motor dies when placed in gear

[breweraz]

I have read and re read almost all the threads on this topic and ended up more confused than resolved. Looking for some help?

About the boat:

Early A4 in a Tartan 27, direct drive
Prestolite distributor, with new points condenser and coil
Raw water (saltwater) cooling
Exhasut goes to riser, Vetus L40 waterlock, to above waterline transom exhasut port
Replace vetus water lock after extreme overheating, melted the connections
The motor will start fine, idles at all 800 and good accleration to about 3000

When I place it in forward and or reverse it looses about 800 - 1000 RPMs and if under 1500 will die If I rev it up to 1700 or more and I baby it into gear, it will lug but not die. We motored for about an hour at 5.5 knots with the motor running at 1200 to 1500 RPMS.

When reading the post on this topic it seems it may not be any of the issues for the reasons I stated but I am looking for advice.

Stuck or fouled shaft - Shaft easily turns by hand when in neutral
Low idle jet circuit dirty or out of adjustment- If this was the case would it not idle at 800 or lower RPMs
Points and timiing. I have replaced coil, lead wires, condensor and checked points. All seem good as she runs like a charm once she is going.
Blocked exhaust - I am leaning this way but the threads state if this was the problem it should be felt in idle and running.

The motor runs smooth so I do not think there are any stuck valves

I live about 1 1/2 hour from the boat, which in on a mooring so I try to do my parts shopping during the week. There are so many ways to go here I am not sure where to start.

Any thoughts and diagnostic suggestions would be helpfull

Tim

[rigspelt]

Frustrating stage of troubleshooting, and there are a number of possibilities. Others will chime in with better suggestions, but my first impression is that you have good spark, which leaves air (in and out), fuel, and transmission/shaft. I know this doesn't give you specific advice, but when I have an issue like this, I like to have a frame of reference to start troubleshooting.

Can you tell a bit more history on the boat? New to you? Any recent engine maintenance? The overheating episode could be important -- is this problem new since then?

Air in: does the engine get appropriate air intake? No new hatch covers or blocked air entry vents?
Air out: I'd be wondering about exhaust blockage, from manifold to transom tip.
Fuel: My solution to a fuel problem was to rip out and replace the lines, filters, fuel pump and carb with all new, so I'm not the guy to help you with troubleshooting fuel possibilities.
Air/fuel/spark come together in cylinder: good cylinder compression? Valves OK and valve-tappet gaps OK? See http://www.moyermarine.com/forums/sh...loss#post12159
Power train: I've only been on the forum a couple of years, but I get the sense that problems in this area are less likely if there are no obvious issues. There have been some interesting findings by some dealing with loss of power, but not as often as in the fuel and air systems.

For what it's worth, I made this up to get me started on issues like this, should they arise in future:

If engine is not running properly, list all the changes that have been made since the last time it ran well, or all the components that have not had maintenance for some time. Then ponder the list before spending money or time.

1. Spark:
1a. Distributor: position, points/condensor or electronic ignition module.
1b. Coil.
1c. Plugs and plug wires.
1d. Wiring: wires, connections, switches, solenoids, wires, fuses.
1e. Charging: battery, alternator, cables, connections, fuses.

2. Fuel:
1a. Fuel condition.
1b. Tank: condition, pickup tube, vent.
1c. Fuel line: air or fuel leaks, hose or tube condition, connections, filters.
1d. Fuel pump.
1c. Carburetor.

3. Air:
3a. In: air vents, engine space air flow/volume, engine space air seal, spark arrester and carburetor.
3b. Out: manifold, exhaust dry stack, exhaust cooling water injection point, muffler, waterlift function, exhaust hose, transom exhaust tip.

4. Cooling (modify if not antifreeze cooled):
4a. Raw water: intake throughull, hoses and connections, filter, flow detector, water pump/impeller, drive belt, exhaust injection point.
4b. Antifreeze: antifreeze condition and amount, hoses and connections, water pump/impeller, pump drive, heat exchanger, thermostat, bypass valve if one installed, coolant passages in block/head/manifold, coolant drain plugs.

5. General:
5a. Bolts and nuts for tightness.
5c. Fluid leaks.
5d. Combustion chambers: valves, pistons, head, head gasket, studs.
5e. Oil: condition, amount, pressure, passages, pump, drain plugs, pressure adjust valve.
5f. Gauges.
5g. Procedures, such as overcranking with raw water throughull open or closed.
5h. Power train: crankshaft, bearings, transmission, propshaft coupling, propshaft, stuffing box, stern tube, cutless bearing, propellor.

[keelcooler]

Tim,
Check plug wire firing order 1 2 4 3.
Check compression, 80 PSI or better.
Check mixer, make sure it's clear.
Check for inner wall hose melting after water trap due to prior overheat (you can use your leaf blower).
Flick the throttle, RPM increase should be explosive and immediate.

[Baltimore Sailor]

I had the exact same problem: engine idled fine, revved up great in neutral, but put her gear and she'd die -- instantly. I have the adjustable main jet, so I reached down there and enriched the mixture and the problem went away -- also instantly.

If you have the adjustable main jet, try enriching the mixture. If you don't have it, take the carb off and make sure the fixed jet isn't blocked.

It's amazing the difference just being a bit lean on the main jet can make -- when it happened to me the boat had been sitting for a month on blocks getting some keel work done, so I got the big surprise when I went to pull away from the dock after being splashed. Started her up -- revved up nicely; put her in gear -- BAM!, died instantly. Repeated this process a few times. Checked the drive shaft -- it turned freely. Thought about it for a moment, then tried running with the choke partially closed: she ran better, not great, but good enough to get me home. The next time I got down to the boat, after I'd had a while to think about it, I tried opening up the adjustable jet, and you know the rest.

Good luck.

[domagami]

I vote with Baltimore

Tim,

I started on the plug wires too, but since it runs fine once warmed up I agree it sounds like a mix issue.

How nice is that? No need for a parts run!

[breweraz]

dies when put in gear

Answers to questions:

New to you?

Yes this is new to me this year and I have limited history except the PO said it "ran great"

Any recent engine maintenance? The overheating episode could be important -- is this problem new since then?

Yes - new alternator, new water pump, new coil, new condensor, replace Vetus water exhaust, exhaust hose from water lift to water trap. One of my thoughts was with this installation I have kinked or bent the exhaust line between the waterlock and the transome as there are seciton I cannot see or get to without pulling out the whole line.

Air in: does the engine get appropriate air intake? No new hatch covers or blocked air entry vents?

No changes here


Air out: I'd be wondering about exhaust blockage, from manifold to transom tip.

This is where i was headed as well but a post stated if there was a block it would show up in idle as well as when running not just when placed in gear.

Fuel: My solution to a fuel problem was to rip out and replace the lines, filters, fuel pump and carb with all new, so I'm not the guy to help you with troubleshooting fuel possibilities.

Air/fuel/spark come together in cylinder: good cylinder compression? Valves OK and valve-tappet gaps OK?

Have not checked these with guages but used thumb test and noise. Again once she gets going she runs fine.

I will try richening the mixby turning the screw in a little and see if that helps. I will proably pull the exhasut line and and go ahead and replace all of that.

Thanks to all.

Tim

[marthur]

I will second or third checking the fuel mixture. I had exactly the same symptoms and it turned out to be a very small speck of crud in the carb.

[breweraz]

stall when out in gear - problem fixed

The problem with the stalling was actually two fold.

I decided since the last thing I "fixed " was the waterblock start with the exhaust hose. When I replaced the waterblock I only replaced the hose from the in side to the exhasit loop not the the exhaust hose from the waterblock and onto the transom. So ibought the replacement hose thinking it was just for peace of mind and ripped out the soft line exhasut..

The exhaust hose runs through a bulkhead through a cutout hole. Upon inspection, at that point the hose went through the bulkhead, there was not wear protection and the the rubbing had worn the sidewall thin. I think from all the moving around to install the waterlock I kinked the hose. It was 3/4 restricted kind of like a water hose would kink.

Replaced the exhasust hose. The problem was better but still stalled.

Then following advice Baltimopre Sailor's advice, a 1/2 on the main jet and she perked right up. Now with the exhasut hose fixed and the fuel adjustment made she is dialed in and at least since I have had her she has never run better. I now have the confidence I need in her to enjoy the sailing season and head into those tight and crowded harbors that maine summer time brings.

Thanks

Tim

[Baltimore Sailor]

Hooray!