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  #1   IP: 75.175.113.60
Old 02-25-2011, 11:09 AM
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new carb good fuel and spark same proglem

This is a new (50 year old) boat to me and am rapidly learning all about the Atomic 4. Thanks everyone for this wonderful site to help me along. Since I purchased my h-28 6 months ago I have had a common problem of the engine dying on me in the fuel related sort of way after 40 minutes or so.

I have clean fuel with the both fuel filters.
My mechanical fuel pump works fine.
No known fuel or air leaks.
Spark at the coil and plugs.
I just rebuilt the carb and installed the indigo crankcase ventilation kit.

After rebuilding the carb and a little difficulty getting it started it ran like never before. purred like a kitten had great throttle response and more power than ever. Then like before after 40 minutes of motoring it bogged down and eventually died. Usually I could just shift to neutral and let it run for a bit and continue motoring but this time I had to get towed. Now she wont start at all. I pulled the carb and everything checked out. Good clean fuel and spark. You could probably guess where my love and hate relationship is right now. Anything ells I should look for.

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Chad
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Old 02-25-2011, 11:16 AM
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Except that you report good spark and up until the point where she won't start at all I was thinking coil all the way. We've seen time and time again where the coil fails with heat and the symptoms mimic fuel starvation. The time required for sufficient heat to build is usually around 30 - 45 minutes, then after 15 minutes or so of non operation it cools enough to start again only to repeat the cycle.
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Old 02-25-2011, 11:21 AM
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Question

Chad, are you sure you have good spark after the 40 minute failures episodes? I thought I had a fuel related shutdown too, but it turned out to be a dying coil...letting it cool off would give me 60 more minutes of run time, but eventually it would get hot and stop running again until cool. edit - oops, ha ha, Neil beat me to it...

Since you just cleaned the carb I might assume it is in good shape for now...Just something else to check...

The real check for a fuel related shut down is to install a fuel pressure gauge inline just before the carb...that will instantly eliminate everything before the gauge if it reads good pressure during a shut down. Dave Neptune is the fuel pressure expert around here. Another way to check during your no-start condition is to see if fuel is puddling in the bottom of the carb throat (near the choke butterfly I think) - you'd need to remove the flame arrestor to observe this area.
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Last edited by sastanley; 02-25-2011 at 11:23 AM. Reason: neil's a fast typer!
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Old 02-25-2011, 11:50 AM
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Wow such quick responses. Thanks.
I should probably clarify when I said good spark all I really saw was that I had spark. And I did pull off the flame arrestor and had some fuel puddling at the bottom of the carb. Is this an issue? I assumed it was from me turning over the engine so much without it firing up and the unburned fuel just collected there. I was told that the engine had been rebuild a couple of years before I acquired it as indicated by lots of new cool stuff that did not come with the early model like fuel and oil filters electric ignition fresh water cooling and a late model carb which barely fits once I installed the spacer for the crankcase ventilation. I guess I shall try new coil and plugs.
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Old 02-25-2011, 11:56 AM
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Yeah, big difference between a good, hot spark and any spark. With electronic ignition be sure to get a coil with the proper resistance, 3 - 4 ohms as I recall. Buy one from Moyer and you can't go wrong.
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Old 02-25-2011, 03:16 PM
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I'll throw in my 2˘ and hope that the raw water through-hull is closed during all this cranking to try to get the engine started. Don't need to add water in the cylinders to any other problems.
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Old 02-25-2011, 03:28 PM
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Thumbs up

chad, fuel puddling probably indicates the carb is getting fuel. Another reason I may move that one down the list & check in on good spark.

A coil ranges in price from $30-40...they often last for years and years (mine lasted 31), but if you do not know when it was last replaced, it probably won't hurt. Keep the old one as a 'limp home spare' since you know it will go for 40 minutes at a stretch.

Champion RJ8 (original Universal recommendation) or RJ12C (slightly hotter plugs) are the most common. If I remember my numbers, I also think Autolite 303's & 437's are OK to use too.

BS's comment is a good one too..during prolonged cranking (& non-running) events there is no exhaust gases to expel the raw water accumulating in the muffler/exhaust system..it is common for it to back up the hot pipe while cranking and then dump into the cylinders. The time it takes for this to happen varies with each system, but I know mine was flooded this way twice before I owned the boat. I usually close my raw water thru-hull until the engine starts if I've done 15-20 seconds of cranking.

One more check, while you have the flame arrestor off, double check that the choke butterfly closes ALL the way when the choke cable is pulled..even a slight mis-adjustment here makes starting these old engines difficult.
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Old 02-25-2011, 05:42 PM
Dave Neptune Dave Neptune is offline
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Lightbulb Hmmm!

Chad, since you said you could let her idle for a bit and then you could power back up makes me think fuel delivery. Usually if a coil cuts out it does so completely and will through a spark again after it cools a bit.
You can check the spark when the power drops but you would need a fuel preassure gage to check the fuel delivery. Are you a mechanical or electric pump?

Dave Neptune
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Old 02-25-2011, 06:30 PM
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I had a problem that was very very similar, and it took me a looooooong time to figure out what it was.

This is what it turned out to be: I had changed my Racor when I bought my boat, and she consistently died with all the symptoms of fuel starvation. Eventually someone (Ken at MM) told me to install a priming bulb between the tank and the Racor. After pumping it a few times to fill the line with a CONTIGUOS column of fuel, the siphoning affect allowed for the consistent flow of fuel to the pump. The problem was magically solved.... Hope this works for you.
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Old 02-25-2011, 09:26 PM
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Quote:
Originally Posted by sailhog View Post
I had a problem that was very very similar, and it took me a looooooong time to figure out what it was.

This is what it turned out to be: I had changed my Racor when I bought my boat, and she consistently died with all the symptoms of fuel starvation. Eventually someone (Ken at MM) told me to install a priming bulb between the tank and the Racor. After pumping it a few times to fill the line with a CONTIGUOS column of fuel, the siphoning affect allowed for the consistent flow of fuel to the pump. The problem was magically solved.... Hope this works for you.
Chad-
What Dave said...
"Are you a mechanical or electric FUEL PUMP?"
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Old 02-25-2011, 09:50 PM
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He said in the initial post that he's got a mechanical fuel pump. A possible source of the problem, but seems unlikely if he's getting fuel pooling in the intake.

Chad, with all the futzing you've done with the carb and the crankcase ventilation kit you might want to check all those fittings again for poor sealing.

I have a pretty good feeling about your prospects here. This is going to be one little thing and you'll be off to the races again.
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Old 02-25-2011, 09:54 PM
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Thanks again everyone. And especially thanks for the reminder to close the water inlet. I keep forgetting that one. So I did buy a new coil and plugs although with a broken hand it took me the entire afternoon just to get the carb back on. That extra spacer supplied with the crankcase ventilation kit puts the bottom of the carb (fuel return line) pinched on the mounting plates of the engine, and can be (I mean is) a pain one handed in 20 deg weather working blind. But I did get it started, it did take a shot of starter fluid. It idled great and in neutral had great throttle response. Oil pressure was 30 and temp was 145. Tomorrow I hope to get a chance to install the coil and new plugs. Worst case I will have an extra set of each just in case.

You guys are great.
Chad
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Old 02-27-2011, 11:35 AM
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Well I made it back out to the boat and replaced the coil and plugs. It took a bit for her to fire up but that may be from the mystery oil I put in the cylinders while the plugs were out. So she sat there idling fine at 700 rpm temp never getting over 145 and oil pressure between 30 and 40 psi. Then after 30 minutes or so the rpms began to drop and it eventually shut down. I had to run to get home for a dinner party so I did not get a chance to diagnose the problem. My gut is telling me this has to be fuel related. The polishing fuel filter I recently installed does have air in it but I can observe fuel being pumped through it. The fuel is clean with no water. What am I missing. I have a feeling that I will end up dumping a couple hundred into fixing a 25 cent problem.

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Chad
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Old 02-27-2011, 11:55 AM
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My A-4 sometimes acted like this before I replaced the distributor points with an Indigo/Electronic system. With the old point system, it is rather hard to set them up "just right". And then, when they look good on the dwell meter, the setting does not account for the fact that the engine warms up and slightly changes the metalurgy of the points which changes the gap.

Of course if you have changed over to Electronic points, this is all moot. However, might there be a way that the gradual warming of the engine changes something else for the worse, like allowing a leak in a fuel line to get worse which lets air in so you lose prime?

Just thinking...
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Old 02-27-2011, 12:00 PM
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Question

Do you have the electronic ignition or do you have points and condenser?
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Old 02-27-2011, 12:05 PM
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Chad-
Don't give up! You'll get there. You're close.

What coil did you get?
Are you sure it's got the correct resistance? (3-4 ohms)
I'm with you on the gut feeling of fuel delivery, but let's completely eliminate the coil as a culprit.

Tenders suggestion of making sure you don't have an air leak is right on.
Double check those fittings. Especially since you had some trouble getting the carb on with your broken hand.

Finally, how confident are you in the condition of your Mech Pump?
An issue there would certainly explain the hard start and delayed starvation after running for a while.
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Old 02-27-2011, 12:08 PM
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Quote:
Originally Posted by hanleyclifford View Post
Do you have the electronic ignition or do you have points and condenser?
"...I was told that the engine had been rebuild a couple of years before I acquired it as indicated by lots of new cool stuff that did not come with the early model like fuel and oil filters electric ignition..."

He's EI.
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Old 02-27-2011, 12:11 PM
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Quote:
Originally Posted by roadnsky View Post
"...I was told that the engine had been rebuild a couple of years before I acquired it as indicated by lots of new cool stuff that did not come with the early model like fuel and oil filters electric ignition..."

He's EI.
Yeah, Jerry, but let's LOOK at it. All ignitions are electric, not so?
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Old 02-27-2011, 12:12 PM
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Sound familiar??

Just read this in the TECH TIPS...


Fuel-Related Engine Shutdowns

This tech tip is focused on the causes of fuel-related shutdowns, with a few suggestions for troubleshooting and remediation.

A good friend of ours from across the Chesapeake Bay had been experiencing regular engine shutdowns after motoring approximately 45 minutes to an hour, virtually every time he took his boat out. Finally, after much head-scratching, he discovered a pinhole in the canister of his primary fuel filter. It was not a RACOR filter, but it was of the same size and type as the RACOR filter and water separator shown in our online catalog. He replaced the fuel filter, and the shutdowns ceased.

The pin hole, though never manifesting as a fuel leak until my friend pressurized the filter, was apparently allowing enough air to be drawn into the fuel stream to form an air bubble which eventually reached the fuel pump and caused it to cavitate.

Around the same time that my friend had been sorting through his difficulties, Brenda and I acquired a small fishing boat to scoot around the tributary of the Chesapeake Bay that extends near our house. The boat has a small four-cylinder inboard gasoline engine, and incredibly enough, it was regularly shutting down every 20 minutes or so from what appeared to be fuel starvation, in much the same way that my friend's engine had been shutting off just a few weeks earlier.

I installed one of our new RACOR fuel filters soon after acquiring our little motor boat, and I had also installed a small rubber priming bulb between the tank (which is located lower than the engine on this boat) and the RACOR. The basic reason for the priming bulb is to prime the filter after replacing an element, without having to fill the canister with fuel and have it spill all over the engine compartment while I'm reinstalling the canister.

Much to my surprise, the first time I pressurized the RACOR and the rest of the fuel system with the priming bulb, two small pre-existing leaks showed up in fittings between the filter and the engine mounted mechanical fuel pump. The leaks were so small that I was never aware of their existence during normal operation, but they apparently allowed enough air to enter the fuel line under suction to shut down the engine for lack of fuel. The engine has never shut down since fixing the leaks.

I've been eagerly sharing these experiences with folks who have called in with fuel-related shutdowns over the past several weeks, and we've already had a few folks call back to report their own success stories in correcting small suction leaks in their fuel supply systems.

I'll try to consolidate and amplify a few key points:

1) Small leaks can apparently exist within a fuel supply system that will not manifest as fuel leaks, but which will allow enough air to be drawn into the lines to cavitate fuel pumps by the suction created during normal operation.

2) The high vapor pressure of gasoline exacerbates the problem of suction leaks by causing the air bubbles to enlarge somewhat after they form.

3) Electrical pumps seem to be somewhat more sensitive to the effects of air in lines than do mechanical pumps, although we have one recent case of fuel starvation caused by a leak above the sediment bowl in a mechanical pump.

4) Boats with tanks located lower than the top of the engine and at distances greater than 5 or 6 feet are more at risk of shutdowns from fuel starvation from small leaks in the system, due to the fact that more suction is created within their systems. Leaks in the fuel supply systems of boats with tanks higher and very close to the engine would probably manifest as fuel leaks and quickly be detected.

5) Air can be also be introduced into fuel supply systems while changing filter elements, and/or other maintenance, which will cavitate pumps, usually after a few minutes of running. Again, electric pumps are more at risk than mechanical pumps, since electric pumps make very poor air compressors. It's sometimes possible to prime filters after an element change by working the priming lever of a well maintained mechanical pump, but electric pumps will frequently never prime until the air is removed in some other manner.

6) Installation of a rubber priming bulb between the tank and the primary fuel filter will enable you to prime the system after replacing a filter element (or other maintenance), as well as to pressurize the system to check for leaks. The bulb also provides a nice diagnostic tool when troubleshooting fuel problems in general, by providing a second method of producing fuel pressure. In normal operation, the fuel pump is able to draw fuel through the priming bulb with little or no measurable head loss being added.

These priming bulbs (commonly used in outboard fuel supplies) are available from West Marine for 1/4", 5/16" and 3/8" fuel hose. At approximately $12, they may represent the best value you'll ever encounter in terms of enhancing engine reliability.

7) Many boats still have small screens over the ends of their pickup tubes which become clogged quite easily, and are really unnecessary after the installation of a proper primary fuel/water separating type of primary filter.

8) Lastly, spring-loaded check valves used as anti-siphon devices sometimes cause or at least exacerbate problems. These valves are usually installed where the pickup tube leaves the top of the tank and function by adding more head loss (approximately 2 psi) than the weight of the fuel in the line downstream of the tank. In this way, if you leave your manual shut-off valve open while leaving the boat unattended and a major leak develops, fuel will not flow from the tank. These valves are OK in principle, but the "controlled restriction" that they introduce, does have the potential of creating problems in some fuel systems. For example, I think they would be really troublesome in the Catalina 30 fleet, with fuel tanks so low and far from the engine.

Hopefully, these suggestions might help to identify a few latent problems that may be lurking in other fuel systems before the onset of frustrating shutdowns related to fuel supply problems.

Whatayathink?
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Old 02-27-2011, 12:14 PM
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Quote:
Originally Posted by hanleyclifford View Post
Yeah, Jerry, but let's LOOK at it. All ignitions are electric, not so?
Good point.
Bad Condenser would explain the problem too...
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Old 02-27-2011, 12:44 PM
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I do have the electric ignition, as best I can tell, where the points should be there is a small black module of sorts however the indigo system I thought had a second external module a bit larger than a deck of cards outside the distributor which mine does not. I did get the proper coil from the parts store 3-4 ohm. I had taken the fuel line off the carb placed it in a glass quart jar and turned the motor and was surprised at how fast it filled up, so I am guessing the mechanical pump is working fine, but I do feel that increased temperatures are affecting something creating a problem. I think the next thing I shall do is replace all the fuel lines and install a fuel pressure gauge as someone suggested.

If my mechanical fuel pump is questionable should I rebuild it or install an electric. There is a significant cost difference in this decision, but reliability is the most important thing.

Chad
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Old 02-27-2011, 12:47 PM
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You mentioned that you are getting plenty of fuel to the carb. Time to look at the inside of the carb for restrictions. When you rebuilt your carb were you able to get all the small jets out? Did you blast all passages with cleaner and compressed air? Start at the needle and seat adjustment. When the shutdown occurs next time shut off the fuel line at once and inspect the carb bowl. If it is full at shutdown, go on to the discharge nozzle and well vent.

Last edited by hanleyclifford; 02-27-2011 at 12:53 PM.
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Old 02-27-2011, 10:14 PM
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Arrow

Chad, FYI - a fuel filter that is clear (glass or plastic) is not USCG approved for inboard motors..take that info at your own risk.. however, for this endeavor it may be helpful for now.

That being said...if you are seeing air in there, double check all fittings and clamps from the fuel tank, up to, including, and past the fuel filter..anywhere in the line...there are reports of air leaks in the fuel line causing shutdowns.

Just to mix it up a little..sailhog reported that a priming bulb helped him..I had one installed, and I desperately pumped away at mine while the engine died with my hand in the engine compartment (mechanical pump) - mine turned out to be a coil (which I think I mentioned earlier)...I had already shifted to electronic ignition (so no parts to fail there), but the ONLY part I didn't replace was the coil...so mine was not fuel related. I am just illustrating that it isn't always clear cut.
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Old 02-27-2011, 11:09 PM
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Priming bulb.... $12....
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Old 02-28-2011, 08:00 AM
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In my A4 I've looked at the following for the same issue after 30 minutes of running, could be fuel tank vent, fuel pump not supplying enough fuel, coil overheated, air getting into fuel lines and fouled plugs. I had 2, fouled plugs, were autolite 437's changed to rj12c and I had a wrong size nipple for the fuel line 1/4 vs 5/16. I noticed when I pulled it off seemed easier than the others.

Sounds fuel related to me with change of performance before stopping altogether.

Steve
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