Added a vacuum pump and now carb overflows.. Ideas ??
 

I've been having fuel flow problems with my DRZ and Clark tank.

The fuel doesnt run well, especially with an inline filter.

Well, I added a Mikuni Vacuum pump. The smallest I could find. The fuel starvation problems are over which is great but now the carb overflows after a few seconds.

The floats obviously have to fight harder to close the float valve with pressurised fuel but I don't really fancy playing the "hit and miss" game with trying to set my float height so it doesnt. That's even if I can adjust them enough to fight back the pressure.

Is there another method to compensate for adding a fuel pump when there wasnt one intended ?? A different float valve perhaps ?? A flow restrictor ?

Thanks in advance !!

Ted

Ted

You could try putting in an other fuel line from the point after the pump and b4 the carb back to the tank as this will reduce the pressure on the carb..:oops2: ( just thinking.. you may have to drill a hole in the tank and fit a one way valve for the fuel to return to the tank. Its not a hard job and should only take about an hour.)

Hope this idea helps.

Oneworld Biker..

To old to die young. To young to care.

Among KLR owners, there've been problems with certain inline filters (and also with their mounting positions), not with others. I think installing a problematic filter, then a problematic fix for the filter, then a problematic fix for the fix....is taking you down a potentially difficult path. Instead, either eliminate the inline filter or find one which works. You might investigate one of the various KLR lists (I use DSN KLR650, a yahoo group which you can easily find) or one of the KLR suppliers (I use Arrowhead Motor Sports in Moab, Utah).

I've got an inline filter and in the 50,000 Third World km since I installed it, it hasn't shown any signs of serving any purpose whatsoever. I'd remove it, but it's easier to just leave it in place. This is the end result you want to achieve on your bike.

enjoy,

Mark

I agree....

Putting the pump in is probably not the best solution, but i'm a sucker for a challenge !!

The fuel filter needs to be there, especially for African jerry can fuel.

I've removed the pump and changed the filter for a bigger one, hoping it solves the issue but only time will tell.

This Clark tank is crap design. It puts the tap much lower than the carb but very close leaving a very difficult angle for the fuel pipe. It's really hard to accomodate the fuel pipe without a kink, let alone a filter. I've been having problems where the float bowl won't fill and starving the carb on the motorway hence my idea to fit the pump.

The pump eliminated the fuel starvation problems fantastically but added one too...

Yeh but.....what makes you so sure African fuel is such a big deal? I mean, if you like challenges that's fine, but I've used a lot of fuel out of rusty drums, jerry cans, whiskey bottles, you name it. I never had problems before I installed an inline filter, and I've not had problems since. Plus I've seen some DRZ's, and they don't all have added filters, and I don't notice them dying by the side of the roads left and right.

I do carry a water-separating funnel with a fine screen, but I've used it only a couple of times, usually to pour from my plastic fuel can on windy days (remember Patagonia?). Seems to me this might be a solution to your troubles, serving perfectly without requiring all sorts of complicated modifications, each of which invokes the Law of Unintended Consequences.

Why did you choose a DRZ in the first place? Did it have anything to do with simplicity, straightforward design or proven technologies? Or was it a question of all the available farkles you could install to make it more likely to break down or in other respects misbehave?

Just asking.

Mark

LOL... You do have a way of putting it into perspective. Maybe I will just remove the filter if it still causes me bother.

The reason I put a filter in is because the carb has a very fine filter under the float bowl. I had the same one in my XT and it kept gumming up in South America when I ran without an inline filter.

It's a lot easier to clean an inline filter than a carb filter. The tank does have a filter, but it's not very fine (like my Acerbis XT one which allowed the carb filter to block)


You do make a VERY good point though. Why am I over complicating things on a bike I bought for simplicity !!!! ???? !!!! ????

I've removed the pump and fitted a larger, higher flow rate filter and looped the fuel line to take out tight angles. I'll see if that cures my problems.

I still would like to run with the pump if I can find a simple, easy fix for the overflow.. Even if I don't use the pump, i'd love to find a way to use one just for reference reasons. There are times where a pump maybe needed (auxilary tanks etc) and I'd like to have the knowledge and knowhow to do it...

Thanks for the reality check though, I needed it !! :smartass:

Ted, have you actually run the tank dry while riding the bike?

I mentioned in another post that I have a similar problem with my CCM tank and I lashed up a means of pressurising the tank to get the last few litres through. In reality though the amount that's left in the tank when you stop is less than you'd expect as all the sloshing around tends to keep the fuel moving through for longer than you'd think. My "level with the carb" amount is about 4 litres but the bike only stops when there's just 2 / 2.5 litres left.

You only need the pump to get that last bit into the carb. The rest of the time the it's extra weight and complexity. In your position I'd dump the pump and make sure I had a small container - say 1 litre, (maybe a petrol stove bottle or something like that) that was going to be my absolute last ditch fuel reserve. I'd fit a fuel tap to the end opposite the filler. When times got hard that 1 litre or whatever would go in the tank first. When the bike stopped with a few litres left in the main tank I'd drain it into the bottle and connect that to the carb with some fuel line. Fix it somewhere higher than the carb and run the bike on that as a substitute fuel tank until you're absolutely out of fuel. Then walk.

The only extra weight is a fuel tap. The fuel line will be the tank breather pipe that goes down the headstock which you'll have anyway.

My problem isn't getting the last few litres, the carb cant/wont fill up quick enough under it's own pressure, even when it's full... On one occasion, i couldn't ride faster than 45mph or the bike would be starved of fuel.... Float height is correct, carb is immaculate inside.

It's a fuel flow, vaccum, air lock problem somewhere. Fitting the vaccum pump is the only thing thats solved it upto now.

The bike won't start if it's been left over a week without manually priming the carb.

I've changed the filter/pipe set up and see if that solves it...

Are there filters fitted to the fuel tap? It may be those, that are restricting the flow. Instead of a filter why not install a trap ? I have a glass see through filter but with the filter removed. The glass bit is down low so any sediment or water is trapped in the glass bowl. Most crud is heavier than petrol.

fuel line runs, tap to trap which is lower than the carb. then trap up to carb. Any sediment remains in the trap and can easily be seen. Both input and exit to trap are higher than the bottom of the trap.

This system presents no restriction to fuel flow, just uses gravity to trap sediment, water etc.

Theres a filter on the tap in the carb but it flows nicely out of there. I've fitted a large transparent fuel filter which will hopefully sort the problem.

I might use your "trap" idea right next to the carb, to see if fuel is coming through.

I would use clear pvc fuel line but the problem is it doesnt stay clear for long. It becomes opaque and brittle over time.

Ted,

Just some thoughts.........

The fuel demand is variable but I assume your pump runs a constant pressure/flow.

As suggested by someone else, I think maybe you need a bypass to let fuel back to the tank that isn't needed by the carb. (does that make sense ??)

Where is your pump located ?
Would a "T" in the pipe just before the carb, running back to the pipe on the inlet side of the pump provide a bypass loop ?? Maybe with an adjustable restrictor.

Perhaps there is a pressure reducing valve available. I can't believe this is an isolated problem.

I will be interested in you conclusions because I have a bigger tank to fit to my Dr Zed and that has an outlet way below the carb.

As far as filters go, I have a filter bag/screen that sits in the top of the tank.

Regards

BYT

A fuel bypass does make sense but I'm worried about making things even more complicated. A bypass could end up giving less flow to the carb than having no pump at all. Having allsorts of T-pieces, pipework, bypasses and valves sounds like a nightmare to set up and get working properly.

I remember reading on a forum something about your float valve which needs to be modded or changed but I can't for the life of me find it again.:censored:

If I can do without the pump, I will... I need to wait a week or so with the DRZ dormant and see if I get the same problem than before I changed the filter/pipes. I used to have to open the drain screw on the carb to get the fuel moving again or give a squirt of power start in the airbox to get things going.

After the bike started cutting out on my on the motorway, I stripped and cleaned the carb out and set the float a little higher which stopped the problem (for now). It still wouldnt start if left a while though. Im guessing once the fuel in the bowl evaporates, its not refilling sufficiently.


What bag/filter do you have on your tank ?? home made affair ?? Pictures ?

Have you ever had any starting , starvation problems with your tank ?? My mate has a 28L Safari (no inline filters) and has no issues at all.

"I need to wait a week or so with the DRZ dormant and see if I get the same problem than before I changed the filter/pipes. I used to have to open the drain screw on the carb to get the fuel moving again or give a squirt of power start in the airbox to get things going."

I used to get that symptom on my TT. I always just assumed it was the fuel in the bowl 'going off' somehow. obviously with the leccy start you can just keep the button on, but I found it fired first time if I drained the old fuel first.

isn't the battery on the drz quite weak ? maybe you've upgraded. but if not could it just not have a fat enough spark to ignite old-ish fuel ? are you definite that there's no fuel between the tank and the carb, after a layup of a week ?

maybe you have two problems that are not strictly caused by the same thing ?

Look what I've just found on ebay !!

Any experinces ?????

Carburettor Fuel Regulator on eBay (end time 08-Jun-10 20:14:18 BST)

http://www.speedflowshop.co.uk/ekmps..._web_ready.jpg

It looks a bit "MEATY" for my little DRZ but it is adjustable !!

Last resort I think...

The fuel has always been fresh and I uprated my battery to a big fat 10ah one ! LOTS OF POWER !

Its not uncommon for fuel to evaporate out the bowl.. Im CERTAIN its fuel flow problem as the bike will fire up perfectly if used every few days, but longer than a week and it would be a bitch. The carb is vented fine !

I cant be certain of if there was fuel in the line... If I pulled the line off at the carb, fuel would piss out but then it would as all restriction has been removed.

Right old head scratcher isnt it !!

but an airlock surely isn't time dependent ?

I always had fuel in the bowl (not complete evaporation), but I am sure some part of the fuel had gone off/became less ignitable. which would make sense if you use an accelerant in the air box and it fires. I don't think a spray in the air box would remove an air lock in the fuel system, or 'fix' fuel starvation. you would still need fuel flow, as well as spray in the air box, to start the engine.

my TT also was completely fine if used every couple of days. but would take a good few minutes of the electric boot if left for a week or so.

I guess you could refit the standard tank and see if your starting problems remain, which would mean the starting problem would not be related to the larger tank.

i can understand fuel flow being an issue when you are running on an open road. but maybe the starting problem is caused by something else. I take it you've removed the fuel cap when experiencing fuel starvation (incase the breather is blocked, I had this too with the TT) ?

cheers

Do you have a vacuum petcock? It should have a PRI (prime) position to fill the carbs before starting. Will it run OK in this position?
Maybe yer petcock/vac line is fecked.

John

Ted,

Interesting that your mate has no issues with the Safari tank. Does he end up with much fuel left in the tank?

The fuel filter is a PROFILL MAIN PAGE ATV01 I have seen some crap in it so it's doing the job.

Maybe that regulator valve will do the job.

I rarely have any issues starting mine even after a couple of months lay up. Might make a difference that it's an "E" so has different carb.

No vacuum petcock.. Just a standard tap (On/off/reserve)

I don't think he's ever run it dry... He says he has about 4l he can never use.

You E has a pumper carb right ?? You get a prime when you twist the throttle before starting.


Anyway, watch this space.. I'll see if she fires up next week ! :cursing:

how does you fuel tank compare to this one : Core Racing - Aqualine Fuel Tanks, Larger fuel tanks for Off Road Motorcycles ?

is the fuel tap on yours lower down ? looking at this the fuel pipe seems to go downwards slightly, implying that the carb is lower than the bottom of the tank. though it's very hard to make it out.

FWIW, I had a DRZ-s model with a Clarke tank and an inline fuel filter and never had any problems. Was able to run it to empty and no pump. Here are some pictures of it in Iceland: Iceland TBSdotCom I had to drop it on its left side to get the last of the fuel from the right to near the fuel tap.

I had 2 long pieces of fuel line ((8cm each long?) with the filter in between) and looped them round. Used a bit of racing wire to keep them as high as possible. Also a breather pipe into the fuel cap. The filter was a 2 or 3 quid one off ebay: the smallest I could find.

The only issue I had was on rough ground the side stand would engage (or disengage?) with the side stand kill switch and the bike would stutter. After disabling the kill switch this ceased to be an issue either.

As also suggested by one or 2 others, IMHO you're wasting money/time farting about with random sh*te :( that's not needed. No other Clarke tank has had a problem and no one apart from you is attempting to use a pump. Save your money and spend it on important stuff like petrol and beer.:funmeteryes:

cheers
Chris

PS Never had to prime anything either. Turn ignition on, pull choke, press button with NO throttle.

Dude,

Not sure if you've sorted this already, and sounds like you've whipped the pump off for the moment anyway but were still interested in solutions for future reference...

It's interesting that the Clarke tanks don't usually need a pump and yours does - unless no one else is using a filter. FWIW, I'm def in favour of having a filter in there. It sounds like the one you have is too restrictive, so my first port of call would be trying a different filter, unless it's already huge - a marginal gravity feed will need a bigger (less restrictive) fuel filter than a pumped system.

If no luck and a pump is still required, plumb the pump in up stream of the filter, otherwise the restriction of the filter may cause vapour to form in the line into the pump, reducing it's effectiveness.

If the pump overwhelms the float valve in the carb, it may be that your float valve is worn - so I'd check that first before doing anything else. How old is the bike? (miles/years?) If the float valve is fine, you need to reduce the feed pressure, and the simplest way to do that is fit a lower pressure pump - I'm thinking a smaller version of the facet pumps commonly used on africa twins.

If you want to persevere with the pulse pump, you will need the "recirc" already suggested. On engine testbeds, we always run a high pressure fuel pump, and then a regulated back-leak to control the pressure. The testbed fuel system has a proper pressure regulator in it, but you should be able to get away with something much simpler.

You'd need two t-pieces, one upstream and one downstream of the pump, with a piece of pipe between the two "short-circuiting" the pump. You then put a restriction in that "short circuit" pipe (or ideally in the end of one of the t-pieces) and that way there is still some pressure rise across the pump - it's still helping. You'd need to do some experimenting with the size of hole required in the "bypass" route to stop the float bowl overfilling. Maybe start with a bit of brass with a 1mm hole in it. If the float bowl still overflows at idle, drill it out to 1.5mm. You get the idea. With a bit of luck, there's a hole size that stops it overflowing at idle (large vacuum "pulses" and min fuel demand) which still provides enough fuel to the carb at rated power (small vacuum "pulses" and max fuel demand).

That is the solution, but it's adding loads of complexity (six pipes, a filter, a pump, an orifice, two tee-pieces) where there used to just be a pipe, so you want to be sure you really need it before putting it in...

Cheers dude.. Very imformative if a little complex !!

You're right ... The pump is a solution but I should be finding the problem.

I'm 95% sure its down to fuel flow. I have a large transparent fuel filter inline now. As long as that is full, the bike seems to start ok. ! If I leave it a few days with the tap off, the filter seems to empty a little (where ?) and then it won't start.

I have to turn the tap on, crank it over a few times then the filter with fill REALLY SLOWLY and then the bike will start.. Still takes a lot of cranking though.

It really doesn't help that I changed the exhaust, jetting, airbox and tank all at the same time. And because its a problem that only sometimes raises it's head, it's very hard to diagnose.

The reason I don't think it's the float valve or jetting is because when it starts, it runs perfectly and then will start effortlessly as long as it's run regularly.

It's a wierd one !!

With the bike parked and the fuel off, fuel will slowly evaporate out of the carb, which is normal. With the tap on, the carb would be constantly replenshed from the tank (which is why you have a tap), but with it off, the pressure in the line will drop. This allows some of the fuel in the pipe to evaporate, forming a bit of vapour which collects in the filter (there'll also be some collecting up by the tap if that's a bit higher than the top of the filter).

Once the tap's back on, the pressure in the fuel line will rise again and the fuel vapour will condense back into liquid (the bubble disappears).

When you turn the tap on, the carb can refill, but as it's not a vacuum tap like the OE one, I'm surprised you have to crank for ages to get it to fire. If you park it for a week with the tap off (or however long it takes to get a good "bubble" in the filter) what happens if you turn the tap on and leave it for 2 minutes? Does the filter fill up without cranking the engine? If it does, key on and crank it, should start quickly...

I've just got back from a week in Cyprus.

I left the bike with the tap on.

The fitler was full and the bike started up second crank !! :thumbup1:

Seems the new filter and routing has helped the fuel flow... For now anyway :rolleyes2:

Cheers for all input... Hopefully I won't have to update this thread anymore. lol

I have just re read through this thread and realise now it was a starting problem.

I think it is a non problem.

Many bikes including nearly all old Brit bikes need you to switch on the fuel a couple of minutes before trying to start. A lot got around this by having a manual float valve to completly fill the carb. A cold engine is difficult to start when with a weak mixture. What I do on my Enfield is this.
When returning from a ride, switch off fuel in the lane to my house and put away the bike. IE drain the carb by using what fuel is in there.
When I next want to ride, I turn on the fuel tap before getting the bike out and putting on my gear. IE allow it time to fill fully.
Turn the motor over on the kickstart to free clutch, then another time or two to position piston just after TDC on the power stroke. Using NO throttle swing the kickstart. It is unusual for it not to start first time and that is a lean burn motor. In winter when it is really cold I will sometimes use the choke (which isn't a choke at all but an enriching circuit).
You really need to allow petrol vapours time and opportunity to get into the cylinders. If you dont you will end up blaming the bike for poor starting which is what happened to a lot of old brit bikes. Adding electronic ignition, electric start or worry beads will not help.

Well, maybe if you have a big battery an electronic ignition system -might- just give you a slightly bigger spark to improve your chances of firing a weak mix.

A tenner says you do!
Hope you enjoyed Cyprus, you missed a good Ripley meet.

Did it rain ?? I bet I missed the only dry Ripley meeting in years ! :censored:

Quote:
Originally Posted by *Touring Ted* http://www.horizonsunlimited.com/hub...s/viewpost.gif

Cheers for all input... Hopefully I won't have to update this thread anymore. lol


A tenner says you do!
Hope you enjoyed Cyprus, you missed a good Ripley meet.

hahaha very funny... I'll post the cheque from middle of the sahara.

I hope it doesn't get lost :innocent:

It seems you have it sorted out, but thought I'd toss this in just for fun.

The carb was never designed for much pressure on the float valve. If you put too much pressure on it it'll blow it open and flood the carb. Those inline regulators do work, but only when there's flow, in my experience. When the bike is stopped and there's pressure on the high side, it can trickle fuel through and still flood the carb if it doesn't seat properly, like a bit of the crud you're trying to filter out getting in the valve. You're also dependent on, lets face it, a cheaply made aftermarket will-fit accessory.

You just need to increase the flow rate at gravity pressure for that height. I would have suggested a larger filter or multiple small ones in parallel, but you've done that. You also could use a screen rather than a filter- so long as it's equal to the filtration of the carburetor's screen you're set.

Good to know that for future reference Donald. Cheers :thumbup1:

You're right ! I did sort the problem.

I bought a much larger capacity transparent filter and looped the fuel pipe so there as little frictional resistance as possible (no kinks, sharp bends, vertical rises etc).

It immediately sorted out the problem. I can leave the bike for weeks now and it still fires up with no issue. I'm so glad it wasnt the carb and just something as simple as a restrictive filter and a poor angle.

What through me is that the bike would run fine once it was going and 95% of the time time it would run at full throttle with no issue.

Gremlins eh !! :D