1972 Chrysler 20hp 203HD Rough Running - Won't run at WOT

[3rdMarDiv]

1972 Chrysler model 203HD 20hp.
Picked up within last 2 weeks and trying to get running at WOT.

http://forums.iboats.com/force-chry...sler-20hp-203hd-electrical-issues-632831.html

Above link is to previous electrical issues thread that will provide more info about this motor.

Below link is to YouTube link showing motor running 11/03/13

1972 Chrysler 20hp Outboard Model 203HD Testing - YouTube

Looks to me like it is surging every few seconds as the water shoots harder out of the discharge port...

Seems to be running decent enough, but when I get out on the lake and try to accelerate it bogs down...

I am hoping that someone has experienced this motor condition and can give me some pointers or direction as to ways to proceed.

Thanks for any help you can offer...

 

[jerryjerry05]

Re: 1972 Chrysler 20hp 203HD Rough Running - Won't run at WOT

Start with cleaning the carb.
Setting the air screw.Base setting is 1 and 1/8th turn out.
Then a compression/spark test.
Then rebuild the fuel pump.
Most motors run great on the hose without a load.
Install a filter between the carb and fuel pump.
Wallyworld, G-12 or G-2 Fram filter.
Also make sure the gas is good,no water.

 

[3rdMarDiv]

Re: 1972 Chrysler 20hp 203HD Rough Running - Won't run at WOT

Start with cleaning the carb.
Setting the air screw.Base setting is 1 and 1/8th turn out.
Then a compression/spark test.
Then rebuild the fuel pump.
Most motors run great on the hose without a load.
Install a filter between the carb and fuel pump.
Wallyworld, G-12 or G-2 Fram filter.
Also make sure the gas is good,no water.

Cleaned Carb Replaced Gaskets, Set Float.
Adjusted Low Idle to best running position at 1 1/4.
Compression at 113 psi per cylinder.
New Fuel Diaphragm Kit installed, Reeds sitting level.
Fuel Hoses replaced with in-line paper filter installed.
New gas non-ethanol marine.
Replaced Cylinder Head with new Gasket installed. No scoring within cylinder.
Ignition coils Ohm checked at 700 primary and 684 secondary.
Ignition Laminated Coils/Magneto cleaned.
Have on order new condensers.
New coupling O-Ring.
Points well cleaned/gaped to .020 and producing good spark.
New Plugs NGK BR6HS gaped to .030.
Rebuilt Impeller Housing, producing good water flow.
All work done as per Chrysler Tech Manual.

Any more suggestions...
See something I'm missing...:faint2:

Let me know...:facepalm:

Thanks for any assistance you can offer...:help:

 

[oldboat1]

Re: 1972 Chrysler 20hp 203HD Rough Running - Won't run at WOT

You might consider running the engine in a barrel (large plastic garbage can works well) because you really need back pressure to tune the engine. It sounds like it might be running a little bit rich, stumbling a little on acceleration. Try leaning out the high speed jet slightly (if it has one). The engine might initially run at 1 turn open, for example, but only a half turn after it's better dialed in. The oil mix is probably 50:1 for a '72, and any additional oil will only cause the engine to bog down some and foul plugs. In what I take to be one of your earlier pictures of the engine(?) the coils showed no wear marks from the spinning flywheel, and I thought that was curious. There is usually some shine -- also on the inner sides of the flywheel, which can be lightly sandpapered to keep the contact points clean. Overall, the engine sounds pretty good -- doesn't sound like it wants to bog down at speeds, but hard to tell without a boat test of course. I've generally found that leaner is better when adjusting carbs, even when it seems counterintuitive.

 

[jerryjerry05]

Re: 1972 Chrysler 20hp 203HD Rough Running - Won't run at WOT

When you cleaned the carb?
Did you remove the welch plugs and clean there?
The main jet? was it rodded out?
The air screw is for low speed and doesn't affect the WOT operation.
The fuel lines,the Ethanol, if it was EVER used can melt the inside of the hose and it can collapse sutting down the fuel???

 

[Big Fish Billy]

Re: 1972 Chrysler 20hp 203HD Rough Running - Won't run at WOT

Didn't see a mention about timing? Also I just found my fuel line connector at the tank a bit loose sucking air.