5.0GL - No Power at Coil

[Blowinup]

Hello,

This is my first post to this forum. Please forgive my ignorance as I'm not a mechanic. I'll try to provide the best information I can and follow forum etiquette.

Pics for everything I could find about the engine model are posted.

Problem:
I have a Volvo Penta 5.0GL that has no power to the positive terminal on the coil.

Question:
I've read everything I can find on this forum that's related to my issue but when someone asks, "Does the coil have 12v on the positive terminal when the key is on" they always say yes. So I'm not sure what to do when the answer is no.

Read on if you're into the long winded stuff

Background
After finally resolving some fuel delivery issues (happy to provide details) she was running great. Of course anything that's going to happen will happen on the water so after taking a lap around the lake she abruptly died as if someone had just turned off the engine (this has happened before). It happened again about half a dozen times on the way back to the ramp. She restarted quickly every time and ran for a while but when she died she died very abruptly. It didn't seem to matter how far open the throttle was.

The next day she fired right up and idled well for about 10-15 minutes. I stopped and restarted her several times without any issues. I suspected it was water in the gas so I shut her down with plans to drain the tank and refill her with ethanol free gas. And that was the last time she started for me.

I drained the tank and was surprised to find nothing but clean fuel.

Having tested the fuel system from the tank to pump and filter (both replaced) to the carb (recently rebuilt) I went back to basics and tested for spark. I honestly thought I was just going to eliminate spark as a problem but found no spark at the cylinders. So I checked the coil and I get little to nothing on the positive terminal when the key is turned to the on position.

I have some related questions about what appears to be a 50amp fuse labeled 'ignition protection' where the 10 pin connector (pics uploaded). There is a red wire running from the positive terminal of the coil to the 10 pin connector and I'm wondering if this is something I should be looking at?

 

[alldodge]

For the GL PWTR the wiring comes from the Battery, thru the 10 pin connector, to the key switch and back to the coil going back thru the 10 pin.

Starter post Red wire to breaker
Breaker red/purple to 10 pin
10 pin to key switch thru 15 or 20 amp fuse
Key switch (RUN terminal) Purple thru kill switch to gauges and 10 pin
10 pin Purple to Coil and alternator

 

[Scott Danforth]

check the MOB switch. the MOB switch is after the key switch, however before the 10-pin connector

 

[Blowinup]

Thanks for the replies. I appreciate y'all taking the time to read my post and offer help.

I decided to follow the red wire that leads from the positive terminal on the coil to the 10 pin wiring harness. I discovered it was spliced into a blueish wire that provides power when the key is in the on position. The connection was in bad shape. I assume this is hack job and not a factory setup.

Unfortunately, this wire only provides about 8v. I made a solid connection and found the coil was now getting the same 8v. Encouraged I was on to something I checked to see if there was spark to the cylinder and there was. I was subsequently able to start the engine.

I'm still concerned that the coil only seems to be getting 8v instead of 12v. I assume that is the voltage it's passing to the distributer. Can anyone weigh in on this? Does the coil need 12v? Will the engine function properly and consistently with only 8v supplied to the coil?

One issue I've been chasing, and yet to resolve, is a problem with hesitation in the lower end of the power curve. If I try to go from idle to WOT it will hesitate and sometimes even backfire. I can however ease it past this point and then go WOT without issue.

I suspected latent timing. When I tuned the carb after the rebuild the vacuum gauge seemed to confirm this. But I've since read a few things suggesting that a coil without enough voltage could exhibit similar symptoms. And that makes sense to me because an engine that doesn't get the spark it needs will hesitate and backfire because it's getting more fuel than it can burn right? Can I get an mechanics opinion on this?

If that is in fact the case I'm wondering if it's safe for me to test this theory by temporarily running a wire from positive terminal on the coil directly to the positive terminal on the battery. Is it a terrible idea or could it be worth a try?

 

[alldodge]

I'm still concerned that the coil only seems to be getting 8v instead of 12v. I assume that is the voltage it's passing to the distributer. Can anyone weigh in on this? Does the coil need 12v? Will the engine function properly and consistently with only 8v supplied to the coil?

The coil needs 12V when starting and running. Getting only 8V at the connector means there is corrosion and could be on both sides of the connector. You could run 12V from the Bat without an issue

One issue I've been chasing, and yet to resolve, is a problem with hesitation in the lower end of the power curve. If I try to go from idle to WOT it will hesitate and sometimes even backfire. I can however ease it past this point and then go WOT without issue.

While lower voltage can cause the hesitation, there would also be an issue at WOT. Your issue would be in the carb. If it has the holley then it is probably the power valve or accelerator pump adjustment

 

[Blowinup]

The coil needs 12V when starting and running. Getting only 8V at the connector means thWhile lower voltage can cause the hesitation, there would also be an issue at WOT. Your issue would be in the carb. If it has the holley then it is probably the power valve or accelerator pump adjustment

 

[Blowinup]

Thank you for your super fast and on target reply alldodge!

You make a good point. I would be getting the same hesitation at the top of the power curve as the lower if it were a voltage issue. But it's good to know I can connect the coil to the battery to get a full 12v if I need to in a pinch (stranded on the water with no spark).

The engine is running relatively good now but still has the hesitation. It's not as bad as when I got it but it's still there. This was my first carb rebuild and, while everything went well and I did see a performance improvement post rebuild, I am open to the possibility that I may have missed something.

The power valve was replaced with the rebuild kit. I can't recall if the accelerator pump was but I don't think so. Can you point me to a resource to learn how to adjust the accelerator pump?

 

[Blowinup]

Found one...

Accelerator Pump Tuning For Holley Carburetors

Take the mystery out of tuning your Holley carburetor with these lessons! Here is how you adjust the accelerator pump, which will eliminate tip-in issues that many struggle with!

www.holley.com

 

[Blowinup]

Thank you alldodge!

I found about an eight of an inch play in the accelerator pump. I adjusted it as best I could without a gap tool and it made a big difference. I can't say the hesitation is 100% eliminated but it's probably 90% better thanks to your help. I suspect the rest might be remedied with proper timing.

I've never timed an engine and to be honest it scares the crap out of me. I bought a timing gun, read and watched a lot of videos but I still haven't built the confidence to give it a go on my own.

But then again I'd never rebuilt a carb a water pump or replaced a fuel pump before buying this boat. It's caused a lot of stress and sleepless nights but taught me a ton as well.

Thanks again!

 

[alldodge]

Timing is easy for your motor. Mark the crankshaft balancer with white grease marker if needed so it can be seen better. Do not have to, sometimes it makes it easier to see.

Slightly loosen the distributor just enough so it can be rotated. The motor needs to be warmed up and idling at the specified rpm. Point light at balancer and turn distributor to spec. Tighten distributor bolt and recheck timing to see that it didn't move.

 

[kenny nunez]

Did you replace the accelerator diaphragm when you rebuilt the carburetor?
Maybe I read something wrong and you did. Depending on the amount of ethanol is in your local gas supply can have a effect on the diaphragm and make stiff and will not supply enough gas when you move the throttle.
If after you get the correct voltage to the coil and the engine still cuts off try replacing the rotor. When they get hot it is possible for the spark current to go to ground.

 

[Blowinup]

Timing is easy for your motor. Mark the crankshaft balancer with white grease marker if needed so it can be seen better. Do not have to, sometimes it makes it easier to see.

Slightly loosen the distributor just enough so it can be rotated. The motor needs to be warmed up and idling at the specified rpm. Point light at balancer and turn distributor to spec. Tighten distributor bolt and recheck timing to see that it didn't move.

I'm going to look up the specs and give it a go.

 

[Blowinup]

Did you replace the accelerator diaphragm when you rebuilt the carburetor?
Maybe I read something wrong and you did. Depending on the amount of ethanol is in your local gas supply can have a effect on the diaphragm and make stiff and will not supply enough gas when you move the throttle.
If after you get the correct voltage to the coil and the engine still cuts off try replacing the rotor. When they get hot it is possible for the spark current to go to ground.

Thanks for your help Kenny!

I'm 99% sure the OEM rebuild kit I used included an accelerator pump diaphragm so I think I did replace it.

I have a gas station near me with outstanding 93 octane ethanol free fuel and it's all I use in my boats. I actually drained the tank in this boat when I was chasing a fuel delivery issue and promptly filled her with the good stuff.

I do intend to replace the rotor and cap. I ordered a new cap and plug wires only to discover that my distributor in not OEM so I couldn't use them. The don't think the coil isn't OEM either.

I need to check the voltage of the coil again and troubleshoot further if the voltage is still hovering around 8.

I haven't had her back out in the water since making some adjustments including the accelerator pump and it's running much better now. I let her idle for about 15 minutes today without any issues. But that could all change under a load. Of course as soon as she knows she's in the water far from shore she'll reveal any unresolved issues.

 

[kenny nunez]

Try to post a picture of the distributor

 

[Blowinup]

I'm going to look up the specs and give it a go.

Well alldodge made it sound so simple I jumped in without really knowing everything I need to know. There are still too many missing pieces for a novice like me.

So I warmed up the engine and connected the light to see what I could see without really knowing how to set it up or what to look for. And I didn't see anything or maybe I did but just didn't know it.

I wasn't sure what to do with the advance dial on my light so I set it to zero.

I watched some videos but every one seemed to have at least one variable that didn't apply to me.

In one of them the guy removed and plugged a vacuum hose from the distributor. I don't have one of those. Another video used advance markings on one of the pullies that were already there. I don't have any that I can find.

The only marking I could find was on a plate behind the harmonic balancer (pic uploaded). But I'm not sure what to do with that. Is that where I draw a corresponding mark on the balancer?

One video explained the advance dial on the timing light, I think, and advised to set it to zero if you use markings on the balance or set it to the advance you're trying to achieve if you're not. I don't think I fully understand that but it doesn't matter since I don't have advance markings anyway.

I apologize for my ignorance and asking for someone to hold my hand and walk me through it but I have tried to find the info on my own without any success so far.

Any chance someone knows of a video showing timing being set on a 5.0 GL or similar engine? Cuz I can't find one. I found some for Chevy 305s but again they always seem to doing something that doesn't apply to my engine.

 

[alldodge]

Kenny is the guy that knows VP

For having just a notch you need to look at the balancer for a larger mark followed by some smaller ones.

Having an advance timing light, need to set the light for 8 BTDC (assuming that is correct timing for the motor). With motor running the point in your pic will align with the notch on the balancer

 

[Blowinup]

Try to post a picture of the distributor

Sorry the picture ain't the best... it's dark outside now. I also included the OEM distributor cap I bought.

 

[Blowinup]

Kenny is the guy that knows VP

For having just a notch you need to look at the balancer for a larger mark followed by some smaller ones.

Having an advance timing light, need to set the light for 8 BTDC (assuming that is correct timing for the motor). With motor running the point in your pic will align with the notch on the balancer

Thanks man.

I've been referring to this thread for timing specs:

Procedural question on ignition timing, 99 Volvo 5.0GL PWTR

The poster mentions a manual I would love to get my hands on. Unfortunately the link to the manual in the thread doesn't work.

BTW I did my best tonight to find any advance markings but came up empty. I even put my phone down there with the light on and took a video. If there are markings I can't see them. The balancer has a decent amount of surface rust so that could be covering it up.

I have some of that stuff that turns rust back into metal so maybe I'll rub some of that on it tomorrow to see if it reveals the markings I need.

 

[alldodge]

Take a piece of sand paper to it. Then bump the starter as brief as possible to see if something comes up

 

[Blowinup]

Take a piece of sand paper to it. Then bump the starter as brief as possible to see if something comes up

Will do. I'll hook my remote starter back up... easier to bump it.