Volvo penta aq125a

[Cjp13021]

Anyone have the specs to adjust the carb 1984 on Volvo penta aq125a ? I took it on the water today for the first time this season, it wouldn’t idle right so I adjusted a screw, idled good, went out and it wouldn’t go over 10 mph. At full throttle it was at 3k rpm’s and 9 mph it should be 4800 at wot. I started messing with the carb and messed it all up, sounds like it’s getting way too much air. It ran great last season and ran great on muffs this year in my driveway. All I did was change dist cap and points and bellows. Carb is all out of wack now and I can’t find the service manual apparently you can’t even get it from Volvo anymore they only gave me the workshop manual.

 

[Cjp13021]

It was kind of weird actually, I’d have the throttle wide open, and I’d hear it start to try to speed up for a split second and go right back down. I’m not sure what’s going on with it

 

[captmello]

I'm pretty sure what you're calling the workshop manual is the only service manual available. approximately 75 pages?
Did you set the points with a dwell meter?
recheck the timing after adjusting the dwell?

 

[Cjp13021]

No I didn’t use the dwell meter, and I have the workshop manual. Doesn’t tell ya how to set the carb. I need the service manual but that’s unavailable. Timing is bang on.

 

[Scott Danforth]

If you didn't set dwell with a meter, it wasn't set correctly

 

[Cjp13021]

So what’s the dwell suppose to be on that engine? Not set right would cause low power? Still need the carb specs because the air screw and the idler screw are way out of wack now.

 

[Scott Danforth]

Check the manual, however I think 62 degrees

 

[Bondo]

So what’s the dwell suppose to be on that engine? Not set right would cause low power? Still need the carb specs because the air screw and the idler screw are way out of wack now.

Ayuh,...... Did you service the fuel filter,..?? sounds like it's lackin' fuel,....

Yer carb is adjusted like 'bout every other carb on the planet,.....
The air screw is turned In, just barely snug, then back it out a turn, 'n 1/2, or two turns to start, then adjust when running,...
The idle screw can just be turned in, til it contacts the linkage, then adjust for a 650/ 700 rpm idle,....

 

[dubs283]

I found this. For an AQ125B but I can't imagine it'd be much if at all different for the A series

 

[dubs283]

Once you get the ignition system tuned proper the best method for setting idle air mix and speed is with a vacuum guage

A mechanically sound engine should be able to have idle speed vacuum at a steady 17 in/hg at most elevations

Not sure on your engine the best place to connect a vacuum guage but needs to be below the throttle plate of the carb in the intake manifold

 

[cyclops222]

You now KNOW why you ONLY change 1 part at a time.
Take the boat out for a fully warmed up run to MAKE SURE the part is GOOD and you did the replacement correctly.
I do this important procedure even with a simple complete sparkplug change. Yes I have had 2 bad plugs in 70 years of boat motors.

Wrong point gap ? Is a great way to create a engine REV LIMITER. Done that more than 1 time.

 

[Cjp13021]

I can go into neutral and rev it up to 5k rpms…would I be able to do that if that gap and dwell was off was off ?

 

[Scott Danforth]

I can go into neutral and rev it up to 5k rpms…would I be able to do that if that gap and dwell was off was off ?

yes, reving in neutral can be done with the motor running on 1 cylinder

it doesnt mean anything

 

[kenny nunez]

After getting the ignition corrected the carburetor needs to be cleaned. Most times there is some gasoline sludge in the bottom of the float bowl. Also the brass plugs and jets need to be removed to get the internal passages cleaned. A good chance the gaskets can be reused but try to get a service kit.
Sierra Marine # 18-7099 should be the gasket kit for your engine.

 

[Cjp13021]

I’m trying to adjust the dwell with a digital dwell meter but I’m either getting 000.2 or 90.0 and no in between

 

[Scott Danforth]

I’m trying to adjust the dwell with a digital dwell meter but I’m either getting 000.2 or 90.0 and no in between

Use an analog meter

 

[Cjp13021]

lol you can’t find an analog dwell meter these days I barely found the digital one

 

[dubs283]

Most/all decent dvms sold these days have dwell capability. It's not reliable though because the signal is analog (slow/sweeping) and a dvm reads mainly peak voltages. The capacitor in the points system throws the dvm reading off

There are a number of reasonably priced analog dwell meters available on ebay

 

[captmello]

this is from the manual, page 33.
Re:the dwell, might try a different meter.

 

[Cjp13021]

I think part of my issue was the fuel filter. It was filthy and barely any fuel in it, put a new one on and it filled right up like it should. I am using an aftermarket set of points, I guess that could be why I can’t get the right measurements. I’m going to order an oem set of points and find an analog meter and I’ll come back with updates.