Problems with Volvo-not getting spark

[Jeepster04]

Ive posted a couple threads now about some small issues that weve been having with our volvos. We were having problems with them dying when idling(shifting and such) and we soon found out the previous owners had neglected the engines. Weve replaced the distributor cap, rotary button, spark plugs, water pump(raw water), fuel/water separator filters, and rebuilt the carb on the starboard engine(It wasnt in too bad shape). After doing all of that to both engines we figured we would check the timing along with the rpms at the engine(separate tach) and the vacuum. We found out the rpm gauges on the boat are 200 rpms too high so weve been running them at 550rpms instead of 750(one problem) and second, the little vacuum thing that opens the choke once the engine warms up had a hole in the diaphragm so there was a vacuum leak. We had been having problems setting the idle-fuel screws and thats why, we plugged off that vacuum hose and had no problem setting the idle-fuel screws.

Now on to the next problem. We had the starboard engine timed(it wasnt off much at all) and got the fuel-idle screws adjusted and moved over to the port engine to check the timing, vacuum, and rpms. We hooked the timing light to spark plug wire #1 then fired the engine up, no flash from the timing light. Hooked the tach up to spark plug wire #1, no rpm's.... At first we thought we had broken both the timing light and the tach but then we figured out that the timing light would not work on 3 out of 8 of the spark plug wires as with the tach. We have no clue what is going on here????? We took 2 of the 3 spark plug wires that were not working with the timing light off and the engine fired right up and didnt sound a bit different. WHAT? It seems our engine is running on 5-6 cylinders and we cant even tell it has a miss? We took the distributor cap off and checked everything out and all seems well. When we first put the port engines distributor cap on it had a slight ticking noise and it appeared the rotary button was hitting the distributor cap on some of the contacts. Once it wore a groove in them the noise went away. We were un-able to check the timing on this engine since #1 spark plug wire was not getting fire. The wires that are not firing are not on the same side of the engine nor are they side by side on the distributor cap.

We went back over to the starboard engine and found out it also has 2 spark plug wires not getting fire but it starts and idles great.

It has electronic ignition with a sensor in the distributor and a sensor wheel. We were kinda thinking they both had bent distributors(our luck) but since the wires that are not getting fire are so random around the cap it just doesnt make sense. They wires not getting fire DO NOT change if the engine is shut down then restarted, etc. Its always the same wires.

If it were a bad ignition module I would think it wouldnt fire at all or move wires.

Any help is appreciated!

Working with Volvo Penta's 500A.

4100113751

Thanks!!

 

[Jeepster04]

Re: Problems with Volvo-not getting spark

Another thing I forgot. We pulled a spark plug wire off the starboard engine that had fire on it(wire #1) and put it on the port engine just to make sure the wires were ok. Still did not get fire on that wire. We then put the wire off the port engine(wire #1) on the starboard engine and it works just fine.

 

[captmello]

Re: Problems with Volvo-not getting spark

That is odd. Have you tried swaping the ignition modules?

reread post, both engines doing the same thing? Could try putting points back into one and running. If you've got the parts.

 

[Don S]

Re: Problems with Volvo-not getting spark

Some of the 500 series engines had rev limiters on the engine. Look and see if you have a black box attached to the coil as shown in the pic below item #22. If you do, disconnect it and see if your problem goes away.

 

[Jeepster04]

Re: Problems with Volvo-not getting spark

As far as I know there is no black box wired to the coil. There is a set of relays beside of it though. Ill check to make 100% sure though.

We thought the rev limiter may of been in the tach's so we unhooked those just to check. Nothing changed.

captmello, yes, both engines are doing it but one only has two wires not getting fire while the other has 3-4. Some of them will cause the tach to bounce around and cause the timing light to flash 'some' but its very inconsistent. We have no parts for points since the boat came with electronic ignition.

If a plug was fouled or a spark plug wire was grounding out would the timing light still work ok? Were hooking them up around the wire right at the cap.

 

[Don S]

Re: Problems with Volvo-not getting spark

The rev limiters are usually mounted on the transom or somewhere hidden. Not on the engine. Look at the number of wires on the coils + and - terminals. There should not be more than two wires on either terminal.

 

[captmello]

Re: Problems with Volvo-not getting spark

When I hook up my timing light I try to stay away from other wires to avoid interference from the other wires. Hook it up down at the plug, and make sure the pickup is clipped on in the right direction. If your running on 4 cylinders, the motor would have to be running rough.

Follow Dons hunch on the rev limiter sounds like an easy check.

Let us know what you find.

 

[Jeepster04]

Re: Problems with Volvo-not getting spark

We tried hooking up the timing light at every location along the wire and got nothing. Same with the tach.

Our coils have two wires coming off of one screw and three off the other screw. On one screw a wire goes to the tach, another to a plug which is plugged into nothing, and another to the distributor. On the other screw one wire goes to the same plug which is plugged into nothing, and then another to the distributor. If you look very closely in the first picture below you will see the two wires going to the plug which IS NOT plugged into anything. Ill assume thats the plug that would be going to the rev limiter which means we do not have one.

NOTE: The intake screens have been cleaned.

Note#2: that little diaphragm attached to the side of the carb is what was causing the vacuum leak. The other thing with the wire going into it closes the choke while the vacuum opens it.

 

[Jeepster04]

Re: Problems with Volvo-not getting spark

Just to update, weve really been looking into our spark problem. We changed out the plug wires which was one of the last things left to replace on the engines, weve replaced everything else. That didnt fix it so we took the distributor out and put a spark tester on the coil wire so we could watch the spark. We set the gap between the sensor wheel and sensor to .006in and spun the distributor......... 8 SPARKS! WOOT! We dont have bent distributors!

Now I guess we have bad distributor caps which is odd since we replace both distributor caps with new ones from Napa. One engine has two not firing and the other has 3-4 not firing. If I push on the side of the distributor slightly you can hear the rotary button rubbing on the contacts which is odd, it doesnt take much pressure at all.

For now weve ordered one cap and one button from a marina in Jamestown, Ky since its the House boat capital, they know their stuff and hopefully use good parts. We also had to get them to order the vacuum diaphragms for the chokes since it seems no one else had them. He said he had to special order them.

Also, another odd thing. We noticed one of the coils was getting a build up of oil on top of it where the coil wire plugged in. Not sure if it was bad or if it was bolted in too tight.. either way, we replaced them on both engines.

 

[Jeepster04]

Re: Problems with Volvo-not getting spark

Anothing thing, we took the boat out this weekend and even though the chokes were tied open, once we got the engines started the first time they fired right up and ran awesome all day(lots of starts and stops). We could smell some raw fuel coming from the port engine which is expected since its down a few cylinders. That was pretty exciting since last fall they were running crappy and dieing alot.

 

[Jeepster04]

Re: Problems with Volvo-not getting spark

Got the distributor cap along with a button straight from Volvo and it seems to have fixed the problem. We had one plug that seemed to be bouncing around when we put the tach on that wire but it smoothed out. We could still hear a slight ticking noise coming from he distributor cap so something isnt 100% square so idk whats going on but were happy with it for now.

The choke pull off's came in so once those are put on the engines should be good to go for the summer. May post another thread about a slight issue we were having though.