Blown Inductor on distributor to coil cable

Hello guys and girls.

Im a novice when it comes to electrical systems and i really need some help. (im from Norway btw so bare with me on my english)

I have a (TBI) GM 350 GI (PDMA) Volvo Penta (boat motor). And after FINALLY getting that son of a gun motor running by changing the ignition module it broke down again. It ran like a kitten for aprox 20 mins and suddenly started dying on me. Started it up again and died almost right away. Third time it was dead and smoke came rising from the engine room.

The wiring to the scanner contact was poor an had desolving insulation under the tape. All have now been fixed and put together again. Tried starting it up again and realized that there was no fuel again (same problem i had first time) so i jumped on ebay an bought a new ignition module again.

Installed that and got my fuel spraying again. But it seems i dont have spark.

Took of the cable going for center distributor and put a wire between coil cable and ground. I had to almost put the cableend all the way in the socket to get spark. It was a very weak spark. Maybe i did something wrong here. Idk.

But my real problem is this. Now the inductor or whatever it is, located on the pink (12 v) wire going from the ignition module to the coil burns up.

I was lucky enough to have an extra cable and installed that along with a new coil. So after cranking the engine once, just after letting go of the cranking, the new cable (inductor) burns up.

This is where im at. And i have asked numerus boat repairshops but no one can help me. So im quite desperate.

To narrow down questions - i have done proper tests (short to ground and open circuit tests) on coil and pickup coil. both is in perfect condition when it comes to these tests.

what i cant understand is that power going through primary circuit in coil and then to the icm is too high (guessing is too high) of voltage that an inductor blows...

could it be possible that power coming from alternator or any other place can have a spike in voltage ?

help is REALLY appreciated

TKS

Sounds like either short to ground on the coil to ICM wire or the ICMs coil driver stuck on.

Thanx For Your input Matt T.

But i dont think so.

The wire that goes from the coil to the ICM is about 30 - 40 cm long. there is no short to ground.

Now i have gotten the correct workshop manual for the engine and if i understand it correctly the blown inductor is not acually a problem that is normal. its not mentioned one place in the whole book. but its drawn in on the circuit drawing.

so what im thinking is that somewhere in the power supplyline that ends up at this conductor must get a spike in voltage of some sort.based on the drawing and my understanding of it, it looks like the power goes from the battery, to the alternator, then to the coil and finaly to the icm. i have changed the coil before blowing two inductor cables. my main syspect at this point is alternator or coil.

i wil try to post a few pics of the drawings.

Paul Danner - i need your guiniusness

Here are some pics that might help.

I would have to say to check your coil resistance feom secondary side to primary side and see if it's shorting to primary and cooking your icm. Otherwise check wires from icm back to pcm for bare spots contacting other wires or pinched between brackets. To me it sounds like your coil is the issue.

Thanx Hardtop.

im thankful for all tips and trix.

When thats said i have tested open cuircuits and short to ground on three coils. (2 old and the 1 new one) all are fine. i have also tested the pickup coil same way. all good.

I can only think of three sources that could give as high voltage that an inductor blows. Alternator, coil or the inductor itself by inductor knockback. but i cant see that the last one is the issue. this is designet this way.

I just have to keep checking those boxes off. one by one.

i think im going to bring my alternator to a company that test them. put it in a bench and see if a read will reveal anything.

thanx for all tips.

Hardtop - ive done these tests. (pickup coil, coil and the 12 v B+ test)

Ok the only other thing i can think of would be the harness is not connected correctly for icm or wires for icm not hooked into connector in the right order/pin placement. Or the pcm has a short in it leaving icm on to where it burns it up. Otherwise a bad ground. This has me scratching my head as well.....

Did you put dielectric grease on the icm metal plate to distributor mounting surface after cleaning up distributor surface?

Thanx Hardtop, its a pickle for sure.

first off.... The stuff you put under the ICM is not dielectric grease. its a silicone compound. the ground in the ICM is in the screws that mount it to the aluminum plate. the silicone compound is to stop the heat from the engine to reach the ICM. its veary of heat.

when thats said.... i have solved the problem. but im not sure what i did.

after blowing two cables (with the inducter on it) i took another round asking ANYONE who had some knowledge about this type of engine. in the discussions we all agreed on it had to be in the isolated power circuit from the battery all the way to the ICM. the general notion was that i had to be a source capable of generating high Voltage. in other words. either the alternator or the coil. i have dubble up on most of the engine equipment so i switched back to the old coil and changed the alternator.

got the new cable yesterday, plugged it in (along with the new ICM which blew up along with the cable) and the engine startet right up. ran like a kitten. and NO blown cables.


The engine was the n testrunning for 30 mins yesterday and 30 mins today.

threw the boat on the water and drove for 10 mins and the engine died.

started a few times but now its all dead.

so.... symptoms..... no blown cable. which is good. but it seems i have my original problem back again.

Last time my injectors stopped spraying the problem went away after changing the ICM. so im curius if something kills my ICM. what can that be?

This motor is starting to be a problem child. but im hell bent on finding the frikkin problem.

all a ideas will be considered.

PentaV8

I hate to say it but pcm is the only common denominator due to it getting most of the wires from pcm/ecm. Open the pcm up an look for damage (water or burned spots). Take a pic too so we can see.

Ill see what i can do. ill take some pics.

BUT, i have now been talking to a few experts. and both tells me that i have a wiring problem. my ICM is burning up somehow.

my coil side on the ICM is still good. that tells us that our problem is on the ECU side. BUT, we also have ground. i have now been instructed to check 3 things.

#1 go over the 4 cables that comes from the ICM on the ECU side and check voltage readings

#2 check for power leakage into ground (from the ICM)

#3 If leakage into ground find the leakage point.

There is a fair reason to think one of these will get me to the real problem.

the problem has probably been there from when it was rebuilt. has never run longer than an hour before ICM dies. i think ive killed 4 or 5 ICM`s since i tried starting up this engine 1,5 years ago.

i will post my findings.

And Hardtop.... i have two ECU`s both acts the same. dont think the ECU is the problem. it might convey a bad voltage (dont know if its possible) but it doesnt create it.