engine runs great, dies, restarts after 15 min, dies

[Bryan Howell]

Ok, at wits end here. After a lot of other issues thought I had my engine in a reliable posture. Not so much. Starts great at the dock, runs great for about an hour then will start a slight miss, that progresses. Taking it out of gear engine revs well, back in gear misses and ultimately dies. Wait 15 minutes, starts right up, runs great for 15-20 minutes then dies again. Wait and will restart, then the process repeats itself.

Brand new carb installed last week, new fuel line, electric fuel pump. new fuel filter, new fuel/water filter, fresh gas. Tried taking the fuel cap off to see if maybe it was a venting/fuel lock situation, no difference. I am virtually certain it is a fuel starvation issue, so maybe gunk in the tank that settles to the bottom when at the dock that gets stirred up while moving and clogs the fuel pickup strainer? After releasing the vacuum after is stalls out and by letting it sit maybe the gunk goes back into suspension in the fuel, lets the engine start and run great but clogs back up more quickly the second time because the gunk is now agitated into the fuel so it clogs the fuel pickup more quickly?

Getting exasperated here. Engine dying while trying to put the boat in the slip stern to is not any fun, not to mention the unreliable aspect of having an engine when needed for as long as needed. Ideas?

Thanks.

[Administrator]

Dr. Dutton? Paging Dr. Dutton to the Forum, STAT.

Bill

[Peter]

A fuel pressure gauge installed between the fuel pump and the carburetor will be a big help in diagnosing this issue if indeed it is a fuel issue.

Does the choke help when it starts to die?

You are stuck with intern Peter while we await Dr. Dutton.

P

[Dave Neptune]

Get a coil and thank N. Dutton.
Don't ever leave the key "ON" when trouble shooting as you can fry your coil and then it will run fine and cut out until it cools ~~repeat.

Some reference reading will be posted to maybe~~read it.

Dave Neptune

[JOHN COOKSON]

BRYAN

Do you have points or an electronic ignition module inside your distributor?

TRUE GRIT

[Al Schober]

Yep, sounds like coil failure. Easy and low cost replacement.
Also recommend the pressure gauge at the inlet to the carb. Why ever be in the position of wondering if you have fuel to the carb? Gauge reads good, fuel supply is good. Gauge reads zip - fuel delivery problem.

[Golfdad75]

Sounds like a coil, I keep two spares on the boat.

[ndutton]

Not really, just wanted to say that.

The symptom set certainly suggests coil but I think everyone will agree it's not conclusive just yet. If the coil is an old museum piece then maybe it's due anyway so there's no harm in replacement. If going this route the questions of electronic ignition and alternator output voltage are huge.

I propose replacement with a Moyer coil** (eliminates coil and electronic ignition issues with a single swipe of the credit card), a quick measure of the coil input voltage at cruising RPM just to be safe (please report back) AND a fuel pressure gauge as others have suggested. As a maintenance item as long as you're there I suggest oiling the advance flyweights found under the points/EI plate when you replace the coil. Do not remove the distributor in the course of this work. That should cover a wide range of possibilities for your problem and leave you in excellent shape for the future.

Friends, it warms my heart to come home from a day's work and read multiple diagnoses of a damaged coil following symptoms of engine shut down, restart after a cooling off period only to shut down again a short time later. Well done. We've come a long way, baby!

**NOT an auto parts store coil. Buy air fresheners from the auto parts store, A-4 parts come from Moyer if you want to eliminate problems for sure.

[sastanley]

+1 what Neil and the others have said. I am hoping Moyer starts sourcing a fuel pressure gauge, but in the meantime some of us are using the 1561 Mr Gasket gauge from Amazon (or your vendor of choice). They are pretty cheap and work just fine. I only wish they had a glass lens, because if you spill fuel on the plastic face, it melts/hazes, but the gauge still works with no lens. This gauge will 100% tell you if you have a fuel delivery problem, and if not, point you somewhere else. It connects to a standard 1/8" NPT (female) fitting..I have a 3-way female 1/8" NPT tee with two male hose barbs to connect inline with my fuel hose, between the fuel pump and carb.

[tomsailmaker]

All the information given to you is good and you should do all of it , in fact you should buy 2 coil's as the shipping is almost as much as the coil so it's nice to have a spare. Because you feel there is crap in the fuel tank you should clean that as well then you wont need to worry that's causing any problems.Eliminate all possible problems.
IMHO

[joe_db]

I really like the full sweep electric fuel pressure gauge I got recently. Viewing the fuel pressure from the helm is good and it has a red warning light if the pressure drops
I also like to remind people our host has this:

Originally Posted by sastanley

+1 what Neil and the others have said. I am hoping Moyer starts sourcing a fuel pressure gauge, but in the meantime some of us are using the 1561 Mr Gasket gauge from Amazon (or your vendor of choice). They are pretty cheap and work just fine. I only wish they had a glass lens, because if you spill fuel on the plastic face, it melts/hazes, but the gauge still works with no lens. This gauge will 100% tell you if you have a fuel delivery problem, and if not, point you somewhere else. It connects to a standard 1/8" NPT (female) fitting..I have a 3-way female 1/8" NPT tee with two male hose barbs to connect inline with my fuel hose, between the fuel pump and carb.

[ndutton]

Considering the discussion in this thread and Bryan's specific issue, the EWDS monitors fuel pressure for a low threshold but please be aware it does not monitor coil function. The monitored coil parameter is input voltage only.

I planted a thanks on Joe's post mentioning it but wanted to avoid any unrealistic expectations.

[TomG]

Originally Posted by joe_db

I really like the full sweep electric fuel pressure gauge I got recently. Viewing the fuel pressure from the helm is good and it has a red warning light if the pressure drops
I also like to remind people our host has this:

I installed the EWDS on my boat and I do so love it. I HIGHLY recommend this system for all A-4 owners. My day job as an airline pilot has taught me that humans are terrible systems monitors. Observing the gauges to catch the water temp as it's rising is more luck than anything. The EWDS does all that mindless but critically important monitoring all day without complaint or fail. It's also a wonderful diagnostic tool, but as Neil says, it's a binary system - logic arguments trigger warning lights - on or off. It is a fantastic system and if any of you out there are looking for Holiday gift ideas to share with your significant other, this is great one! I got my wife the EWDS for Christmas two years ago! (That sounds dirty but it really isn't).

As to the problem here, my initial thought was to use an outboard tank with known fresh fuel to connect to the carb and run for a bit. That would eliminate the tank only. Replacing the coil (which is what it sounds like is the problem) would actually be easier than rigging a temporary fuel tank. If the new coil didn't cure the ill, well at least you have a spare coil!

[ndutton]

Originally Posted by TomG

[The EWDS] is a binary system - logic arguments trigger warning lights - on or off.

It also provides an audible alarm if any of the monitored parameters are out of range, known to radar operators as a comic book or Playboy alarm. Buzzer sounds, give the light display a glance to see what's out of whack. The buzzer will not sound without at least one indicating light illuminated.

[joe_db]

+1 on lights and buzzers.
I'll never know if this was going on for 10 seconds or a few minutes before I saw it. Wrecked a $15,000-$20,000+ engine

Originally Posted by TomG

I installed the EWDS on my boat and I do so love it. I HIGHLY recommend this system for all A-4 owners. My day job as an airline pilot has taught me that humans are terrible systems monitors. Observing the gauges to catch the water temp as it's rising is more luck than anything. The EWDS does all that mindless but critically important monitoring all day without complaint or fail. It's also a wonderful diagnostic tool, but as Neil says, it's a binary system - logic arguments trigger warning lights - on or off. It is a fantastic system and if any of you out there are looking for Holiday gift ideas to share with your significant other, this is great one! I got my wife the EWDS for Christmas two years ago! (That sounds dirty but it really isn't).

As to the problem here, my initial thought was to use an outboard tank with known fresh fuel to connect to the carb and run for a bit. That would eliminate the tank only. Replacing the coil (which is what it sounds like is the problem) would actually be easier than rigging a temporary fuel tank. If the new coil didn't cure the ill, well at least you have a spare coil!

[Bryan Howell]

After spending the day on the boat, trying running it from an external tank to take my fuel tank and possible gunk out of the equation, only to have the EXACT same thing happen at almost EXACT same time frame (an hour) I was so hoping to find some responses on this board. As always I was not disappointed. My next "thought", based in large part on earlier posts here, was coil, and I do have a spare, so tomorrow will swap it out and see what happens.

Afourians are the best!!!!! Thanks all. I'll let you know how it goes.

[ndutton]

Please describe your ignition system. Points or electronic ignition? It's now an important question.

[Bryan Howell]

Originally Posted by JOHN COOKSON

BRYAN

Do you have points or an electronic ignition module inside your distributor?

TRUE GRIT

Electronic.

[Bryan Howell]

Originally Posted by ndutton

Not really, just wanted to say that.

The symptom set certainly suggests coil but I think everyone will agree it's not conclusive just yet. If the coil is an old museum piece then maybe it's due anyway so there's no harm in replacement. If going this route the questions of electronic ignition and alternator output voltage are huge.

I propose replacement with a Moyer coil** (eliminates coil and electronic ignition issues with a single swipe of the credit card), a quick measure of the coil input voltage at cruising RPM just to be safe (please report back) AND a fuel pressure gauge as others have suggested. As a maintenance item as long as you're there I suggest oiling the advance flyweights found under the points/EI plate when you replace the coil. Do not remove the distributor in the course of this work. That should cover a wide range of possibilities for your problem and leave you in excellent shape for the future.

Friends, it warms my heart to come home from a day's work and read multiple diagnoses of a damaged coil following symptoms of engine shut down, restart after a cooling off period only to shut down again a short time later. Well done. We've come a long way, baby!

**NOT an auto parts store coil. Buy air fresheners from the auto parts store, A-4 parts come from Moyer if you want to eliminate problems for sure.

Well, it warms my heart to know there are so many folks out there wiling to share experience and ideas on these old but so reliable motors. Ordering a Moyer coil this pm.

Thanks so much!

[ndutton]

Good to hear you're going to a Moyer coil, good on ya.

Please read the following threads. They are important to understand what happened to avoid a repeat of the problem.

http://www.moyermarine.com/forums/showthread.php?t=5845
http://www.moyermarine.com/forums/showthread.php?t=5748

[Bryan Howell]

Originally Posted by ndutton

Please describe your ignition system. Points or electronic ignition? It's now an important question.

Electronic.

[sastanley]

Neil, thanks for posting those links...boy, I sure did ramble on back in the day!

[ndutton]

Originally Posted by sastanley

Neil, thanks for posting those links...boy, I sure did ramble on back in the day!

There are more threads but those two hit the high points. It's a lot of reading but it's worth the time investment.

I wouldn't worry too much about word counts. This was a highly technical and perplexing problem that we were able to solve thanks to the input of many forum members. The wordiness is behind us now, coil failure symptoms and their causes are engraved in our brains.

[joe_db]

I thought I was going nuts back then. A coil swap mid-trip was happening a LOT

Originally Posted by ndutton

There are more threads but those two hit the high points. It's a lot of reading but it's worth the time investment.

I wouldn't worry too much about word counts. This was a highly technical and perplexing problem that we were able to solve thanks to the input of many forum members. The wordiness is behind us now, coil failure symptoms and their causes are engraved in our brains.

[sastanley]

So Bryan, the short answer is that often with a switch to electronic ignition, you start frying coils...they should run for 45-60 minutes after they cool down, but once they are fried, they are unreliable even for testing.

What was determined was some external resistance is needed in front of the coil, unless you get the Moyer coil now offered in the store which has enough internal resistance to handle the issues discussed in all those threads. What I think we all realized was the extended dwell from an instant on/off electronic ignition was allowing the voltage in the coil to build up in between sparks and short itself out...with points, this was not an issue.

It has been a while, so if I screwed something up in my short story analysis, I am sure I'll get corrected.