Older Volvo Weird WOT Issue

[rucaradio]

Just got back from a 3 day weekend of boating. My Volvo AQ131D is acting a bit strangely.

When she's given gas to get up on plane she'll accelerate to 3000 RPM without a problem, but won't accelerate further for about 3 minutes. After 3 to 5 minutes of chugging along at 3k, she'll slowly accelerate to WOT (around 4700 RPM).

She'll stay at WOT until I back her off, but if I let the RPM's drop below 3000 the process starts all over.

I've got some suspicions, but before I tear into her I'd like some opinions.

Fuel filter and lines are brand new. Carb was cleaned last season. New plugs, cap, rotor, and points last year.

Any ideas?

 

[captmello]

Re: Older Volvo Weird WOT Issue

I wonder if your mechanical advance is sticking in the distributer. Just my WAG.

 

[rucaradio]

Re: Older Volvo Weird WOT Issue

...and that'd be why I decided to pose the question on iBoats before I tore into it.. I never even thought about the mechanical advance!

So, how do you get it not to stick? WD-40? Electrical contact cleaner? Any ideas?

 

[captmello]

Re: Older Volvo Weird WOT Issue

Really, is that what's wrong? Did you check the advance timing?

I've never have that problem but I think some WD 40 would do it, PB Blaster...

You may want to take it out and really give it a good once over. Is it corroded?

 

[rucaradio]

Re: Older Volvo Weird WOT Issue

I had the motor completely out of the boat for about two months while I did the stringers and the floor. While it was on the stand in the garage I changed all the water system seals, rewired it, and repainted it.

In the past month, I've probably had her out a dozen times and haven't had any problems. This weird WOT issue just developed 2 outings ago.. The first occurrence I didn't have a chance to figure out the problem. The second time, I was able to go to a secluded area of the lake, take off the motor box, and try to troubleshoot while I was on the water (since without a load it revs fine).

I tried to make some minor carburetor adjustments (accelerator pump, air mixture), and that just made it stall at idle. I then retarded the ignition timing by a few degrees by turning the distributor, which just made the WOT issue worse.. I reset the timing and the engine ran much better, but still bogged for a few minutes around 3000 rpms....which leads me to believe it just might be the mechanical advance.

I suppose corrosion is to be expected in a marine environment, albeit a freshwater situation. I didn't get a chance to dig into it today, but tomorrow I'll pop the cap and rotor off, check the points, and see what I can see.

 

[rucaradio]

Re: Older Volvo Weird WOT Issue

Just an update...

Finally got a chance to tear into her. I popped off the cap and (per the Clymers manual) grabbed onto the rotor and turned it. It was supposed to snap right back into place, which it did - kinda.

I pulled the distributor out, removed the condenser and points, tried to remove the bottom plate (which I didn't - thanks to the manual for its advice 'if the mechanical advance needs service, take unit to the dealer'), and ended up soaking the top of the dist. in blaster. I'd let it sit for a little bit, blow it out with an airchuck, spray some more, blow it out, spray in some WD-40, blow it out, etc.. After about an hour she loosened up nicely.

Dropped the distributor back into the boat today, re-timed it, checked the advance with the timing light, everything seems to be working great and she's running beautifully (until I went and bought a light today I had never really timed her, just kinda adjusted her to where I thought she was good).

I'm taking her out tomorrow and hopefully I'll be back to report the odd WOT issue has been solved.

Thanks again iBoats!

 

[rucaradio]

Re: Older Volvo Weird WOT Issue

Problem solved... and then some! It's amazing what a timing light and a can of WD-40 will do!

 

[captmello]

Re: Older Volvo Weird WOT Issue

Problem solved... and then some! It's amazing what a timing light and a can of WD-40 will do!

Glad to hear you got it working.

Now How did you adjust the points? Dwell meter or matchbook? Be honest. A match book and feeler guage are the same, IMO.

This is for all the boaters running around with untuned motors complaning about lack of performance.

 

[rucaradio]

Re: Older Volvo Weird WOT Issue

Didn't use the dwell meter, just a feeler gauge or "matchbook". lol.. .016

I plan on getting a petronex and converting over to solid state for the next season, just need these points to last another 2 months.