A-4 problem

[Mike Thomas]

All,

I'm having a problem with my 1976 Universal Atomic 4 and I hope someone can help.

The engine is running very rough with a distinct rhythmic shutter, almost like a cylinder is misfiring. When I give it more throttle it sounds like it's starved for fuel. It will idle very rough and continue to idle rough when the transmission is engaged. There is also a constant "whoosh" sound coming from the exhaust as if there blower or hair drier in the exhaust. There is water coming out of the exhaust at good flow. No water in the oil or oil in the exhaust.

I have replaced both fuel filters, all spark plugs, spark plug wires, dist cap (electronic Ign), coil and squirted marvel mystery oil in each cylinder.

Checked that I have a spark at each plug and checked for compression on each cylinder. I don't have a compression gauge but held my finger over each sparkplug hole and had compression on every cylinder. #1 may have been a little soft but it didn’t feel like a valve was stuck.

Anyone have any ideas where to look from here (or am I calling Moyer Marine)?


Thanks for any help
Mike T
Babylon NY

 

[Howard Keiper]

My bet is that you have cylinder #'s 3 & 4 mis-wired.
hk

 

[Mike Thomas]

Howard

Thanks for the input.

I thought the same thing and triple checked it twice. The plate in the front of the engine says 1-2-4-3. I have been running the engine for a month or two before this problem and nothing changed before it reared it's head.

While trying to trouble shoot. I unplugged each sparkplug one at a time. Every time one was disconnected the engine ran worse. That leads me to believe that if two were in fact mis-wired there would be no change when they were disconnected. Does that make sense?

Mike T

 

[Emerald]

Hi Mike,


Have you checked that somehow the timing isn't off? Also, even though you don't have points with the electronic ignition, how about rotor issues? - didn't mention it's replacement in your parts list. I've had rotors that were visually perfect but didn't function.


-David
Independence 31
Emerald

 

[Mike Thomas]

Dave,

Just the man I was looking for.....

Yea, I did replace the rotor, just forgot to mention it. I find it hard to believe it's the timing. The bolt holding down the distributor has not been loose for years and I don’t think could work it's way loose on it's own but the way it's running sounds just like a timing problem but there is more noise.

I spent most of the night reading Moyer’s rebuild manual and old newsletters. I'm starting to think it's either the mechanical fuel pump or the wiring from the distributor to the coil.

Are you home this morning (Sunday)? I have to run to the airport in a minute but would like to talk to you about it if you have the time. Would you mind if I gave you a call during the drive?

Mike T

Babylon.

 

[Emerald]

Mike,

by all means, give a call and we can brainstorm this.


-David
Independence 31
Emerald

 

[rgoff]

Mike,

Saw your post on the Moyer forum.

In the past I've had recurring problems with the exhaust system "plugging up" (carbon, etc.). Engine would run fine at idle, but when I gave it gas in neutral it would die (due to the back pressure).

Not the same symptoms as you, but thought I'd mention it.

I thought I finally had my A4 in good shape after replacing the fuel tank and coil last summer. However, this week after firing it up for the first time in 2 months it appears the electric fuel pump isn't working. Going to try a new one this week and hopefully take a one week trip the following week.

Good luck,

 

[HGSail]

Have you checked the dry portion of your exhuast for restriction? This will cause back pressure and will make the engine act like it's not getting enough fuel. And if you have any variations in your cylinder pressure will be accentuated (Rough running)and water flow will not be affected.

Pat
E29
'73
#224
Holy Guacamole

 

[treilley]

Sticky valve

Sounds like one of your valves is stuck. You should be adding Marvel mystery oil to your fuel to avoid this. See the excerpt from Don Moyer below:



Unfortunately, we only have a rather short list of ways to unstick stuck valves. If the valves aren't stuck too hard, we can sometimes free them by bending a small common screwdriver in such a way as to work it into the spark plug hole to press down on top of the valve. This is quite easy to accomplish in the case of intake valves (which are directly below the spark plug holes), but the exhaust valves are off to the side and very difficult to reach. To make matters worse, it's the exhaust valves that usually stick.

The only other technique with which we've had a small amount of success is to remove the valve cover and grab the very bottom of the valve stem with a needle-nose vise grip and attempt to rotate the valve.

If more than one valve is stuck and/or they don't yield with the bent screwdriver, it's usually necessary to remove the head.

After freeing up the valve, use Marvel Mystery Oil in the gasoline at a rate of at least 8 to 10 ounces per 10 gallons of fuel to keep the valve(s) free.

Don

Tim R.

 

[hodo]

A-4

If you are lacking water flow at any speed above idle, you will have overheating related problems. I had a friend remove his A-4 from his e boat for the exact reasons you specify. He called me to help move it up the ramp and load it in his pick up. When he told me what it was doing, we fired it up there in the dock cart, and it ran like a dream. Found a severe exhaust restriction at the exhaust riser where the raw water enters. Seems the temperature differentials cause the salt cristals to precipitate out, and carbon to form at that point. If the boat is not run and warmed up regularly, this will occlude the riser. Quick check is to disconnect the riser from the manifold and run for jusyt long enough to see if your problem goes away. OPEN ALL HATCHES AND WINDOWS, ETC. FOR VENTILATION ! Could save you a lot of tune up stuff, valve adj., timing stuff etc. Good Luck, HArold

 

[hodo]

Sorry, thought I read water at low flow.Still, the exhaust plugging will cause the WHOOOSH sound coming from the exhaust, as it will be creating back-pressure as it tries to go past the restriction. Harold

 

[soup1438]

Exhaust valves sticking?

I recall from my days spent under my car(s) that unleaded gasoline tended to be "bad for valves" when it first appeared on the scene; apparently the lead additives would provide some kind of "lubricant" for the valve seat.

Could there be a correlation here? ISTR that there were new valve seat materials that made the rounds for automobiles but have no idea regarding the A4.

Note: I've partially defected; one foot in my Ericson 25 w/ o/b and the other in a Catalina 30 w/ an A4, so, of course, I'm paying close attention. Additionally, I did a lot of work on gasoline engines so I'm going to have to regain all of my mechanical skills on the off chance that IBM decides to downsize another group of people. If I can work on boat engines it might not pay as well but, if work that gets off-shored, well, I'll be off-shore too.

 

[Mike Thomas]

All, Thanks for the help.

After some more head scratching we confirmed a good spark and when we had it running (rough) there was ample exhaust pressure. I couldn't plug he exhaust outlet with my hand and good water flow.

Getting a very good spark
Moved the timing throughout the range of the distributor while it was running but this had little effect.
Seeing 100+ compression at each cylinder so a bad/stuck valve is not likely
Started to look at the fuel system

It runs normal for about 1 second after it starts then goes bad. There is no throttle response. If I put the throttle all the way up it just runs a little rougher not faster. When I spray starter fluid into the flame arrestor it stalls instantly (that is confusing me). I blew back into the fuel supply line at the tank to make sure there was no blockage in the pick up tube. Now I'm thinking needle valve in the carb. The fact that it runs good for a second when first started leads me to believe that the valve is allowing some fuel to drip by and fill the bowl when it's not running, once that's burned off I think we only have a trickle and fumes. This might explain the lack of throttle response?

The plan at this point is to rebuild the carb.. Unless someone has a better thought.

Mike T

 

[hodo]

A-4

Mike, I really think you should check your exhaust for a restriction. It is possible to have good water flow and exhaust pressure and still be restricted. You need to have exhaust flow as well as pressure. Do you have a check valve in-line between the engine and muffler? They are notorious fo coming apart and plugging up the exhaust. Remember, if the exhaust can't leave the engine, it cannot pull the needed fuel/air mixture in. Kind of sounds like what may be happening. Well,this opinion is free, so, hopefully it is worth more than that. Keep us posted with what you find out. good luck, Harold.

 

[Art Mullinax]

Fuel Pump?

Mike,
Do you have the mechanical fuel pump or have you replaced it with an electric pump. My mechanical pump went out and it would pump enough gas to fill the carb. bowl for a few seconds and then the bowl would run dry, especially if I tried to throttle up. Had a hole in the diaphram. This was before I new about Moyer. Went to the local NAPA store and bought an electric pump. Working great for the last 10 yrs. If you still have the mech pump, remove the carb bowl (carefully) and actuate the pump lever to see if gas is coming into the bowl. When you disassemble the carb, hold it over an old pie pan and catch the gas. Look it over for water and/or trash. This info may help with future problems.
Turn the bilge blower on as some gas will spill and ask the smokers to stay back!!!

 

[Bill Sanborn]

These are the same symptoms I had with a plugged exhaust pipe. The blockage was in the pipe between the exhaust manifold and the heatriser. This section is not water cooled.

Once you take this apart you are commited to replacing it and I don't know of any way of testing it first. Maybe somebody else has figured out a way, if so I would sure like to know it.

I used sched 80 black iron pipe, it has a thicker wall and may last longer. If you haven't replaced the heat riser recently you should probably do so now. Don't try to clean and reuse it, the damage is internal where you cannot see it.

If you have access to threading tools for 1.5" pipe you can fab the pipe yourself, otherwise I would take all the pieces to a plumbing shop. The fiberglass wrapping is available thru EJ Bartells or possibly a commercial chandlery. I think Moyer has the adapter that connects the pipe to the exhaust manifold. I alse took my exh manifold to a radiator shop and had it "boiled out" and tested for leaks.

Be sure to use anti-sieze when reconnecting.

I bought a new heat riser from the original mfg whose name escapes me right now. I will look it up if you need it. About $450 I think.

Good luck. When you are done it will seem like a new engine.

 

[Sean Engle]

...how about rotor issues? - didn't mention it's replacement in your parts list. I've had rotors that were visually perfect but didn't function...
-David
Independence 31
Emerald

Could the rotor have a mis-assignment on it (ie - the plug v. wire assignment being incorrect)?

//sse

 

[HGSail]

Yes, There's no way to check it without destroying the pipe. But when you buy a new Exhaust flange from Moyer, They put a port in it so you can install a pressure guage to keep an eye on your backpressure. The higher it goes up, The more the blockage.

Pat
E29
'73
#224
Holy Guacamole

 

[Emerald]

Could the rotor have a mis-assignment on it (ie - the plug v. wire assignment being incorrect)?

//sse

my failed rotor experience has usually been a massive increase in resistance - looks fine, but conductive capability shot. I've also had rotors that arced across their back surface, so as you suggest the spark didn't go where it should. OK, you say arc across the back, what?! Rotors and caps can develop hairline cracks that can become alternate routes for the electricity. Often these cracks will be black from carbon. I've had ignition systems you could see arcing on the wires at night....


-David
Independence 31
Emerald

 

[soup1438]

Carburetor issues...

Don't forget the possibility of problems with the needle valve in the float bowl; these can look intermittent and only surface when the fuel flow jumps. (I can tell you horror stories about the carburetor in a 1976 Rabbit that had me going crazy, especially since there were TWO float bowls...)

Despite the simplicity of these carburetors (i.e. "no accelerator pump", etc) there are still a lot of teeny mechanical parts that can get gummed up. A good dose of gumout *may* be helpful if you spray it from the supply side of the needle valves (i.e. "line from fuel pump disconnected").

As others have pointed out this is a time for your fire paranoia to go to at least 17-- if not higher-- just go WAY past 11.

air, fuel, ignition, low backpressure... 4 key needs for an engine.