Volvo AQ125B Problems

[Bankowski]

I have a 85 Bayliner Capri with a volvo 125B. I took it out for the first time and noticed big problems right away. the boat doesn't go over I would say 10mph @ no more than 3000rpm's. It has had a complete tune up before I took it out. out of the water it runs super smooth in the water it will back fire from time to time under load and the speed will change some times it will go a little fast then next time I use it it will be slower. each time it back fires the boat will start to slow down and then it will back fire then I throttle back up and it will be fine for a little while longer. Also reverse seems not to be functioning properly. when put into reverse it will wonder to the left no matter what. Any sugestions? I am lost

 

[Bondo]

Re: Volvo AQ125B Problems

The loss of Power,+ Backfiring is a Fuel Starvation Issue,........
Start with changing the Fuel Filters.......

 

[Bankowski]

Re: Volvo AQ125B Problems

thanks for the reply. It didn't have a filter when I rebuilt the carb I put a in line filter in. could it be anything else?

 

[Bankowski]

Re: Volvo AQ125B Problems

I checked the fuel flow last night and seems to be entering the carb pretty good. any other sugestions?

 

[Don S]

Re: Volvo AQ125B Problems

Try checking it like this.

http://forums.iboats.com/showthread.php?t=167561

 

[Robj]

Re: Volvo AQ125B Problems

Do a compression test. If the numbers are OK, then check your timing and your timing belt to make sure it has not jumped.

Good luck

Rob.

 

[Bankowski]

Re: Volvo AQ125B Problems

I had a volvo specialist come out and look at the engine when I got it and he did do a compression check and that was ok. I will check the timing next to see where that is at. does anyone what the timing is for this engine?

 

[Bankowski]

Re: Volvo AQ125B Problems

Thanks Don S. I will try that next time I get to the lake its 2 hours away from me. Thanks everyone for the replys. It seems that these Volvo engines are a diff. monster. (very tempermental) I think my next boat will have a GM or ford engine?

 

[slia67]

Re: Volvo AQ125B Problems

You could have a coil breaking down. But backfiring usually happens when coil gets hot. Was coil changed? If so, was the correct coil put back on? Some coils need 12V going to "+", some need stepped down voltage.

 

[Bankowski]

Re: Volvo AQ125B Problems

Yes the coil was replaced. it was doing it before I replaced the coil and I pulled the boat out of the water and replaced the coil. I got the coil from a volvo specialist in town and he said it was a direct replacment. I really think it is some kind of electrical problem just not sure where to look. the volvo specialest seemed to think it was also thats why he suggested the new coil.

 

[Don S]

Re: Volvo AQ125B Problems

It seems that these Volvo engines are a diff. monster. (very tempermental)

That is kind of an understatement, even when running perfect they are tempermantal.

They are also very touchy about dwell and timing being right on, but I suspect you have a fuel problem causing your low rpm and power.

Here are the tuneup specs.

Type designation ............................................................AQ125B
Type of operation ...................................................4 stroke overhead cam
Max (Hp) ........................................................................120 hp
Full throttle operation range ..........................................4700–5000 rpm
Compression pressure ......................................................128–156 psi
Idling speed ..................................................................... 900 rpm
Spark plugs..................................................................... Bosch W6DC
Spark plug gap.............................................................. 0.7 mm (0.028 in.)
Basic setting.................................................................. 6? BTD (0–750 rpm)
Advance timing ............................................................ 32?–35? BTDC (4200 rpm)
Gap .............................................................................. 0.40 mm (0.016 in.)
Dwell .............................................................................. 62??3?

 

[Bankowski]

Re: Volvo AQ125B Problems

Thanks Don S for the spec's.

 

[Don S]

Re: Volvo AQ125B Problems

Hold on, some them are wrong. I posted for a 145, not a 125.

Fixed it, all is correct now.

 

[Bankowski]

Re: Volvo AQ125B Problems

thanks. I will check that stuff out this weekend

 

[Bankowski]

Re: Volvo AQ125B Problems

I ran into someone that had the same problem as I do and they told me to check the centrifugal advance with in the distributor. does that sound possible to you guys? If so what do I look for?
Thanks.
Jason

 

[Don S]

Re: Volvo AQ125B Problems

That is why you check the advance timing (See specs above) when doing a tuneup. If it doesn't advance, you have a problem.

 

[Bankowski]

Re: Volvo AQ125B Problems

just wondering how would I fix that problem if that is it? never had to deal with that. sorry for having so many questions?
Thanks for all your guys help

 

[Don S]

Re: Volvo AQ125B Problems

just wondering how would I fix that problem if that is it?

First you would inspect them and determine WHY they aren't working, then you can determine HOW to fix it.