Volvo penta 5.7GL A-PMDA weak spark & won't start

[Mannie]

Decided to give engine a service, changed distributor cap & rotor arm, starter also faulty so changed that too. Engine turns over but it won't start. Replaced the coil, still nothing. Plugs also changed & getting a spark but its weak. Spark at ht lead (earthed) from coil is strong but yellow.
With ignition in ON position:
Hooked meter up from battery + to coil + & getting 10.33v Battery is fully charged (12.7v)
Hooked meter between battery - and coil - getting 2.78v
Carried out voltage drop test meter between battery - and sensor housing & getting 0.5v.

Red wire at ignition switch reads 12.4v however when ignition turned on, purple wire reads 11.7v (bad ignition switch?)
Any help/further suggestions, manual suggests to check advance mechanism in distributor & ignition timing...HOW?
Would have thought the coil should give a reading closer to battery voltage

 

[Don S]

Re: Volvo penta 5.7GL A-PMDA weak spark & won't start

Hooked meter up from battery + to coil + & getting 10.33v Battery is fully charged (12.7v)

Well, that tells you that you have 2.3volts getting to the + side of the coil. Now somewhere between the battery and the + terminal of the coil you have a bad connection.

What you need to do is forget the dropdown test, and do a straight voltage test with your meters black lead (with a long test lead) hooked to a good solid ground on the battery negative terminal. With the red test lead, start at the battery Positive terminal and follow the red, and red/purple wires from the battery to the ignition switch. Then with the key in the run position follow the purple wire back to the coil and find out at which spot you loose your 12.7V.

View attachment 7796456 MD Electrical and Ign. 133.pdf

 

[Mannie]

Re: Volvo penta 5.7GL A-PMDA weak spark & won't start

Don I made a mistake in the first message. I got 10.33v when I hooked the meter between the battery - and the coil + with the ignition key in the on position. Sorry about that, I had a 2 year old on my knee screaming for Mickey Mouse when I was typing that!
10.33v to the coil still seems a little on the low side?

Is there an ignition cut-off switch built into the throttle control? I've already bypassed the emergency shutdown switch. There are a couple of wires that seem to be coming out of the back of the throttle control but they arent very accessible.

 

[Don S]

Re: Volvo penta 5.7GL A-PMDA weak spark & won't start

You aren't doing a voltage test the way you are doing it, your doing a voltage drop test of the entire system.

Test it like I said and see what your voltages are.

As an example.

With your method of testing and your fully charged battery (12.77V), If you tripped the main 50A bresker on your engine, and tested like you said
(With ignition in ON position: Hooked meter up from battery + to coil + ).
Then your meter would show 12.77 volts.

 

[Mannie]

Re: Volvo penta 5.7GL A-PMDA weak spark & won't start

Hi Don Thanks for replying. I'll test it as you've said tomorrow. Thanks again

 

[Mannie]

Re: Volvo penta 5.7GL A-PMDA weak spark & won't start

Hi Don,
Grounded (-) on meter to (-) on battery
The red and red/purple wires test good right to the ignition switch (12.6v)
With the key turned to on, the purple wire at the ignition drops to 11.29. i tried bypassing ignition & I connect purple directly to the red/purple wire probing the purple wire still gives 11.29. I re-crimped the connectors but it made no difference. I probed purple wire right to Main Cable Connector & it gives 11.29 on both sides of connector. Short length of wire between Connector & coil I tested the resistance & it was fine however at the coil I still only get 10.9 at the + terminal.
I'm stumped!

 

[Don S]

Re: Volvo penta 5.7GL A-PMDA weak spark & won't start

Disconnect everything on the - terminal of the coil and recheck the voltage to the coil.

 

[Mannie]

Re: Volvo penta 5.7GL A-PMDA weak spark & won't start

Cheers Don, I've no Internet access at the boat so cant do this in realtime. when I disconnect wires from -of coil what kind of voltage am I looking for?

 

[Mannie]

Re: Volvo penta 5.7GL A-PMDA weak spark & won't start

Hi Don, with wires disconnected from - side of coil I get 12.6v.

 

[Don S]

Re: Volvo penta 5.7GL A-PMDA weak spark & won't start

Ok, should have put this in the last reply. If you have good voltage at the + terminal of the coil with everything off the - term. The hook up the black wire from the distributor (item 2 in the drawing) and see if you have good spark.
Your 12.6 volts is good.

 

[Mannie]

Re: Volvo penta 5.7GL A-PMDA weak spark & won't start

Cheers Don,
I hooked up the black wire and the voltage drops to 10.9. I disconnected the black wire and hooked up the grey wire and voltage is 12.6, looks like the black wire is doing the damage

 

[Don S]

Re: Volvo penta 5.7GL A-PMDA weak spark & won't start

Here is some further troubleshooting information on your ignition system.

View attachment BID Troubleshooting.pdf

 

[Mannie]

Re: Volvo penta 5.7GL A-PMDA weak spark & won't start

Thanks a million Don, sneaking suspicion I'm looking at replacing ignition module.
Thanks for all your help, it's very much appreciated

 

[Don S]

Re: Volvo penta 5.7GL A-PMDA weak spark & won't start

If the module is the problem, you are probably looking at replacing the distributor. Those modules are NLA and if you do find them they cost more that upgrading to the EST distributor like Volvo did in future engines.

An example http://www.michiganmotorz.com/delco-voyager-marine-electronic-distributor-p-119.html

 

[Mannie]

Re: Volvo penta 5.7GL A-PMDA weak spark & won't start

Thanks again Don.
Just one question (actually 2!), I want to check the distributor for a bad earth on the module. Would I be right in thinking I can just screw the module out and check for corrosion on the back side of it? Also where does the distributor actually earth, is it the bolt and clamp that secure it to the engine block? Obviously want to check the obvious before splashing out on a new ignition system.

 

[Don S]

Re: Volvo penta 5.7GL A-PMDA weak spark & won't start

Here is some further information on the BID system. It's from a much newer model, the the information is same and the pictures are clear enough to see.

Click here to download.

 

[Mannie]

Re: Volvo penta 5.7GL A-PMDA weak spark & won't start

Hi Don, thanks so much for helping me out, it's definitely an ignition module so I'll have to bite the bullet & get the new system. Couldn't have worked it out without you so thank you very much

 

[Don S]

Re: Volvo penta 5.7GL A-PMDA weak spark & won't start

Glad you found the problem, sorry it had to be the module. Years ago I had a 5.7 with a points system that I replaced with the BID, even had a second module. Never needed it, and then the modules were only $100 or less.
The EST is great all electronic and the module is common and around 100 or less, but no advance weights or springs.
Lots of info on it as well. Well worth the upgrade.