I just got off the phone with honda after being told by my local parts dealer that the fuel pressure regulators are on backorder from honda,honda has told me that there has been a increase in the sales of these regulators on the injected blackbirds.i have less than 6000 miles on my bike and told him that and he said there was some honda techs that were looking at some of the failed regulators and said they looked like the rubber diaphram had been eaten away,they say at this point it could be fuel additives (injector cleaners) reacting with the rubber.This part is covered under honda's 5 year emmisions warranty.

The symptoms are fouled plugs in the 2 center cylinders as fuel is drawn through the regulator vacuum hose and into the 2 center throttle bodies.starts out as stumbling, rough idle, and leads to missfiring and loss of power eventually running on only 2 cylinders.

eh? I can't hear you... speak up!!

thats as loud as it lets me talk, turn up your contrast (the computers hearing aid)

It's the 10% Ethenol in the fuel eating the rubber if I had to guess...

Mike

ya it may be. i remember reading a couple posts about some regulators doing the same (failing), i wonder if they were using additives and what kind.

almost all fuel now comes with 10% ethenol, instead of the MTFB or whatever they used to put in it...

MIke

What's a regulator?

LOL on your bike its called a float

Yeah...The gas isn't eating my floats.

Carburetors for ever.

I knew there was something special about my '97 tractor-technology 'bird

I have been working on my friend's 1999 Honda EFI BB for several months now and just yesterday afternoon finally figured out the pressure regulator was shot. Then, a friend from the UK BB Board told me of this topic on the US board.

The symptoms I had matched precisely what you had...I even sat next to the bike for several minutes and pressurized the fuel system. Sure enough, when the fuel pump spinned up, I saw a small quantity of raw fuel come through the vacuum hoses and into the intake manifold for #2 and #3 cylinders. The main point is, though, that after I TURNED OFF the ignition the fuel rail is still pressurized. Then...the vacuum hose continued to deliver raw fuel into the air manifold. About one drop ever 2-3 seconds in fact.

If you let the BB sit for one day this flow rate will literally fill up the air manifold for the #3 cylinder. This is because the vacuum hose is the shortest length to this cylinder. Then, if it sits another day or so, the #3 cylinder will totally fill up and the raw fuel will back up and go further downstream through the longer hose to the #2 cylinder.

Here is the longer term issue....

When you try to start the BB with both cylinders full of fuel, the starter will spin up and suddenly with a loud CLICK will stop. I think this is part of its one-way clutch system. It stops because the cylinders are full of raw fuel and the fuel cannot be moved fast enough through the valves. The starter does not have any strength to compress a liquid (nothing does!) and you now have a bike that cannot start due to this liquid compression lock.

But there is more!

The compressed liquid is being forced past the rings when you try to start it, and, it gently seeps past the rings when it is just sitting there for several days. Thus, the fuel is dumped directly into the crankcase and it totally MIXES WITH THE OIL.

So, when the symptoms first appear of the regulator failing, I am quite willing to bet you have had a gradual mixing of fuel and oil for some time and have been totally unaware of it. What will this do to the clutch, transmission, gear, seals, etc, as they all depend on this oil for lubrication?

Not any good!!!!!!!!!

Bob in Arkansas