new carb good fuel and spark same proglem

[roadnsky]

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.

[roadnsky]

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.

[hanleyclifford]

"...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?

[roadnsky]

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?

[roadnsky]

Yeah, Jerry, but let's LOOK at it. All ignitions are electric, not so?

Good point.
Bad Condenser would explain the problem too...

[chiron]

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

[hanleyclifford]

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.

[sastanley]

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.

[sailhog]

Priming bulb.... $12....

[smosher]

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

[Dave Neptune]

Check this too

Chad, have you checked the plugs after it died? If so what did they look like? How did the ceramic protecting the electrode look and how did the ground look (the piece you gap with) compared with the rest of the plug that is exposed to the combustion chamber not including the ceramic bit?

Dave Neptune

[rickinnj]

I've had similar symptoms twice in my life. Once on my C-22 with an outboard where I developed an air leak between the gas tank and the outboard priming bulb resulting in a stall after about half an hour. And once in an old Chevy pick-up where the gas cap vent was plugged.

Just my $.02

[JOHN COOKSON]

You might check the fuel tank vent for blockage if you haven't done so already.

TRUE GRIT

Edit: A easy work around is to loosen the tank fill cap.

[chiron]

Its not the fuel

Well I finally made it back to the boat for some more searching for the problem. Here is what I came up with.

100% convinced it is not a fuel related issue.

As someone suggested I checked for spark after the engine died and had spark at the coil but none at the plugs.

I pulled the distributor cab and noticed some water or oil condensation on the inside of the cap, like someone had given it a shot with a spray bottle.

I cleaned that out and replaced the rotor since I had one

I forgot to open the water supply and hit 220 deg. whoops.

I got her fired up again and it died after 15 min. Checked the dist cap and found water vapor or oil (I cant tell which, it has no smell and there is so little I simply cant tell) I cleaned it out again and had to wait 15 min for it to fire up again. I had to leave before it would die again ( it sounded like it was trying) I shut it off and yet again found, although minimal, more condensation. This slow shutdown has been happening off and on since I got the boat at the end of last summer.

I have a couple of questions.
Why are there two holes in the new dist cap that I have not installed yet?
Is there supposed to be a magnetic ring at the base of the rotor mine is missing?
And finally why did I get a good shock when I touched the distributor base while the engine was running?

Thanks every one for your help

Chad

[ndutton]

Is there supposed to be a magnetic ring at the base of the rotor mine is missing?

It depends on what type of electronic ignition you have. If it's an Indigo, they're optical with no magnetic collar under the rotor and an external module.

The Pertronix has the magnetic collar and no module. Compare yours to the picture in the Moyer online catalog if there's any question as to what you have and go from there.