zxr400 fuel pump problems

[Celticdan]

hello tirpitz. thanks for helping out with my wiring dilema the other day.i havent posted since i got the picture as ive been away on holiday.ive since put the plug back onto the fuel pump relay tried to start it with no hint of starting,ive now relised that the points on the pump are welded together.first of all where is the cheapest place to buy a repair kit and secondly would a faulty relay have caused this problem? this is the second pump in 2 months and ive only started it up a few times!! ive noticed that there is a constant live to the pump when the ignition is turned on and when the starter button is pushed it pulses is this correct ? any info would be great.Celticdan

[Tirpitz]

TBH I'm pretty good at spannering, and I can sort bits of electrics out, but the latter are not my strong point. There's plenty of others on here though that will probably chip in with better advice than I can give you on this one.

My own experience in respect of spares is to try ebay. A lot of breakers trade through there. Wemoto do a fuel pump repair kit for £22.34 see http://www.wemoto.com/bikes/Kawasaki/ZX ... nt_Switch/ It looks to me like that is a cheaper way to repair a pump. Make sure you get the right one for your model.

I don't see how a faulty relay could have caused the problem - for one thing the pump takes its supply straight from the battery, so it can't really be overloaded in this way. Also, it would run constantly if you were riding for hours so it has got to be used to be under load for a long time.

I think the pump runs all the time that the ignition is on and the floats in the carbs take care of shutting off the supply when they are full. I would suspect the pulsing is caused just by the srarter motor nicking most of the available battery power.

See if you can get Mori Man or Cargo to chip in. They seem to be on the ball with stuff like this but I hope the above helps a bit.

[cargo]

I think the fuel pump only starts pumping once the bike is actually started or when the starter button is pressed.



The fuel pump on my race bikes starts as soon as the ignition is turn on cos it's wired differently

[noelb]

From what I can recall Cargo is on the money - the pump operates when the starter switch is pressed and then when the engine is running. Once running, it only pulses as the fuel is drawn off into the carbs (not the constant clicking you hear when its running dry) so it rarely sees a huge constant current draw if its wired up as standard. I've done the same as Cargo on my race bike, mainly to be able to check if its running each race day when I switch on the ignition. My first season was plagued with fuel probs (you get 3/4 of warm up lap of mondello on the juice in the carbs ........I'm going for one of those rebuild kits myself for this season, as I reckon the diaphram and mechanicals of the pump will outlive those pesky points a few times over.

[cargo]

I actually had one bike with the pump wired to run all the time once ignition was on and the other was wired like the road bike.

I had a fault in the relay I think and as a quick fix I just wired the live side of the pump to the nearest switched live wire I could find it was something in the fuse box dont even remember what it was ? horn or something LOL and then just earthed the other side..............works just fine. LOL

[Tirpitz]

I was thinking a bit more about this - if the guy has a fault which is causing an electrical feed to the fuel pump all the time, irrespective of whether the ignition is on or not, odds are it's going to burn out before too long. That might be what is happening. Worth a quick check with a multimeter to see if the feeds to the pump are live with no ignition.

[Mori Man]

Fuel pump is gravity feed pressure sensitive

What that mean is , initial start it will pump , if you have a full tank it will cut off and allow the " head " of fuel to feed the carbs. ( NB: The fuel pump is not a shut off valve so you should switch your fuel tap to off when you park up)

As the tank empties and reaches reserve the pump detects the drop in fuel flow pressure and will start to kick in again by the time your on reserve it will be feeding the carbs on demand.

I know Exups run constant and some carb problems develope from float height and can take an age to correct , think the ZX9 runs constant to ie. on demand. FCRs are also picky about their float height and poor fuel flow developes bad throttle responce so taps like Pingle are used to counteract.

FCRs are hungrey buggers so it would be beneficial to have it running constant or race prep'd CVKs

When I laid my bike up after initially getting it going the fuel pump refused to work on the rebuild, that took a while to figure out as it wasnt a problem before I had earmarked the spare for fitting onto the ZRX to feed the TMRs as I am sure they would benefit from one, always on the look out for another Mmmmm think I bought one the other day - must check the box when it arrives !

[Tirpitz]

Fuel pump is gravity feed pressure sensitive

Well, I rest my case. That's why I said I'm not the man to ask about this. Well out of my depth.