Just Another Power Loss Issue

[Bruce A]

Hi All,

My Islander 34 with Atomic 4 is exhibiting a power loss problem similar to that seen by many others who are posting on the forum. However, the problem I am observing has a different wrinkle. We have been sailing the boat regularly about once a week for the last 18 months (we sail in the Southern California Channel Island area) . The engine ran perfectly (until 2 months ago) such that while motoring in the harbor under still conditions we could achieve a speed of 6.3 knots @ 1700 RPM (this speed was only maintained for a few seconds for testing purposes as we have a 5 knot speed limit in the harbor). At present the best we can do is 1500-1600 RPM with speed of about 4.6 knots. The 1500 RPM is reached with about 1/3 throttle and any increase in throttle beyond 1/3 does not produce any results, just a slight suffocating sound at the air intake. At an idle the RPM is not limited---engine revs to 3000 RPM very quickly. We probably have 3-4 hours on the motor with this power loss situation and recently developed the unusual wrinkle I mention earlier in this post------after motoring in from a sail the engine quit abruptly. In the instant state of panic I tried to restart the engine. Engine would not restart so I took about 2 minutes of deep breaths and tried again--engine fired up and we motored into the slip. Yesterday we were entering the harbor from a sail (had been motoring for about 5 minutes) when the engine quit---this time I immediately choked the engine and it fired up instantly. This allowed us to drop sail and motor in which took about 15 minutes with no engine problems other than the steady state power loss issue.

Here are items of interest in chronological order---NOTE: power loss started about 2 months ago:

1. The PO installed a rebuilt Zenith carb (new design) about 2 years ago. Engine running fine until 2 months ago.

2. Seven months ago I replaced the fuel tank sender unit.

3. Six months ago I replaced the water pump with MMI unit.

4. 2+ months ago I replaced the water separating fuel filter cartridge (Sierra unit) and the fuel line from the tank to the filter housing.

5. In the last two weeks I replaced the entire leaky exhaust system because I suspected that high back pressure may have been responsible for power loss---it looks like back pressure was not an issue. At the same time I also replaced the thermostat housing and we now run at a consistent 140 degrees. Also checked compression: #1=100psi, #2=85psi, #3=82psi, #4=100psi.

6. Checked the low oil pressure switch and noticed that it has been bypassed by PO so that it is not causing the engine to quit abruptly.


Note that I replaced the water separating fuel filter before the power loss issue was noticed (I think). I cannot be sure that we did not have the power loss before the filter was replaced nor can I be sure that the engine did not run OK for a few outings after the filter was replaced. The problem with my observations is that we usually only need about 1200-1400 RPM to get in and out of the harbor. The power loss was first noticed when bucking a head wind where we wanted to make some way in order to get back to the dock in a timely fashion.

The engine quitting whenever it feels like it is my greatest concern since it creates considerable unrest.

At this point I am not sure where to begin an analysis---maybe with the fuel filter? And how would I check the fuel filter issue?

Any and all suggestions on how to approach this problem would be greatly appreciated.

Thanks,

Bruce

[roadnsky]

Troubleshooting Intermittent Shutdowns

Bruce-
Attached is advice from Don from an earlier post about shutdowns...

Hopefully, this gives you some places to start hunting it down.
-Jerry

[roadnsky]

Choke?

Yesterday we were entering the harbor from a sail (had been motoring for about 5 minutes) when the engine quit---this time I immediately choked the engine and it fired up instantly.

Bruce-
One thing that jumped out at me in re-reading your post was about the engine firing immediately when using the choke.
Another of Don's quotes says,
"If you can affect the engine performance (even a little bit) with
the choke, it is good confirmation that you're correctly hearing a fuel starvation message."

-Jerry

[Bruce A]

Good Point

Thanks Jerry,

I had not seen the note about various engine dying syndromes although I thought I read everything on the forum relating to engines quitting. The interesting thing is that Don says an abrupt shutdown would usually mean that the primary ignition system suddenly develops and open circuit. But if that happened pulling the choke is not going to help with the intermittent contact problem. I suppose that the float or (float needle) could get stuck in the closed position and the fuel would be shut off so quickly that it would appear as an instant shut down. I would think that if, due to a power interruption, my electric fuel pump stopped pumping that the engine would die slowly not abruptly.

Thanks for the food for thought.

Bruce

[roadnsky]

Don't rule out the FUEL PUMP...

I would think that if, due to a power interruption, my electric fuel pump stopped pumping that the engine would die slowly not abruptly.

Bruce-
If the fuel pump is electric and stops for any reason, the engine would actually die fairly sudden, rather than the sputtering you'd get with running out of gas; where the pump is draining the bottom of the tank. So, bear that symptom in mind too during your search. Depending on the pump, you should be able to hear the "clicking" sound of it pumping away.
Also, next time it happens check that your fuel tank is venting properly.

The power loss is a bit of a mystery and could be a totally separate issue.

My money is on something related to dirt or specifically the float needle at this point. However, I am by no means an expert, so I'm sure soon others will jump in here with more sage advise...

[roadnsky]

One last thought and then I'll lay low...

At the risk of totally leading you down the wrong path; check out some of the posts regarding coils getting hot as a possible cause of shutdown after running for a while.
-Jerry

[Bruce A]

Jerry,

I don't think the hot coil applies because the engine restarts so quickly after it quits, that is, no cool down time is required.

Also, thanks for reminding me about listening for the ticking of the electric pump. I have used the sound many times as an indicator of "ignition key on", etc. but I guess in the panic of the engine quitting I blanked out and do not have the slightest idea if the pump was ticking after the shut down. Next time I will listen for sure.

With so many things that can cause the instant shutdown I may be better off troubleshooting the power loss problem first. That way if I fix the problem I know it is fixed. Since the engine has to be run for quite some time before it quits (which has only happen twice) it could take a lot of experimentation to finally determine that the shutdown problem has really been fixed. If the two problems are related maybe I should concentrate on the more obvious prob and with luck will get two birds with one fix.

This is really good input,

Thanks Jerry,

Bruce

[Baltimore Sailor]

At present the best we can do is 1500-1600 RPM with speed of about 4.6 knots. The 1500 RPM is reached with about 1/3 throttle and any increase in throttle beyond 1/3 does not produce any results, just a slight suffocating sound at the air intake. At an idle the RPM is not limited---engine revs to 3000 RPM very quickly.

This sounds just like my engine right at the moment when I put her away for the winter. For my spring startup I'm planning on replacing the wires, distributor cap, rotor and plugs to see if that helps any. I already know I have good fuel flow from running the electric fuel pump with the output line into a cup, my water separator filter is brand-new, as is my polishing filter. I have a new carb and coil already.

The only other thing I can think of is: have you checked your prop for growth lately?

[Bruce A]

I agree that it sounds like prop fouling could be a problem but we have the bottom (and the prop) cleaned and checked every 45 days. The power loss was occurring before the last cleaning and of course is still a problem.

I don't have a polishing filter installed---that will be the next project. I haven't drained the fuel line under pump pressure nor have I opened up the carb main jet to drain the bowl etc. I was hoping that the carb is OK since it was recently rebuilt (at least it does not have many hours on it).

[Kurt]

If I were in your situation, I would take the carb off and apart and give it a thorough cleaning - this is a really simple job. Being only 2 years doesn't matter. Crud can still build up in there over this period of time. A couple of things point to a fuel issue related to crud in the main jet. 1) Engine fired right up that time when you pulled the choke out. 2) You get full throttle when in neutral, but not in gear. If your low power/rpm issues were consistent in neutral as well as in gear, you would have been right to suspect elevated exhaust back pressure. Seeing as the low power issue is on ly present under load, I would start with the carb and see if that solves your problem. This is proabably the easiest thing to start with - hopefully you have decent access.

Kurt.

[Don Moyer]

Bruce,

After reviewing this entire thread, I'm inclined to make one observation and one suggestion which might be useful in directing your future diagnostic efforts. The assumption is that you have two issues going on at the same time; e.g. your power loss and your recent occurrences of intermittent shutdowns probably have their own separate cause factors. The suggestion is to focus your diagnostic efforts on determining if the intermittent shutdowns are ignition or fuel related.

In terms of the power loss, you seem to have covered most of the usual problems external to the engine that routinely result in an "apparent" power loss (dirty prop, blocked exhaust, etc). Moving to things that explain a "real" engine related power loss, low compression is usually a key factor. Compression in the range of 70 psi or below would begin to affect performance, particularly in cases where someone was operating an engine at a respectably high cruising power setting as you've been doing. I may have missed it, but I don't see a recent compression test in your prior reports.

Still in the area of your power loss, if your compression check comes in around 90 psi or above in all cylinders, we'll have to retrace a few of our steps in terms of causes external to the engine. For example, the "suffocating" sound when you reach wide open throttle at around 1500 RPM is symptomatically very consistent with a blockage within your exhaust system.


In dealing with intermittent shutdowns, it's very important (and also very difficult as you point out) to determine whether the shutdowns are caused by an ignition or a fuel problem. Until this determination is made, you risk spending an inordinate amount of time chasing an ignition problem through your fuel system or vice versa. I like to point to the similarity between scene and trying to play football on a tennis court or vice versa. You can go though all the correct moves but the outcome will seldom be anything anyone would care to watch.

Here are several general points which may be useful in dealing with the difficulty of differentiating between ignition and fuel related issues:

1) Assuming that the engine will NOT start back up immediately, try to perform steps 3 and 4 of the attached check list. It will help if you have tools, flashlight, etc at the ready; and I would even condone leaving the flame arrestor housing off the carburetor to shorten your response time in completing this checklist. The concept here is that determining why the engine won't start is presumably the same reason that it shut down in the first place. If you can limit the reason for the intermittent shutdowns to fuel or ignition, the other two check lists may help.

2) If your engine starts too quickly after an intermittent shutdown to use the non-starting checklist, the problem is most likely a faulty electrical connection within the primary ignition system. All other typical causes of an intermittent shutdown (ignition or fuel) take at least a minute or so to "heal" after an intermittent shutdown. To confirm or rule out a faulty connection in your primary ignition system, you can run a short jumper wire between the positive terminal of the coil and the large battery cable on the starter solenoid. This wire will "jump" across any faulty connection in the entire primary ignition system external to the engine (which is 95% to 98% of it). If your intermittent shutdowns cease with this jumper wire installed, you can troubleshoot the primary ignition system further to pinpoint the exact location of the faulty connection.

NOTE: The remaining short leg of the primary system leads from the negative terminal of the coil to ground through the distributor. Problems in this leg of the primary system include a corroded terminal on the coil, broken wire passing under the cap of late model distributors, and a rusty breaker plate (creating a faulty path to ground).

3) If for any reason you're forced into a diagnostic exercise with absolutely no information to direct you in either direction (ignition or fuel), fuel issues do tend to be at the root of most intermittent shutdowns. Tech service calls involving intermittent shutdown issues dropped close to 50% after posting our "fuel related shutdown article" on moyermarine.com (the second item in the tech tip section).

4) The general rule of troubleshooting applies to intermittent shutdowns as well; e.g. the causes of many problems are introduced in the course of recent maintenance work. It's therefore usually very productive to reflect back to the last time the engine ran OK and then meticulously consider everything that could have changed between then and the time the problem(s) began.

Hope this helps,

Don

[Bruce A]

Don,

Thanks for all the info--looks like I have my work cut-out. I did list the compression results in my first post. From two weeks ago the numbers are:

#1=100 psi, #2=85 psi, #3=82 psi, #4=100 psi

Two values are under 90 psi but these numbers are in fact slightly higher numbers than when the engine was running fine (no power loss). Should I be concerned about the 85 and 82 psi values? The engine has been running cold for many years and we now have the cooling system fixed to run at a steady 140 degrees so I hope the valves may clean up a little and the compression numbers may be even higher after another 10 or so hours on the engine.

Bruce

[J.MILES]

Bruce,

Wow, that sounds just like what happend to me and is repeating itself again. Last summer the spark arrester was the culprit, as it was partially clogged, I guess it was starving for air. It was cleaned and wa la, ran like new. I just launched the other day and the same thing is happening that you are experiencing. This time however, the spark arrester is clean. I am going to look for a blockage in the exhaust next weekend but nothing definitive yet.

Good luck. By the way, the arrester comes off easily. Don't take the whole carb off like I did the first time.

John M.

[Bruce A]

Hi John,

I have done a lot to the engine/drivetrain to try and solve the problem first reported in this thread but to no avail. I have checked the spark arrester and it is clean. I still have the power loss problem but have noticed a few new things. It would be interesting if your engine exhibits these symptoms.

1. I removed the spark arrester/air filter and peered into the carb throat will cruising yesterday. I had my buddy run at our max available rpm--1600 @ 6.1 KTS which is about 2/3 WOT throttle. While looking into the carb I observed what looked like normal conditions ie. no presence of puddling fuel. As the throttle was increased toward WOT there appeared in the bottom of the carb throat a pool of fuel and I could see fuel running down from the main nozzle.

2. Just for laughs I tightened down on the idle adjusting screw as this is the only adjustment available and I just had to do something! RPM's increased to 1700 (but no more) and speed to 6.3 kts. The puddle still formed at WOT. This is a minor improvement but I just replaced the prop with an indigo three blade and Tom Stevens said that I should be able to cruise at 2000 RPM and push to 2400 RPM with his prop (assuming the Atomic4 is in reasonably good shape).

Since I first encounter this problem I have done the following:

1. All new exhaust including hot section and water lift muffler.

2. New plugs, points, rotor, condenser, cap and coil.

3. New thermostat and housing.

4. New Indigo prop.

5. The carb is basically new but I stripped it down and checked it out and it was clean as a whistle. I went ahead and rodded out the jets even though they were clean and not clogged in any way. (I did not reset the float as it seemed to be OK).

6. New water separating filter.

7. Tank vent is free and clear.

8. Fuel pump (electric) puts out high volume of fuel--(much more than 1.5 gal/hour)---I measured it but don't recall the exact flow rate but it was plenty.

9. Last compression check (with engine warm and all plugs removed)

#1 = 105 psi
#2 = 80 psi (Note: Cyl 2 and 3 have vaired from 70-85 psi
#3 = 80 psi over the past few months)
#4 = 100 psi

Adding MMO does not seem to affect compression.

10. Engine runs at a consistent 140 degrees.

11. No water in oil.

12. No oil consumption.

13. Exhaust is nondescript. I do run MMO and Stabil in the fuel so I would expect to see a little blue/grey smoke but I cannot notice any exhaust color at all (I must confess I am a little color blind however).


14. Plugs 2 and 3 seem to foul a little more sooty than 1 and 4.

15. PO replace the head and gasket. He used the Universal single gasket (Universal's instructions are to just used one of their new style gaskets as it is thicker) I think is is a copper clad assembly not the old paper type.

16. Lastly I checked the timing with a light and got 17.5 degrees advance at 1600 rpm also dwell was per spec. I double checked the mechanical tach on the atomic four against my electronic shop tach and the mechanical is spot on.

At this point I am about to give up and just ignore the dilemma and go sailing/motoring although I would really appreciate any comments that may shed some light on the power loss issue ESPECIALLY the fuel puddling in the bottom of the carb throat at WOT. Also, does the lower compression in # 2 and #3 necessarily imply a blown head gasket or are there other explanations. Also, my distributor is STUCK and I cannot rotated it when the clamp bolt is loose---has anyone tried to unstick a frozen distributor????

Thanks in advance for any and all suggestions.

Bruce

[roadnsky]

Also, my distibutor is STUCK and I cannot rotated it when the clamp bolt is loose---has anyone tried to unstick a frozen distributor????

Bruce-

Hmmm, could the fact that your distributor is "stuck" be causing a timing issue that may be the source of your problem?
It certainly doesn't seem right that it shouldn't move...
-Jerry