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  #1  
Old 3 Aug 2003
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Urgent help required, XRV750 fuel supply problem

Hi All, (Kiwi Pete here but I've forgotten my username and am using my travel partners)

I'm currently in Cappadocia, Turkey, en route to India and today has been a nightmare! About 40k's out of Mersin my RD07 came to a hault, as if it had run out of fuel. I pondered for a bit (having refueled in Mersin) and 5 mins later it started again. This time I got 5mins down the road and the same thing happened again. I'm using a Mikuni vacuum fuel pump (supplied by Africa Queens) with 2 fuel filters just after the fuel tap. Next time it happened I disconnected the fuel line (after the filters, before the pump) and only got a dribble of fuel out (I would expect it to flow). Thinking it was a air lock I removed firstly one of the filters, then the other, to no avail. Each time it would run for about 5mins then appear to run out of fuel. So, thinking it was the pump I dissassembled it and found oil in the space between the diaphram and the vacuum hose (I'm concerned about this too but will get to that later). So, once this had been cleaned out (and the fuel changed) the bike ran for 50k's or so then the same bloody thing happened! I pulled it appart again, no oil, so removed the filters (which I had previously re-installed). It ran for 50k's, we stopped and had a fag and it ran for long enough to get me to Goreme. It seems that if you let it cool down for 5mins or so it will run okay for a while which has me wondering whether it is actually a fuel prob or perhaps some electrical component is not coping. My personal suspicion is that there is something in the carbs.

If anyone has any ideas please email to my address (see button above) or call/text/SMS my mobile +44 (0) 7967 105 516.

Theres several s in it for whoever comes up with the right answer!!!

Cheers in advance,

Pete (Kiwi Pete)
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  #2  
Old 3 Aug 2003
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my first suspicion is a dodgy fuel pump. af twins have a history of this. do you have a problem when the tank is full of fuel? i.e. there is fuel above the level of the carbs and hence the pump is not needed.

see these links on the topic
http://www.horizonsunlimited.com/ubb...ML/000002.html

http://www.horizonsunlimited.com/ubb...ML/000023.html

my second suspicion is that your tank bag or something is sitting on top of your petrol cap. the af twin cap normally has the breather in where the key goes... if it is covered there is a vaccum in the tank and the pump can't pump against the vaccum... particularly a problem if you are low on fuel (more air in tank, more vaccum...)

does your mate have the same bike? if so, swap components and see if the problem stops.

to check if your carbs are ok, take the tank off and manually pour a little fuel into them via the fuel hose. if the bike runs for a bit (until it runs out of fuel) then the carbs are ok.

these are my theories. hope to share some s in manali in india in late august/ september.

good luck,
ChrisB
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  #3  
Old 3 Aug 2003
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Thanks Chris,

I'll try removing my map holder from the top of the tank. Though thinking about it you're right, it runs for 50 k's or so after filling the tank, then the problems start. Which I guess points at the pump as being the problem. I had hoped replacing Honda's legendary self destructing pump with a Mikuni vacuum pump would have prevented this from happening, bummer!

One other thing, in the past I had noticed the fuel supply line coming out of the pump used to move up and down as if it was, well, working. It doesn't appear to do this any more.

I guess if I can rig up an alternative fuel supply to the carbs I can double check the pump is working.

Catch you in Manali,

Pete
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  #4  
Old 3 Aug 2003
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Hi Pete
I suppose that the problem could be some water presence in the fuel. Try to pump some fuel in clean container and check if some water are mixed with the fuel. If you look water you will have to drain the carburetors by the screw provided by that. You can find it at the bottom of the carburetor. And then you have to change all the fuel. Your mate put the same fuel? Does he have any problem?
To check the pump: takes off the out line of fuel and try to start the bike. If the fuel don’t go out check very well the vacuum line. May be that’s your problem.
If you dissembled the pump check if you close it well.
Well if any of my suggestion is corrected I accept the s. But you have to come here (Argentina). You will not disappoint.
Greetings and good luck
Cheers
Javier


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  #5  
Old 4 Aug 2003
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Thanks Javier,
My mate used different fuel when we filled up before the problem started. I have replaced the fuel and could not see any water in the container with the old fuel. I drained the carbs yesterday (but didn't replace the fuel). Vacuum line appears to be secure.
The frustrating thing with this is that it will run for a bit (I got 15k's yesterday before it stopped), then if you let it sit for a while it will run again. What I need to work out is what is happening in the "cooling off" time. I'm just about to go for a ride without the map holder in place (which covers the petrol cap) and if/when it stops I'll remove the fuel line exiting the fuel pump to see if it is still pumping.
Have been in Goreme 2 days now and have yet to see the sights!
Pete
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  #6  
Old 4 Aug 2003
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had some other thoughts.

i previously had an airhead bmw where when the bike had run a while, it stopped. after waiting a while (cooling it down), it worked again. the problem was a crack in the ignition coil... i replaced the coil and all was ok. sometimes what seems to be a fuel related problem is actually an electric problem.

having said that, i suggest you also check all your electric connectors with a volt/ resistance meter. start off with your fuel pump, then the coil, then...

i think, the test for the fuel pump

1.)with a full fuel tank. if it works fine for quite a while (until the fuel level is below the carbs), then it is the problem.

2.)with a nearly empty fuel tank (i.e. way below the carbs). does the problem happen any quicker?

if it isn't related to fuel level, it may be something else like the coil, ht leads, spark plugs etc.

i hope you get it sorted.
cheers
ChrisB

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  #7  
Old 4 Aug 2003
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Gidday Pete.
This may only add to your confusion but when my electric pump failed in the alps last year, the honda shop just bypassed the pump & sent me on my way relying on gravity feed (ie keep the tank full above the level of the carbs). However the same thing happened. The bike would run for 5-10 miles and then stop. Wait for 5mins to cool down, and then fire up again for another 10 or so miles before coughing to a stop again. Eventually found a replacement pump. So - no help at all really, but my guess would be (assuming it is not electrical, and all lines, filters,taps etc have been checked for blockages) that it will be a vaccum fault.
Hope you get it sorted - good luck.
Gibbo
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  #8  
Old 5 Aug 2003
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Hi Pete

I'd go with Chris's original suggestions first off. It sounds like the fuel pump should be more reliable than the original AT pump as you've changed it to an Africa Queen's jobbie. I'd put money on a vacume in the tank caused by a map holder etc. especially if there is condensation between it and the tank (better seal) or if its hot as the map holder will be more flexable and mold itself to the tank over the breather.

Its not evaperation in the lines as you only got a trickel when you looked at the lines. If it isn't a breather problem then its electrical I'd say, but go for the most obviouse problem first.

Hope this helps

Chris

If Chris B. is right do I get half his bear for support? (Don't answer that Chris B.!)
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  #9  
Old 5 Aug 2003
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mr smith,
you can have the bear all to yourself. grizzy, polar or teddy? the 's mine
CB
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  #10  
Old 6 Aug 2003
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Hello

Bought a AQ mikuni fuel pump this spring. After a short time i had the same symptoms as you. When i opened the fuel pump there were fuel on the wrong side of the membrane. I reinstaled the orginal pump, and it has now run for over 10 000km.
My guess is that some fuel is left on the wrong side of the membrane and create a sort of vakum lock when its get hot and evoporates. When cooling down you can ride for a short period, as the pump wil start working again.
Try to rebuild the pump with new membranes and seals. I think KTM adventure use the same pump, so a ktm dealer shold be able to give you spare parts. Maybe yamaha??
If you have not taken of your orginal fuel pump relais you can get a fuel pump from a car. The orginal unit is an Mitsubishi.

Hope you sort it out

Frode

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  #11  
Old 7 Aug 2003
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Hey guys, thanks for all the replies. To keep you up to date, I pulled the pump apart again and put it back together, removed the map holder and rode for 45k's without a problem. Next day I did a couple of hundred k's and again, no prob. However I have contacted Mike at Africa Queens and he has seen this before. As I am slightly paranoid about riding any further into Turkey, Iran and Pakistan with a potential problem he is sending me another one.

So, I'm kicking back in Goreme (which has a disproportionate number of single female travelers as it happens!) and waiting for it to arrive. I must thank you all for the suggestions and also Mike at Africa Queens for sending a new pump out gratis, cheers mate.

Will let you know how I get on,

Pete
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  #12  
Old 12 Aug 2003
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Hi all,

New pump arrived yesterday so we hit the road today. Made it 200k's with the old pump before it died again. Put new pump in and got 500meters down the road! I had accidentaly not correctly clicked the quick release fuel coupling together correctly!!! Talk about heart stopping moment. After that the speeding fine we got later in the day was easy to deal with! So, fingers crossed this ones gonna get me to India!

Pete
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  #13  
Old 15 Aug 2003
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Aaaaaarrrrrrggghhhh!!!!!

Made it To Kahta (Nemrut Dagi) no prob, then on to Diyabakir. Next day filled up after 70k's, 80k's later the bike died. I noticed there was no fuel in the first fuel filter so gave the tanks a few bangs and it eventually trickled down and I went for another 40 k's no prob. Then it died again, we waited, got going again and made it to Tatvan. I pulled it all appart again, changed the first filter, cleaned out the oil/fuel on the vacuum side of the pump membrane and checked (as much as I could) the fuel tap. I don't have the map holder over the tank cap anymore (but there are 2 breathers built into the tank which are both clear, so...). Today we were going well, I went onto reserve, then 30k's later it died (just after a check point!) Filled up, then filled up again after 60k's (so as to keep the tank fullish) then made it the 90k's to Doggy Biscuit no problem (great road by the way). So in my mind it must be the bloody pump(?) I now have 2 of them so will try to keep the fuel level up at all times and I am also going to try to move the vacuum hose onto the front cylinder. How could this liquid (which looks like caremalised fuel!) make it into the vacuum side of the membrane?

We're heading into Iran tomorrow so I'm hoping like anything I can get this sorted.

Sorry to bore you with all this but if anyone has any further suggestions (nice ones that is!) please let me know!

Pete
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  #14  
Old 18 Aug 2003
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Hi,

Don't wish to tell you how to suck eggs here but sometimes the most obvious thing...

Have you checked that the inline filters are set in the correct direction?

Do the fuel lines run close to anything hot? You maybe getting fuel starvation because it is evaporating. A cardboard heat shield and reflective tape is often the cure for that.

Andy.
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  #15  
Old 5 Sep 2003
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The problem appears to have resolved itself as soon as we arrived into Pakistan! (I removed one of the filters and the Q/R fuel clip but was still getting stutters). You may well be correct about the heat/evaporation issue Andy. When I get the chance I will put the other filter etc. back in and make some kind of a sheild, it is quite close to the rear cylinder.

Anyway, we've made it to India so I'm happy (though my rectifier has just packed up!!!)

Thanks again for the help guys.
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