Another 1997 gtx ignition mystery

[ltbordo]

Looked all over for a summary of this unusual ignition system and can’t find in on the threads or web in general.

this system does not spark to ground but between the plugs, fires both plugs at the same time, has the coil continuously grounded and is fired by a pulsed 15Vdc signal from the MPEM that it has amplified from a standard magnet and coil trigger mounted along the stator?

this is very different to a traditional 12 Vdc fed coil triggered by a pulsed ground signal from a triggering device firing the spark plug to ground

I have a weak intermittent spark and cannot figure out a way to bench spark test the coil to eliminate it as a bad part. Just taking resistance measurements is not conclusive enough for me to rule it as a good coil or bad coil.

Can any guru out there explain this system to me and give me a way to bench spark test the coil through the wire,resistor cap , and plug using a 12 Vdc motorcycle battery?

All the old components are lying on the bench ready to go.

john in Roswell Ga

 

[ltbordo]

Mystery solved! Thank you Stephan Morrell of the forum!

Both the CDI module in the MPEM box upfront and the coil in the black box in back are poorly grounded. But that I mean one 14 gauge wire feeds each box from an indirect non-battery ground and supplies grounds via a shared post with one plastic screw holding the terminals together.

Supplying direct grounds to these posts both upfront and in back directly from the battery brought a consistent spark back. Once I put in a fresh coil and wires it was a consistent bright blue spark in the daytime!

 

[ltbordo]

The white wire at the coil was always giving a pulsed 10 V DC signal but without good grounds to the components the ignition system was not strong enough to fire the plugs consistently

 

[ltbordo]

Here she is

 

[vogs77]

Is that a picture of the spark jumping between the 2 wires. I am currently dealing with intermittent spark issues on my 96 GTX. I will check those grounds you mentioned in your post. Thanks for sharing you info also.

 

[ltbordo]

Call me! I’m gonna pay this forward! Stephan Morrell took me under his wing and walked me through this

John 6783607655

 

[etemplet]

I'm curious where is the plastic screw that holds the grounds together?

 

[ltbordo]

I'm curious where is the plastic screw that holds the grounds together?

In the front white box on the cover There is a metal plate with two posts on it, each one has approximately three ganged grounds held on by at 10 mm bolt

 

[ltbordo]

In the front white box on the cover There is a metal plate with two posts on it, each one has approximately three ganged grounds held on by at 10 mm bolt

In the rear black box one of the bolts that holds the coil gangs three grounds together as well

 

[ltbordo]

I'm curious where is the plastic screw that holds the grounds together?

 

[ltbordo]

I'm curious where is the plastic screw that holds the grounds together?

Not a plastic screw, sorry, metal screw screwed into plastic on the rear box and 10 mm bolt into a metal plate in the front box

 

[vogs77]

Thx for pics

 

[etemplet]

Yes thanks for the pictures I was wondering. Probably a good idea to put a real ground on those.

 

[ltbordo]

it restored consistency....the new coil and wires provided the bright "blueness" and the ability to arc nearly a full inch! Do we really need to run resistor caps AND plugs? (thats nearly 10K ohms of resistance) and makes for a very weak spark at the plug with a 2mm gap

 

[etemplet]

If I remember correctly resistance with the caps on is like 13 -15k. The skis work so as long as they run I don't care. Seadoo knows what they are doing. Most of the time. Ha ha

 

[ltbordo]

lol, I agree with you! The engineering on a 25 year old item operating in the water environment is pretty impressive.

there are 5 k and 10k caps for these units. I have 5 k caps as indicated by the part number and 5k plugs from measuring the plugs themselves.

 

[etemplet]

Sometimes the troubleshooting gets interesting that is for certain. We all have our stories. Glad you got it done.

 

[mikidymac]

I honestly haven't looked at the seadoo caps but it is typical that you either have resistor plugs or resistor caps, not both. As seadoo's require BR8ES plugs that are resistor plugs, the caps shouldn't be resistor caps. At least this is what I have always understood.

 

[ltbordo]

I honestly haven't looked at the seadoo caps but it is typical that you either have resistor plugs or resistor caps, not both. As seadoo's require BR8ES plugs that are resistor plugs, the caps shouldn't be resistor caps. At least this is what I have always understood.

me too! I think it should be one or the other.

Having both (new resistor caps and new BR8ES resistor plugs) turned my big blue inch long spark from the new plug wire ends by themselves to nearly nothing at the spark plug gap.