volvo penta AQ170 bogs down with cowling shut

[bwolfe]

First time poster, I have a '77 glastron w/ the 170 volvo penta inline 6 and 3ea. solex carbs on top. Carbs are rebuilt, engine runs pretty good (working on that right now), but when the cowling is closed down the engine will choke itself out. I have also checked/cleaned out all the vent tubes from the sides of the boat. I have drilled venting hole in the cowling and even added a 15"x15" vented louver on top and it still wants to choke itself, yet not as bad.

The original owner said that this boat never ran good and had it in the shop to fix with no accurate results. So it sat up for 10 years until we got it.

I've gone buy the owner's manual and set everything to specs, but I am still a little unsure of the accelerator pumps adjustment for each carb. I just have the adjusting nuts the same amount screwed in on each lever. Is there a certain amount?

Here's whats been done:

The old fuel was drained/siphoned out, new fuel filter, timing on spot (still need to check dwell), plugs, wires, dist cap, rotor, coil are all new. I believe the altenator went out last weekend, so we are having it tested and/or rebuilt this week. I'll do some more testing this weekend on the water.

Sorry for the blabbering on, just needing some advice about what I got. Thank you for all and any replies.

Kirk Jorden

 

[bwolfe]

Re: volvo penta AQ170 bogs down with cowling shut

Last night did a dry dock tune, here are my settings:

TDC on harmonic balancer confirmed- good.

All plugs gapped 0.030"

Timing set a 12 degrees BTDC @ 1000 rpm (.

Dwell = 36 degrees

All carbs sync. with 1 1/4 turns out mixture screw and throttle shaft alignments are correct.

Using dated wires and as well as points and condenser, but still good spark.

We have plenty of fuel and the pump works good.

I idles really well, but when shut off after running 15 - 20 min. it will not start until it has really cooled down. Could this be the points, condenser and old wire maybe? One note, this has happened before and would not start, we tried @ 30 times within @ 45 minutes to get it started and no go. We unhooked the battery going to charge it, but then had to hook it back up to do something, and just for grins we tried to start it again...and what do you know, started right up.
What in the world? This engine has a mind of its own. Any advice from the experts would be greatly appreciated, thank you.

Kirk Jorden

 

[Don S]

Re: volvo penta AQ170 bogs down with cowling shut

Can you post some pictures of the engine and the cowling?

 

[BAYLINER185]

Re: volvo penta AQ170 bogs down with cowling shut

You definetly have dirty, loose or bad battery connectons.

The way you describe dissconnecting and reconnecting and then the motor starts is a 100% dead on suggestion the terminals and connection are in question.

 

[CharlieB]

Re: volvo penta AQ170 bogs down with cowling shut

Could you have an exhaust leak in the engine bay, choking the engine when the cover is on closed?

Or insulation inside the cover restricting air to the carbs?

 

[bwolfe]

Re: volvo penta AQ170 bogs down with cowling shut

Could you have an exhaust leak in the engine bay, choking the engine when the cover is on closed?

Or insulation inside the cover restricting air to the carbs?

Yes sir, we do have an exhaust leak. I would have never thought of that, thanks for the heads up.

Kirk Jorden

 

[bwolfe]

Re: volvo penta AQ170 bogs down with cowling shut

Took it out last weekend, started great, ran fine as long as the cowling was cracked open (exhaust leak may be the cause). Had the no start issue, started checking electrical and found a loose wire at the fuse block. Tightened it up and had no more start issues hot or cold.

I'll fix the exhaust leak and confirm back on the bogging down with cowling shut situation in a week or so.

I'll keep you updated, and thanks for all the help and replies.

Kirk Jorden

 

[Don S]

Re: volvo penta AQ170 bogs down with cowling shut

You may have an exhaust leak, but you still don't have enough air flow around that engine for some reason.

 

[obezag]

Re: volvo penta AQ170 bogs down with cowling shut

Didn't see spark arrestor mentioned or even if your engine has one but if so is it clean?

 

[boaterinsd]

Re: volvo penta AQ170 bogs down with cowling shut

so the tune up specs above are good for this motor? TIA

 

[Don S]

Re: volvo penta AQ170 bogs down with cowling shut

http://forums.iboats.com/showthread.php?t=468286