Volvo Penta 4.3gl frustrating ignition problem! Driving me mad!!!!!!

[Sicobra]

I am really hoping someone can help me as I am pulling my hair out over this problem. I have a 4.3GL Volvo Penta engine with the EST style distributor in my sports cruiser and despite replacing the plugs, leads, distributor cap and rotor all the usual service items I have an issue with intermittent missfires on plug leads number 1 and 3. I have found this while using my timing light, it fires the light consistently and evenly on all plug leads apart from these two, the timing light flash is sometimes regular but often irregular on these leads only!!!).
I found a surprising amount of build up on all the plug contacts inside the new distributor after about 20 hours running and I am also surprised at how big the gap is from the rotor arm tip to the internal cap contacts(what should the be? They are about 3mm on mine!)
Can anyone tell me what I am missing or doing wrong? Could it be a problem with the ignition module inside the distributor? I am getting very frustrated with this problem as the engine starts great, runs OK except for this annoying slight missfire which is stopping it run as smoothly as it should.
Please, please, please put me out of my misery!!!!!!!! Cheers, Simon

 

[Maclin]

Re: Volvo Penta 4.3gl frustrating ignition problem! Driving me mad!!!!!!

Can you run and observe it at nite? It will be easier to see any cross-firing arcing or plug wire "leaks" then. Watch the coil as well, could be arcing there too.

 

[Don S]

Re: Volvo Penta 4.3gl frustrating ignition problem! Driving me mad!!!!!!

Change the spark plugs, use the correct AC or NGK sparkplugs, DO NOT use Champion.

 

[Sicobra]

Re: Volvo Penta 4.3gl frustrating ignition problem! Driving me mad!!!!!!

We have the right plugs and have run at night and can't see any sparking, we have swapped the leads for new ones on the number 1 and three and also tried different ones to be sure there is no issue with the new ones. What I can't understand is if it was the main coil why it would only be on leads 1 and 3 and not show up on the rest. Could it be to do with the Ignition module in the distributor or the Coil, shield or pole shoe under the rotor arm???
Can any one confirm the distance between the rotor arm tip and distributor contacts?
By the way thanks for the help so far, keep the idea coming, cheers, Simon

 

[Pesimist]

Re: Volvo Penta 4.3gl frustrating ignition problem! Driving me mad!!!!!!

Can you run and observe it at nite? It will be easier to see any cross-firing arcing or plug wire "leaks" then. Watch the coil as well, could be arcing there too.

You can also tune your radio to an AM station and listen for suspected spark jump. If it misfires and you don't hear it on the radio, start looking at the spark plugs again.

 

[Sicobra]

Re: Volvo Penta 4.3gl frustrating ignition problem! Driving me mad!!!!!!

Guys, thanks for all the advice, it has been a great help and we have now through trial and error managed to sort the problem and it was all down to faulty spark plugs! I can't believe it after all the messing about, we had tried more new plugs in the first place and it made no difference, a friend mentioned he had access to a professional plug tester and took all twelve newly purchased plugs away for testing, result, 8 were bad!!!!!! Took them to our supplier who made a call and once the batch cross reference had been made to his supplier it seems that he had been missed out from a recall from the manufacturer for a batch of faulty plugs and I got them, he had over 100 sitting in his stores which have now all been returned. I may have been the victim of this situation but at least I know that no one else will be put in the same situation.
So thanks again for all the advice, my engine is now purring like a kitten, cheers, Si

 

[Don S]

Re: Volvo Penta 4.3gl frustrating ignition problem! Driving me mad!!!!!!

What brand were they? Who knows of others will have the problem from a different supplier.

 

[Sicobra]

Re: Volvo Penta 4.3gl frustrating ignition problem! Driving me mad!!!!!!

Hi, they were NGK and I was told supplied only to the UK market and a very small batch, I will try and get more details just incase anyone else has an issue, cheers, Si

 

[Lynall]

Re: Volvo Penta 4.3gl frustrating ignition problem! Driving me mad!!!!!!

Hi, they were NGK and I was told supplied only to the UK market and a very small batch, I will try and get more details just incase anyone else has an issue, cheers, Si

Sicobra please let us know the NGK model number as i would be very interested.
Ones fitted to mine are NGK PTR5D-10 3784 laser platinum, guy who supplied thed told me he had a bit of a job getting them, so im curious they may be the same ones as you, although they did look identical to the old ones.


Lynall