89 Volvo Penta AQ271C ignition or carb, maybe something else

[Dillon36]

Hello,
My 28' Carver with a Penta AQ271C is extremely low on power, RPM's will not pass 2800 underway. I see that the secondary's are not opening so i has the carb rebuilt with no change. From there i was verifying the timing and it was good. While leaving the dock for a test run i notices that i had left the trimming light connected and that the #1 wire was randomly not showing spark. I then move to other wires and saw that 2 others were not showing spark as well. with fouled plugs upon returning to the dock. Once we replaced the plugs all fired again, but once underway the timing light shopped showing spark and plugs were fouled again. My friends say carb is fouling the plugs and stopping spark, I say ignition system issues not sparking and causing plug build up (fouling plugs).

Any ideas? compression is good and equal across all cylinders with an electronic ignition

Thanks

 

[kenny nunez]

Is your ignition system electronic or points and condenser?

 

[Dillon36]

Is your ignition system electronic or points and condenser?

I added that it is an electronic ignition. I took out the "donut" to look for some type of marking buy there were none

 

[kenny nunez]

It could be. Prestolite system. Try to post a picture of the inside of the distributor.

 

[Dillon36]

It could be. Prestolite system. Try to post a picture of the inside of the distributor.

yes, thats what the marine place told, a Prestolite

 

[QBhoy]

Hi. Have a check at this ballast resistor. Had one failing on a friends boat last year. Exact same engine. Heard of a few since then too. Caused very similar issues to yours.

 

[Dillon36]

ok, I have not seen one of those on the boat, I'll look today. This would be connected to one of the coil + correct?

 

[Lou C]

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I think this is what you should have, which appears to be the Prestolite BID system, it has an electronic module but still uses centrifugal advance like the points distributors did.
Might try replacing the cap n rotor first and checking the ohms of all the plug wires should not be more than 1000 ohms per foot of length.

 

[Dillon36]

Home | iBoats

Since 1998, iboats is the most trusted water lifestyle online store for boat parts and accessories, boats for sale, and forums. Enjoy great priced products with fast shipping.

www.volvopentastore.com

I think this is what you should have, which appears to be the Prestolite BID system, it has an electronic module but still uses centrifugal advance like the points distributors did.
Might try replacing the cap n rotor first and checking the ohms of all the plug wires should not be more than 1000 ohms per foot of length.

Yes, its have a centrifugal advance that its working as it should. Have already replaced cap, rotor, wires, plugs

 

[Lou C]

What's the voltage reading at the positive terminal on your coil when you turn the ignition to on but not starting the engine?
I had a low voltage to the coil problem on my OMC for years before I tracked it down. After that much better starting and running.

 

[Dillon36]

What's the voltage reading at the positive terminal on your coil when you turn the ignition to on but not starting the engine?
I had a low voltage to the coil problem on my OMC for years before I tracked it down. After that much better starting and running.

I'll check that today. what should it be ?

 

[Dillon36]

 

[Dillon36]

i know its old and crusty looking but the distributor shop said it was working fine. I wonder if it heats up and causing the problems

 

[QBhoy]

ok, I have not seen one of those on the boat, I'll look today. This would be connected to one of the coil + correct?

Yeah. Down there local to it. You’ll almost certainly have one. Known to occasionally cause issues. Intermittent spark usually or total failure

 

[Dillon36]

Yeah. Down there local to it. You’ll almost certainly have one. Known to occasionally cause issues. Intermittent spark usually or total failure

My friend is at the boat and does not see one of those resistors, but said the coil has an internal one? Does that make sense?

 

[QBhoy]

My friend is at the boat and does not see one of those resistors, but said the coil has an internal one? Does that make sense?

That’s fair enough. May well be a more modern ignition system that the 88 model I was familiar with. That had it sat bolted on a bracket near the coil.

 

[Dillon36]

That’s fair enough. May well be a more modern ignition system that the 88 model I was familiar with. That had it sat bolted on a bracket near the coil.

thank you though.. this is very confusing to me. I'm thinking i need to replace the ignition part i showed the picture of.

 

[kenny nunez]

As Lou said you need to check the voltage on the + or bat side of the coil. There should be 12 volts or slightly more with the engine running. Just considering the age of the Petronics system if it was my boat I would have a spare so maybe you should try replacing the original one and keep the it for a spare.
I keep a spare in my current jet boat.

 

[QBhoy]

Have a look here.

Volvo Penta AQ271C back firing 3000 rpm

1990 Carver 2357 Montego Volvo Penta AQ271C 5.7 V8 Duo Prop Engine back fires at 2800 to 3000 rpm's. Boat will not climb above 3000 rpm. Just pops and fouls a plug or two each time. But then will idle perfectly at 650 to 700 rpms New wires, plugs, distributor cap & rotor, holly carb equipt...

forums.iboats.com

 

[Dillon36]

As Lou said you need to check the voltage on the + or bat side of the coil. There should be 12 volts or slightly more with the engine running. Just considering the age of the Petronics system if it was my boat I would have a spare so maybe you should try replacing the original one and keep the it for a spare.
I keep a spare in my current jet boat.

Thank you, good idea of a spare. I do have slightly over 12V with the engine running at the coil. As recommended, I have not yet tested with the key on but not running.