A Honda NT650V Deauville causes in fact only few trouble, most of the time it's simply working. In the European Deauville forums, here and there an unfortunate rider appears whose fuel pump gave up the ghost suddenly. This page describes how to guard against this problem with very little money and half an hours work. The details refer to my Deauville modelyear 2005 - Deauvilles from modelyear 2006 (NT700V) are not affected due to fuel injection.
Postings in the UK Deauville Owners Club Forum and the tip at Günter Louisoder's homepage caught my attention. Even in German-speaking forums this issue was discussed every now and then, but up to now I could'nt find a foolproof and clearly arranged description. I will have a try on this page. Important Notice: This is a report about my modifications at my Deauville. Any other party's action based on the information given here is carried out completely at their own risk. I assume no liability for the integrity and correctness of all details and I shall not be deemed to be responsible for any loss or damage of any kind as a result of regarding or disregarding the given information. My terms of use (German) apply.
The fuel pump: The NT650V's engine is supplied with fuel by an electric fuel pump. This in fact is not essential, but it's the only way the last 3 liters of fuel can be pumped from the tank towards the engine, and fuel supply can be interrupted by a relay in case of emergency. In addition, the Deauville is always supplied with the right amount of fuel, that is, the fuel-mixture is always rich enough when accelerating or at higher revs. In case of a breakdown it's possible to simply take the pump out of the fuel pipe, but one should preferably ride "with it".
The pump is driven by a stroke"motor", which delivers fuel with each single stroke. The propulsion is carried out by a solenoid (coil). At the end of each stroke a contact opens, to interrupt the current entry. The contact closes again, when the pump has completely returned to its starting position. When the carbs are full, the pump is unable to return. When more fuel is needed, the pump returns, the contact closes which causes the pump to stroke and spit a "mouthful" of fuel.
When the contact interrupts the current flow, a noticeable spark forms at the contact. This is unavoidable with this mode of drive, almost "by design".
About the technical background: The solenoid works with so-called inductive electrical energy. Inductors don't like sudden changes of current. When the contact opens, the current tries to flow on. Because the opening conctact increases the resistance, the voltage rises far in excess of the usual 12 Volt of the vehicle's electrical system.
This high voltage causes spark formation, the spark formation by and by erodes the contact, and the fuel pump eventually breaks down...
If the pump manufacturer (did I notice a Mitsubishi logo on the cap?) were aware of basic electrical matters - this must be doubted -, he would have done in the production line, what I had to make good...
There is need for something which keeps the "bad" current away from the contact like a lightning conductor, but lets the "good" current pass to drive the pump. A diode helps in this case, because diodes let the currency pass only in one direction. When the diode is connected in parallel to the coil, it can devert the "bad" current before it reaches the contact and send it back to the coil. The "good" current is blocked by the diode, therefore the current flows as desired through the coil and drives the pump.
What is required? A universal silicon diode 1N4007 (1A, 1000V) which costs about 0,05 Euro. This part is a standard item for electronic tinkerers and should be available in any well stocked electronic shop (to a lesser extent in discount shops).
Circuit diagram: The diode is connected in parallel to the coil. Translation: Kontakt=contact, Spule=coil, schwarz=black, grün=green, schwarz/blau=black/blue
Photo: The diode is only about 5 mm long, the cathode is marked with a ring.
What else is required?
If everything is laid out, go ahead step by step:
Step 1: Remove the seat.
Put the key into the lock above the left saddlebag, turn the key while lifting the rear end of the seat. I usually press down the seat in the middle (between driver and pillion seat) down/backwards, while I lift the rear end further on. This makes the two plastic catches leave the clamps more easily released.
To reach the fuel pump, the black side cover has to be removed.
Step 2: Remove the black left side cover.
Loosen the hexagonal screw of the side cover, remove the cover. Now the target object is visible!
Important: The fuel pump does not need to be completely removed! It is sufficient to loosen it from the rubber shock suspension and pull it a bit upwards. The two fuel pipes can stay connected to the pump.
Step 3: Loosen the fuel pump
No tools are needed to loosen the fuel pump. Simply lift the pump with your fingers from the rubber shock suspension!
Move the mouse pointer over the photo to clarify the loosening (JavaScript has to be enabled).
It can be better to disconnect the ventilation hose (not the two thicker fuel pipes on the left side!) from the black plastic cap: First widen the hose clamp with long-nosed pliers and push it further onto the hose, then pull off the hose from the nipple.
Step 4: Remove screw from the cap.
On top of the black plactic cap there is a cross-head screw which was decorated by Honda with a blue sealing wax. Loosen this screw - the sealing wax jumps off and everybody knows: Somebody has fumbled here...
Now the black cap can be removed. The two cables glide easily through the grommet, if they have been sprayed with silicone.
Step 5: Determine soldering points
Now the fuel pump's front side with the contact is open. The diode has to be soldered with its cathode (ring-shaped marking, see above) to the black/blue cable (point A, see step 6). The other end of the diode, the anode, is to be soldered to the end of the thinner black cable (point B, see step 7).
Step 6: Solder the cathode.
Dismantle the black/blue cable carefully with a sharp knife for about 10 mm, so that the copper wire is exposed. If you tin the copper right now, soldering in the diode will be faster later.
Important: Diodes are susceptible to soldering heat. Hence don't cook it too long, rather sold it quickly and cleanly! Additionally protect the diode by not cutting the conductors too short and by clamping long-nosed pliers between the soldering point and the diode to divert a good portion of the heat.
Form the diode's cathode conductor (ring marking) so that it fits to the bared and tinned lenght of the black/blue cable. Grab the diode's cathode conductor with the long-nosed pliers between the soldering point and the diode (see photo), then sold it quickly and cleanly.
Step 7: Soldering the anode.
Bend the other conductor so that it leads to soldering point (B), maybe it will need shortening. Solder as described above.I covered the bared part of the black/blue cable and the diode's conductors with insulating tape to avoid short circuits. A function test (start Deauville engine and open throttle) ended positively. After that I re-assembled all parts in reverse order:
That's been all. Anyway, writing and translating this page took much more time than the soldering itself.
Many thanks to Andy B. for ironing all those errors out. If someone would like to send me corrections, supplements or advice about this page, I would be more than happy to receive your email: deauville@es-ist-liebe.de.
Copyright © 2005, Michael Hankeln. Alle Rechte vorbehalten.
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