Adding a fuel pump to my 89

[T Legg]

I have no experience with pressurized fuel but I would bypass the fuel pump and see if they still leak . If they don't I would try the 1.5 mm needle valves that  oldktmdude is using .

Mine leaks overnight with the pump off.

         If I understand correctly your problem is only when it sits not running overnight and  Melloncollie' s RS carbs leak when it is idling on the side stand .
  If your fuel pump doesn't stop the flow of gas when it's off then over time even the most minute seepage will accumulate and overflow. The fj models I own all have vacuum actuated fuel petcocks my older bikes have manual petcocks and I always shut them off when I shut the engine off .

[Waiex191]

         If I understand correctly your problem is only when it sits not running overnight and  Melloncollie' s RS carbs leak when it is idling on the side stand .
  If your fuel pump doesn't stop the flow of gas when it's off then over time even the most minute seepage will accumulate and overflow. The fj models I own all have vacuum actuated fuel petcocks my older bikes have manual petcocks and I always shut them off when I shut the engine off .

I added a solenoid fuel shutoff, but my bike still runs poorly off idle and has dropped fuel economy. It was good for a year after I got it running again, but something has changed.

[T Legg]

One of your new float valves may be bad. It's happened to me before . One of the many nice things about rs carburetors is they have individual overflow tubes making it easy to spot which one is leaking .

[Pat Conlon]

I have no experience with pressurized fuel but I would bypass the fuel pump and see if they still leak . If they don't I would try the 1.5 mm needle valves that  oldktmdude is using .

Mine leaks overnight with the pump off.

When your pump is off it should be able to hold back fuel, if not, get another pump or install a 12v shut off solenoid.

[melloncollie]

So I did a lot of testing and spent way (way) too much time on this.  I went in knowing it may not be my solution but could give me some insight.  It was fun in a masochistic sort of way.  I went through millimeter by millimeter changing the float height, checking for leaks/overflow, and checking actual fuel level with a clear tube until it didn't leak anymore.  Ended at 21mm float height and it didn't leak when on the side stand but when flat the fluid level was ~5mm or so lower.  I'd feel better about doing all that if I didn't invalidate the results.  On one of many reassembles I noticed the seats looked a little off like they weren't seated fully.

 

I took them all out, made sure they were wet with gas and re-seated the seats.  Set my float height back within spec hoping it was that silly mistake the whole time but they still drip on the side stand when pressurized.  Not nearly as much as before, but all four still drip.  I won't be able to look at it again until maybe Tuesday so I'll stew on it until then.  Thinking I should have just went with the 1.5's like Pete said at the very beginning.

When your pump is off it should be able to hold back fuel, if not, get another pump or install a 12v shut off solenoid.

He's got a solenoid in already.

I added a solenoid fuel shutoff, but my bike still runs poorly off idle and has dropped fuel economy. It was good for a year after I got it running again, but something has changed.

My FJ is mostly stock - but maybe my float level is too high.  Could be over the stock vent hole as Randy pointed out.

Maybe try what almost worked for me?  Verify seats are seated and check o-rings.  I re-read through your thread quickly and see you replaced the needles but I didn't see anything about replacing the seat o-rings specifically.  Maybe give that a shot if you haven't. 

[oldktmdude]

   I have my float heights set at the recommended 17mm. I'm also using the R6 fuel pump. Float valve orifice is 1.5mm. My RS38's have never leaked since
I have been using this combination.
   I suspect that your leak is due to the residual fuel pressure left in the system after the engine has been turned off. My theory is (purely speculation and have no evidence to back up what I think) but when your bike is on the side-stand, fuel moves to the low side of the float bowls and the higher half of the float loses some of its ability to help shut the float valves off, allowing fuel to slowly bypass and overflow.
   Regards, Pete.

[melloncollie]

Maybe you're on to something.  I've got until after the holiday to overthink it too.  I'm split between trying to lower the floats again or just biting the bullet with the 1.5's.  What's a float set too low/lean show as? 

I should point out I haven't tried running it yet with the seats re-seated.  I'm guessing that's why it was leaking while running earlier and its fixed now (hopefully).  It leaks much less than before.  But I'll find out maybe tomorrow if I can get to it before I need to leave for the weekend.

[oldktmdude]

   A low float (fuel) level will definitely affect your top end performance. You may not notice it so much down lower in the rev range but it will
run poorly at WOT. I suggest you set your levels back to the recommended 17mm and buy some 1.5mm float valves. It will save you at lot of time and frustration.
   Hope you get it sorted soon. You will absolutely love the quicker throttle response and some power increase from your flatslides.
   Regards, Pete.

[Waiex191]

Maybe try what almost worked for me?  Verify seats are seated and check o-rings.  I re-read through your thread quickly and see you replaced the needles but I didn't see anything about replacing the seat o-rings specifically.  Maybe give that a shot if you haven't.  

I bought the RPM O-ring kit and new needles.  So I definitely replaced those O-rings.  I will check to make sure the seats are bottomed though - that is a great thing to check.

I am going to try the new needles I bought and check/reset the float height to the minimum spec.  It seems our issues are similar, but not the same.  One thing that my bike is doing is running really poorly off of idle.  It had been turning on like a 2-stroke at 2000 RPM, however that has crept up to about 2500.  Between that, the poor fuel economy, and the overnight leaks before I added the solenoid fuel shutoff, I really suspect the float valves.

Do the floats themselves ever go bad?  I've got two sets I think.  woodcreekpete sold me a set of parts carbs which were only missing diaphragms.  

Hey we are practically neighbors melloncollie.  I'm 10 miles south of the Wisconsin border.

[melloncollie]

I bought the RPM O-ring kit and new needles.  So I definitely replaced those O-rings.  I will check to make sure the seats are bottomed though - that is a great thing to check.

It seems our issues are similar, but not the same.

Do the floats themselves ever go bad?

Hey we are practically neighbors melloncollie.  I'm 10 miles south of the Wisconsin border.

I didn't have any running issues, bike ran great just poured gas all over the ground.  Sounds like a solid next step for you.  I wouldn't expect floats to go bad but I'm not sure.  If I had to guess a failure point it might be they take on gas so you could test by submerging them and check for air bubbles?

Just checked a map, yeah you're pretty close.  I ride through Whitewater area pretty often when I'm not leaking gas everywhere.  I think its an hour and change freeway ride from my city to yours.  If you want to go for a ride sometime shoot me a message.

   A low float (fuel) level will definitely affect your top end performance. You may not notice it so much down lower in the rev range but it will
run poorly at WOT. I suggest you set your levels back to the recommended 17mm and buy some 1.5mm float valves. It will save you at lot of time and frustration.
   Hope you get it sorted soon. You will absolutely love the quicker throttle response and some power increase from your flatslides.
   Regards, Pete.

Thanks Pete.  The bike came with flatslides so its all I've ever known.  But I do love it.  At risk of overthinking it or even over-complicating things I'll play a bit of devil's advocate here: any concern for starving the carbs at WOT with the smaller float valves?  It sounds like you've been happily using them for a while now, so I'd assume no issues.  Some quick math and a little guessing: 1.3mm (130 main) + .175mm (17.5 Pilot?) =1.475 < 1.5 float valve.  But bumping up to a 135 main, if needed, puts you over.  Or does the fuel pump push more fuel through 1.5mm needle valve than the carbs can take through the same size orifice? 

I think my concepts are correct, if not feel free to correct me anyone.  And if I should just shut up and stop thinking too much you can say that too.

Thanks again for the help Pete, I'll order the 1.5's when I get back from my weekend away.

[oldktmdude]

  My previous motor had a Wiseco 1219cc kit installed, it had a 4 into 1 exhaust, foam pod air filters and aftermarket cams. Tuned with the use of a dyno, it
produced close to 140 rwhp and 90ftlbs of torque. The RS 38's had 130 mains, 17 pilots, 1.5mm float needle valves and float height set at 17mm.
It pulled really well out to almost 11,000 rpm, absolutely no sign of fuel starvation.
Regards, Pete.

[melloncollie]

Finally got a chance to install the 1.5's this week.  No leaks!  I waited a few days to update just so I don't jinx myself, but everything seems do be working a-ok.  I had to adjust the float height just a little after installing the factory style seats since they were a hair shorter (.030").  I noticed one of my throttle cables was very frayed so I replaced both of those also.  The throttle is so smooth with the new cables that I lessened the spring tension on the carbs one setting and I may even drop it one more.  The bike seems to like higher revs more, hopefully this doesn't get me in too much trouble.

I read something interesting in the Sudco literature: they recommend bench/mechanical syncing the RS (and all smoothbore) carbs as the only method of syncing the carbs, no vacuum gauges. Then with the carbs mechanically synced use a vacuum gauge to dial in the fuel screws with the highest vacuum reading generally leading to the correct fuel screw setting.  Anyone have any thoughts on this?  All I've done so far is a bench sync while telling myself I'll use some gauges later.  But its been smooth after the bench sync so far that I haven't bothered to sync with the gauges.

[Pat Conlon]

Interesting, thanks for info.
Re: Throttle cable return tension: We have heard stories of the RS flatslides sticking open at high vacuum levels and thus a heavier return spring is needed to overcome the slide stiction.
This condition is applicable to the RS family of flatslides and not the roller flatslides of the TMR or FCR families.

[melloncollie]

So, a quick summary for anyone wondering or anyone searching/reading this thread in the future.  I had fuel pouring out of my carbs while the bike was running on the side stand.  That issue was because my new needle seats were not seated properly in the carbs, as pictured earlier.  Once seated properly with the RS specific 2.0 mm seats the carbs still dribbled out of the overflow at pressure, not nearly as bad as before.  I finally took Pete's suggestion and used the factory (fuel pump model) 1.5 mm seats at 17mm float height and have not had any issues since.  I also returned the throttle spring to its heaviest setting.  At the lighter setting the return to idle was a little too erratic for me, it would often hang and/or hold anywhere from 2-3k rpm.  No issues back at the heaviest setting.

Now for the new: I put about 3k miles on the used ebay fuel pump before it wasn't pumping anymore.  Luckily I found out in the garage rather than on the road.  Long story short, it just pushed fuel back and forth rather than into the carbs.  I have a feeling it was starting to go ever since I got it.  So I ended up with a $35 pigtail and a free reminder why I shouldn't have purchased a used fuel pump.  Or maybe a free pigtail and a $35 reminder..

I found a local racing shop that stocks facet fuel pumps on the shelf, this was the one I ended up with https://aftermark.net/40178-facet-cube-solid-state-fuel-pump-12-volt-2-0-3-5-psi-15-gph/  Made sure to get one with a positive shut off valve.  As far as I can tell the stock pump is 2-4 psi and this one is 2-3.5.  Went for a short ride today and everything seems good.  The bracket is part of a pipe hanger from the hardware store and I used rubber washers at the mounting points.

[melloncollie]

A few weeks ago my bike hit 60k miles so I checked valves and compression because it felt like the right thing to do.  All exhaust valves were 7 or 8 thousandths and all intake valves were 5 or 6 thousandths.  Then started the bike and let it warm up.  Compression readings were 145 152 142 150.  Everything seemed good so I buttoned it all back up and went out for a ride.