Stalls at idle, hard to start Volvo Penta AQ131D

[TrevorStott]

I recently purchased a project boat which is in worse shape than I thought however the motor runs but it's hard to start and stalls at idle. The previous owner did disclose this and spent $1800 on it last year replacing the distributor, wire and plugs and I'm not sure what else. Any thoughts on what could cause this? I'm thinking of ordering the carburetor rebuild kit.

 

[aimlow]

Is that the little Volvo 4 cylinder? What carb?

 

[TrevorStott]

Yes, it's the 2.3 liter 4 cylinder. In the parts catelog it looks like its part number 856123 which is also listed as an obsolete part. Not sure if that helps.

 

[kenny nunez]

The gaskets that the carburetor has can most times be used over. They are easy to service. Also most of the hard starting problems with the 4 cylinder models is because there is no ignition by pass circuit. Look closely at the starter solenoid, on the 3 o’clock position there is a male spade connection, make up a wire going from that to the + side of the coil. You should see an improvement in starting.

 

[dennis461]

Hello,
This is a simple engine with simple repairs, but,
you need to determine first if you have a
1 electrical problem
2 fuel problem
3 engine mechanical problem.

Here is the approach I use.
Hard to start, use spray starting fluid while cranking. One quick shot will tell you if fuel delivery is a problem.
If it works, its fuel, if it does not work its electrical or mechanical.
Find the fuel jet adjustment screw and turn it counterclockwise one full turn from it's present position
See if it starts better.

Stay safe, do not try starting fluid too many times.

Stalling at idle makes it hard to separate the electrical problem from mechanical problem.
So check timing belt alignment, ignition point gap, spark plug condition, the usual suspects.
RETARD the timing slightly to see if will idle, then check timing.

Lastly, a mechanically worn out 2.3L will burn oil, be hard to start and idle poorly.
Burning oil may be difficult to spot as the exhaust in the water will mask it from view.
Try a compression check

 

[TrevorStott]

Thanks everyone, I'll try the suggestions here. Starting fluid did work but I had to winterize before I could try the adjustment screw. I found an inexpensive carb rebuild kit on ebay that I can do over the winter and try the the adjustment screws as well in the spring.

thanks again!

 

[dennis461]

OK, winter's here too.
When doing the carb rebuild, some hints.
Be very careful with the fuel line 'banjo bolt', you can easily strip the threads in the carb top.
Do the rebuild in a shallow plastic tub so as not to lose any parts, most are unobtainable.
The rebuild kit will only have about half the parts you need, the others you reuse.
There is a tiny cylindrical bronze screen in the bottom that is difficult to remove-clean-reinstall.

If your carb version has a single mixture screw, it serves for both idle and mid-range.

 

[TrevorStott]

thanks for the tips!

 

[QBhoy]

Keep an eye on that timing belt. The Achilles heel of these things.

 

[kenny nunez]

Make sure that there are no mud diver nests present under the belt before you try to start it after it has been sitting. That happened to one of my customers, he was lucky that none of the valves got bent when he tried to start it.

 

[dennis461]

Make sure that there are no mud diver nests present under the belt before you try to start it after it has been sitting. That happened to one of my customers, he was lucky that none of the valves got bent when he tried to start it.

Kenny,
FYI, All single camshaft versions of the engine are of 'non-interference' design. At least for the normal displacement AQ125-aq131, I am not certain about the AQ151.