Starts and Runs (sort of)

[jsmickey19]

Hi All

Have an A4 that starts and will barely run at idle (just chugs) when the throttle is applied she dies. In the last three years new points, plugs , rotor, and cap have been installed as well as a new electronic fuel pump.

This engine has run flawlessly for the last 30 years (until I sold it to the present owner ). We thought it may be the carb and rebuilt it however the problem still persists.

Thanks

[tenders]

Clogged exhaust?

[zellerj]

Clean and dry fuel?

[Dave Neptune]

j-19, how do the plugs look? A few pics of them may be a big help.

If the exhaust has not been done for 5~6 years or longer this would be a big possibility. This scenario "USUALLY but not always" sort of sneaks up over a few months not all of a sudden. Give this some serious thought and it is not to difficult to test in most cases.

Fuel can be an easy test with an aux tank with fresh fuel also an easy test.

One other possibility is the choke not "opening" when you think it is so a visual check will eliminate this possibility.

Clean fuel, properly timed spark and clear exhaust equal good performance.

When cleaning the carb was special care done with the float setting and the sealing of the emulsion well in the center of the fuel bowl? this seal is very important for proper metering.

Dave Neptune

[jsmickey19]

Thanks All!

Didn't think about the exhaust. Will definitely take a look at it. Had the choke problem in the past so that was one of the first things I checked.
This problem began at the very end of last season and they limped into port with the engine just barely running. The new owner rebuilt the carb himself with a kit from Moyer as well as the instructional video and nothing changed. We used the starter to winterize the engine and are now trying to figure things out.
I have a strong suspicion that this is a fuel problem as this boat does way more sitting than sailing.
Will try running off of a jug of fresh fuel and see what happens.
Thanks , will keep you posted!

[Mo]

Check compression, especially if it has been sitting a while. Some will start with partially sticking valves but just have nothing and die on throttle up. Worth a check. Many overlook this until they've tried everything else. Air, fire, fuel and compression.

[tenders]

You might also check that the curious new owner removed the plug wires to check things out but didn't put them on in the correct order. Maybe less likely if it started happening while underway though.

[jsmickey19]

Thanks Mo, so far we have spark, clean fuel and air and still nothing. Going to play with it this afternoon. Will take the MMO with me.
Tenders. No worries about the wires (this guy touches nothing but the starter button !). See you over at the Ericson forum, I post there as JSM.

[JOHN COOKSON]

Thanks All!

This problem began at the very end of last season and they limped into port with the engine just barely running. The new owner rebuilt the carb himself with a kit from Moyer as well as the instructional video and nothing changed.
!

If the problem started suddenly while motoring maybe something wrapped around the prop.
Has the prop been checked for fouling?

TRUE GRIT

[zellerj]

If you have spark, clean fuel, and clear exhaust, the only two things left are 1) compression and 2) timing. The spark has to happen at top of the compression stroke when both the intake and exhaust valves are closed, and compression is needed to push the crank around on its circular journey.

Compression checks are easy with a guage that you can borrow from auto parts stores. Timing does not usually change unless the distributor hold down bolt is loose. Is the distributor still tight and not loose in its shaft?

[jsmickey19]

Spent some more time with it this afternoon. Checked compression (with my thumb) seemed like plenty. Gave all cylinders a liberal dose of PB Blaster and MMO and cranked the engine over a few times. Checked spark at all 4 plugs and it looked good.
Checked the distributor to see if it was loose and had moved and it seemed fine.
Will check the exhaust again. It is a stand pipe type.
The new owner rebuilt the carb last fall after this problem began. Anything I should be looking for there ?
Prop not fouled. Boat was splashed today.

[Al Schober]

JSM,
Check the flange where the exhaust attaches to the manifold. It just might be a recent one and have a 1/8 NPT female for checking back pressure. If it doesn't, you may want to order one from Don.
Exhaust will take you a day to rebuild. Black iron pipe is not expensive and you can try different nipple lengths to find what works for your boat. Keep a record, as down the road 6 years or so you may want to re-do it in stainless.
What you do NOT want to do is what I did. Wait for it to fail during a trip, get towed into a marina, then pay the marina for parts and labor. The tow was under insurance, but parts and labor at the marina were about $1200. I think I split the cost with the new owner.
I'll add that the $1200 was not out of line. Mechanic was on board at 0730, and we were under way at 1630. He looked at the situation, said "Atomic 4, no problem. Did this same job 4 years ago." And off he went. Removed everything, replaced bad with new stainless, reinstalled, and wrapped. Class A job.
TowBoat had wanted to take us back to New Bedford, but I held out for Marion (Burr Bros.). Took a double tow. I think the New Bedford fix would have been a soup can and a couple of hose clamps - no thanks.

[jsmickey19]

Will concentrate on the exhaust tomorrow. Is there a spot where these normally get obstructed ? I know on saltwater diesels its usually the mixing elbow. This boat has been in Lake Michigan its entire life.

[CajunSpike]

When I started on my project I too had a no start.
Turns out points were in fact new, but whoever installed them knew nothing about points gap.

It worked just enough to have a weak yellow spark. Reality is supposed to be a bright blue spark.

Adjusted points from about .4 to .2
Along with other things, engine cranked right up.

Check your points gap!

[zellerj]

Sometimes the inner portion of the exhaust hose collapses and closes off the hose, but it looks perfectly fine on the outside. To check for this, some people attempt to start the engine with the exhaust hose disconnected. Messy, but it points you to the right direction if starts with no exhaust back pressure. Typically with a collapsed exhaust hose it will run better in neutral than under load.

Have you tried starting the engine with a short squirt of starting fluid into the intake of the carb? Be careful that you have good ventilation when you do this, because ether is much more explosive than gas. If it starts with starting fluid then the issue is carb or fuel delivery related.

I bought a new carb from Moyer when I was having issues. It was cheap when one considers how much time is spent tracking down a carb issue. If you go the new carb route, make sure the gas delivery system is pristine, no water in tank and new polish filters, or you will have the same issue down the road.