Volvo-Penta AQ 125a/270 with trouble under load

farmdoc

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Helo all, I am new to this forum but have been reviewing it for a awhile. Anyway, not an engine or boating newbie, but not a certified mechanic either.

Bought a 'new to me' boat last month, engine is AQ125a/270 outdrive, I believe a 1984 (84 stamped on block in two sites, only made few a few years), serial number 7679013352.

Had not been weatherized when I obtained. Would turn over but not stay on. Had local boat mechanic work on it and now runs very well at idle. He did not rebuild carb because he said the Sierra rebuild kit I purchased, 18-7000, from another marina was the wrong kit (looks correct to me though). Also changed engine and outdrive oil, new oil filter and water impeller.

Put in water 2 weeks ago, would idle fine, as soon as I tried to throttle up, would bog down and spit and backfire. Was able to cruise just in gear after warmed up.

Pulled out of water, replaced fuel filter last week, put back in water, able to tease it up to full throttle, but tach was broken so don't have numbers. Actually able to innertube my 80lb daughter awhile. No throttle response, tendency to bog down and backfire.

Yesterday, replaced fuel lines from tank to fuel pump, put in water and still doing same thing. I hooked up an auto tach and brought along old GPS, once able to open up wide, was turning 35-3600 rpm at WOT, speed 25.8 gps (23-24 indicated). (Boat is a 1974 18ft Glastron-Carlson CV-18ss) Temp was running at 180. Ran great for a good 10 minutes.

Turned off, threw 120 lb son in water with small inner tube, same problems started. Would start, run great in neutral, put in gear and sputter along, if I tried to throttle up, no good. Changed to daughter (see above), did a little better but still bogging down. Pulled tube back in (and daughter, lol) and now it gave me tons of trouble trying to get back to ramp. Finally able to get it cruising around 10 mph or so, but never wanted to get back to smooth.

That's where I am at right now. Additionally, ran with and without fuel cap on to see if vent was working, did not seem to make a difference. Also, fuel filter never completely fills with gas, but not sure that is a problem? Under load filter looks less than half full, 3/4 at idle. Put 10 gallons hi-test gas in before going out yesterday. Also on second bottle of gumout carb cleaner additive.

Last info, prop is chewed up a bit, it is an old michigan wheel, left hand, 14 x 17 (guesstimate) with some nicks and two blades with nickel sized pieces missing. I am having repaired this week.

So, pending your help and advice, I am planning on rebuilding carb this week, it is the Solex 44PAI assembly with Sierra carb kit 18-7000. I am going to purchase a NAPA marine fuel pump, M-60029, according to another thread will work on my engine, in case it doesn't improve after the carb is rebuilt. My goal is improve throttle response well enough to ski, get closer to 5000 rpm wot(guess per Clymer manual which doesn't list WOT for 125a) and decrease amount of times that engine has to be started to get moving ;)

Thanks for any and all help,

John
 

captmello

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Re: Volvo-Penta AQ 125a/270 with trouble under load

That is the right carb kit. You may need to pull the anti-siphon valve at the tank, or the tank pick up may be clogged. Water in the fuel?

3500rpm is not where you should be, you should be getting close to 5000.
 

Don S

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Re: Volvo-Penta AQ 125a/270 with trouble under load

Sounds a lot like water in the fuel. Do you have a water seperating fuel filter? If not, you should have. If you do, and that is the filter you changed, did you empty the contents of the old filter and check it? I would get a new filter, remove the one you have on there now and see if there is a lot of water and dirt in it. Do NOT reinstall a filter after you empty it. During emptying it, you contaminate the good side of the filter.
IF there is water, you need to clean the tank out. and the carb probably needs rebuilt.
Here are some things you will find very helpful
1. Download the OEM service manual for your engine here. http://www.4shared.com/file/89797330/b32e5bf9/AQ125145_AB_Service_Manual.html

2. Here is the manual for your outdrive http://www.4shared.com/file/51930153/3a7e6375/270_Outdrive_service_manual.html

3. Here you can download the Owners manual and some other things for your engine.
http://www.volvopenta.com/volvopent...lication_search/pages/publication_search.aspx
 

farmdoc

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Re: Volvo-Penta AQ 125a/270 with trouble under load

Will put in a water separating filter. Other than draining the tank, is there more to cleaning it? It is a large steel tank underneath the bow and not easy to get to/remove.

The other fuel issue we are having in my area is ethanol. A lot of the bass boaters are replacing fuel injectors this season. I intend to keep the fuel remaining in the tank very minimal throughout the week when not using.
 

captmello

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Re: Volvo-Penta AQ 125a/270 with trouble under load

You could hook up a temporary external tank to eliminate the whole fuel storage/supply side, and see if it runs right on fresh gas. Sounds like you need a filter either way.
 

amuller

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Jun 12, 2010
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Re: Volvo-Penta AQ 125a/270 with trouble under load

Assuming you have checked out the ignition, IMO you need to:

Pump from the bottom of the tank with a transfer pump--see what comes up.

Open up the carb and check for water and crud blocking things up. If you run it under load with out adequate fuel feed for whatever reason you can cause all sorts of major damage.

See if there are any screens in the pump or carb inlet or anywhere else that you might be overlooking.

Install a pressure gauge on a tee fitting between the pump and the carb and check for pressure under full load. If the pressure doesn't hold up go through the fuel system from one end to the other, starting at the tank. Could have a blockage, a bad anti-siphon valve, an air leak.....

Another logical approach is to use an outboard tank and primer bulb to bypass things right to the pump inlet. But start with the carb.

am
 

farmdoc

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Update, and a related question. Re: Volvo-Penta AQ 125a/270 with trouble under load

Update, and a related question. Re: Volvo-Penta AQ 125a/270 with trouble under load

Carb is rebuilt, not a lot of particles in it but a few, very shiny now:)

Have fuel/water separator from Sierra arriving tomorrow. Also have replacement fuel pump on order from NAPA marine but will only place if all else fails, no need to spend $50 if I don't have to.

Will install all this Saturday and drain tank as well, which leads to my next question:

I am going to drain the fuel tank. I have a 55 gallon drum, planning on extending the pre-filter fuel line and then using compressed air, start the siphon going (air into fuel filler neck, extended fuel line below boat into drum) and let it drain out.

Obviously this won't get out all of the old fuel/water, nor will it get any dirt out of the tank. I was then planning on taking off the fuel sender/vent/filler assembly at the tank (sorry if terms are incorrect) and cleaning all.

Are there any suggestions on cleaning out the remaining fluids/debris in the tank?

Thanks,

John
 

bbeck10

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Jul 14, 2010
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Re: Volvo-Penta AQ 125a/270 with trouble under load

Hi, im also new to this forum. I am having very similar problems with a 3.0 liter 1994 volvo/penta chaparral i purchased. It wiil not get over 3500 rpm or 25 mph...I recently replaced cracked intake..leaking exhaust elbow, plugs, plug wires, distributor cap, rotor,cleaned/rebuilt the carb..and still not fixed. I have pulled the water/fuel seperator off and there doesnt seem to be any trash in it.....my question is the only other thing it could be is fuel right....should i follow the same steps...also, did a compression check on each cylinder and they are all around 150...
 

farmdoc

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Re: Volvo-Penta AQ 125a/270 with trouble under load

bbeck,

I am not sure how new you are to forums like this. This thread is about my trouble. We want you to start a new thread about yours.

Hijacking threads (just what it is called, not picking on you), muddies up the water and makes it difficult to figure out who is responding to what.

Thanks,

John
 

farmdoc

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Re: Update, and a related question. Re: Volvo-Penta AQ 125a/270 with trouble under l

Re: Update, and a related question. Re: Volvo-Penta AQ 125a/270 with trouble under l

Bump - any help on draining and cleaning fuel tank?

Carb is rebuilt, not a lot of particles in it but a few, very shiny now:)

Have fuel/water separator from Sierra arriving tomorrow. Also have replacement fuel pump on order from NAPA marine but will only place if all else fails, no need to spend $50 if I don't have to.

Will install all this Saturday and drain tank as well, which leads to my next question:

I am going to drain the fuel tank. I have a 55 gallon drum, planning on extending the pre-filter fuel line and then using compressed air, start the siphon going (air into fuel filler neck, extended fuel line below boat into drum) and let it drain out.

Obviously this won't get out all of the old fuel/water, nor will it get any dirt out of the tank. I was then planning on taking off the fuel sender/vent/filler assembly at the tank (sorry if terms are incorrect) and cleaning all.

Are there any suggestions on cleaning out the remaining fluids/debris in the tank?

Thanks,

John
 

sqbtr

Senior Chief Petty Officer
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Feb 23, 2010
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Re: Volvo-Penta AQ 125a/270 with trouble under load

Pull your fuel level sender out, zip tie your siphon hose to a long enough probe, get the bow as high as possable and you can siphon the junk out the bottom of the tank
 

farmdoc

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Re: Volvo-Penta AQ 125a/270 with trouble under load

sqbtr,

Great idea, will do that.

I am getting excited about this weekend, new fuel water filter, pump, rebuilt carb... Hope I don't find out its something else!

Thanks for your help guys,

Will update Saturday night.

John
 
Last edited:

farmdoc

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Update

Update

Lots of improvement....

Prop is like new now. Fuel sender removed and cleaned, vent cleaned. Installed fuel/water filter (replaced lines last week), rebuilt carb placed.

Fuel tank emptied, not the greatest job, had to revert to the old suck and start siphon method but most of fuel emptied.

Freash gas with stabil marine added.

Put in water, idleing high at 1400 but at wot getting 4300 rpm/30 mph gps reading.

Runs good at 4300 for a few minutes then gets rough, have to work throttle a little, but can take back to idle, no backfire and throttle right back up. No more delay when throttle-ing up either.

This morning adjusted throttle linkage and idle air and now have idling at 900, as per clymer engine manual.

need to add some antifreeze to engine side coolant system, then will take back out.

Any opinions on why getting a little rough at wot?

I have a new napa marine fuel pump, but don't want to use unless need to ($50). Can't change this weekend anyway because don't have hex sockets with me.

Thanks to all, any other ideas appreciated.

John
 

captmello

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Re: Volvo-Penta AQ 125a/270 with trouble under load

whats the condition of your ignition parts? Plugs, wires, points...

Have you check to see that the timing is advancing correctly?

Did you rebuild the carb? Set the float height, etc.
Have you done a compression test on this engine lately? I do one every spring.
 

farmdoc

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Re: Volvo-Penta AQ 125a/270 with trouble under load

Ignition appears to be good. We reset to 10 degrees BTDC last night, made sure the wires were in correct order, runs very well.

No compression test - only had for 2 months, will get done soon.

Ironically bad news...put prop on same as always but guess what...it fell off. So...back to the drawing $$$$ board to get a new prop and cone for it. No fixes now until next week.
 

captmello

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Re: Volvo-Penta AQ 125a/270 with trouble under load

That sucks, I lost my prop and prop cone last weekend.:eek: Props are 90 dollars on iboats with free delivery on the long hub props.
I bought the sierra prop cone, comes with the bolt.
http://www.iboats.com/18-4210-Propeller-Cone/dm/*******.226022006--**********.720371017--view_id.704011

In the mean time do a compression test. Do you have points and a condenser or electronic ignition?

If you don't know the condition of the tune up parts then they need to be changed as well.

Welcome to old boat ownership. BTW, what boat is this engine in? model,year?
 

farmdoc

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Re: Volvo-Penta AQ 125a/270 with trouble under load

The ignition system is in decent shape. The plug wires were misrouted and timing was not set right but that is corrected and she runs smooth. both idle and speed (still has times under throttle when I have to goose throttle though).

After doing timing and wires, no more back fires either.

Will do compression test next weekend. Probably getting a prop here as well. Solas has short hub 17 spline props for around 100.

May drop to a 14x15 since my wot was maxed around 4300 or so with the 14x17 prop.

Leads to next question.....Had a 14x17 michigan wheel prop. Got 43-4400 WOT with it. Want over 4500 rpm (closer to 5k the better) According to prop guide, decreasing 2 inches pitch adds 3-400 rpm. If I switch to a 4 blade, I will get better pulling and skiiing power, solas has a 15 inch, so in my simple math (decrease pitch 1 inch going from 3 to 4 blade) I will still be getting 150 to 200 more rpm from a 14x15 4 blade.

Does that make sense to anyone? Any opinions?
 
Last edited:

captmello

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Re: Volvo-Penta AQ 125a/270 with trouble under load

Does that make sense to anyone?

No. Ha ha!!

Better not talk too much Prop here in the I/O section, they're watching...

I just bought a 4 blade prop since I lost mine in the lake last week. The four blade can help some boats. Post your questions in the prop forum, see what you find out.

Have you been running long or short hub props?

Again, what kind of boat have you got? Year, Model, size?
 

farmdoc

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Re: Volvo-Penta AQ 125a/270 with trouble under load

I know, I know....just hoping to sneak it in since it also affects the performance of my stern-drive ;)

I am used to my Land Cruiser forum where as long as it's tech related, you just post on the correct model year board...but I digress.

It is a 74 Glastron-Carlson CV-18ss. Solid boat. Still has original vinyl, but needs redone. A previous owner re-engined and I am working through the bugs. Nice thing, they did either use the original engine mounts or they made an engine mount so the 125a is not suspended from the transom.

Will fix the prop issues and get back to it this weekend with a compression test, and maybe check the fuel pump.

John
 

captmello

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Re: Volvo-Penta AQ 125a/270 with trouble under load

Thats a cool boat. We've got tons of Glastrons around here. I used to run an old 16 foot runabout with a volvo 4 cyl., seems to me, we ran a 15p for good towing, and a 17p for cruising.

The 125a is a very common engine and easy to work on, IMO. Even though I've never owned on.:rolleyes:

I'm also a fan of the front motor mount.

Post a picture of the mount, I'd like to see it.
 
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