2004 GTI LE RFI bogging stalling after 5-10 min X2

[NIL8er]

x2-- have 2 2004 GTI LE RFIs rebuilt with exact same running issues . Starts on first click of button runs great for about 10 min then bogs down and dies. Will starts right up again after 10-15 min run for 10 then same .
New batteries
all good grounds
New OSD heavy duty 4tec rectifiers
rebuilt motors, compression good
new plugs.
trimmed plug wires
running rich per black sooty plugs(dry)
fuel tanks air vent patent

What else can cause too much fuel/ weak spark (not igniting the fuel)
I know coil pack is unlikely but possible(How to test?)

I wouldn't think fuel pump would cause a rich condition? Gotto be voltage /spark issue?

 

[POPPS]

Could be weak compression,,,sounds nuts,,,but I have had motors where the rings did not seal,,,chased the issues for months,,,weak coil,,,I’d just swap parts,,,but you said they both do the same??,,,impossible honestly,,,could be excessive Rotary valve clearance.

 

[NIL8er]

compression 160 each hole, sorry i thought i put that. and yes EXACTLY same cut off times and symptoms for both 2004 GTI LE RFI total motor rebuilds. rotary valve is timed correctly and clearance is within specs.

I pulled the position sensor ant there was pressure from the case is the flywheel cover area supposed to be under pressure?

 

[POPPS]

Nope,,,last time I pulled an rfi…this spring…no pressure,,,,maybe front seal is leaking,,,??

 

[NIL8er]

shouldnt be, its new. But who knows at this point. im thinking since the common factor is me that assembled these motors. I wonder if its something i did wrong assembling them. I followed all the torque specs,

 

[POPPS]

Hhmm…mind you I did not pull the sensor,,,left in tact with the front cover,,,and have only done one this past spring,,,just doesn’t make sense,,,

 

[NIL8er]

Hhmm…mind you I did not pull the sensor,,,left in tact with the front cover,,,and have only done one this past spring,,,just doesn’t make sense,,,

Followed all sealing compound recommendations per service manual. No water intrusion in motor.

So charging system is in question. 12.4 v cranking and doesn't increase with increased RPM. New rectifiers OSD so I suspect the stator can't provide enough support to the electrical system to increase spark with extended use it prob floods(although plugs are dry but black soot). I Guess I get a good known stator and try it on one. Anyone know how to test the stator while on it

 

[POPPS]

Take the time to check out your stator,!,,,basically,,,bypass the rectifier,,,start the machine and check the AC voltage coming out of the 3 yellow charging pairs in total…you can put black sharpie on them,,,1,,,2,,,,and 3…pair up 1.
and 2,,,then 1and3,,,then 2 and 3…the manual better explains,,,if it is putting out to specs,,,then you can eliminate the stator,,and therefore the rectifier will be the culprit.

 

[NIL8er]

Take the time to check out your stator,!,,,basically,,,bypass the rectifier,,,start the machine and check the AC voltage coming out of the 3 yellow charging pairs in total…you can put black sharpie on them,,,1,,,2,,,,and 3…pair up 1.
ghe manual better explains,,,if it is putting out to specs,,,then you can eliminate the stator,,and therefore the rectifier will be the culprit.

THANKS! I'll do that !Obviously that's my next move! Rectifiers are new OSD heavier duty than OEM.

 

[NIL8er]

Take the time to check out your stator,!,,,basically,,,bypass the rectifier,,,start the machine and check the AC voltage coming out of the 3 yellow charging pairs in total…you can put black sharpie on them,,,1,,,2,,,,and 3…pair up 1.
ghe manual better explains,,,if it is putting out to specs,,,then you can eliminate the stator,,and therefore the rectifier will be the culprit.

stator checks out.
Black dry soot plugs definitely means Rich for these?
If it was rich wouldnt the plugs be wet with gas and have gas smell(not wet or gas soaked)

 

[mikidymac]

Black and sooty could also be carbon from being lean. Typically a rich plug will be black and wet.

 

[NIL8er]

air temp sensor resistance is .96, water temp resistance is .92 but its 95 degrees outside the specs are 2.8-2.73 in 70 degree weather. Does temp matter that much?

 

[NIL8er]

Black and sooty could also be carbon from being lean. Typically a rich plug will be black and wet.

View attachment 59880

My thoughts are its rich and the spark gets weak after heating up? Coil, water temp sensor, air temp sensor

stator checks out , rectifier is new , battery is new,

only charging to about 12.11 with 3500 rpm though. does not increase voltage with RPM up to 5500

OR if what you say is also correct( i have no doubt, you seem to know these well) then its fuel starved , which is what it sounds like while riding after 5- 10- min.

So do i chase electrical or fuel systems?

 

[mikidymac]

At only 12.11V at full rpm you are not charging, either the regulator or stator is having issues.

 

[NIL8er]

At only 12.11V at full rpm you are not charging, either the regulator or stator is having issues.

I concur but the rectifier is new OSD and the stator checks out with Manual testing procedures. so I'm stumped Obviously

 

[NIL8er]

so as i stated the air temp and water temp sensors only show resistance of .96 and .92 while 90 degrees outside.
Should be 2.86-2.374 with 70 degrees ambient temp . any thoughts on this.

i have not reinstalled the hull air flow tubing , could that be a problem I wouldn't think so but IDK.

 

[NIL8er]

just rechecked battery while rev to approx 3500-4000 rpm and voltage does increase from 12.14 to 12.44.

 

[mikidymac]

Any new rectifier can be bad. I would buy one of the cheap ebay/amazon ones to verify but make sure it is shipping from the US. not China.

12.14-12.44 is not a working charging system. You should be seeing 13.5V at 4,500 rpm.

 

[NIL8er]

Any new rectifier can be bad. I would buy one of the cheap ebay/amazon ones to verify but make sure it is shipping from the US. not China.

12.14-12.44 is not a working charging system. You should be seeing 13.5V at 4,500 rpm.

i have 2 NEW OSD 4 tec rectifiers and have and tried them both. There higher output and highly recommended.

 

[NIL8er]

am i understanding this right. If charging system isnt up to par then over time (5-10 min) the ski losses its ability to adequately produce the spark to burn the fuel. ???

 

[mikidymac]

Yes, the RFI and DI are power hogs and will loose spark if under 12V.
With the voltages you are showing you are running on battery voltage only, not charging.

 

[NIL8er]

Yes, the RFI and DI are power hogs and will loose spark if under 12V.
With the voltages you are showing you are running on battery voltage only, not charging.

Sounds like stator is not working properly but is within spec on all tests in manual?

What do you know about the water temp sensor and air temp sensor with the .94. .92 resistance readings? per manual testing procedure. Can one of these or both of these cause a rich condition? ie they malfunction and cut out spark or reduce spark
also the readings all are within normal range for the stator per manual testing procedures.

 

[mikidymac]

Yes, I have seen stators test fine but still not work.

Honestly I would try the cheap rectifier first.

Not sure on the sensor values.

 

[NIL8er]

Yes, I have seen stators test fine but still not work.

Honestly I would try the cheap rectifier first.

Not sure on the sensor values.

ive put 2 OSD rectifiers in it Im confident its not the rectifier. Thats 4 different rectifiers 2 new high quality and 2 oem. I think its the Stator. If not mpem is in question.

 

[NIL8er]

At only 12.11V at full rpm you are not charging, either the regulator or stator is having issues.

whats a good stator manufacturer for these units