F115 shutting down

[fishon195]

CAN anyone help out with a 2001 F115 shutting down like turning the key to off symptom while running on plane or even idle . Motor will restart after 10 mins or so. I have been chasing a delayed starting problem (4 seconds to fire after key start) for about a year, and now has evolved into this problem ,
Checkd all fuel ideas, replaced both fuel pumps, cleaned out VST, cleaned out injectors, filters, replaced primer bulb, tank fuel line, all this over 6 months, SO now I think I should look to electrical like the stator or the rectifier, Would the computer check show anything? Doubt it! Could the stator be slowly breaking down after 11 years?
I got a service manual but unclear as to how to check the stator for resistance and if this reading is good I heard it could still be bad. Any ideas are grateful?

[99yam40]

If you can hook up a computer then do it, but not sure on your motor if you can. Service manual should say if you can.

Taking peak voltage readings like manual states and comparing to specs is better than ohms.

Did you try monitoring the fuel pressures to see what was going on with the fuel system? monitor high and low/medium pressure simutaniusly at problem

[fishon195]

All fuel pressures normal, no access to computer (probably gonna have to take it in)but I doubt it will show anything for any sudden power loss like this. Im really thinking stator at this point.

[99yam40]

You need to have computer hooked up while problem shows up was my thinking or monitor pressures while it happens.

[fishon195]

Takin a chance on a damaged newer F115, I was able to find a used stator and other parts off a 2008 F115 for $150. Picked up the spark coils too for half price. Will install this week. If I was to pay a mechanic around here 95 an hour to do the same thing, why not take a chance on a used part.

[99yam40]

You can test and find problem or spend money on parts and hope

[rodbolt17]

carefully test all electrical conections starting at the battery terminals.
why would you think its a stator issue?
that engine will run without the stator and 1 pulser coil missing.
the ign system relys on 12v and the pulser coils tell the ecu when to shut off primary current.
its a TCI waste spark system.
at shut down,touch nothing.
lift the hood and check primary ign coil voltage,injector voltage and fuel pump voltage.
basically any yellow/red wire for 12v.
the ecu turns the main relay on or off depending on key switch signals.
if the ecu fails or the main relay fails or you lose 12v to the relay the engine quits due to no spark,no injectors and no fuel pump.
if 1 of the 2 pulser cols fail the ecu defaults to fixed timing,idle speed increases and top speed cannot be reached but it wil still run and spark all 4 cylinders.

[fishon195]

Thanks for the response Rod, red this after replacing stator, glad i got a deal on it, I read in other forums that a stator will shut down a motor, but i guess not this one, because exact problem still there.
I thought the stator produces the voltage for the coils to produce spark.

Ok So ill check for 12v after shutdown at yellow/red wire at injector is the easiest spot for me,
Also seems that the motor (after warmup) is looking for a good idle speed, flutters between 6rpm and 9rpm but never settles, maybe the TPS,

[fishon195]

Ok so I reproduce failure in driveway. Tested voltage at the yelow/red wires after failure, voltage was 1.08V after I figured out i should pierce the insulation instead of takin the plug apart.



Idle speed seemed to be a little more stable

[fishon195]

Okay Things are becoming clearer, Double checked myself finally found injector wires and fuel pump wires Duh??
Had 14v before failure and 1v or so after? IS this a power relay? , So now I gotta check the voltage coming outta the power relay at failure? Right?

[fishon195]

!V

Checked the 2 red/yellow wires at the plug to the main relay (thinking 1 is input v and other is output V) before n after failure but both drop to 1.0V. I thought maybe there might be one wire with good voltage so i cud say the main relay is bad!!. Am I thinking straight?

[rodbolt17]

bummer.
remember
when you turn the key on. the ecu now wakes up.
the ECU now applies the ground path for the main relay.
at shut down the process is reveresed and the ecu toggles the ISC in anticipation of the next restart.
carefully test eveything.
you may be the one of the few with an ECM failure.
but the F115 does NOT use any stator inputs for ign.
it uses a TCI ign as oppossed to a CDI.

[fishon195]

You don't think that the reg/rect could be draggin everything down. i an get one of them cheap, but the ECU gonna be $942

[fishon195]

Problem ended up being the main power relay dragging down the 12v on the harness and on the ECU. Thanks Rod for all your help.