Engine Cutting Out

Check the fuel filter? Don't ask how I know this! More then once! lol

Michael,

Quite a few possibilities here. I would check the electrical first.

What ignition system do you have? Stock? Aftermarket?

When the engine quits running, does the tach immediately drop to zero before the engine stops rotating?

It could be anywhere from the ignition switch to the ignition system, and/or points in between.

John

I'd be looking at fuel delivery.

Larry

I disconnected the fuel line on the outlet side of the fuel filter and turned the key forward (electric fuel pump). Gas was flowing out like a water fountain, so the pump and filter are not clogged. I had someone crank it as I manually blipped the throttle from the carb and watched fuel squirting in the primaries while it VROOOOOMED and died. That tells me it's not likely a fuel issue.

Then I thought the pin in the distributor gear could have broken, so I moved the dist both back and forth quite a bit in small increments. No change. When the timing got too far retarded, it backfired while cranking. When it was too far advanced, it cranked in fast spurts (RRR RRR RRR), like when the timing is too far advanced. The first time I advanced it, it started and purred, so I grabbed the dist and slowly brought it back to the original setting and the motor cut off. When I re-advanced it to where the motor started, it did not restart again.

At several points in all this cranking, I removed a spark plug wire and watched and orangish-blue spark flicking away through the VROOOOOM and cut off. The spark was always going, even when I would just hold the starter on and let it crank.

It's a vacuum secondary carb, but I don't think that matters.

So I have spark, I have fuel, and I have air. What's missing?

Michael

quote:

orangish-blue spark flicking away through the VROOOOOM and cut off

Are you saying that you had spark through the last few revolutions of the engine (before the engine stopped rotating), or did the spark stop as soon as the engine stopped maintaining RPM?

When the engine stops maintaining RPM, does the tach instantly go to zero, or does the tach continue to indicate the decreasing RPM?

Does the engine quit as soon as you release the key from the start position?

What type of ignition system do you have...points and coil or....?

If your distributor has a vacuum advance, remove and plug all of the hoses and try starting the engine.

John

...Sounds like the 'Ignition Switch'!(Or the wires From the switch to the Coil). You get Spark while cranking, But No Spark when the Key is released back into the 'Run' Position. So the car starts and then dies as the Key is released from cranking. For this to occur, There would have to be 'The' Bypass wire from the Starter Solinoid to the Coil + side, it Bypasses the Ballast Resistor and supplies the full 12 Volts to the Coil, ONLY During Cranking!!...

quote:

That tells me it's not likely a fuel issue.

Agreed.

As John asked, what type of ignition?

Age of coil?

Any problems recently with the ignition key tumbler?

Larry

I had a simular issue after a WOT run last summer. I run a Deamon 650 double pumper on a Blue Thunder intake. The symptoms were the same as yours and what it turned out to be fuel pouring out of the secondaries at idle. Larry W. came over and helped me resolve the problem.

Good luck!

George

I appreciate ALL of your input and suggestion! Thank you.

Marlin,

The engine will keep sparking even when I keep cranking through, then past the VRM. Whenever I'm cranking, the spark is sparking. The engine DOES NOT run if I keep the key forward in the cranking position although spark is present. It will just VRM and die, every time.

If a float was stuck and fuel were dumping, I'd smell gas, which I don't. The engine doesn't stumble at all when trying to start, or when it dies. In fact, at first I thought there wasn't enough gas getting through the carb, so I pumped the pedal about 8 times, smelled gas, and it spit and popped a few times before I got a clean VRM again.

I'm going to disconnect my fuel line feeds from the carb and check those filters in the a.m., just to rule out a blockage there.


George,

I don't see any fuel in the secondary barrels at all. Nothing is squirting, and there is no pooling on the blades (they don't even look wet. Did your engine stumble when it happened to you? Were you blowing black smoke from the tailpipes? Did you smell gas?


John,

I have an MSD box, and my right arm pit can attest to it's 'jolt'! My MSD tach adapter bit the dust at the end of last season and I haven't gotten around to replacing it yet, so I can't answer your 'tach needle' question. I guess I'll order a new one tonight so I can answer it. What does the needle's reaction tell you? I'm not sure what type of distributor I have, or whether it has points or not. I'll check that out in the morning. It may be a Mallory unit. It does have a vacuum advance, though. My answer to Marlin above should answer your 'spark & revolution' question.

There is a standard Ford coil that was replaced in Sept. 08 while on my way to Canada. That was the second or third one I replaced in 7 years, but each time, there was no spark at all. I'll try your vacuum advance disconnect in the morning. What would the vacuum indicate to you?


Larry,

Being an '86 car, the ignition key and tumbler are different than the earlier cars (I don't know if that makes a difference). I haven't had any key turning or other issues with the tumbler, but once or twice during all of this cranking, when turning the key back, it felt a touch like it catching, like I was using a newly cut key. I didn't think anything of it. It could have been the angle I was twisted into trying to look at the engine, or the speed at which I was turning it (too fast).


It was suggested to me that the gas could be bad. The gas in the tank is probably 6+ months old, but I think stumbling would be involved, maybe some popping too. My feeling is that it's electrical.

Michael

Michael,

quote:

What does the needle's reaction tell you?

It would tell me that either the ignition system lost power or the triggering device (distributor points or electronic sensor) was not functioning properly.

quote:

What would the vacuum indicate to you?

It would indicate that the primary distributor wire (or the ground wire) inside the distributor is not making contact when the vacuum advance moves the breaker plate inside the distributor. An insulated wire could have a break in the conductor, but not in the insulation. Pulling on the ends of the wire will pull the conductor apart, and the insulation will stretch and shrink (slightly) into the void (clue). This type of break is hard to find. Or the ground wire inside the distributor could be loose.

There is always a possibility that you could have a severe restriction at the fuel entry to the carb. I have seen needle seats slowly unscrew to the point that the float is virtually at the bottom of the float bowl. This forces the needle valve to be bottomed in its seat, letting little or no gas into the bowl, and certainly not enough gas remains to function properly, other than to allow the accelerator pump to be able to suck up and deliver a shot of fuel out the discharge nozzles. Car starts and immediately dies. Don't ask me how I know.

Old gas can certainly be a problem, but what usually happens is that the engine will either be very difficult to start or will not start at all, not even one sputter. If you squirt (or pour) a small amount of fresh gas down the two primary bores, the engine will start instantly and will continue to run. In some cases, a second "primer" squirt is needed. Once the engine is warmed up, the engine will continue to start and run normally for the rest of the day, as long as the engine doesn't cool down very much. Once the engine has cooled (especially overnight), it will not restart unless it gets a squirt of fresh gas. Ask me how I know.

John

John,

In regard to the float bowl, what about when I blip the throttle at the carb and can see gas shooting into the primaries as the engine cuts out? What's the best way to verify the float's location? Thanks.

Michael

Michael,

quote:

when I blip the throttle at the carb and can see gas shooting into the primaries

That should at least cause the engine to rev. Fuel delivery is not the problem.

quote:

What's the best way to verify the float's location?

You will be verifying the fuel level. There should be a clear sight plug on the side of the float bowl. The fuel level should be at the bottom of the sight plug. Adjustment is done by loosening the lock nut at the top of the float bowl and turning the setscrew....clockwise to lower the fuel level, and counterclockwise to raise the fuel level. If the level is close, don't adjust it at this time.

John

A quick one, pull a plug. Is it wet with fuel or bone dry? Then you know if it's ignition or fuel problem.

My guess based on the "sudden death" is: ignition problem

...Next: I would pull ALL the SparkPlugs for examination. AND Pull Off the Distributor Cap to Inspect the Rotor and The Inside of the Cap for 'Carbon Tracking'! Also, Inspect the High Voltage Cable from the Coil to the Center of the Distributor Cap, Looking for an 'Intermittent Connection' or Short! Since You DO have fuel squirting down the Carb Throats; 'Fuel' Can't Be Your Problem. The Only Other Thing it could be, would be a 'Machanical' Problem; Such as a 'Slipped' Timing Chain, Sheared Distributor Drive Pin, Broken Piston. The list is Near Endless! You'll Have to perform many Intensive Tests to Zero-In on the Cause. An Intermittent Problem is the Most difficult to find!...

Michael,

Is the MSD box fed with the original wire from the ignition switch, or is it fed from a relay that was added when the MSD was installed? If there isn't a relay, try putting a jumper from the battery side of the starter solenoid directly to the MSD box.

John

Ok, this is what happened today;

When I started the engine this moring, I pumped the pedal once to close the choke and it started right up and ran for a minute or so again. It was responsive to the pedal. Then it shut off when things started getting hot. Then it was back to the cranking, VRM, and off.

I took out the sight plugs on the float bowls, and the gas was at the botom of the openings. Then I took off the fuel lines and removed the internal filters. They were clean, but I rinsed them with some carb cleaner before putting them back in.

I walked away from from it for a half hour or so, and when I came back I removed a spark plug to observe spark behavior again. The car started up and ran on it's own again for about 30-40 seconds when I turned the engine off with the key. I immediately tried to start it back up and it didn't restart. What was happening was now it cranks first, and it will VRM after cranking for a few seconds as I blip the throttle. It seems to VRM right through the blip, then cuts out.

I noticed 2 things. First, the car seems to shut off after as it is getting hot, and won't start again until it cools down somewhat. Second, The spark stops when the engine dies. So the engine will still turn some revolutions as it comes to a halt without any spark. I would crank the engine and watch it spark through cranking and VRM, but once it cuts out, the spark was gone.

I know coils are susceptible to heat. Could it be the damn coil yet again?!?

Responses are welcome.

Michael

Marlin,

It's a Motorcraft vacuum advance distributor with 12127 stamped right next to 'Motorcraft'. It has Mallory Unilte internals. I pulled the cap and rotor. It appears to be a Motorcarft cap, and a Mallory rotor with the removable black window skirt around it (for the pickup). The cap and rotor are carbon scored up, and need replacing. I cleaned them both up and out then back for now, with no change. The plugs are black, but dry, and hardly look worn. The wires don't look so hot, but didn't 'glow' last night.

I'm ordering new plugs, cap, rotor, wires, fuel filters for the carb, external fuel filter, and tach adaptor tonight. I may as well change it all while I'm at it.

Michael

quote:

Originally posted by jb1490:
Michael,

Is the MSD box fed with the original wire from the ignition switch, or is it fed from a relay that was added when the MSD was installed? If there isn't a relay, try putting a jumper from the battery side of the starter solenoid directly to the MSD box.

John

John,

I'm not sure. It's probably wired directly to the MSD. I take it this test will expose, or eliminate the ignition key circuit?

Michael

quote:

It's probably wired directly to the MSD. I take it this test will expose, or eliminate the ignition key circuit?

Yes. You really should have a relay for the MSD power supply.

John