Volvo AQ120/270 After lots of work Boat Starts run 5 seconds and dies

[MikeCaldwell]

Boat Techs out there, question.. As short as possible, harness shorted out against pipe and killed boat, took points and coil with it. rewired everything , all good, new power distribution blocks with meters for 12+ and for Neg. New coil , points, condenser, fuel pump, rebuilt carb, everything looking good. Compression check around 170 on each cylinder, Set Piston 1 to TDC on compression stroke and marks lined up and made sure Distributor had points fully open and the rotor o...n Cylinder. So off we went. Started the boat.. Finally started up but each time about 5 seconds and then shutdowns like its being starved of something, kept trying things until the starter sheared off a pin in the starter gear so the little gear just spins. Ordering a starter now to get here this week.
Big question before I get this new starter in. Any help or idea why it keeps starting and dies would be appreciated? I can't help to think its a blocked port in the Carb or Carb related. New plug wires on the way. Ideas? Volvo Penta AQ120B / 270 Stern 4 cyl, points (still trying to the electronic working).. Thanks ahead!

 

[MikeCaldwell]

I am still working on the issue, its a bit messy with the wires but it will be much better once its all cleaned up.

 

[jerryjerry05]

The ballast resistor: is it hooked up right?
​Measure the voltage to the coil at the + side.
Should be at 9v or close.
Battery voltage at 12.7 or whatever is too much.
​

Try starting using a second tank(outboard tank) and see if it continues to run then.
​Try it at 2 spots.
#1 is before the pump and see if it draws through the pump.This tells you if the anti-siphon valve is sticking .
​#2 is before the carb using the squeezie to supply fuel.This tells if the pump is bad.

 

[wrench 3]

I'm curious about your description of setting the base timing. You said #1 was at TDC and the points were fully open. The crank should be 6'BTDC and the points should be just starting to open.
Hook an ordinary 12V test light between a ground and the coil negative terminal. With the points closed and the ignition on, the light should be off. With the crank on 6' and the rotor just before #1, rotate the distributor opposite to the rotor direction until the light comes on. Lock the distributor at the position where the light just comes on.
BTW the ballast resister won't give you a voltage drop unless the points are closed. Or at least opening and closing (engine running).

 

[dennis461]

From my point of view, you did too much work for troubleshooting to begin.
I would start by disconnecting all wiring, install a simple switch to the starter and another switch for ignition.
Follow the Volvo manual.
Make the wiring as simple as possible.
Try to rule out any wiring problems first.

Two (or more) things come to mind.
Some ignition/starter relays bypass the coil resistor while cranking, putting more voltage/current to the coil.
1. If hooked up wrong, when you let go of the starter key, it will disconnect the ignition.
2. Timing should be close enough as-is, meaning if it 'starts', it should idle OK.
3. Did you remove/replace spark plug wires correctly?

Perhaps you should provide your definition of 'starts',

 

[Glastron_V210]

Do you have an electrical fuel pump? If so, many times this problem is with the oil pressure switch circuit. What happens is that the start contact on the ignition switch allows the pump to run and give the engine fuel. When you let the switch back to the run position, a positive runs through an oil pressure switch to maintain fuel pump operation if there is oil pressure.

If there is a mechanical fuel pump, then absolutely check to see if the +12 on the coil is maintained. What can happen to the ignition system is similar to the above. When the switch is in start, the resistor should be bypassed. The idea is that when the starter is engaged the voltage will be lower due to the current draw, therefore bypass the resistor to get the maximum spark energy possible. Then, when the engine starts and you release the ig switch to the run position, then the resistor is back in the circuit to limit the current draw to the coil. If it is not wired correctly, the resistor may not be getting power when the ig. switch is in the run position.


Try to find a schematic for your engine and make sure it is connected correctly.

 

[MikeCaldwell]

I set the marks on all the wheels to match the belt marks and TDC. I got it started, now I can't seem to get the distributer centered. To get to 10 BTDC the bolt on the distributor is maxed out left or right can't seem to get it centered so it idles at 900 @ 10 BTDC

 

[jerryjerry05]

If the dist can't turn then it's 1 tooth off.

 

[wrench 3]

Do you have the idle down to 900rpm or lower when your trying to set the timing. If not, the distributor could be advancing the timing and throwing the reading off.

 

[Scott06]

I would second Dennis comment, with ignition key to run check voltage on + side of coil. Would bet your dropping power to the ignition after the stater kicks off.

 

[MikeCaldwell]

NOW It starts instantly dies in 3 seconds, I apply gas and start keep at about 3K it runs RPM wavers and dies now. I'm losing my mind and patience. I am so close....
--
Latest History: I got all the wiring done and its exactly like the original setup. I rebuilt the carb, clean every port, replaced everything I could inside it. The coil never had a ballast resistor and the coil has a built in resistor , ign to coil + and - coil to distributor as it was. Replaced points and condenser. I did my best to align all 3 pulleys on point and I set distributor point to #1 but now the distributor seems to be advanced to much and not centered again. Set point gap to .016, new plugs wires and set plug gaps to .028. Manual Gas Pump

 

[wrench 3]

To find out if it's a fuel problem you can get a spray can of carb cleaner or intake system cleaner. When it starts to die spray the cleaner into the carb intake. If it picks up and tries to run on the spray you will know that it's not getting fuel. If it has no effect then the problem is most likely spark. Since it starts up, the problem is not likely to be mechanical.

 

[MikeCaldwell]

Not a starting problem until I rev it drops and I can't restart... Sorry (I'll do another one) this is not a great video but I grabbed my phone and started recording. I was a bit occupied looking at everything. Last night I put the Fuel line in 1.25 Gal New Gas Can with New Gas with a rag around hose pressed in can not that it has any pressure so I was good I am guessing. I reinstalled the Timing Belts with all marks on point AGAIN. I lined up the Rotor in the Distributor and got everything back together for the third time. It started right UP! I could adjust idle and timing was 10-12 degrees btdc and 1000 RPM it ran for 10 minutes at least until I reved it. What I did notice in the video was the Main Jet looks like it releasing gas at the base (not good I assume) I had the same problem with accelerator Jet washer and tighten screw while cleaning and it works good but the Main Jet output doesn't look right. But the BIG question is right around 2:02-2:04 into the video I rev it up to about 1/2 throttle, it revs up and I swear I hear a "CLUNK" (if you listen close with good speakers you can hear it around 2:02) and then it just backs down and shuts off. THEN I can't start it anymore so I stopped there last night. The plug testing light was showing a spark so what could possibly just shut it down like that and NOT start anymore until I try again around 6pm the next day. it might start and run 10 minutes again and I rev it and OFF it goes again.Tonight I am going through the Carb again and fuel pump to install and fuel filter and double check the fuel pump and reexamine the carb in and out. I think I have the fanciest AQ120 out there with the new voltage meters and colors like Google ;-)

 

[MikeCaldwell]

[FONT=&quot]Also, All the meters are to show me the voltage is fine, The plugs are cleaner less rich and I have 3 different spark testers inline, outside that all show spark on plus. I installed a new 50Ohm 100W wire wound resistor inline to alternator sensor post not B+. I spark tested the primary coil wire to distributor and it jumps about 1/2 inch. The dashboard is better than ever and meters are all good and I have a main voltage meter shows me the voltage going to dashboard and it's all good. Compression was good last check 2 weeks ago. I could retest and review plugs again tonight. My bet is I can go home tonight kick it over and it will run. While running I can adjust the idle (I set Air/fuel to 4 1/2 as it requires after I verified it on 3 manuals and not 2 1/2 like most) I installed a generic Coil with built it resistor. I add a heavy duty 1.5 OHM Resistor and used it on COIL + didn't make a difference and it didn't use a resistor before. I swapped out original and new coil new difference. I think it's time to apply an AXE, Gas and a lighter on this SOB. ;-)

Damn. Thanks guys for posting back.[/FONT]

 

[wrench 3]

The noise doesn't sound unusual for an engine making a rough stall. If it still has spark when it won't restart, we're back to fuel. If it stalls and won't restart until it cools down, it's probably over fueling when it switches to the main jets.

 

[dennis461]

Beg, borrow or steal another carb.
Other option might be to have someone else take the carb apart and rebuild it (In case you are making a subtle mistake each time you touch it)
Sound like it is flooding, then backfire, then too wet inside to restart.

Oh, one more thing.
Do NOT curse at a boat motor, you can do that to cars all day long, but the boats take offense.

 

[Grub54891]

I have to say, it does look like way to much fuel also. I agree to have someone else look at it, or find a doner carb to try.

 

[MikeCaldwell]

Well the nightmare continues and replaced the timing belt again, made sure all the marks lined up. I have another Solex 44 PHN 3 used off a running boat coming and of course the worse thing happened I stripped the Fuel Line port where the Banjo bolt goes and I was careful as possible. I heli-coil it or have to do something more drastic and come up with something else I can replace the line from carb to fuel pump. It has been cold so I backed off doing anything tonight.

 

[dennis461]

I was always careful with my carb, but eventually the threads gave out on my fuel line connection.
I made a fixture to hold the carb in a drill press and drilled out for the helicoil.
There is not much meat on these carbs, so you need to be really careful with the helicoil process.

Now when I put my carb back on the boat in the springtime, I use aluminum crush washers instead of the brass, gasket cement.
Hand tighten and see if it leaks, then tighten just enough to stop the leak.