E48 acting crazy. Any ideas?

[sutor623]

Hey guys. E48esledc. '96 48spl

Got a buddies motor Im trying to help him with. When I first saw the video he sent me, I said "I got this, its a timer base or damaged flywheel." But than I indexed the flywheel, and timing is SPOT ON!! When the motor acts up, each cylinder is only firing when it is supposed to be firing (according to the timing gun and indexes on the flywheel.

I pulled the temp sensor wire and it didnt change anything. Rectifier tests fine, and is not the cause.

The powerpack has already been changed prior to me getting this motor. The issue is when I get the motor to start acting up, I walk around to the back of the boat to put the dva meter to check stator and powerpack output, and the motor RUNS AWAY!!! It will try to run til it blows.

Idles like a happy kitty cat, so cranking DVA will not show the issue.

Stator and timer base are only $50 each. I was going to pull the fly, make sure it isnt damaged, then just change out timer and stator for a whopping total of $100, and have my buddy well on his way.

Here's a vid of it acting up. Only happens at 2000rpms and up.

 

[sutor623]

Oh one other thing. For the first 2-3 mins it doesn't do it so I think the ignition parts are heating up causing it.

 

[58rude]

Have you tried testing them after it runs and starts acting up?

 

[sutor623]

Have you tried testing them after it runs and starts acting up?

Yes but it won't show the fault unless I increase the rpms to where I get uncomfortable running it in a test barrel. It tries to run away on me so I can get it to duplicate while I'm comfortable testing it. I did get w timing light on both cylinders during the fault and they are not cross firing. I may put a shop tach on each cylinder during fault and see what is causing this? I could've sworn it was going to have erratic firing with the indexed flywheel.

 

[sutor623]

Also checked blocking diode and it tests ok.

So far I have ruled out fuel pump, powerpack, blocking diode, temp sensor and rectifier. I am also pretty sure that the timing sensor is good to go because I have indexed the flywheel and both cylinders are firingat their proper time. I am thinking it is stator. Any input?

 

[AlTn]

was it doing this prior to the new power pack installation and the new pack fixed it for some period of time?....or was the new pack a shot in the dark fix that didn't work?

 

[sutor623]

Dealer Threw a powerpack at it to try and fix it, with no resolve.

 

[AlTn]

k..and it will go to a runaway w/o any throttle movement from the controls?...just thinking ...the hopping and skipping in your vid appears to be ignition related and a runaway condition is gonna require a fuel component as well...so yeah...looks to me like you need to check the ignition out puts w/o the motor running, using the starter only... if all good then take the ignition switch side out of the equation...if these are good, go to the fuel side including the primer and reeds, then check for air leaks into the crankcase...it's a "dandy" for sure

 

[sutor623]

Yea I'm with you. I told my friend that I would be happy to start from square one and get the ignition system squared away, but that there was a good chance there was a leak somewhere into the crank case or the fuel system whether it be intake mani, reeds etc.

The only time it will runaway is when it is in neutral, and I rev up to about 2000rpm. It starts to bounce back and forth and will start screaming before you know it. I have to double check, but I am pretty sure that the idle lever isnt changing position while this is happening. When the motor is in gear, it will act like it did in the video. It wont try to run away, but just jolt violently. Only time I have seen this happen before is with a toasted charge/power coil on the stator.

I think I am just going to disconnect the throttle linkage so I can control it from going crazy right by the motor.

I hate working on friends stuff, and it just becomes one thing after another.

 

[WernerF]

Flywheel key sheared? Check #1 piston position against timing pointer.

 

[sutor623]

Flywheel key sheared? Check #1 piston position against timing pointer.

Im going to pull it tonight and check, but the timing is not being erratic, it is spot on. Plus it runs well at 1000-1500rpms so I would imagine that wouldnt happen with a bad key.

 

[sutor623]

So some new info that I just received. Motor ran great for a number of trips. Took a trip a couple weeks later, took off running good for about 300 yards, and then started acting up, and been doing it ever since.

 

[AlTn]

k..well if the voltages out of the pp are good, I'd look closely at that coil and the ignition wires to the plugs

 

[sutor623]

10-4 I'm going to disconnect the throttle linkage and put it on a dva meter tonight. That way I can be right up on the motor and keep it from trying to run from me.

 

[sutor623]

Ok, update. I am pretty sure that I have isolated the issue.

Firstly, I disconnected the throttle linkage so that I could control it at the motor and prevent it from taking off.

Timing is advancing properly. I put the timing light on cylinder 1, and right when the motor starts to act funny I have dropped/ intermittent spark on cylinder 1. Moved the timing light to cylinder 2. It does the SAME THING. I put some test leads onto the brown and brown/yellow wires on the stator and hooked up my DVA meter. DVA is 200V and climbs to 280V at about 2000rpms, then it happened!! The motor started doing its skipping around thing, and the DVA dropped down to 100V, and sometimes even 0V!!!! The stator is failing at upper RPMS preventing voltage from hitting the power pack and so-on.

You guys agree? CDI says these motors will typically only drop spark on BOTH cylinders at RPMS if it is a fault in the stator.

 

[AlTn]

from the engine diagrams, it appears you could remove the stator and it would still have the charge coil and trigger under the flywheel....can you try running it w/o the stator in place for troubleshooting purposes?

 

[sutor623]

Sorry, the charge coil is what the brown and brown/yellow wires I tested are. That is where I believe the issue is. Without that the motor won't fire at all

 

[AlTn]

right...if the trigger is providing ~.5 v consistently then the charge coil is the last suspect standing

 

[sutor623]

Thanks, yea while I'm in there I am just going to replace the charge coil and timer, for good measure. For research sakes, even if the timing sensor were bad it wouldn't change the output voltage of the stator while hooked up to the brown leads would it?

 

[AlTn]

looks completely separate to me