Yamaha F150XA Hissing Noise

[slads5874974]

I have a hissing noise coming from the intake area on my Yamaha F150. Any thoughts on what this could be?

Video of motor and sound here:

https://vimeo.com/217325790

The motor is definitely not running well. Compression is good on all cylinders. Leak down test performed with no issues. All valves are set at TDC.

There is an electrical issue going on. I haven't figured that out yet. I will get another three going on that issue once I get my head wrapped around that issue.

Looking for thoughts on the hissing sound first. Anyone out there have any ideas?

thanks

[pstephens46]

You are in process of rebuilding this motor?

[slads5874974]

Yes, pretty much. More so with the electrical components. Not the powerhead or cylinder head. Fortunately everything in that department is to spec per the service manual.

Just can't figure out this hissing noise. I have more test to perform from the service manual. Hopefully it will help out at some point.

[99yam40]

could it be the idle air control valve?
It has to let air in while idling

[TownsendsFJR1300]

Mine does not have that sound however it sounds like a positive pressure leak.

With it idling, spray some soapy water all around the intake, valve cover and start looking for bubbles... (very little at a time)

Almost sounds like an automotive exhaust manifold leak....

It seems to idle fine, I would say look real hard at all the induction parts (plastic manifold) for cracks, loose/missing bolts..

Short of the sound, how is the engine mis-behaving?

[slads5874974]

Well, I took it a little further this afternoon/evening. I removed the intake manifold completely. Wanted to inspect the rubber gaskets maybe find a crack or something in the plastic. everything looked pretty good.

So I reinstalled everything properly. But something new has developed and its making me think there is something with the Idle air control. The hissing still there though, but now engine idles EXTREMELY high. Like REALLY high. I stays at high idle for a few seconds and then it to backs down, but still very high idle once it does back down.

I am not sure what happened. Going to take a break and work on it tomorrow. I feel like I am making bad decisions. Start fresh in the morning. I will take video tomorrow of what occurs with the extremely high idle.

Not sure why all the sudden its idle so high???

I am thinking I should bench test the Idle Air control tomorrow just to confirm that nothing is wrong.

thoughts?

[rodbolt17]

I will save you some time.
other than motor resistance tests there are no bench tests avalible .
if you have an intake leak you will see an abnormally low ISC% request and an abnormally high intake air pressure.
if an injector is not firing/flowing you will see an unstable idle and an abnormally high ISC% request.
if any sensor is out of range or unplugged you get high idle locked base ign timing and a high ISC request.

now is where you need the laptop.

[slads5874974]

I will save you some time.
other than motor resistance tests there are no bench tests avalible .
if you have an intake leak you will see an abnormally low ISC% request and an abnormally high intake air pressure.
if an injector is not firing/flowing you will see an unstable idle and an abnormally high ISC% request.
if any sensor is out of range or unplugged you get high idle locked base ign timing and a high ISC request.

now is where you need the laptop.

Good info! Thanks very much, rodbolt. So the ICS is ridiculously hot when the motor was running. I pulled the Sensor and tested it with power to the middle prongs, and tapping the ground on and off connected to the outer prongs. Nothing moved. It tried to move, but seemed stuck. I am assuming that the its no good anymore? Sure is a pricey little sensor, sheeeesh.

I just hope that my ECU isn't bad now. I have read that this issue can damage the ECU at some point with overheating.

Rodbolt, I need to order the YDS and cable. Any suggestions where to purchase? Any downloadable software for fast access?

I will keep everyone posted on the hissing noise. Its still there. I am really nervous that its something with the intake valve, specifically #3 cylinder. I pulled the Cylinder head cover and the noise is coming from inside the intake valves area. Just don't get it though, leak down test doesn't reveal anything and shows a solid seat.

Going to pull the manifold again and run a leak down again and watch the valves at TDC to see if there is something I am missing.

Let me know if you have any other ideas (i will get the YDS and cable, but something tells me that its not going to help with the intake leak)?

[TownsendsFJR1300]

When you did the leak-down test, the cylinder being tested was at TDC on the compression stroke correct?

For S&G's, with the valve cover off, check your valve clearances....

Plus 1 on the ICV getting real hot = failure....

This is the set up I have, no issues and very reasonable:
YAMAHA YDS/YDIS DIAGNOSTIC SYSTEM , WAVERUNNER & OUTBOARD 60V-WS850-00-00

[rodbolt17]

the ISC will typically run 170-180*F or so.
it is when they start over the 200* mark that I worry.
however with YDS version 2.3 or higher you can toggle or lock the ISC.

[slads5874974]

fixed (partially)!

https://vimeo.com/217510856

Hissing Issue: Two fuel injectors, 3 and 4 where not properly installed and the seals on the tip of the injector were not creating a sealed connection.

Engine sounds much better. Except it's missing now. I need to figure out what is going on. I also have complete mess of electrical issues. Maybe they are related?

I ordered the YDS software and cable. Hopefully it gets here this week so I can get a diagnosis.

the Idle issue: The IAC was stuck. I dissected the sensor (I also ordered a new one), and hooked it back up and its working again. It was definitely messed up. Still is but I can use it for now until the new one is delivered.

After that... onto the electrical nightmare and the missing issue.

Thanks for all the help everyone!

PS.. I am probably going to need to start another thread for the electrical. I will describe everything there.

BTW, Townsend, I pulled the valve cover and checked the clearances. Good advice, everything looks good. thanks! I got the YDS software and cable on order, hope it comes this week.

thanks again!

[TownsendsFJR1300]

Oh yea, WAY BETTER!!!! Guess that would count as a leak!!

Thanks for the update.

Buying / getting something USED, you don't know what the heck they screwed up. So trouble shooting, is MUCH more difficult from a monitor as one assumes the injectors are installed corrected (duh)..

Unfortunately, you'll probably be doing a lot of going over VERY basic things including / especially the wiring...

Keep it up, you'll sort it out..