Volvo Penta AQ131a CANNOT GET TO RUN

[JStew810]

Hello everyone. I am brand new here, so I apologize if this is in the wrong place.

TO BEGIN: This is my father-in-law's boat and I'm unsure of the exact year. I know it is a Volvo Penta AQ131a. I will also disclose that I am not well versed in the marine industry, however, I turn wrenches on cars/truck/bikes quite often.

Last summer, I was recruited to get this boat running. The owner had put a new "flamethrower" ignition coil, a petronix 2842, new spark plugs, new wires, everything and it still would not run. NOTE: he ran a jumper wire to the coil to provide the petronix with the necessary 12 volts (eliminating the resistance wire). When I began working on it, I discovered that the countershaft timing could be causing the issue.

Low and behold, the countershaft timing was incorrect. We bought a new timing belt and installed it according to the manufactures guide. After reassembling, we got the boat to run, but it was at the end of boating season.

The other day, we went to get the boat running again and it will NOT start. The spark seems to be weak. We also can barely get the engine to even fire on any of the cylinders (like there is no spark). We just put a brand-new battery in it, check the distributor ground, and seem to have checked everything and CANNOT GET IT. The ONLY way it will even act like it wants to start is when the distributor is maxed out, clock-wise rotation. Any insight is appreciated, thank you.

[Nauti_Mike]

Rick, aka Mr Volvo will help you but first he’ll tell you about his dislike of that ignition system.

[JStew810]

If I had the means too, I would switch it back to the points. However, These are starting to get more and more difficult to find parts for!

[Nauti_Mike]

I Rick hasn’t yet replied. I would test the spark with a gap tester that you insert on the plug wire and adjust the thumb screw to the gap rating for your spark plugs and look at the color of the spark to determine if it’s weak. I find it best to do this test at dusk so you can see better. When you replaced the belt did you verify that the crank, cam and auxiliary shaft were all aligned?

[2850Bounty]

I just saw this thread.
I’ll post to it Saturday morning.

[2850Bounty]

..................

.............I know it is a Volvo Penta AQ131a.

Last summer, I was recruited to get this boat running. The owner had put a new "flamethrower" ignition coil, a petronix 2842, new spark plugs, new wires, everything and it still would not run. NOTE: he ran a jumper wire to the coil to provide the petronix with the necessary 12 volts (eliminating the resistance wire). When I began working on it, I discovered that the countershaft timing could be causing the issue.
Very likely!
If the counter-shaft indexing is off, it is likely that the camshaft is off also.

Low and behold, the countershaft timing was incorrect. We bought a new timing belt and installed it according to the manufactures guide. After reassembling, we got the boat to run, but it was at the end of boating season.
By the way, the timing belt tensioner is the same as the Automotive version, and for a fraction of the cost.
I would replace that as well.


The timing belt would have been equipped with the 3 markings. You can use the markings, or you can align each of the 3 cogged pulley TDC marks (with their corresponding marks) while installing the new belt.
If memory serves me, the white marks on the belt are only good during initial indexing........ once rotated, they will no longer align.

NOTES:

....... these distributors are known for having rust compromised flyweight systems. check to see if the flyweight system is working properly.

....... *** the distributor "driven" gear must be indexed to the counter-shaft's "drive" gear correctly.
If not, the adjustment slot will not allow for correct distributor housing indexing, and will not allow for the correct BASE advance.

....... see your OEM work shop manual for the correct BASE advance, Progressive advance, and Total Advance specs!
this means that you will want to strobe the timing marks as you increase RPM and view the advance.
but again, see your OEM work shop manual for the specs.


The other day, we went to get the boat running again and it will NOT start. The spark seems to be weak. We also can barely get the engine to even fire on any of the cylinders (like there is no spark). We just put a brand-new battery in it, check the distributor ground, and seem to have checked everything and CANNOT GET IT.
The ONLY way it will even act like it wants to start is when the distributor is maxed out, clock-wise rotation.
See *** above


If I had the means too, I would switch it back to the points. However, These are starting to get more and more difficult to find parts for!
I would encourage you to switch back to the contact points system.

A good spark will be whitish/blueish in color, and will make a "snapping" sound.

A weak spark will be yellowish in color.

Be sure that the correct ignition coil is being used.

I would suggest that you:

Change, test, etc, one item ONLY at a time.

Replace the water neck fitting and special beaded gasket.



Replace the OEM starter motor with a HTGR starter motor. It will spin the engine over faster and will consume less Amps.

[2850Bounty]

I failed to mention that if you do switch back to the contact points system, you will want to use a Dwell Metter to set the contact points.
The proper dwell angle will be listed in the OEM manual.

You should be able to find more related postings by doing a Google search, following your Key Words with "2850Bounty", or "RicardoMarine".

[JStew810]

Awesome! I will hopefully have some time this week to dig into the boat again. When installing the new timing belt, I triple checked all the marks were lined up and truly feel that the timing belt was installed correctly. This is backed by the fact that the boat did run, and rather well, after the new timing belt was installed. I DID replace the tensioner pulley as well. I will have to pull the distributor to check the flyweights. I was also going to take out the bolt, so I could have more timing adjustment.

I will keep this thread updated with new finding and hopefully a solution. Thank you all!

- Jacob

[2850Bounty]

Jacob, where is the BASE advance set now?
What are the progressive and total advance doing now?

[JStew810]

Jacob, where is the BASE advance set now?
What are the progressive and total advance doing now?

According to the air cleaner, I need the timing set to 6 degrees BTDC at 850 rpms. This is what I have it set to. As for progressive and total advance - I'm showing my ignorance here - I'm not too sure.

I'm use to working on later model stuff, so distributors and carbs aren't my speciality, still learning.

Doesn't the boat need to be running to determine progressive and total advance?

[2850Bounty]

.............

According to the Flame Arrestor, I need the timing set to 6 degrees BTDC at 850 rpm. This is what I have it set to.
OK, that's a good start!

As for progressive and total advance - I'm showing my ignorance here - I'm not too sure.
Easy-peasy...... read on!

I'm use to working on later model stuff, so distributors and carbs aren't my speciality, still learning.
Understood.

Doesn't the boat need to be running to determine progressive and total advance?
No......... the Engine needs to be running!


Since this is a mechanically advancing system, the engine does not need to be loaded...... you can do this while in Neutral.

With your timing light connected to the # 1 spark plug cable, you will strobe the timing marks as you increase RPM.
(mark sure that the pulley mark and timing degree marks are clean and visible)

Look closely at my detail (lower right side) regarding the adjustment bolt slot in the distributor housing.
If you are not able to achieve the correct TA, it means that the counter-shaft gear and distributor gear are not indexed correctly.
In which case, you will need to re-index the distributor gear.






As RPM is increased, you should see the spark event increase progressively.


See your OEM work shop or Service manual for the AQ131a ignition timing specs.
I would NOT use a Clymer or Seloc manual........ too many errors.

I apologize....... I do not have the specs for the AQ131.

Here are two examples for the AQ145 and AQ125 as per OEM.

AQ145:
Base advance = 4* BTDC @ 750 RPM
Total Advance = 29* @ 4,200 RPM
if plotted out in graph form, the progressive-to-total advance should be rather linear.

AQ125:
Base advance = 10* BTDC @ 750 RPM
Total Advance = 34* @ 4,200 RPM
again, if plotted out in graph form, the progressive-to-total advance should be rather linear.


NOTES:

..... you may not see any progressive advance begin until you reach 1,000 or 1,200 RPM..... very normal.

..... at 4,200 RPM (this is the "Full In" RPM), you should see no further spark advance.

...... if you are not able to see a Progressive/Total advance in a nice linear fashion, you have an issue with the flyweight system.

..... if you see a big jump in advance too early, you have an issue with the flyweight system, which will lead to Detonation. Rust compromised springs, for example.

..... as with any gasoline Marine Engine, ignition timing is so very important and critical. If not within specs, performance will suffer.


If need be, find a shop who owns/operates an old school Sun, Allen or King distributor machine.
They will be able to freshen things up, and correct the curve for you.

[dktool]

The typical standard dwell angle is; 8 cyl = 30 degrees
6 cyl = 40 degress
4 cyl = 50 degrees

[cfoss]

Aha, I missed post #8, but for info anyways:


Sounds like there are some things that need sorting out for sure. Once the basics are covered-cam shaft timing is proved etc, then:

If all that is good, and you still have to clock the distributor to get any action like in your first post, consider that you may have you spark plug leads connected wrong, and clocking the distributor enough will get 1, or maybe multiple cylinders close to firing in the correct place.

Any easy way to check this is to get number 1 cylinder at TDC compression. Then look at the position of the rotor...is is pointing at the Home lead? Can it be made to point at the number 1 lead by adjusting the distributor? If not, the leads are not connected properly. Reconnect Home lead to the stud that the rotor is pointing at, then triple/quadruple check the lead order from there, knowing the firing order of the engine and matching it.


Chay

[2850Bounty]

Here is the deal with the OHC 4 banger ignition distributor


The adjustment slot limits the angle of rotation at which the distributor housing can be adjusted for ignition timing.

If the counter-shaft's "drive" gear and the distributor's "driven" gear are not indexed correctly, the adjustment slot will not allow for the correct timing adjustment.

When that is the case, the distributor must be re-indexed.

[JStew810]

Hello everyone! My apologies for the delayed replies.

I currently am house hunting in a new state, so I have been travelling and extremely busy.

As far as correct orientation of the spark plug leads, or wires, as mentioned in post 13, it is right. I have checked it more times than I'd like to admit. I have put cylinder number 1 at TDC on compression, and the rotor is pointing at cylinder number 1. That is why this is so frustrating/confusing to me.

I am starting to believe the petronix is just not providing a strong enough spark. For a name like "flamethrower" (or whatever it is), it is very underwhelming.