VFKR dirty tank? Bad gas? Help! I wanna ride!

On Sunday I finally had everything together and had a chance to go for a nice ride. Temp in the low 70's and sunny. Perfect day. I've been deployed for the past year and haven't rode in about that long (had a few short rides on leave in April) so I just wanted to go. Had my bike apart for the last week adding stuff here and there and making sure she's good to go.

On Friday I was finally ready to start her up and see where we were. Well, The first thing I noticed was the fuel pump not clicking. Did some research and found that they are a common failure point so I followed Jamie's suggestion in older posts to ditch the pump and use a gravity feed. Got a new fuel filter and some fuel lines and after throwing some fuel in the tank I found that it didn't have a very good flow out of the tank. It started with just a trickle so I blew air into the fuel exit and that helped a lilttle. blew out the holes in the petcock and sprayed some carb cleaner on the inside of the fuel cap to ensure it's clean and venting.

This stuff helped the fuel tank flow increase from a trickle to a steady, fast trickle. I hooked it up and it filled the fuel filter up so I thought all was good. Got on the bike and rode about 50 miles. Highway, city, fast two lane twistys and the bike was running like a raped ape. Couldn't be happier. I get on the highway again and cruising at 60 it starts to act like it's running out of fuel. It finally dies and I sit waiting. Start it up after a minute and it fires right up. Then after a mile or two it dies again.

I went about 30 miles going about 2-5 miles at a time before it would die and I had to wait to start it back up. Then, for whatever reason it ran fine and I went the final 20 miles home non stop! What the hell? I go to start it yesterday to see if the issue would come back up and low and behold, started up cold first try. Let it warm up and after a few minutes it dies in the driveway. I wait, it starts back up and 1 mile down the road it acts like it's out of fuel again.

So, I've searched through the posts and found the most common issue is crap in the tank clogging the fuel flow but in rare occasions it can be the pulse generators or other things.

So, I've done everything I think but clean the tank. Before I deployed I emptied the tank. It was coated by the previous owner so it's rust free inside. I just don't understand why it'd go 50 miles then act up. Any suggestions? dump the tank out and try to clean it out?

 

Just a wild guess - but could you have a filler cap airlock - which after a while would reduce the flow so much that you experience fuel starvation? Certainly what you describe sort of fits - especially as you mention other bits of the fuel system were bunged up. I don't know anything about the VFKR tank design but I assume somewhere on the filler cap or the tank there is a route where air is supposed to be drawn in. It may be worth checking that is clear, and not clogged with debris.

Skimad4x4 6th Gen Militia # 218

 

My bike wouldn't even start without the pump. I heard people having starvation issues at higher speeds w/o the pump as well. Are you sure it's the pump and not a fuse or relay? I'm a big fan of the pump, constant fuel at all demand levels and it's never left me stranded in 26 years, my 2 cents. If it sat for awhile the carbs could be funked up. I'd throw some Seafoam in it and see what happens. When it dies, try opening the fuel cap and see if it starts easier, could be a vapor lock problem.

The weird part is it comes and goes.

 

Yeah, I'm thinking about going out to autozone and picking up a lil auto fuel pump just to try. The carbs are great. The 50 miles I rode trouble free there was no hesitation, no hiccups. She idled smooth and showed no signs of dirty carbs. I do have a lil seafoam in the tank. Force of habit. Always run seafoam in the first tank and last tank for the season. The first thing I tried when it first happened was popping the tank and listen for a air rush but there was none. It didn't start right after opening the tank either which makes me think that's not the problem. It always takes a few minutes of waiting to get the engine to start back up.

 

When it dies, does it just shut off like it was electrical or does it stutter then die? If something was waiting to heat up before failing, it would have to cool down before a restart. How long after it dies can you refire it?

 

How do you know the pump is bad? There's a relay that supplies voltage to the pump. Have you directly attached the pump to a 12v source? If not you should try that first. It could be the relay. I have several if you need one.

I tried my 750 without a pump. It didn't run worth shit. Came back hooked pump up and all was fine again. I thought I had a bad relay. It turned out to be dirty connection at the plug. You said the tank had been coated on the inside. The coating may have gotten inside the pickup tube a little and reduced it's dia.

If your throttle is just cracked for cruising I can see being able to ride a while. Once you start opening the throttle more it is most likely using more fuel at that time and will drain the carbs faster than what they are filling by gravity. Wondering if your carb vent tubes are kind of blocked or not properly run. My vent tubes go in to the carb plate and has a raised cover w/open ends over them. I've heard there was problems venting that way. I've never had a problem. So in 84 they vented to the outside.

I wouldn't even look at the pulse generators until you get the fuel problem sorted out.

 

No, it sputters and hiccups like it's running out of fuel. It takes a minute or 5 before it'll restart. Seems like the gravity feed isn't sending fuel fast enough to the carbs. Strange since it ran so long without an issue.

 

Sounds a bit like you fixed something that was not broken. You need to test the fuel pump WHILE the bike is running. The fuel pump relay on the earlier bikes is energized only when the engine is turning and the location of the petcock being half way up the tank does not lend well to gravity feeding.

 

yup, I tested the pump with power and nothing. i just got a universal pump from autozone so I'm going to see if that helps at all. It does seem as though the gravity feed is sending fuel to slowly to the carbs though. This would explain why it takes a few minutes before it'll restart since it is refilling the carb bowls. Unfortunately it doesn't explain why this didn't happen for the first 50 miles of riding or why it didn't happen the last 20 miles of riding.

 

On my EX 500 I installed a Pingel petcock with an on/off position. Capped off the inlet once used for reserve as the old one was a vaccum operated petcock with the reserve feature.

I run this bike wide open pretty much on the highway and saw a seat of the pants performance increase. Much like shimming my needles did on this particular bike.

My understanding the way the fuel pump works is that the way they the factories designed some of the gas tanks, at some point when the bike hits reserve you will need the added funcition of a fuel pump becasue the gas is below the carburators. Fuel pumps are low psi, me thinks maybe 5 psi? you could hold your thumb over it and it wont exactly blow it off. Side note, I replaced mine on the Gen 3 bikie, seems like it starts and idles a little better, havent really ridden it all that much though.

 

Well, I installed a new (autozone 2-3psi) fuel pump yesterday and put it all back together. It was raining so I had to wait till today to test it out. Long story short, it took me an hour and a half to go 7 miles. Yeah, it sputtered and coughed like it was out of gas every mile or so. So, the same issue happens with or without the fuel pump. I'm going to dump the gas out of the tank and see if I can't clean it out some. Any other suggestions?

 

the 1000R has an internal petcock. No way to take it apart and clean without cutting the tank apart. I've already blown it with compressed air and blew air in the exit with the tank open. No joy.

 

The seat for the needle and seat will have a screen on it, not uncommon for junk to collect there and plug up. PIC.
http://vfrworld.com/forums/mechanics-garage/22449-cleaning-carbs.html#post170040

 

Pic 4 and 5 are not that great but the yellow section on the bottom of the seat is a very fine screen.

 

Well, the only reason I'm thinking it's not the carbs is because as soon as it sits for a minute it runs like a raped ape!

I have somemore info. So, for fun I took the tank off and found that it has a very good flow now out the exit. On and Res. are good and off works like it should so I hooked it up again via gravity feed (bypassed the pump) and ran it around the block. Made it back to house and died. I took off the seat and saw the fuel filter was empty, disconnected the line from the tank and got fuel flow. Hooked it back up and nothing flowing to the fuel filter until................it cooled for a few minutes. Could I be experiencing vapor lock? The heat from the engine affecting the fuel in the filter since it has the least insulation (thin clear plastic type) and creating vapor lock keeping the fuel from flowing from the tank to the filter to the carbs until the engine/line cools enough to let the fuel flow freely again? This is a new filter type I've never used before and I have it sitting right above the rear valve cover. It doesn't get really hot there though.

I don't know, I didn't pull the filter or try troubleshooting anymore tonight. I'm hungry.

 

Try a test with the main filter removed, but i'm thinkin clogged screens (from a rusty, dirty tank )above the inlet needles as mentioned.