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

Michael,

Don't get carried away with replacing parts just yet. While the parts that you mentioned may be "worn", that is not the source of the problem.

The two simplest things that you should do first are: 1) jumper the MSD input power, and 2)try a replacement coil.

John

John,

I'm going to try a replacement coil tomorrow. While I'm there, I'll jump the MSD. Thanks for the suggestion. I'm going to order the tune-up parts because I need them anyway.

Michael

I was finally able to get back to this today and here's what I found:

I was going to do John's MSD jumper test when I noticed one of the wires for the ballast resistor was hanging off and just barely making contact. I pushed it back on and it was very easy to slide back off, but I tried to start the engine anyway and it fired right up! I turned it off and on several times and let it idle a bit. Before the engine got too hot, I slid the loose connector back off (it was a crimped on female), and used a pliers to sqeeze the prongs down a little tighter. It was nice and tight going back on, but I noticed the blade coming from the resistor was wobbly.

I tried to start the engine again and it just cranked. I took a plug wire off and had no spark. I removed the connector again and slid it back on, but not as deep. The engine started back up and idled just fine. I wobbled the blade with the connector on it while the engine was running and it did not cut out, or even stumble.

I took it for a test drive, and the car hesitated a few times, like it wanted to shut off, but caught itself. After about 15 minutes, I shut the engine off, and it would not restart, it just cranked. After a while it started and shut off, then started and ran. I headed for home, but had to stop for gas. The engine started right back up, but cut out before I got to the street. This last time it started, and stayed running all the way home, but stumbled many times.

Am I right in guessing that the wobbly ballast resistor blade is giving me inconsistent contact internally? I don't see what else it could be, as the loose resistor connection solved my 'no start' problem.

It looks like an MSD type of resistor (.8 ohms). I have an MSD 6AL, with a stock coil, and a Mallory Unilite pickup in the Motorcraft vacuum advance distributor. Should I be using the Mallory type of ballast resistor (.75 - 1.5 ohms), or does it not matter?

Michael

This situation has gone from bad to worse.

It turns out I don't need a ballast resistor with an MSD box, so I bypassed it by connecting the two wires together. That seemed to work for a short while. It barely stumbled once or twice on an hour long ride, but when I turned around to come home, it really started bucking and lurching (from constantly wanting to cut out). I didn't think I was going to make it home, but I did.

I got back to it today to attack some of the excess wiring in my engine bay. Whoever was in there previously seems to have not known the slightest thing about wiring, or maybe just didn't care. There are about 4 or 5 wires on each of the coil's terminals when there's only supposed to be one on each. Some of these wires are even cut somewhere down their length. Wires are butt spliced here and there for the electric fuel pump, the choke, the tach adapter, etc. It's a horrible mess.

I removed the cut wires that went nowhere and isolated some of the others. So now I turn the key, and the exact opposite of what was happening is happening. At first, The engine would crank a little and try to start, but when I released the key it would cut right out. Now it cranks endlessly and when I release the key it starts and runs! I let it warm up, and shut it off just to restart it. Normally, flick the key and it will kick right on. Again, it cranked endlessly and when I released the key, it started. I did this several times with the same results.

I took it for a test drive and barely made it to the corner. Now not only is it wanting to cut out, but it's also spitting and popping and backfiring like it is now out of time! WTF ?!? I tried for the next corner, but it wasn't happening by a long shot. I turned around and put it back in the garage.

Kingston is next weekend and I'm at a loss. How could the engine all of a sudden be backfiring? I didn't change anything except removing cut wires. I even put those back just because it was the only thing I did differently, but no change. I can see an electrical issue causing the engine to cut out cleanly, or go on and off. I can't see an electrical issue causing the engine to pop and backfire (badly) all of a sudden.

Any thoughts? (Tomorrow is just about my last day to conquer this before I miss Kingston.)

Michael

Michael,

Try the jumper directly to the MSD box. There really should be a relay feeding the MSD. It also sounds like there may be a problem with the ignition switch, but try the jumper first.

John

John,

I'll try that. I haven't yet because the ballast resistor exposed itself and that seemed to fix it. Besides jumping the MSD box, do you think a bad MSD box could cause what's happening?

Michael

Are you using the Ford horseshoe connector to your coil? I had a similar situation with my car that was driving me crazy. I bought a spare MSD Blaster 2F and swapped it and my problem went away for a while. I was driving back home and my car died at the stop light and was hard to restart. I was able to make it home and found the positive lug on the horseshoe connector was black and the plastic was melted around it. The connector was loose and was arcing on the gap.
Good luck in your troubleshooting.

I once had issues a little like you have. Could run well for a few miles, then start to spit and backfire and lose power. Next day, while testing with another component, it would run fine, and then the next day with nothing changed, the problem would reoccur. For me it was something simple, the vacuum advance could get stuck. When I disconnected and plugged the vacuum hose, the problem was gone. A new vacuum advance (adjustable) solved it.

Michael,

quote:

do you think a bad MSD box could cause what's happening?

Yes, it certainly is possible. Try another one.

You might check your ignition timing to make sure that the timing chain hasn't jumped.

PM sent.

John

I had a simular problem happen to me last night. The car started as usual and ran strong for20 mins. Stopped at a local store for maybe 3 mins and went to start her up and she back fired and stumbled for a couple of mins. before clearing herself out. Ran great for another half hour at highway speeds and local traffic speed. Picked up my son from soccer practice and stopped for gas. (go figure) Then it did the same thnig..back firing and stumbling. But this time she would not start. I had my son crank her over while I was in the back looking for a reason. While he was cranking her over I could hear sparking and noticed a lot of oil steam blowing by the breathers. We pushed her to the side of the parking lot. (Gas pumps and sparking don't mix) I inspected all the plg wires which looked fairly new when I bought the car two years ago. Then the coil wire, and found thet the connector on top of the dist. had come apart! Pulled the wire out and found it to be very old and full of corrosion. Probably the original wire! Called the wife and she went and bought a wire kit and I fit the new cable by means of my truck's headlights and she started on the first crank! Drove her the half hour home at high highway speeds with no problems. I actually feel a big difference in the power off the line, much stronger pull. I'm guessing that wire has been like that since day one and just hanging on by a thread.

With that said, a closer inspection of your wires couldn't hurt at all.

George

By the way, I'm one of the lucky ones that this was the first time with my car that I had to almost call for a tow.

Michael,

Your "endless crank" then start when you release the key, is indicative of no "crank voltage" to your MSD box. Could be a starter relay sort of thing.

Fords (and others perhaps) supply 12V to the coil when "cranking", then once the engine fires, the operator lets off on the key and it returns to the "run" position, and the ignition system now provides a reduced voltage amount (6-9V) to the coil for normal operation (via a resistor wire from the ignition switch to the coil, or an external resistor of sorts). With the aftermarket setup, I suspect it operates in a similar manner, but you perhaps inadvertently removed one too many wires!

You are correct in removing the fuel pump wiring, electric choke, the subwoofer wiring, alarm, fog lamps from the coil hot lead.....!

If you have a Mangusta, it's 12V cranking and 12V run.....but you must have a coil that is made to operate that way....some old Chevys were like that.

You may want to check the coil to see if it is now getting 12V at cranking....

The fact that it is running at all says your coil and plug wires are "OK". Misfiring under load is something that could be attributable to a bad coil wire or one or two spark plug wires....check for header burns!

I suspect your butchered wiring to be the problem. I've heard this symptom before on other members cars, and I think even my car too, when I first got it....crank like the dickens, and as soon as you let off the switch, VROOM! Now, I barely turn the engine over one turn and it is running.

I'm an advocate of Ford Duraspark II systems....simple, easy to troubleshoot, and you can steal parts off of almost any Ford product made from the 70's to early 90's to get you down the road!!! A little harder to get aftermarket parts out in the weeds....

Keep on with it, you'll nail it!

Steve