AQ125A Hesitation

Dr. Velocity

Cadet
Joined
Jul 24, 2007
Messages
24
First of all, here's what's been done on the boat:

New alternator
New battery
New plug wires
New plugs
New rotor
New distributor cap
Timing checked: 10? BTDC @ 900 RPM, 36? BTDC @ 4000 RPM
New impeller
New Fuel pump
New inline fuel filter
Carburetor Rebuild kit
Lots of seafoam run through engine

Running the boat in the driveway in neutral, applying full throttle causes the engine to stumble and die. If I give it a bit of throttle (to take to around 2000 rpm) and then open the throttle wide open, it hesitates and then gains RPM. Even running at 3000 RPM, when WOT is applied, it hesitates for a second and then gains RPM.

I've checked the accelerator pump and it's squirting plenty of fuel into the carb throat. I haven't checked the engine compression yet, could this be the cause?

It's probably worth noting that when the engine was run on 87 octane fuel, the hesitation was almost non-existent. However, the engine pinged quite a bit on 87 octane fuel. Currently, it has 91/93 octane fuel in it with some octane booster as well. I'm wondering if this could be a bit too much octane?

Also, when I put the flame arrester on the carb (actually, just the plate with the crankcase vent tube attached), the engine runs considerably rougher. Is this a symptom that something is wrong deep inside the engine?
 

Maclin

Admiral
Joined
May 27, 2007
Messages
6,761
Re: AQ125A Hesitation

I do not know the specs on the AQ125 engines......but that 10 degrees btdc timing may be too much advance. 36 total is pretty high as well in my experience with other engines. Pinging usually indicates too much timing or too lean of a mixture.

I would set the timing back 4 or 5 degrees and go back to 87 octane to see if it behaves differently.
 

Starflight

Seaman
Joined
Sep 1, 2006
Messages
55
Re: AQ125A Hesitation

My book says 10deg btdc@ 750? (750 seems a bit low) and 36btdc@4200.
Did ya set the dwell @62deg before setting the timing? Dwell will effect timing a bunch. Set dwell 1st, then timing.
 

bruceb58

Supreme Mariner
Joined
Mar 5, 2006
Messages
30,454
Re: AQ125A Hesitation

I would definitely want to check the compression.

How old is your fuel?
 

Dr. Velocity

Cadet
Joined
Jul 24, 2007
Messages
24
Re: AQ125A Hesitation

As far as the timing goes, don't forget premium fuel is recommended for this engine in the owner's manual.

Actually, I took another look at the accelerator pump. It was squirting fuel in, but not as soon as I would have liked. Looking at the shaft the spring is situated on, I noticed there was a small flange that a washer should be placed at. When we got the boat, there was nothing there. So, I installed a washer, allowing the spring to be far more compressed. Sure enough, the hesitation is completely gone.

Now that I look at the parts fiche, the washer should have been there all along:

44PAI.gif


Now I've gotta find out why there's water in my oil. :confused::mad:
 
Top