Problems with 84 AQ125A

[varg24]

After filing through all of the other posted threads, and fixing a lot of little things with the previous topics, I am still stuck with problems on this motor. To start, it is a 1984 Bayliner, with an AQ125A motor and 270 outdrive. The motor came to me with the boat, in pieces. The motor had a lot of machining done to it, and basically just needed assembling. So the things that have been done are, rebuilt block, rebuilt carb, new starter, new plugs, new wires, new alt, both cooling systems rebuilt, most hoses replaced, belts replaced, new exhaust manifold, bellows replaced, and probably some other stuff I am forgetting.

This is my first boat, and has been completely rebuilt, as I have been following a book for this Volvo from page 1. I am extremely new at boats, but I am somewhat familiar now that I have read from front to back, and back to front the manual that I bought to go with it.

The problem I am having is that the book says to time this at 10deg. I replaced the points/condensor with an electronic conversion and cannot get the timing to be any less than 20deg and that is bassically stalling the motor. It runs pretty well at 35 deg, but I am thinking that that is way to early. When I do get it to 'sound good', it will run for about 30seconds to a minute, and then get choppy and die. I have a new fuel pump to replace, but has not been put in yet. I am not sure if that is the problem though. It seems to be getting fuel for a while, and then the thing just dies. I have also installed an inline fuel filter, so I can see the fuel is moving. I also drained the tank, and it has all fresh fuel. I put it on the water after tuning the motor to sound good, and as soon as a load was put on the motor it died, and took a while to get started again.

I apologize for the long post, but I am hoping someone has seen an issue like this before, and can tell me it is something simple. I think I have gone through all of the hard stuff so I am not sure what is left to check. Any and all help would be greatly appreciated, and also thanks to anyone who has posted answers here before, alot of this motor was resurected based on some replies on this board.

Please post your thoughts, and I will try any and everything to get this thing to work.

 

[Mischief Managed]

Re: Problems with 84 AQ125A

Maybe the advance mechanism in the distributor is flakey or the timing belt is off by a tooth. When you do get it to run, does the timing advance smoothly with RPM? IIRC, it's a simple mechnical advance distributor. A compression test could reveal a timing belt issue since one could reasonably expect the compression to be reduced if the cam timing is off.

 

[Robj]

Re: Problems with 84 AQ125A

The problem I am having is that the book says to time this at 10deg. I replaced the points/condensor with an electronic conversion and cannot get the timing to be any less than 20deg and that is bassically stalling the motor.

Sounds like your distributor is out by a tooth. You have to remove your distributor, and advance it a tooth and then reinstall. Check the timing again, it should be within range. If it is worse, then you need to remove it again, and move it two teeth, but in the other direction. Don't run it the way it is or you will damage your engine. At idle is OK, but not on the water.

Have a great day,

Rob.

 

[varg24]

Re: Problems with 84 AQ125A

Thanks for the quick replies. I have taken the distributor apart to check the springs, but everything looked fine. In fact, when I have it started, I can get it to go up to 3K rpms (maybe higher, but never tried), but after a few minutes, it dies.

As for the turning the distributor a tooth, I have tried in both directions. In one direction it would backfire and sputter miserably, and in the other direction, it would not start at all. I could definately try it again, but that is the results I had last time I tried.

Any other ideas? Does the electronic ignition change the timing?

 

[Don S]

Re: Problems with 84 AQ125A

Does the electronic ignition change the timing?

Yes, many that have done that conversion have to reset the distributor.

On thing you haven't mentioned, is when it dies if you still have spark or not. It could be a carb or fuel problem that is causing it to die.

 

[varg24]

Re: Problems with 84 AQ125A

Is there a way to check to see if I have spark or not? When it dies, there seems to be a big gasp from the carb. Sometimes, if I have the flame arrestor off, I can see it spit fuel up into the air as it dies. I try not to do this often so I keep the arrestor on it most of the time.

How do I check to make sure it has spark?

Thanks

 

[varg24]

Re: Problems with 84 AQ125A

I just noticed something else that was interesting. In my manual, to rebuild the carb, the manual states to put the spring for the accelerator pump diaphram between the diaphram and the cover - on top of that shaft. When I see some others have posted pics of the assmbly where the spring is between the diaphram and the carb.

Which way is correct? Could this be a cure to this problem?

 

[varg24]

Re: Problems with 84 AQ125A

Don S,

I am not sure how to tell if I have spark, but tonight I did some more work on it, and I noticed that with a timing light , I was losing my strobe at around 15? and then it would die. Is this a sign of a bad coil? I know I checked it once, but maybe it is not holding its charge.

If its not the coil, where else would I look, the distributor cap? The plugs, and plug wires, rotor, and electronic ignition are all new. I also checked all of my grounds and connectors for corrosion and tightness and all seemed fine.

Any help is appreciated - thanks,

-M

 

[varg24]

Re: Problems with 84 AQ125A

OK, not sure if I keep adding to this post, or start a new one, but it is still the same problem.

I replaced the coil this weekend, and switched the spring back around on the accelerator pump. Took it out on the water and it idled fine and even moved when I shifted to gear. The problem was as soon as I tried to go aove 1500 rpm, it spitted, sputtered and just bogged very badly. I pushed the throttle all the way forward and the motor never went above 2000 rpm, with the throttle completely forward. I brought it back to neutral and it died.

The only way I could get it to start again was by turning the distributor way before 0?. It stalled maybe 6 more times before I could get it back in, and each time it stalled, I had to turn the dist. a little more. By the time I got it in, I am willing to bet I was at 50? BTDC.

Any clue to why this is happening?

 

[Maclin]

Re: Problems with 84 AQ125A

Sounds like you changed a lot of things all at once and it is hard to single out any one particular system (spark, timing, fuel, etc...) for their contribution to the problem.

Can you switch back to the points system? I would try that first and see how it behaves with new points set at the proper dwell and distributor timing.

 

[Robj]

Re: Problems with 84 AQ125A

OK, not sure if I keep adding to this post, or start a new one, but it is still the same problem.

I replaced the coil this weekend, and switched the spring back around on the accelerator pump. Took it out on the water and it idled fine and even moved when I shifted to gear. The problem was as soon as I tried to go aove 1500 rpm, it spitted, sputtered and just bogged very badly. I pushed the throttle all the way forward and the motor never went above 2000 rpm, with the throttle completely forward. I brought it back to neutral and it died.

The only way I could get it to start again was by turning the distributor way before 0?. It stalled maybe 6 more times before I could get it back in, and each time it stalled, I had to turn the dist. a little more. By the time I got it in, I am willing to bet I was at 50? BTDC.

Any clue to why this is happening?

Sounds like a timing problem to me. Look at the advance system in the distributor. Make sure the springs are intact and not broken. Also make sure the assembly moves freely. My guess is the springs may be broken.

Have a great day,

Rob.