Volvo penta AQ 125 A timing

[reptileguy]

Hey guys AQ 125 A backfires out carb at 2800 rpm just as I'm trying to plane. I can push past it but will backfire 6-7 times then smooth out and run good on plane. Will do this everytime I throttle up. I checked with a timing light and I'm at 11 degrees btdc at 1000 rpm idle in my lane way. I'm sure in water is best to test but can't do it at the moment. I know it should be at 10 btdc can 1 degree cause this? Also what is proper carb setting ? I have it around 1 turn out from light seated if I turn it out it won't run rough until 6 turns out and if I turn it in to say 7/8 to 3/4 it barley changes sound or rpm but valve cover gets hot

 

[bruceb58]

It's a lean carb issue.

 

[reptileguy]

When I idle at the dock it's fouling the plugs and I mean complete black sooty foul . The manual says to turn 1 turn out and set from there. Also when I have a cold engine and turn it over it will get 1 revolution then fire without pumping any gas or giving any throttle

 

[bruceb58]

Mixture at idle is different than mixture while running. Which carb or carbs do you have on that engine? Solex? You may need to rebuild the carb.

 

[reptileguy]

Solex 44 pa1 downdraft single carb and only one mixture screw on it. Been rebuilt 2 times in the last 3 years most recently a month ago but did this same thing last year as well. I was in a salmon derby and worked great for first 3 days but I had regular gas in it at that point ( says on top minimum USA 87) but I put premium in it as that's all fuel dock at marina had and a day after that she started backfiring . I went back to regular but problem is still tgere

 

[dennis461]

try this.
Engine OFF
Key OFF
Carburetor cover(spark arrestor) OFF

Safety glasses ON
Look down inside carb while someone pumps the throttle.
Look for a squirt of gasoline.

 

[reptileguy]

Lol accelerator pump new and have it set to start squirting when throttle starts to open.

 

[dennis461]

Lol accelerator pump new and have it set to start squirting when throttle starts to open.

OK, then open the idle mixture screw another 1/2 turn, try it out, open another 1/2 turn try it out.

I can check mine tomorrow, I think it is more than two turns out.
The screw as near as I can tell is both the idle an intermediate jet.

Also, you may want to check actual TDC on your front pulley.
Use a dial indicator in the spark plug hole.
Mine is off about 6 degrees due to a chip in the key on the timing belt sprocket at crankshaft.

 

[captmello]

I wonder if the fuel pump is weak..can you check the volume?it should pump a pint in 15 seconds.