Another Volvo penta aq125a problem

[reptileguy]

Hey guys I will give you a little history about the problem and what IV done to try to fix my aq125a. Engine will not get above 2100 rpm under load ,it stalls out and I can't even feather it higher I hear the carb open up sucking air loud. I can rev it up to 3500 no problem in water in neutral and it idles at 1100 then 900 rpm in gear. I have compression tested and is 147-150 psi across the board I have replaced all fuel lines and filters , cleaned pick up tube, screen filter and anti syphon from fuel tank I have lots of gas going to carb .rebuilt carb 2 weeks ago set mix screw 2 1/4 turns out. I have checked timing belt and did not skip a tooth . Set points to 0.016" . Timing light says 10 degrees BTDC at 1100 rpm advance goes to 30 degrees BTDC at 3000 rpm but jumps all over the place any higher rpm than that. Don't think that's normal but not sure . I have followed hundreds of posts regarding this engine on here but never seems to fix my problem any help would be great

 

[dennis461]

Re: Another Volvo penta aq125a problem

look for a loose connection on outside of distributer where the capacitor screws on.
Run the engine at night, in the dark, look for sparking along the spark plug wires.
What spark plug gap did you use?

all ok?
then take carb apart again and push skinny little wire through the gummed up passages.

 

[reptileguy]

Re: Another Volvo penta aq125a problem

Plugs are all gapped to 0.028" and all plug wires separated ( not touching) and do not see any sparking . I just finished taking carb apart and using wire , carb cleaner and air compresser to blow out passages . I put carb back on waited 10 mins started back up on muffs now as to dark to be on water and sprayed carb cleaner around outside of carb to listen for idle changes for air leak but idle did not change

 

[dennis461]

Re: Another Volvo penta aq125a problem

did you see a capacitor on the outside of the distributor?

 

[reptileguy]

Re: Another Volvo penta aq125a problem

Yes there is a capacitor / condenser on outside of distributer wire is in good shape how do I test if capacitor is working

 

[jerryjerry05]

Re: Another Volvo penta aq125a problem

Try checking the tank vent line?
The wasps like to build nests there.
Then do a fuel pump pressure test?
The coil is it too hot to touch after the motor warms?
The capacitor is probably good as it's running at slow speed.
Look inside the dist. for rust and crud .

 

[reptileguy]

Re: Another Volvo penta aq125a problem

Tank vent hose is clear, dist cap and rotor clean and no burnt marks or build up I will check to see if coil gets hot shortly

 

[reptileguy]

Re: Another Volvo penta aq125a problem

I warmed up engine for 10 mins on muffs in pitch black and looked for spark along dist and wires even sprayed water on them and nothing the shut er down and touched coil and it's about body temp so I'd rule that out I think

 

[reptileguy]

Re: Another Volvo penta aq125a problem

Is there a way to check weights in dist? I took out points but there is a plate riveted above weights. Do I drill these out ?

 

[captmello]

Re: Another Volvo penta aq125a problem

You should be able to test the dist. without taking it apart. You said the dist was advancing,..


Did this problem just come on without notice? was it running great one day and the next day it won't get over 2100 RPM?

 

[reptileguy]

Re: Another Volvo penta aq125a problem

No this was a project boat I purchased cheap and it advances to 36 at 3500 rpm then timing mark bounces all over the place with any higher rpm. I have never been able to get above 2500 rpm in gear

 

[reptileguy]

Re: Another Volvo penta aq125a problem

How expensive would a new coil and plug wires with dist cap be up here in Canada?

 

[captmello]

Re: Another Volvo penta aq125a problem

I thought you ruled out the coil...Do you have a dwell meter? I would set the dwell and readjust the timing. Also I'm wondering if the float is is sticking...or the needle and seat...

I hate these types of issues.

Have a look at this.

http://forums.iboats.com/mercruiser-i-o-inboard-engines-outdrives/list-possible-causes-low-wot-295070.html

 

[dennis461]

Re: Another Volvo penta aq125a problem

I'd like to see the inside of the distributer cap, does it still have the spring loaded carbon button in the center?
Does it look like it is all full of tiny cracks?

Is the throttle linkage opening up the carb all the way at full throttle?

 

[reptileguy]

Re: Another Volvo penta aq125a problem

Yes it still has carbon button in dist cap no cracks on it and cap is clean , throttle linkage opens all the way when engine off I have revved to 4000 rpm in water but not in gear. When in gear if I go above 2100 rpm it stalls before I can get to wot . I do not have dwell metre only timing light I set points to 0.016" and set timing to 10 degrees BTDC . I have about 3 weeks left before the snow flies and the boat gets put away until next year it would be nice to solve this problem soon lol

 

[dennis461]

Re: Another Volvo penta aq125a problem

Yes it still has carbon button in dist cap no cracks on it and cap is clean , throttle linkage opens all the way when engine off I have revved to 4000 rpm in water but not in gear. When in gear if I go above 2100 rpm it stalls before I can get to wot . I do not have dwell metre only timing light I set points to 0.016" and set timing to 10 degrees BTDC . I have about 3 weeks left before the snow flies and the boat gets put away until next year it would be nice to solve this problem soon lol

Try this, boat in water running at a good speed.

As you open the throttle to the 2000 rpm mark.
Rather than just put the throttle full open, jog it a few times. Then go full open.
[ pull it back to almost neutral, throw it forward, pull it back to almost neutral]

If the mid range setting on the carb is out of whack, you should be able to use the extra gas from the diaphragm (accelerator pump) to get a little more gas in.

It it makes a difference, then you need to find the mid range adjustment screw and open it up, or open the idle adjustment jet a little more (some carbs ahve a single jet adjustment).