[Heavywrecker]

Starts fine but when it hits 170 it starts to run rough and idle drops and gets worse as the temp get higher. Fans are kicking on at 220 like they should and holds temp. Fuel pump getting hot? Bad sensor? Any ideas I would appreciate

 

[dannoxyz]

Hi and welcome!

Usually electronics are what craps out when things heat up. As test, when cold starting, hit various electronic components with hair-dryer and see what causes idle to get rough. Could be ignition-coils, ECU, harness at various spots, relays, diodes, etc. One of these components is acting up when it gets hot.

 

[Heavywrecker]

Hi and welcome!

Usually electronics are what craps out when things heat up. As test, when cold starting, hit various electronic components with hair-dryer and see what causes idle to get rough. Could be ignition-coils, ECU, harness at various spots, relays, diodes, etc. One of these components is acting up when it gets hot.

I will give that’s shot.

 

[Heavywrecker]

I will give that’s shot.

Think it could be a collapsed breather tube? Pressurizing the tank and the fuel pump staving?

 

[dannoxyz]

Maybe... test by leaving gas-cap open.

With modern EFI and high-pressure pump, clogged breather will actually cause fuel-pump to suck tank into smaller crumpled wad.

 

[tary preisser]

Yes, it will collapse tank, several threads about collapsed tanks (from pinched breathers) OTF
Its easy to pinch one if you've had tank up and aren't really careful about getting tubes routed correctly...from experience.

 

[Heavywrecker]

I’m

Maybe... test by leaving gas-cap open.

With modern EFI and high-pressure pump, clogged breather will actually cause fuel-pump to suck tank into smaller crumpled wad.

left the cap open. Helped slightly but still ended up stalling. Also ran it with cap closed and then opened the cap to see if the was back pressure but there wasn’t. Smelled the exhaust and it’s smells rather rich wondering maybe a MAP sensor is bad or possibly bad injector.

 

[dannoxyz]

use vaccum-T and tap into hose going into MAP sensor.

1. measure vacuum with cold engine. Vacuum = ??? MAP-sensor voltage @ ECU connector = ???

2. measure vacuum with hot stumbling engine. Vacuum = ??? MAP-sensor voltage @ ECU connector = ???

MAP sensor hardly ever goes bad. More likely bad leaking hose going to it. Will cause higher-than-actual load signal to ECU. Thus too much petrol.

Also measure IAT & ECT resistance at room-temp and boiling.

 

[Heavywrecker]

use vaccum-T and tap into hose going into MAP sensor.

1. measure vacuum with cold engine. Vacuum = ??? MAP-sensor voltage @ ECU connector = ???

2. measure vacuum with hot stumbling engine. Vacuum = ??? MAP-sensor voltage @ ECU connector = ???

MAP sensor hardly ever goes bad. More likely bad leaking hose going to it. Will cause higher-than-actual load signal to ECU. Thus too much petrol.

Also measure IAT & ECT resistance at room-temp and boiling.

Wouldn’t they be the same regardless of temp? Not a bike tech so I would know. But warmer air would be thinner I suppose.

 

[dannoxyz]

no, those sensors are critical since they tell ECU about environmental conditions. Cold air has more O2 density than warm. Sensor readings are completely different depending upon temperatures. Same with ECT. In this case, perhaps sensors aren't responding to temperatures properly and ECU isn't adjusting for temp/changes properly.

Follow manual's procedure for testing every sensor and it'll be obvious what problem is.

Do MAP vacuum test 1st since it doesn't require voltmeter. Seems to scare people off.