89 Volvo Penta AQ271C ignition or carb, maybe something else

[QBhoy]

I have a thought in mind that this might be a Holley carb too. Very hard to set up right if not in the known all sorts of power valves and feeler gauge required to set things up too. Is it popping at any point to indicate an ignition fault ? But thought I’d mention the carb set up too.

 

[Dillon36]

I have a thought in mind that this might be a Holley carb too. Very hard to set up right if not in the known all sorts of power valves and feeler gauge required to set things up too. Is it popping at any point to indicate an ignition fault ? But thought I’d mention the carb set up too.

Yes, i thought about that as well but when the carb was rebuilt the tech came to the boat and conducted some fine tuning and replaced the power valve along the way.

No popping of any sort, I'm thinking ignition because of the timing light randomly stops flashing while conducting a tests runs. Even of the plugs were fouled there still would be an energy pulse though the plug wire allowing the timing light to flash correct?

I read the post to shared, thank you. Going to check out the Rev limiter that it referred to.

 

[QBhoy]

Yes, i thought about that as well but when the carb was rebuilt the tech came to the boat and conducted some fine tuning and replaced the power valve along the way.

No popping of any sort, I'm thinking ignition because of the timing light randomly stops flashing while conducting a tests runs. Even of the plugs were fouled there still would be an energy pulse though the plug wire allowing the timing light to flash correct?

I read the post to shared, thank you. Going to check out the Rev limiter that it referred to.

Ok. Sounds like you’re on the right track then. Don’t think you’ll have a rev limiter to be honest. And certainly nowhere near those rpms. Quite sure of it. I also know that a lot of these have had their ignition system upgraded over the years too. A friend with repower engines not long ago replaced the AC system with petronic for a world of difference. As for the timing, his was all over the place at certain rpm and difficult to get right. But the main issue he had was setting up the holleys

 

[Dillon36]

Ok. Sounds like you’re on the right track then. Don’t think you’ll have a rev limiter to be honest. And certainly nowhere near those rpms. Quite sure of it. I also know that a lot of these have had their ignition system upgraded over the years too. A friend with repower engines not long ago replaced the AC system with petronic for a world of difference. As for the timing, his was all over the place at certain rpm and difficult to get right. But the main issue he had was setting up the holleys

I'm hoping for a rev limiter problem, that would be the easiest thing to identify, if it even has one. We are also getting to new ignition control module since the one i posted show signs of heat on the bottom. If its not one of those ill be back to square 1 again.

 

[Lou C]

Given what you said, it may be that the module in the Prestolite is bad. Last I heard those were NLA but I bet you could convert it to a Petronix (aftermarket electronic conversion) they don't cost much either. First though make sure you have enough voltage at the coil as Kenny said.

 

[Dillon36]

Given what you said, it may be that the module in the Prestolite is bad. Last I heard those were NLA but I bet you could convert it to a Petronix (aftermarket electronic conversion) they don't cost much either. First though make sure you have enough voltage at the coil as Kenny said.

You bet, fingers crossed.

I'll let you know about the voltage. I know there is 12V+ while running but i need to look with just the key on.

 

[Dillon36]

Given what you said, it may be that the module in the Prestolite is bad. Last I heard those were NLA but I bet you could convert it to a Petronix (aftermarket electronic conversion) they don't cost much either. First though make sure you have enough voltage at the coil as Kenny said.

one last question for you.

Do you agree that power should still be transmitted though the plug wires even if the plug is fouled?

 

[Dillon36]

one last question for you.

Do you agree that power should still be transmitted though the plug wires even if the plug is fouled?

Look what we found

 

[kenny nunez]

Lucas, also known among the British auto enthusiast as “The Prince Of Darkness”.

 

[Dillon36]

Lucas, also known among the British auto enthusiast as “The Prince Of Darkness”.

LOL

 

[Lou C]

one last question for you.

Do you agree that power should still be transmitted though the plug wires even if the plug is fouled?

Power may be transmitted but the plug may foul for a variety of reasons and not fire properly...
reasons:
oil leaking past valve seals
carb set too rich

 

[Dillon36]

Power may be transmitted but the plug may foul for a variety of reasons and not fire properly...
reasons:
oil leaking past valve seals
carb set too rich

totally agree,
that's the main reason I'm digging into the ignition since 3 of my 8 cylinders don't register power traveling though the wires on my timing light. Very strange to me.

 

[Lou C]

Are you sure that the cap, rotor & wires are good, just for fun, ohm out the wires and see what you get.
We had a 3 year old Toyota Camry 4 cyl years ago that all the sudden started running on 2 cyls, when I checked the wires, two were totally dead. Very strange, igniton problems are not common on Toyotas.

 

[Dillon36]

Are you sure that the cap, rotor & wires are good, just for fun, ohm out the wires and see what you get.
We had a 3 year old Toyota Camry 4 cyl years ago that all the sudden started running on 2 cyls, when I checked the wires, two were totally dead. Very strange, igniton problems are not common on Toyotas.

I haven't done an actual ohms test but I had three different sets of cap, rotor, and wires and all did the same. I have my meter now so i can test to be sure.

 

[Lou C]

In that case then I’m thinking module or coil…

 

[Dillon36]

In that case then I’m thinking module or coil…

agree, also going to unhook the rev limiter

 

[Scott Danforth]

Swap out the prestolite dizzy

Your secondaries won't open until you have enough RPMs and the vacuum drops to about 5 inches of vac

 

[Scott Danforth]

Look what we found
View attachment 371088

Remove the rev limiter as it's not needed

 

[Scott Danforth]

If you want another prestolite dizzy, PM me. I switched to a Mallory and haven't looked back

 

[Dillon36]

If you want another prestolite dizzy, PM me. I switched to a Mallory and haven't looked back

thank you,