AQ125A Electrical Problem

[Dr. Velocity]

Here's the specifics:

Boat: 1982 Bayliner 19' Capri
Engine: Volvo AQ125A
Stern Drive: Volvo Penta 270

As I've said before, it's a tired old engine. After draining the oil from the stern drive (which came out with the consistency and color of Elmer's Glue), the drive quit whining and the boat was running great. I used gasket maker to seal up the top of the stern drive (the old gasket was shot and was letting tons of water into the drive).

I've always told my brother to check the oil before he takes it out, as the engine consumes quite a bit of oil when it's run (I'd say a quart every 6 hours of running time). Well, as usual, he doesn't heed my advice.

He had the boat out on the lake and had been running at full throttle for more than a half hour (this is after 2-3 hours of boating done earlier in the day). Suddenly, the boat dropped about 1000 RPM and he backed the throttle down to neutral where the engine promptly died. He tried to fire it back up and cranked it for a long time (he says spent almost five minutes cranking it, hope he gave the starter breaks during that 5 minutes), but had no luck.

He called me and I asked him what the temp gauge said. After the boat had been sitting for 10 minutes, the temp gauge was still reading around 215?. I know the impeller is fine and that the cooling system works. I had him check the oil and he said it wasn't even registering on the dip stick.

After getting towed in by a sheriff (boy do they have some impressive boats! Ben was promptly written a ticket for some violation as well...), I took a look at the boat. We put in around 2.5 quarts of oil to bring the level back up between the lines on the dipstick.

However, when I turned the ignition to on, nothing registered. I jiggled around the ground cable where it connects to the engine and the gauges lit up. I tried to crank the engine and it turned for a few seconds, so it isn't seized and the starter is still working.

However, now I get absolutely nothing at the gauges. Whether the key is in the on position or the start position nothing happens. The only things that do work are the bilge pump and the blower.

I got out the multi-meter and started testing voltages at various points with the common probe attached to the engine:

Battery: 12.6 volts
Alternator: 12.6 volts
Starter: 12.6 volts
12 V feed to fuse block: 12.6 volts
All fuses in the fuse block have continuity

There is continuity through the main fuse near the flywheel of the engine. The terminals on (what I am guessing is) the ignition relay are fairly corroded. I'm thinking we might have a bad ignition relay, but with no wiring diagram, it's a bit hard to tell where all the wires go and what their purpose is.

Any tips or insights as how to fix this problem?

 

[Dunaruna]

Re: AQ125A Electrical Problem

ice.

I jiggled around the ground cable where it connects to the engine and the gauges lit up. I tried to crank the engine and it turned for a few seconds, so it isn't seized and the starter is still working...........................................



the ignition relay are fairly corroded.

Voltage tests mean nothing unless you do it under load conditions, in other words, fix what you KNOW is bad before you proceed. Get a manual, replace corroded relays. Remove all battery conections and starter and block ground and wire brush them and reconnect tight.

Personally I think your oil problem is of more concern, the engine needs serious TLC.

 

[Dr. Velocity]

Re: AQ125A Electrical Problem

Voltage tests mean nothing unless you do it under load conditions, in other words, fix what you KNOW is bad before you proceed. Get a manual, replace corroded relays. Remove all battery conections and starter and block ground and wire brush them and reconnect tight.

Personally I think your oil problem is of more concern, the engine needs serious TLC.

If you don't know what is bad, then you can't exactly fix it. Voltage tests don't have to be done under load (depending on what you're trying to diagnose). Testing voltage is testing the electromotive force between two points, regardless of current (load). Now if you want to test current, that has to be done under load (unless you want to read zero) and cannot be done between two points.

I rewired the fuse block area and solved the problem. All of the electrics work now. You are, however, right about the oil problem. I've known the oil problem would show it's ugly head sooner or later. Truth is, my brother bought a lemon and there's really no way to recoup what he put into the boat. I knew from the start that the engine would need a rebuild or have to be replaced. No one wants to rebuild/replace an engine in the middle of the season, so I told my brother to maintain it properly and use it 'til it dies.

Well, that moment is now. When the starter turns the engine, the timing belt does not turn. Time to pull the engine and replace/rebuild.

 

[Dunaruna]

Re: AQ125A Electrical Problem

If you don't know what is bad, then you can't exactly fix it. Voltage tests don't have to be done under load (depending on what you're trying to diagnose). Testing voltage is testing the electromotive force between two points, regardless of current (load). Now if you want to test current, that has to be done under load (unless you want to read zero) and cannot be done between two points.

I rewired the fuse block area and solved the problem. All of the electrics work now.

What do you mean by your first sentence?

You wriggled wires and the gauges came to life - HELLO? That is a bad connection - a KNOWN bad connection.

You (not me!) identified CORRODED connections on a relay - That is a KNOWN bad connection.

You are correct about current testing. Humor me, what happens when you excite the starter? Oh yeah, that's right - IT DRAWS CURRENT