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Space Emperor
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Discussion Starter · #21 ·
Fuel filter and tank tap both working OK?
Yes, fuel flows freely out of the filter ...

It still sounds like a fuel problem. How long does it take to start to run rough and then cut out? Perhaps worth trying to simulate it running out of fuel so you control this to see if the symptoms are the same? If it takes 10 minutes for example, you could starve it of fuel after say 5 minutes and see what happens. If it runs rough and cuts out in the same way then it looks like fuel but if its different then perhaps something else.
Yes, that could be a good idea, except it seems like it only uses the fuel already in the bowls. I accidentally ran it until it stopped and then noticed that I hadn't even turned on the fuel tap.

I could try emptying both bowls, and then see how the flow through the drain tube looks after they empty ... if it flows uninterrupted, I'll know if it's fuel or electricity related
 

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Remove your carbs and clean the choke plungers. This sounds like it runs fine until it warms up. The chokes may be stuck on and therefore the engine is getting too much fuel once it is warm.

Plus, a good thorough cleaning never did any harm to a carburetor.
 

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Space Emperor
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Discussion Starter · #24 ·
OK, so lazy guy here FINALLY got the carb out an cleaned it thoroughly. This seems to have solved the problem of the engine stalling, yay! I guess it was a stuck float valve, not letting new gas in. I didn't put the tank back on and test ride it, but it idled fine for 15 min, so I assume THAT problem has gone away.

But now I have problems with the idle. When revving, it sticks at 2k+ and takes a while to come back down. I have removed the choke a long time ago, so that can be ruled out.

Airbox looks to be seated well, but I'll take it off again and see if there are marks on the edge from bad contact with the carb intake. Rubbers look good on the cylinder.

I tried adjusting the idle mix screws, but it didn't really change anything. After the engine got hot, the problem disappeared for a while, but returned when I left it to cool and started it up again 10min later.

Any other ideas on what to do next?
 

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Space Emperor
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Discussion Starter · #25 ·
By the way, the Facet fuel pump was dead. Grrrr! A bit disappointed, as this is my second Facet. Testing the bike with gravity fed fuel from a bottle.
 

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As HAT Rider says, check the throttle return action. Mine behaves like the carbs are out of balance every now and again, and snapping the throttle closed usually fixes it. In between removing the tank to clean in there, I just target a bit of WD40 at the linkages - seems to work. A comment on the fuel pump, I find the original works fine, I just treat the breaker points as a service item every two years or so and never allow it to race when going to reserve. One further thought, possible sticking/poorly seating float needle?
 

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Space Emperor
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Discussion Starter · #28 ·
I assume the throttle snaps back ok?
Yes, the wires is definitely slack on return

As HAT Rider says, check the throttle return action. Mine behaves like the carbs are out of balance every now and again, and snapping the throttle closed usually fixes it. In between removing the tank to clean in there, I just target a bit of WD40 at the linkages - seems to work. A comment on the fuel pump, I find the original works fine, I just treat the breaker points as a service item every two years or so and never allow it to race when going to reserve. One further thought, possible sticking/poorly seating float needle?
Lensman, what do you mean by "never allow it to race when going to reserve" ? But yes, just had the carbs off and cleaned them. I did however forget to take out the idle mix screws and clean that passage. Dumb*ss, hahaha! I will try to clean them with the carbs in the bike, if possible. Cheers, mate
 

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TJE, when the main tank empties the pump 'races' because it is only pumping air. If you run the pump off the bike with the cover removed, the points spark like Nov 5th! NB, only do this with the old points, not the new ones you have put in, as this is what kills the points - there should be a back EMF diode across them. Personally, I never get down to reserve and look to refuel at 180 - 200 miles.
 

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Space Emperor
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Discussion Starter · #30 ·
TJE, when the main tank empties the pump 'races' because it is only pumping air. If you run the pump off the bike with the cover removed, the points spark like Nov 5th! NB, only do this with the old points, not the new ones you have put in, as this is what kills the points - there should be a back EMF diode across them. Personally, I never get down to reserve and look to refuel at 180 - 200 miles.
Ah, yes, I see! But I have a Facet pump.It shouldn't get damaged (as much) from running dry ...

Anyway, I thought the pump was dead, so took it off and planned to run on gravity feed. Just for the hell of it, I tried to connect it directly to the battery, and it ran fine.So I'm definitely getting close to solving the issue, but need to check the diagrams to see which wires affect the pump
 

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Ah, yes, I see! But I have a Facet pump.It shouldn't get damaged (as much) from running dry ...

Anyway, I thought the pump was dead, so took it off and planned to run on gravity feed. Just for the hell of it, I tried to connect it directly to the battery, and it ran fine.So I'm definitely getting close to solving the issue, but need to check the diagrams to see which wires affect the pump
I had a similar intermittent cutting out fuel problem and was also running a new facet fuel pump, so unlikely to be that.
I have used facets in race and rally cars for years and never had one fail. Any how my problem was traced to an intermittent fuel pump relay, replaced it and no more cutting out.
I traced the problem by connecting the pump directly to the battery via a push pull connector and riding it for a few miles with no problem. As this was only a temporary measure, the connection/disconnection had to be done manually, but it proved the point. Having replaced the relay, as a belt and braces measure, at the fuel pump connection i have a 'stand by' lead that can be swapped over to give a direct feed (via fuse) to the battery.
From memory the new relay was quite expensive at £40 ish, so i wanted to be sure it was faulty before replacing it.
Hope this helps!
Dave
FYI to all AT owners, the biggest single improvement to performance i have done and i highly recommend you do,
is upgrade the Ignition map for decent UK and European fuel. The stock map is very retarded to run on crappy fuel found in the likes of Africa. My AT RD07A did not like to drop much below 3000 RPM ( or 2500 after exhaust mods) before the dreaded chain snatch set in, which i believe is responsible for the wear on the gearbox sprocket shaft.
After reprogramming the ignition map, the motor now will pull from 1500 RPM In top gear !
It is now so much nicer to ride and is now the bike it always should have been.
The only sensible way to do this (dont even think about moving the ign pick ups!) is to change the Ignition module to a modified pre programmed box, or a programmable box. But a slight hitch here, RD07 and RD07A boxes are different, the RD07 has twin pickups and the 7A only a single.

The map i used (brilliant!) came from this company who also supply pr-programmed or programmable boxes for a whole range of AT models etc.
Digital Double-CDI for Honda XRV750 Africa Twin (RD04/RD07)
They are a very helpful company and a contact name is Felix Möhrle <[email protected]>
However they dont do one for the RD07A !
There is another company called Carmo which does units, for the RD07 (not 7A) but they give very little information, which i was uneasy about.
The box i used for my 7A came from this company:
SPARKER HONDA TCI - IgniTech Přelouč
You will need to program this with a laptop, but is not difficult and i just used the Ign map from the prev. CDI shop.

If any one is interested, I have the ignition maps, std and up rated, along with wiring dias for the plugs, photos etc.

Do this and be amazed at the difference.!!
 

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I have the same problem.
I've been driving for a long time when the engine just dies and lose all power. Immediately I thought it was the fuel pump couse the milage is 58900km. So I had a spare OEM pump under the seat. Change it by the road and thought it was all good but after about 5km the same think happened. Let the bike cool down and got another 5-6km until the same thing happened. Really frustrating.

And the odds of two fuel pumps are bad can't be that big. The new fuel pump was really hot so I look for vacuum in the tank but it seemed that is was good.

Hope that it is the fuel pump relay. Will order one. Update if it work out or not.
 

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Try 'Hot wiring' the fuel pump (with a fuse!) as i did. This will see if the relay is intermittently playing up like mine was.
Process of elimination. FYI, if it is fuel starvation, the engine tends to cut out one cylinder first, so a lack of power is immediately evident.
 

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Space Emperor
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Discussion Starter · #34 ·
I had a similar intermittent cutting out fuel problem and was also running a new facet fuel pump, so unlikely to be that.
I have used facets in race and rally cars for years and never had one fail. Any how my problem was traced to an intermittent fuel pump relay, replaced it and no more cutting out.
I traced the problem by connecting the pump directly to the battery via a push pull connector and riding it for a few miles with no problem. As this was only a temporary measure, the connection/disconnection had to be done manually, but it proved the point. Having replaced the relay, as a belt and braces measure, at the fuel pump connection i have a 'stand by' lead that can be swapped over to give a direct feed (via fuse) to the battery.
From memory the new relay was quite expensive at £40 ish, so i wanted to be sure it was faulty before replacing it.
Hope this helps!
Dave
FYI to all AT owners, the biggest single improvement to performance i have done and i highly recommend you do,
is upgrade the Ignition map for decent UK and European fuel. The stock map is very retarded to run on crappy fuel found in the likes of Africa. My AT RD07A did not like to drop much below 3000 RPM ( or 2500 after exhaust mods) before the dreaded chain snatch set in, which i believe is responsible for the wear on the gearbox sprocket shaft.
After reprogramming the ignition map, the motor now will pull from 1500 RPM In top gear !
It is now so much nicer to ride and is now the bike it always should have been.
The only sensible way to do this (dont even think about moving the ign pick ups!) is to change the Ignition module to a modified pre programmed box, or a programmable box. But a slight hitch here, RD07 and RD07A boxes are different, the RD07 has twin pickups and the 7A only a single.

The map i used (brilliant!) came from this company who also supply pr-programmed or programmable boxes for a whole range of AT models etc.
Digital Double-CDI for Honda XRV750 Africa Twin (RD04/RD07)
They are a very helpful company and a contact name is Felix Möhrle <[email protected]>
However they dont do one for the RD07A !
There is another company called Carmo which does units, for the RD07 (not 7A) but they give very little information, which i was uneasy about.
The box i used for my 7A came from this company:
SPARKER HONDA TCI - IgniTech Přelouč
You will need to program this with a laptop, but is not difficult and i just used the Ign map from the prev. CDI shop.

If any one is interested, I have the ignition maps, std and up rated, along with wiring dias for the plugs, photos etc.

Do this and be amazed at the difference.!!
That's very interesting info, snowmad. Unfortunately I have an RD07a. Anyway, I think I know the cause of the failing pump. The bike had been standing unused for basically 1-2 years, with only one or two short rides. Fuel here in Vietnam seems to get bad very quickly. When I took the pump out, I sprayed degreaser into it, and it came out brownish. I think the plunger was stuck, simple as that. I still need to re-connect the pump and see if it works without hickups now. I'll try just connecting it and see if it runs when cranking. If it does, I can rule out bad wires, because it definitely didn't run before I cleaned it.

The idle issue must be related to the idle circuit, which I failed to clean when I had the carbs out. I can live with that, to be honest, but of course, it would be nice it it went away :p
 

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Space Emperor
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Discussion Starter · #35 ·
I have the same problem.
I've been driving for a long time when the engine just dies and lose all power. Immediately I thought it was the fuel pump couse the milage is 58900km. So I had a spare OEM pump under the seat. Change it by the road and thought it was all good but after about 5km the same think happened. Let the bike cool down and got another 5-6km until the same thing happened. Really frustrating.

And the odds of two fuel pumps are bad can't be that big. The new fuel pump was really hot so I look for vacuum in the tank but it seemed that is was good.

Hope that it is the fuel pump relay. Will order one. Update if it work out or not.
I've had the same issue some years back. It turned out to be the main fuse and / or some bad connectors under the dash or airbox, I forget. The main fuse melted, and I bypassed it with an external fuse. The problem with engine cutouts I've experienced recently is definitely fuel related, as the time it ran matched the time it would take to drain the carb bowls of fuel, without new fuel being added. After a while, the carbs would fill up again, and I could run it again for 5-6 min, until it cut out again, and show absolutely no signs of wanting to start again.

Either way, I think it's in order to check all these flimsy connectors Honda has used on the AT. I recently discovered a few more, that had started to melt the plastics a bit. I simply cut them off, and solder the wires instead. Not gonna bother with new connectors, as it's unlikely that I will ever need to disconnect them.
 

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Hi Thomas, i also have an RD07A so i am not sure why you mentioned that. When i first bought the bike i read up on the most common causes of AT breakdowns, mainly fuel pump related and battery Voltage regulator, so addressed them.
Contact point fuel pumps were/are always unreliable in motorsport, so i learnt years ago to replace them with Digital. Facet's were reasonably priced and i've never experienced one failing, so it was an obvious choice and fits in nicely to the original bracket with a bit of bending! If the fuel goes off so quickly in Vietnam, i would suggest fitting a drain off point to empty the tank if stood up for a while.
The other problem with the voltage regulator, fit a Mosfet type (info here on the forum) more efficient and avoids the 3 pin Honda connector corrosion problem that can cause battery boiling. Mine was second hand from a Yamaha!
Hope this helps!
 

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Space Emperor
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Discussion Starter · #37 ·
Hi Thomas, i also have an RD07A so i am not sure why you mentioned that. When i first bought the bike i read up on the most common causes of AT breakdowns, mainly fuel pump related and battery Voltage regulator, so addressed them.
Contact point fuel pumps were/are always unreliable in motorsport, so i learnt years ago to replace them with Digital. Facet's were reasonably priced and i've never experienced one failing, so it was an obvious choice and fits in nicely to the original bracket with a bit of bending! If the fuel goes off so quickly in Vietnam, i would suggest fitting a drain off point to empty the tank if stood up for a while.
The other problem with the voltage regulator, fit a Mosfet type (info here on the forum) more efficient and avoids the 3 pin Honda connector corrosion problem that can cause battery boiling. Mine was second hand from a Yamaha!
Hope this helps!
Yeah, I have both, mate!

I can probably eliminate the CDI, as I experience no other electrical issues.

Here's the odd thing going on with the fuel pump:

When I connect the pump to the bike, it doesn't run. When I connect directly to the battery it runs fine.The battery measures 12.8v, engine off. If I measure the harness wires going to the pump, they show 0v when the ignition is off, 11.5v when ignition is on, engine off,and 12.4v when the engine runs. Still the pump doesn't run when connected. I have no idea what's going on? Maybe the leads got switched? Hard to believe, as they are red and black ...

It's all getting a bit tiresome :(
 

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It still sounds like a fuel problem. How long does it take to start to run rough and then cut out? Perhaps worth trying to simulate it running out of fuel so you control this to see if the symptoms are the same? If it takes 10 minutes for example, you could starve it of fuel after say 5 minutes and see what happens. If it runs rough and cuts out in the same way then it looks like fuel but if its different then perhaps something else.
Hi Thomas. I have never known a facet fail, but on my RD07A i had a similar problem that was caused by the fuel pump relay.This manifested itself by the engine cutting out on one cylinder and running rough on the other. For me when this happened whilst riding, If i turned off the ignition, then quickly turned it back on again, it cleared the problem for a few miles, then it happened again.
If the carbs are empty,(run the engine with the fuel shut off until it dies) turn on the ign and just stab the starter. this should initiate the facet pump to start pumping, a rattling sound. When the carbs are full, it should change to a ticking sound. Then you know the pump is ok. Try by- passing the pump relay by just fitting a temporary live feed from the battery (with a fuse if possible!). If this cures the problem, its the relay at fault. You could just bridge the wires across the relay to do the same and the pump will turn on with the ignition.
FYI the relay is supposed to cut off the fuel supply if you drop the bike, but when i dropped mine, the engine continued to run because it still had fuel in the carbs, so is pretty pointless (and about £40 to replace).
 

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Space Emperor
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Discussion Starter · #39 ·
Hi Thomas. I have never known a facet fail, but on my RD07A i had a similar problem that was caused by the fuel pump relay.This manifested itself by the engine cutting out on one cylinder and running rough on the other. For me when this happened whilst riding, If i turned off the ignition, then quickly turned it back on again, it cleared the problem for a few miles, then it happened again.
If the carbs are empty,(run the engine with the fuel shut off until it dies) turn on the ign and just stab the starter. this should initiate the facet pump to start pumping, a rattling sound. When the carbs are full, it should change to a ticking sound. Then you know the pump is ok. Try by- passing the pump relay by just fitting a temporary live feed from the battery (with a fuse if possible!). If this cures the problem, its the relay at fault. You could just bridge the wires across the relay to do the same and the pump will turn on with the ignition.
FYI the relay is supposed to cut off the fuel supply if you drop the bike, but when i dropped mine, the engine continued to run because it still had fuel in the carbs, so is pretty pointless (and about £40 to replace).
Thanks for the help, snowmad! The Facet isn't failing, as it runs fine when connected directly to the battery. The bike also runs fine on gravity feed. It's the voltage reading that doesn't make sense.

Great idea to bypass the fuel relay. I thought it was there to switch on power to the pump when the engine runs (or cranking)? Not sure it will stop running when the bike dropped?
 

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Thanks for the help, snowmad! The Facet isn't failing, as it runs fine when connected directly to the battery. The bike also runs fine on gravity feed. It's the voltage reading that doesn't make sense.

Great idea to bypass the fuel relay. I thought it was there to switch on power to the pump when the engine runs (or cranking)? Not sure it will stop running when the bike dropped?
Hi Thomas, the relay is there to switch on the pump when the engine is running or cranking, but if you drop the bike it has no motion sensor in it, so it doesnt know! It will still keep on supplying power to the pump if the engine is still running (like mine was when i dropped it!). It only shuts off the power if the engine stalls as it does not detect a pulse from the ignition. It sort of has a purpose, as my carbs leaked fuel all over the road and would continue to be fed by the pump if the engine had stalled if the relay was bypassed. This risk has to be balanced by the fact that if the relay has never been changed and is quite old (like my 1997 unit) they can become intermittent. I replaced mine, but as a belt and braces measure i have also wired in a switchable by pass for the relay to be doubly sure!
Dont worry about the voltage irregularities as this is probably being caused by the relay! Either replace the relay (recommended) or remove it and bridge the wires (so a direct fused feed to the fuel pump), operated when you turn the ignition on.
 
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