23 replies to this topic

[curlylegend]

Has anyone had any experience with this......https://www.highflow...-1989-1998.html  ?

 

Certainly seem cheap enough.

 

My TDM has lain idle for a month and now won't start....bugger !!

I'd noticed that if it lay for more than 4 or 5 days it was slow to start, but when it did there was no problems.

 

So what do I do, try one of these or go for an electric pump system ?   Or is that another can of worms ?   I'd prefer to keep it simple.

 

Thanks....

[fixitsan]

When you say slow to start do you mean it turned over slowly (weak battery), or it took a long time to fire ? That pump looks pretty good

[jiff]

.....noticed that no-one had inputted into this query.....
so.... in my ignorance, wondered what it is that points you to the fuel pump ?

.......when you say ’ slow to start , but then....no problems’

does that imply that it spun over OK, but was just reluctant to fire up, .....I presume that’s it,
and assuming an adequate spark, you conclude a lack of gas is the issue.

or

if you meant that it laboured to turn over, but eventually managed to ‘catch’ , and then ran OK ?
....that sounds like the battery to me....
but, since I mentioned my ignorance.....just saying...

Jiff

[Studley Ramrod]

I leave mine for a good 3-4 weeks without starting and it takes ages before it fires into life.  I always turn the petcock to off when I park it up. I reckon it's partly due to the pump drying out and then struggling to pump fuel to the carbs, and partly due to a worn pump diaphragm.

 

Banggood also sell fuel pumps and they're very inexpensive, about £12 delivered iirc.

 

You could go electric but you need to make sure your carbs are in good order or the pump might flood the carbs, plus it's another leccy item that can go tits up in the middle of nowhere.  Vac pump method means you can carry a spare if need be, and they tend to wear out over time so ya get plenty of notice before it stops working.

[Pedro]

Mines the same. if it hasn't been started for a couple of weeks or more, the battery spins fast enough but it takes ages to fire. I put it down to the carb fuel evaporating a bit and takes a fair bit of engine spinning for the vacuum pump to fill it again and by that time, the battery is nearly flat. From now on, if it hasn't been started for a week or so, i automatically stick jump leads (connected to a spare car battery ) to the live solenoid connector and to any earth and help the battery spin the engine for longer. This method has always worked for me and it saves flattening the battery and killing it. I have also wired in a digital volt meter so i can tell what state the battery is in as soon as i turn the key.   I have often thought about some sort of priming system directly plumbed in after the fuel pump but never got round to looking into it in depth.

Edited by Pedro, 01 November 2018 - 05:12 pm.

[curlylegend]

Actually it spins over briskly enough and it was only when I left it for just over a month that it failed to start just as the starter motor was beginning to flag.  So, not the battery, or the starter motor.  And there's no smell of excess unburnt petrol from the exhaust, which leads me to suspect the fuel supply. I've recently overhauled the carbs, the fuel lines and the fuel tank, which only leaves the pump itself.  It is, after all, nearly thirty years old ! Like Studley, I also always turn of the fuel supply so I suspect the problem to be the pump drying out ?

I'm reluctant to complicate matters by introducing an electric pump to a system that wasn't designed for one so I'd rather replace the pump itself.

I was just wondering if anyone had experience of dealing with these people …...https://www.highflowfuel.com/i-23900534-quantum-yamaha-oem-replacement-fuel-pump-xtz-750-supertenere-1989-1998.html ?? and whether their pump would suffice ?

 

Once the bike's fired up, there's no problem, it runs cleanly right through the range and always re-starts immediately.....but after a few days ?? gets more reluctant to start immediately.

[SingleCylinder]

I replaced my fuel pump with a Polaris ATV pump, it works fine. If I let the bike stand for longer than a week or two with the fuel tap closed there is evaporation of fuel in the float chambers and maybe the pump and I have to try two or three times before it fires up.

But I live in warmer climes than the UK.

 

Maybe a manual prime pump in the line between tank and fuel pump as was suggested above or just ride more often?

[dapleb]

Changing the pump will prolly not make a difference but to check if it is the pump, you could try the arsey tate trick.

The Polaris pump is the OEM Juan.

[curlylegend]

Thanks for the replies, folk.

 

Changing the pump will prolly not make a difference but to check if it is the pump, you could try the arsey tate trick.

The Polaris pump is the OEM Juan.

 

What's the arsey tate trick, dapleb ?  I'm intrigued...

[drewpy]

Just bypass the pump direct to carbs and see if it starts.

 

that's the easiest way to determine the pump status

[dapleb]

If ewe search for arsey tate it should appear.

Don't think this is likely to be the prob though as mine does it after a long rest. With old fuel pump, new arsey tate fuel pump and new OEM fuel pump.

[Studley Ramrod]

My theory is that the vac pump gets a vac lock when left for a while without starting.  It can also be a problem if you're switching over to reserve and don't make it before the engine stalls, can take ages to get the fuel through again.

[curlylegend]

I replaced my fuel pump with a Polaris ATV pump, it works fine. If I let the bike stand for longer than a week or two with the fuel tap closed there is evaporation of fuel in the float chambers and maybe the pump and I have to try two or three times before it fires up.

But I live in warmer climes than the UK.

 

Maybe a manual prime pump in the line between tank and fuel pump as was suggested above or just ride more often?

 

Well, I've taken a gamble and ordered up a super cheap Chinese thing....probably the same one I was looking at originally but much dearer !....

 

I'd left the fuel in the ON position since yesterday while I was recharging the battery and when I tried it today it fired up pretty quickly  !

 

I agree about using it more, but what with one thing and another, that's just not going to happen....bugger !   So when the new pump arrives I'll fit it and see what happens.

 

But a priming system would not be a bad thing at all, I think.  Any ideas out there ?

[dablik]

I should'nt worry about the Chinese version curly, i've had one fitted for nearly 2000 miles without an issue.

[dapleb]

It can also be a problem if you're switching over to reserve and don't make it before the engine stalls, can take ages to get the fuel through again.

Just loike dis.

[Hombre]

On my 3VD, if the fuel level in the tank was above the carbs then it would start easily once gravity filled the carb float chambers.  If the tank level was low then engine cranking would be necessary to fill them.  The standard vacuum pump is not a constant displacement pump but will lift fuel from a low tank level when needed.  It still 'pumps' even when the float needles stop the flow when the engine is running, it just doesn't deliver anything.  Gravity on a full tank drives fuel through the pump even when the engine is stopped - never leave the pet-cock on when the tank level is above the carbs and the bike is parked up or the fuel will travel down into the crankcase.

[Studley Ramrod]

I should'nt worry about the Chinese version curly, i've had one fitted for nearly 2000 miles without an issue.

 

I bought one at the same time and it's not let me down yet.  That said, it's still wrapped up in plastic !   Gonna fit it over winter.  Quality looks to be pretty good looking at the outside.

[TKH]

The American pump was probably made in china. Also shipping costs can be as much as the item!

[Rallyist]

What must be remembered when starting after a longish time do not open the throttle at all otherwise you reduce the vacuum available to operate the pump.

[curlylegend]

On my 3VD, if the fuel level in the tank was above the carbs then it would start easily once gravity filled the carb float chambers.  If the tank level was low then engine cranking would be necessary to fill them.  The standard vacuum pump is not a constant displacement pump but will lift fuel from a low tank level when needed.  It still 'pumps' even when the float needles stop the flow when the engine is running, it just doesn't deliver anything.  Gravity on a full tank drives fuel through the pump even when the engine is stopped - never leave the pet-cock on when the tank level is above the carbs and the bike is parked up or the fuel will travel down into the crankcase.

 

 

What must be remembered when starting after a longish time do not open the throttle at all otherwise you reduce the vacuum available to operate the pump.

 

All good points and duly noted.