Power loss at 1.5k RPM general ignition issues

[PGlaves]

When the cell in the battery went bad, could it have shorted out/broke the TPS and the O2 sensor?

Not likely

 

[roger 04 rt]

I agree with Paul, it's unlikely to have been caused by your battery.

Do you have a DVM and are you able to measure the TPS and O2 sensor? If you feel comfortable doing that I can walk you through some voltage tests that will confirm whether they are working or not. One of the tests may require removing the tank to measure the O2 sensor connector with it unplugged.

 

[roger 04 rt]

If you want to confirm fuel pump, filter, in-tank hoses, disconnect the return line at the QD (upper hose) and make sure you get a strong flow of fuel coming from the fuel distributor when you turn the key on (press in the check valve first).

 

[blockade]

I agree with Paul, it's unlikely to have been caused by your battery.

Do you have a DVM and are you able to measure the TPS and O2 sensor? If you feel comfortable doing that I can walk you through some voltage tests that will confirm whether they are working or not. One of the tests may require removing the tank to measure the O2 sensor connector with it unplugged.

Yes, I have a DVM and should be able to measure the TPS and O2 sensor but will definitely need some guidance.

 

[blockade]

If you want to confirm fuel pump, filter, in-tank hoses, disconnect the return line at the QD (upper hose) and make sure you get a strong flow of fuel coming from the fuel distributor when you turn the key on (press in the check valve first).

I understand most of what you're suggesting here, will need some clarification on what you mean:

• "...make sure you get a strong flow..." what would a strong flow look like? I assume a weak flow would be pretty evident but it's all pretty relative.
• "...(press in the check valve first)..." I am not sure where the check valve is.

Thanks for all the help.

 

[roger 04 rt]

Yes, I have a DVM and should be able to measure the TPS and O2 sensor but will definitely need some guidance.

Start by measuring the TPS voltage with the key on and fast idle lever off. Measure between pins 1 & 4 on the TPS connector. Note the voltage. It should be about 340 mV.

Then slowly rotate the throttle 1/8 of a turn. The voltage should slowly rise to 5 V.

Next measure between pins 3 & 4. From 1/8 to wot it should rise from 0 to 5 V.

 

[roger 04 rt]

I understand most of what you're suggesting here, will need some clarification on what you mean:

• "...make sure you get a strong flow..." what would a strong flow look like? I assume a weak flow would be pretty evident but it's all pretty relative.
• "...(press in the check valve first)..." I am not sure where the check valve is.

Thanks for all the help.

For the two seconds the pump is on at key-on the flow would be like a faucet fully opened. At idle you should get 2 liters per minute.

The check valve is on the end of the male QD. It blocks fuel leakage when the QDs are unplugged. Pushing it in allow fuel to flow.

 

[blockade]

Start by measuring the TPS voltage with the key on and fast idle lever off. Measure between pins 1 & 4 on the TPS connector. Note the voltage. It should be about 340 mV.

Then slowly rotate the throttle 1/8 of a turn. The voltage should slowly rise to 5 V.

Next measure between pins 3 & 4. From 1/8 to wot it should rise from 0 to 5 V.

Ok Roger, I got the readings you specified at the throttle positions you specified. does that mean that it is the TPS?

I'll be checking the fuel later and will update with those results then.

 

[blockade]

Also, I started the bike with the TPS connector still disconnected, and it ran horribly. Way worse than it does with the TPS connected.

 

[roger 04 rt]

Ok Roger, I got the readings you specified at the throttle positions you specified. does that mean that it is the TPS?

I'll be checking the fuel later and will update with those results then.

If you got the results specified the TPS is fine. What was the TPS reading with the throttle closed?

 

[blockade]

If you got the results specified the TPS is fine. What was the TPS reading with the throttle closed?

Okay, maybe I misunderstood. Forgive my ignorance, should I pull the connector to the TPS and check the voltage there (the connector) or check the pins on the TPS?

 

[happy wanderer]

Okay, maybe I misunderstood. Forgive my ignorance, should I pull the connector to the TPS and check the voltage there (the connector) or check the pins on the TPS?

You check the TPS with the connector in place. You can use a paper clip and slide it down (carefully!) into the top of the connector. My preference is to use speed wire or just a thin wire strand which I sort of trap in the connector by making a "V". Others carefully pierce the wire with a small pin and measure it that way.

Easiest way? Put the negative of the meter on the ground at the bottom of the left hand throttle body and the positive on the pin you stabbed the wire with and that should work fine. Then turn the ignition on but don't start the bike. Take your measurements. Done

 

[blockade]

OK, I did do the voltage check correctly. But retested again to make sure I got the correct values. Everything looks good. Also checked the fuel supply and I'm getting a good stream of fuel.

So about this possible grounding issue? Where do I go from here?

Definitely steping into unknown territory.

 

[blockade]

Don't know if this is helpful, but I uploaded a video of the TAC at idle. You can see the fluctuation in the RPM.

https://youtu.be/MlBTu-u752Y

Some additional info, took the bike out for a spin to see if my poking around has changed anything. Found a couple of of things:

- the hard start is back, but only when the bike is cold.
- the stalling only occurs under load.
- I noticed the starter button wouldn't do anything until I rolled the bike a bit. Almost like it was unsure if the clutch was all the way in.

 

[gsaddict]

Don't know if this is helpful, but I uploaded a video of the TAC at idle. You can see the fluctuation in the RPM.

https://youtu.be/MlBTu-u752Y

Some additional info, took the bike out for a spin to see if my poking around has changed anything. Found a couple of of things:

- the hard start is back, but only when the bike is cold.
- the stalling only occurs under load.
- I noticed the starter button wouldn't do anything until I rolled the bike a bit. Almost like it was unsure if the clutch was all the way in.

\

Oilheads idle that way, normal IMO

 

[blockade]

\

Oilheads idle that way, normal IMO

Good to know, thanks.

 

[roger 04 rt]

OK, I did do the voltage check correctly. But retested again to make sure I got the correct values. Everything looks good. Also checked the fuel supply and I'm getting a good stream of fuel.

So about this possible grounding issue? Where do I go from here?

Definitely steping into unknown territory.

Two questions: You mentioned you got the correct value, but what was the TPS voltage with the throttle closed?

At 1500 rpm, when the engine stumbles, what does the L/R balance look lie between the TBs?

Also is the good stream of fuel on the return outlet from the fuel distributor?

 

[blockade]

Two questions: You mentioned you got the correct value, but what was the TPS voltage with the throttle closed?

At 1500 rpm, when the engine stumbles, what does the L/R balance look lie between the TBs?

Also is the good stream of fuel on the return outlet from the fuel distributor?

1. If you're asking what the value was between pins 1 and 4 at idle, I got 340mv (or more like 352mv).
2. I tried to measue/adjust the TB's at 1500 RPM last night. The bike would die after about 3-5 seconds held at 1500 RPM.
3. I checked the fuel flow at the quick connect. I disconnected the top line, not certain if it was the return outlet. How can I confirm?

The behavior of the stall has changed. Previously the bike would die as I passed 1500 RPM, now it will rev right past it - unless I'm riding it, then it will stall. While riding I can overcome the stall if I rev up to 2500 - 3000 RPM from a stop.

 

[blockade]

Additionally, I ran the bike out of fuel last night while messing with it. The fuel indicator light seems to be out. Not sure if that is symptomatic of a larger issue, but it is new.

 

[roger 04 rt]

1. If you're asking what the value was between pins 1 and 4 at idle, I got 340mv (or more like 352mv).
2. I tried to measue/adjust the TB's at 1500 RPM last night. The bike would die after about 3-5 seconds held at 1500 RPM.
3. I checked the fuel flow at the quick connect. I disconnected the top line, not certain if it was the return outlet. How can I confirm?

The behavior of the stall has changed. Previously the bike would die as I passed 1500 RPM, now it will rev right past it - unless I'm riding it, then it will stall. While riding I can overcome the stall if I rev up to 2500 - 3000 RPM from a stop.

The top line is the return. That means the fuel should have been coming from the Male QD on the left, connected to the short hose, that's connected to the plastic fuel distributor line. Was that it?

Based on what you've measured in the TPS, it is fine. I will suggest some O2 sensor measurements next.