1994 K75S High-pitched chirping noise when hot?

[naddy100]

"toot-sweet" - wow, got to love thy French (toute suite).

However, do you have the fuel pressure parameters/range handy, eg. 10 - 12 psi?

My Clymer's page 273 says 36 psi (248 kPa). Use a dampened gauge for a better reading. I borrowed a gauge from Autozone. It was an undampened gauge and made it more difficult to read.

Here's the video from (one of the times) I was having fuel problems:

http://nsaddy.net/Videos/Gauge_2/Gauge_2.html

http://www.bmwmoa.org/forum/showthre...=fuel+pressure

[deilenberger]

My Clymer's page 273 says 36 psi (248 kPa). Use a dampened gauge for a better reading. I borrowed a gauge from Autozone. It was an undampened gauge and made it more difficult to read.

Here's the video from (one of the times) I was having fuel problems:

http://nsaddy.net/Videos/Gauge_2/Gauge_2.html

http://www.bmwmoa.org/forum/showthre...=fuel+pressure

Clymers is almost right.. That's at idle with the vacuum line to the FPR connected. If you rev the engine, you'll see the pressure increase, if you disconnect the vacuum line to the FPR, (from memory) it should rise to around 42PSI (and the fuel gauge will smooth out also..) The vacuum line in question is the small hose going to the rear-most throttle body nipple on the base of the TB..

[naddy100]

Clymers is almost right.. That's at idle with the vacuum line to the FPR connected. If you rev the engine, you'll see the pressure increase, if you disconnect the vacuum line to the FPR, (from memory) it should rise to around 42PSI (and the fuel gauge will smooth out also..) The vacuum line in question is the small hose going to the rear-most throttle body nipple on the base of the TB..

My big learns for today are more about the fuel system, and how to get Tapatalk working!

Thanks for the time and effort as always.
Noel

Sent from my Transformer Prime TF201 using Tapatalk 2

[Zagando]

My new ABS relay arrived this morning so I thought I'd replace that at least.

Once I had the gas tank off I examined both external fuel hoses and deemed the return line questionable enough to warrant replacement---so I called Sandia BMW at 10 minutes to 5pm on the the Friday of Labor Day Weekend.

They had one meter of the fuel line in stock, I paid for it over the phone and dashed over in my truck to pick it up as they were closing up shop.

Got back home and proceeded to take the bike apart so I could replace the return line as well as the main fuel line to the fuel rail.

My wife actually came out to help me but we are currentlly stuck---we cannot get the blasted air filter out even though I removed all three spring clips and pulled out that hard air input thing that goes in on the starboard side of the air box. It doesn't want to budge! I don't want to chew it up with pliers as it's still in decent shape but I do need to take it apart so I can undo the far end of the return hose (which appears to connect in the middle of the throttle assembly if I am reading the Clymer diagram correctly).

Maybe tomorrow (when it's light out and we can see what were doing) we'll succeed. I did replace the air filter three years ago all by myself but I still remember it being one of the worst things about working on the K75.

So that's it for now but will report as soon as any further progress is made (fingers crossed).

Since the fuel return line (hose) looks a bit funky I might also replace that Z-shaped breather hose and the fuel pressure regulator hose at the same time, once I eventually get to the other end of the return line when the airbox is off the bike. Probably a good idea and worth the minimal cost and hassle to go back and get the additional Z-hose on Tuesday.

[TED]

This has always worked for me:
http://www.ibmwr.org/ktech/air-filter-change.shtml
It slides out on the throttle side.

As for the "Z Hose", that is the notorious crankcase breather hose, the cause of many a lean running condition on many K Bikes (my K75RT included.) Those things go bad every three or four years and allow unmetered air into the system resulting in all kinds of shenanigans. Mine looked fine and was only two years old, but I had a spare so I swapped it out and when I got the one on there off I realized what looked like a little dry rot was actually a crack a half the way around.

Pics here
http://www.bmwmoa.org/forum/showthread.php?t=56654

[Zagando]

You slide the filter out on the throttle side, Ted? Really? I'll go out and see if it looks doable by me but I remember doing from the other side the one other time I replaced the air filter.

Or perhaps I'm misreading here. By throttle side do you mean in regards to the handlebar/throttle or to the throttle bodies which are on the opposite side? Sorry to be so dense but I'm a bit confused. Maybe I'll figure it out when I get working on it again that it's daylight (I started too late yesterday afternoon and it got dark all too soon).

Thanks for the info, too.

[Zagando]

I just wrestled, pried, jiggled and wiggled the airbox and filter some more---and got the filter out at last! Came out on the starboard side of the bike as per Clymers (and Ted's) advice (realize that you meant handlebar throttle side, Ted, sorry for my confusion).

Now I've got the bottom half of the airbox unbolted and out for a thorough cleaning and eventual reassembly---and I can now see clrearly where the other end of the fuel return line is attached for the first time in my K-bike life. Whew! What a relief!

Now for the really good news: My crankcase breather (Z-shaped) hose is cracked!

That is good news for me because it means that that may be the root cause of my chirping noise that has been plagueing me for some time.

If Don, Paul, Lee or Ted or anyone else that might be reading this knows if my cracked hose assumption is correct please let me know. At the very least, my efforts to get to the fuel return line have paid off as I know that Z-hose can or will cause all sorts of other problems down the line and now I have the perfect opportunity to replace it ASAP.

Knowing where and what the problem is feels like 90% of my battle is won!

The only possible hitch in the immediate future (this long weekend wait for the BMW dealer to reopen Tuesday) is the fuel line that I got there yesterday is a bit smaller than my old fuel line. Since I specified that it was for a '94 K75 the parts guy probably got the right part # but I am wondering if the hose size changed at all over the years?

At any rate, a minor detail that I can correct by getting something equivalent at Napa or Auto Zone if need be. I'll try to fit one end of this BMW hose over one of my tank's fittings beforehand and if it fits all the way on I'm still good to go.

Further updates to follow as warranted and boy, am I relieved to be seeing a tiny ray of light at the end of the tunnel!

[Zagando]

As suspected, the fuel hose I got yesterday is the wrong size. Just a mm or so too small to fit onto my tank's nipples. The part # is 13 11 1 338-115 and comes up as "bulk material, fuel, size 6x11" I suspect I need 7x13 if that exists.

In looking at the parts fiche at Max BMW I'm getting all the more confused as there may be different types of external fuel lines to begin with. The hose to the fuel injection rail is one, the return hose is another, the hose to the FPR is another and so on.

So maybe it isn't such a good idea to use generic hose cut to length from Napa or equivalent sources. ???

Suppose I'll await any advice before I proceed since I won't be putting it all back together for a few days anyway (will await an OEM Z-hose after reading Lee's comments in one of Ted's links above).

[TED]

There are basically three ratings for fuel hosing: SAE 30R7, 30R9, and 30R10. Hoses rated 30R7 are low-pressure/non-Fi (35psi), 30R9 is for fuel injected systems and rated at 100+ psi, and 30R10 is similar to the 30R9 but for submersible applications.

The two types of fuel hoses used on your (and my) K75, 8x13 (NOT 6x11) or 5/16" SAE 30R9 for use outside the tank, and the submersible rated 8mm or 5/16" 30R10 for use inside the tank (aka the expensive stuff...) These are usually available by the foot at the corner auto parts store, but often the better price is from the dealer for some reason.

The vacuum line from TB to FPR is a completely different animal - might as well replace while you have all the stuff off it if it is the original as it is only $10 or so [11 72 7 545 323 - same exact part used on BMW cars too!], or at least give it a really good going over (especially anywhere that has small cracks or what appears to be surface dry rot.)

[Zagando]

Thanks for the clarification, Ted. I will check with the BMW dealer first but may stop by a Napa store if one is open tomorrow.

I will need to get one of those ear clamp crimping tools (aka CV joint boot pliers) so I can get the clamps off the FPR hose(s) first. I've never used one of those before so hopefully I won't have much trouble getting the clamp off and then back on again.

I will also get more vacuum hose, new FI caps, etc. as you recommend; can't hurt.

[deilenberger]

Thanks for the clarification, Ted. I will check with the BMW dealer first but may stop by a Napa store if one is open tomorrow.

I will need to get one of those ear clamp crimping tools (aka CV joint boot pliers) so I can get the clamps off the FPR hose(s) first. I've never used one of those before so hopefully I won't have much trouble getting the clamp off and then back on again.

These clamps are one-time use.. the pliers used to tighten them won't remove them. Removal is done by spreading the compressed part with a tool - flat-blade screwdriver is what I've used. I'd suggest replacing them with screw type fuel injection clamps - which have a smooth interior surface so they don't cut into the fuel line when tightened. Regular hose clamps will distort and cut into the hose.. so you want to use the real deal.

I will also get more vacuum hose, new FI caps, etc. as you recommend; can't hurt.

[Zagando]

I had a hunch, as I couldn't easily see how they worked---that one-time usage explains it.

Will go with quality or OEM worm-drive clamps as needed.

Cheers!

[Zagando]

I got all the old fuel lines removed today and it's a good thing I did.

The fuel line return hose that went to the FPR was clearly marked NOT FOR USE IN FUEL INJECTION SYSTEMS. Great. A previous owner was some kind of genius...

Anyway, it held up long enough and didn't have any obvious damage that I could determine but it's one more bit of relief to have it outta there now.

Before I remove the FPR vacuum hose I may try sucking on the outer end to see if there are any leaks (as per something I read in my Haynes Manual this morning). If there are then I will need a new FPR, @$155 or so with the shipping; but a necessary component that will not be overlooked.

Now onto my question;

While I can clearly see that removing the vacuum hose from near the fuel rail is simply done by pulling it off, I'm a bit worried about the other end underneath the FPR.

The spring cover doesn't seem to want to come off, either.

Do I pry or otherwise pull off the FPR end of both the spring cover as well as the hose?

If so, I hope I can do so without damaging the spring. Any tips or tricks would be welcome once again.

[98lee]

I would be surprised if the crankcase vent hose was making the noise, but I guess I can see how it might. Do not use the reproduction hose from Beemerbone yard. Use factory for this hose.

The spring just slides over the vacuum hose, but it makes a sharp 90 degree turn just under the FPR. I don't remember whether there is enough room to pull straight down on that hose and spring with the FPR still mounted in place. All the ones that I have replaced had the throttlebodies off for intake rubber replacement. IF there is room just pull straight down on the spring, grabbing it as close to the FPR as possible and work it around the bend. then slide it of the hose.

Then the hose is probably stuck to the nipple on the bottom of the FPR. Break it loose by rotating it back and forth around the nipple until it is loose , then pull straight down. No clamp needed on new hose.

[Zagando]

OK, Lee; I suppose it won't be catastrophic if I end up stretching the spring some when I try to pull it off.

I might be better off removing the FPR before pulling off the spring and hose, looks like two Philips head screws and it's out. Then I can remove and reinstall the new hose easily.

Tomorrow's the day! (off to Sandia BMW in the morning for OEM bits otherwise it's Max online for whatever they don't have in stock here)

Thanks!