Another stalls when put into gear thread

[Catfish]

I'm in the process of getting an old A4 running in my "new to me" Catalina 30. After discovering and replacing a broken exhaust valve the engine still doesn't want to idle up and sometimes stalls when put into gear. I've checked the prop for fouling, checked and rechecked the firing order and timing, checked the exhaust (and even ran it disconnected to verify potential clogs/collapses) I've got compression and I have spark to all cylinders. I'm about to rebuild the carb but noticed last night that the ignition coil had oil in the top of it where the coil wire connects. Is this normal and could this be the source of my grief?

[Dave Neptune]

The coil should not leak oil, replace it. Not wanting to idle in gear is usually "tune" related. IE idle speed, idle mixture, timing and/or stuck C-advance or an air leak. Once you know the timing and spark are good and it still dies it would be time to look to the carb, fuel and fuel delivery.

Did you check the C-adv? How do the plugs look, piics would be nice? Are you sure the valves are adjusted properly and supplying good compression?

Dave Neptune

[JOHN COOKSON]

Is the choke adjusted correctly so the choke is open\closed all the way when you think it is?

ex TRUE GRIT

[Sam]

well, I am assuming "late" model A4. Does it have distributor points or electronic ignition?

[Bratina]

I chased two stalling problems for a while, which I eventually fixed by:

1: clean fuel. I had around 10% water in my fuel, the engine would run at low power, but stumble and die in gear or under load. I pumped out the tank, replaced the Racor, changed a deck-fill o-ring (water had to come from somewhere).

2: low fuel pressure due to a blocked polishing filter. Same symptoms; I added a small in-line fuel pressure gauge after this incident, which would have narrowed down the possibilities rapidly. Changing the filter immediately cured this.

Are you sure you have clean, dry fuel? Do you have a fuel pressure gauge? I used a $20 'Mr Gasket' which users here recommended.

[sastanley]

Catfish, Welcome from a fellow C-30 owner!!

These are all good questions, and each one valid. Work thru all responses one by one and we can help. In addition to the data points you've already provided, we are gathering data to help diagnose the potential problem. If you aren't sure how to answer one, just ask, we can help (Advance, Electronic ignition, etc.)

[JOHN COOKSON]

Another Thought Or Two

the engine still doesn't want to idle up and sometimes stalls when put into gear.

How warmed up is the engine then you try to back off on the idle RPMs and shift into gear?

A cold A4 needs to warm up at fast idle for a minute or two before it will idle normal and shift into gear without stalling. A bit of choke usually will speed up the warm up process.

A good diagnostic test is to see if the engine runs better with a bit of choke. If it does there is a problem in the fuel system.

Welcome to the forum. Your engine will run correctly.

ex TRUE GRIT

[Catfish]

Whew. That's alot to take in lol. As far as timing I've just checked with a light to make sure I had the distributor close. I tuned by ear and the timing mark is close at idle. The engine now starts immediately, runs great, and has a responsive throttle. However when eased into forward gear struggles to stay running. I verified the choke was in the open position and the engine starts to bog down when I apply it while running. I ordered a replacement coil and cleaned the carb out. I also verified operation of the electric fuel pump and oil pressure switch. Hopefully I can find some time to get back at it tomorrow evening. I plan to delve into the distributor. It's a late model engine with points ignition. I haven't checked the advance or springs yet. Sorry if I'm missing some answers to your questions. I didn't expect so many responses....but I appreciate them!

[Administrator]

Just curious... Does it also bog down when you do the same thing in reverse?

Bill

[roadnsky]

When was the last time you checked your STUFFING BOX?

[Catfish]

It goes into reverse just fine and stays running. I have spun the prop shaft by hand in neutral with ease, but I have not taken the stuffing box apart for repacking yet.

[roadnsky]

Here is a quote from the FAQ's. Note the mention of exhaust repair AND item #4

What would cause my engine to run with almost no power in forward, while it runs OK in neutral? It also seems to have more power in reverse than in forward.

This condition is usually the result of low power caused by something that was done incorrectly during recent engine maintenance.
The reason the engine seems to run better in reverse is because the reverse mode has a 1.7 to 1 gear reduction. Here are some examples of maintenance problems that we've heard about:



Three to five times each year, spark plug leads were found to be installed in an improper sequence following a tune up! Cylinders 2 and 3 can apparently be reversed, and the engine will run fairly well in neutral, but will have practically no power in forward.
According to one caller, his plug wires were reversed for an entire season before he found the cause of his power loss.



Another recent maintenance "oops" involved a minor repair of the exhaust system which required that the manifold be removed. On reinstallation, the old gasket was improperly installed, resulting in intake leaks and very poor power under load. 

Assuming that there was absolutely nothing done to the engine since it was last running OK, check the following areas for potential problems:



1) Check for something hanging on to the prop.


2) Check basic integrity of the engine by a quick compression check. For the purpose of diagnosing a major power loss, a simple check using your thumb over each spark plug hole is more than adequate. If your compression is sufficient so as to make it impossible for you to hold your thumb over each spark plug hole while cranking the engine with the starter, the cause of your power loss is not a major mechanical failure. If compression is weak in two adjacent cylinders, or water is observed in any of the combustion chambers, the head gasket has probably failed. If compression is "zero" in any of the cylinders, a valve has probably stuck open. If you are using a compression gauge, compression values over 80 psi are considered adequate.



3) Check for proper carburetor function. Normally, an Atomic 4 will accelerate almost "explosively" as you flick the throttle forward. If there is any hesitation or mild backfiring, a lean condition caused by dirt in the main jet is the most frequent cause. In most cases, a problem related to a fuel issue will manifest itself in neutral as well as in forward, but in mild cases, a lean condition might be missed in neutral, but will surely show up under load.



4) Check for proper ignition. As in the case of subtle lean fuel mixtures, there are subtle ignition problems that can show up under load but not necessarily in neutral. In this category, plug condition is the best indicator. If one plug is noticeably blacker (or oilier) than the rest, look for the relatively few things that can affect only one plug, such as the plug itself, the plug lead, or a cracked distributor cap. If all the plugs are badly fouled, check things that can affect all plugs, such as a loose condenser, badly worn points, shorting coil (or oil leaking from the coil), cracked distributor cap, or a bad coil lead.

[Catfish]

That all makes sense. I was able to get the carb cleaned and reinstalled and the stuffing box repacked. A small improvement as I can now get it into gear without it dying but still doesnt want to throttle up. I inspected the plugs and all appeared black soot covered. Would that be a weak spark indicator? My new coil I'd scheduled to arrive tomorrow. Again, thanks for the advice and feedback everyone.

[Bratina]

That all makes sense. I was able to get the carb cleaned and reinstalled and the stuffing box repacked. A small improvement as I can now get it into gear without it dying but still doesnt want to throttle up. I inspected the plugs and all appeared black soot covered. Would that be a weak spark indicator? My new coil I'd scheduled to arrive tomorrow. Again, thanks for the advice and feedback everyone.

Have you checked fuel cleanliness and pressure yet? A quick decant into a jar, and a $20 gauge, will take at least those two items out of the guesslist.

[Catfish]

I've been using clean fuel from a remote tank to troubleshoot. I haven't got a fuel pressure guage yet, but have verified the pump is pumping. I ran about a pint into a container to flush the lines and check the pump.