2005 150 TPS Questions

[CodeBlue]

New to me 2005 Yamaha 150 TXRD (550 hours). Runs great except that at WOT max RPM is 4500 (should be 5-6k). Could just be the current prop (PowerTech 4 blade 15.00 x 15 [ELE4-Y]). Before I go down the rabbit hole of props I wanted to ensure I wasn't overlooking a mechanical issue. Compression is good. I'm in the process of refurb the injectors. Results from my laptop are below (cold engine, engine off with throttle in idle position and then again with throttle at WOT). Visually, the throttle body butterflies are fully open when throttle is WOT. Atmospheric pressure is verified correct. I noticed TPS voltage/position to be out of spec. Could this be a source of my low WOT RPMs?

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[boscoe99]

Yes, the TPS could be the problem.

But don't just throw a TPS at the motor. First verify that the voltage to the TPS is correct. At idle and at WOT.

[CodeBlue]

Yes, the TPS could be the problem.

But don't just throw a TPS at the motor. First verify that the voltage to the TPS is correct. At idle and at WOT.

Hope I understand what you were asking to verify.
I measured the voltage from the plug that goes to the TPS. With throttle at idle 5.02v. Moved throttle to WOT and same reading at 5.02v

I assume we were testing to ensure the ECM was supplying the TPS with adequate voltage, which it looks like it is. Does this mean the TPS should be adjusted or needs to be replaced?

[boscoe99]

Yes. I was referring to the input voltage.

Try adjusting it and see what happens.

You might also want to inspect/test the ground lead wiring.

[CodeBlue]

Yes. I was referring to the input voltage.

Try adjusting it and see what happens.

You might also want to inspect/test the ground lead wiring.

Ground lead wiring has continuity to the battery.

To adjust (rotate) the the TPS, it looks like I may also need to adjust the throttle stop screw and then further require the throttle valves to be sync. Can the TPS be adjusted without messing with throttle valve sync? or do I need to purchase a manometer to sync them.

[boscoe99]

New to me 2005 Yamaha 150 TXRD (550 hours). Runs great except that at WOT max RPM is 4500 (should be 5-6k). Could just be the current prop (PowerTech 4 blade 15.00 x 15 [ELE4-Y]). Before I go down the rabbit hole of props I wanted to ensure I wasn't overlooking a mechanical issue. Compression is good. I'm in the process of refurb the injectors. Results from my laptop are below (cold engine, engine off with throttle in idle position and then again with throttle at WOT). Visually, the throttle body butterflies are fully open when throttle is WOT. Atmospheric pressure is verified correct. I noticed TPS voltage/position to be out of spec. Could this be a source of my low WOT RPMs?

What are you seeing that is telling you that the TPS is out of specification? This is an F150TXRD correct?

[CodeBlue]

What are you seeing that is telling you that the TPS is out of specification? This is an F150TXRD correct?

Correct F150TXRD

The out of spec or what I though was area of concern was from data in the table in my first post. At WOT TPS was 3.994v and throttle valve opening was 82.4 deg (I believe it should be 4.5v and 90deg at WOT)

[TownsendsFJR1300]

From Rodbolt, 2016

11-26-2016, 03:11 PM
there are actually two newer methods.
there is a tech bulliten on it.
but basically what Boscoe said.
while a laptop with YDS and a tech-mate vacuum mate makes it go easier.
I had to do my 07 F150 back in 07 way before Yamaha came out with any words about it.
something about maneuvering around my dock aand the motor stumble and stall and that annoying stall alarm that alerted all my neighbors that my motor just stalled.

this while wearing a Yamaha master tech ball cap.

my first attempt was successful but took me about 6 hours.
only tools I had was the one between my ears, a multimeter and some paper clips.
my procedure was basically increase the idle speed using the idle speed screw.
I think I opened it to a TPS reading of about .8V.
then I loosened the TPS and moved it to a value of about .7V.
I had to play a bit.
but when I was done I had a stable idle at about 700 RPM and no more stumble/stall at low speed throttle movements.
took it to the shop and recorded an ISC request of about 40%.
the original setting had it at 60-65%.
I showed the other techs at the shop how to do it.
that was about 3 yrs before any words from Yamaha but most 09 and older F150 motors suffered from this stumble/stall until the sync was redone.

now this procedure is only done AFTER the motor is running correctly. it wont help anything but the annoying stumble/stall just off idle.

I think a guy named High Sierra had an issue that I beat on for days until someone did it.

[CodeBlue]

Thanks TownsendsFJR1300. I read that long post from High Sierra/Rodbolt. It seems that main purpose of that post was to fix a stalling and off idle issue. Are you suggesting that Rodbolt's solution would possibly help with my concern?

To recap, my concern is a max WOT RPM of only 4500rpm (should be 5-6k RPM). This could simply be a prop issue but I wanted to ensure I wasn't overlooking an engine issue.

[boscoe99]

Here is what data I could come up with.

[CodeBlue]

Thanks boscoe99! The table with Fully closed and Fully open specs confirmed my TPS is within specs. My service manual was only showing specs for Fully closed.

[pstephens46]

Just to confirm. You have a 15 pitch prop with a 15 inch diameter?
4 blade to boot? Seems like a lot of metal to swing. My F150 HAD a 18 pitch 14 1/4. Ran 5900rpm. What type of boat and weight? My boat weighs around 3300 lbs with no bodies onboard.

[boscoe99]

Just to confirm. You have a 15 pitch prop with a 15 inch diameter?
4 blade to boot? Seems like a lot of metal to swing. My F150 HAD a 18 pitch 14 1/4. Ran 5900rpm. What type of boat and weight? My boat weighs around 3300 lbs with no bodies onboard.

I am a nobody. Am I onboard your bote?

[99yam40]

I have a feeling Boscoe is bored and drinking

[pstephens46]

Roscoe is invited most anytime!