we really hit the rev limiter a few times. No problems today.
Now that the warranty is long gone, how much higher could I adjust the limiter and be safe? 6500, 6800? The reason I ask is because the motor is hitting her stride at 6200 (current limit), she's seems to have alot left. Any of you guys mess with the rev limiter?
Back to the original problem, are the Fireball ignitions good? My friend said they didn't have a good reputation quite a few years ago. Any suggestions?
Thanks, I really appreciate thr brotherhood!

[rodneym]

jhv48,
You're right about the golfer gods. I live in a golf course, and these wierd problems only happen around the perimeter of the course.
Next time I'm getting a dirty look at a guy about to tee off, I'll throw him a Cohiba

[Fordzilla]

Unless you are racing it competitively, I can't see any reason to spin it more then you are. I'd play it safe & enjoy the motor for a long time. If money isn't an issue, then let her rip!

[Blas]

Well, if you say the powers & grounds are good...both at battery and by starter....I'm thinking coil, MSD box or ignition switch.
Go to the MSD website and find the coil test information.
Simple test with a volt/Ohm meter....
You can also find the test procedure there for the MSD box, also quite easy to do. Get thru that testing first. Costs nothing but some time...Did you look at the rotor and center contact in the distributor?

[traveler]

I had something happen to mine that sounds exactely what is happening to yours . I have an MSD Ign. in mine and the Rev limiter was bad .

I dont race mine so I just removed the limiter switch and no more problems .

Rick

[rodneym]

Blas,
I checked the ditributor tonight. There was a tiny bit of scoring? on the outer magnets but O don;t think that's it. I'm going to check the MSD site and get that test procedure.
traveler,
What do you mean 'removed the rev limiter'? You mean set the limit very high? Mine is in the finned Fireball box that looks like a car stereo amp. Doesn't that control the coil when to spark or is it only the limiter?

[patrickt]

Originally Posted by rodneym

What do you mean 'removed the rev limiter'? ... Doesn't that control the coil when to spark or is it only the limiter?

He means pull the chip out of the side of the MSD unit -- that chip is the "rev limiter" and interrupts the spark at a given RPM. And yes, the MSD unit controls when the coil's field collapses to cause the spark at the plug. FWIW, the way I tackle intermittent electrical problems (assuming that's what you've got) is to hook up different colored test lights to each part of the equation and have the lights literally right in front of me (taped to the dash, sticking out from the hood, it doesn't matter). When the problem occurs, look down and see what light(s) are not working and that will give you a clue. I just did that recently for a faulty ignition switch in my Cobra that was giving me intermittent no crank situations, and seconds later, cranked up perfectly. Before hooking up my test lights, I was sure it was the solenoid (wrong), battery (wrong), starter (wrong) ... and it proved to be the ignition switch. When the car wouldn't crank the light feeding the ignition switch was on and the light feeding the solenoid from the switch was off. Jiggling the switch just right could make the light blink on and off. By any chance do you have your coil mounted horizontally? If so it needs to be the "Hi-Vibration" Coil, otherwise you can get air pockets over a winding that can cause intermittent faults. Unless you know that little trick, it's a real pain to diagnose.

[cdog]

Check the wires to the ignition coil. I mean pull on them.

Also, check to make sure the battery clamps are tight. And pull on the wires to the battery.

It sounds like nothing serious, but rather a loose wire somewhere in the battery-coil connectin.

[Madmiles442]

I had something similar and it was the battery connection. But not from clamp to post, but from wire to clamp. The connection had an ever-so-slightly loose connx and ever-so-little corrosion on it but it was just enough to get it to cut out ocassionally. Cleaned off the copper, changed out to a flat-clamp style of post clamp, put on anti-corrosion spray and hadn't had a blip since.

PS - Many thanks to Joe Wicked for my actual diagnosis. I'm just passing on what was found.

[undy]

As I said, do the simple resistance check on your MSD ignition module. (400 to 1300 Ohms) is the correct range. The ignition module does not necessarily fail catastrophically. It failed on mine intermittently, duplicating the same symptoms you have. I did a web search and it's a v-e-r-y common failure.

Dave

[Metal-morphous]

I had this happed 3 times and everytime is was the MSD box. I had a hell of a time finding it the first time because it would start and run fine untill the next mishap. I talked to many others that run the MSD and have no problem and some that do, I am one of those that DO so after 3 MSD boxes I have now changed to Mallory

[Joe Wicked]

Intermittent problems are always a pain. A few things to check for as well, is to pay attention to when it happens. I had an issue where the motor would cut out in my old T/A only when it was 90° or hotter outside. Let it sit for a bit and you were good for another 30 min. Had to do a road trip from San Diego to OKC in it in July. Long day. I did not get to Arizona until 8PM. Turned out to be a clogged fuel filter.

Miles' problem was diagnosed because it happened when he hit bumpy areas in the road in Austin last year. That told me it was definitely a connection issue. It was causing fuses to blow, so it took a little run down and an issue that morning proved fateful as it led us strait to it. Little things like outside weather, road conditions, and other things that may not seem like they would matter are often the key to finding electrical issues.