Popping noise from exhaust on a 6th gen

I have an all stock 2002 6th gen with 10k miles that just started making this *poomp *poomp deep pop sound randomly at idle. I haven't noticed any power drops, and the idle doesn't drop when it does this, but I'm not sure what it is. It also only seems to come from one muffler
At first I thought something was loose in the exhaust, but it's definitely not that.

any ideas?

 

shit, and I just realized I only got 28 miles per gallon on this last tank! 85 miles on 3 gallons?

 

Was initially going to say Pair valve stuck open but when it stuck open on mine it would Pop most noticeably on underun when rolling off the throttle. My first suggestion would be to check if the spark plugs are all firing, maybe one is not sparking ?

Have had something similar also after some smartarse pulled one of my front plugs at a Gas station for a laugh, surprisingly the VRFs motor was still smooth just feeling a little down on power and higher than expected fuel use. A Quick check would be to make sure each of the leads is properly homed if they are you could from cold mist a little water on each of the headers to see if ones not evaporating as quick as the others and / or remove and sight each of the plugs for non firing.

 

Thanks for the reply.

I would think if a cylinder wasn't firing I would notice? The engine doesn't run rough, idle is smooth. Just randomly get that poomp sound when idling. It revs fine, I've noticed a gas smell when I start it up like it's running rreally rich (but it should when it's cold) the noise is still there when hot too though. I'm going to check vacuum lines tonight.

 

So are you really gonna start a second thread for the same bike and the same basic issue?

http://vfrworld.com/forums/mechanics-garage/42115-another-weird-issue-2002-vfr800.html

i'm betting you never did inspect the wax unit did ya? (from the first thread about having idle issues)

 

So I pulled the airbox and noticed some things. There was some brown liquid in the throttle bodies, and it looked like some dried liquid in the corner of the airbox. Not sure what this is.

All the vacuum lines appear to be tight.

Here are the pics

 

Did you check the air pressure on your tires?

 

Yeah air pressure is good.

You can smell the gas coming from the exhaust. I can't find any leaks in the exhausts, or loose vacuum lines. This has got me stumped. I really want to figure it out and not have to pay a shop, but I'm stumped.

I was at the track on Sunday, she ran fine on the track. The idle is still really low, and the idle adjustor won't move. Gas mileage was horrible still.

There was a couple of times I had to give her throttle to get her to crank.

 

I just came across this post about the FPR failing on a 2002 and dumping fuel into some of the cylinders......which would explain the liquid I saw in some of the throttle bodies in the pics I attached.

here is the post Nashville Motorcycle Repair » 2003 Honda VFR800 running problem


Looks like I'm ordering a new FPR

Still doesn't explain why my idle adjuster won't move though

 

OK, to test I pulled the vacuum line to the FPR.

I pulled it, turned the key.....and fuel dripped out. BINGO, bad FPR. Glad I came across that article of a similar issue on an 02. Apparently there is a hole in the diaphram in my fuel pressure regulator. Glad it's a cheap easy fix

Here are the pics just to be sure I'm seeing the right thing. In the picture you can see the FPR, and I pulled what I am pretty sure had to be the vacuum line, but I want to be 100%.

You can see the port where the vacuum line was at the bottom, with the large hose on the left coming from the fuel tank.