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Discussion Starter #1
So as the title says I have low fuel pressure and no clue why. A little bit of history on the quad I got it knowing that it didn’t run right I went through checked I was getting fuel check that the injector was working checked the valve lash everything that you would think to check. ended up checking the fuel pressure it holds 43 PSI at idle but when revved drops to near zero and dies. So I got a new fuel pump from eBay put it in put the new filter and everything looked fine start up and same problem low fuel pressure when revved. Got to thinking and I thought it was the fuel pressure regulator so I went and got a fuel pressure regulator could only find them with the pump so got a Nother pump and fuel pressure regulator. Put it in everything worked fine let it idle and warm up then went to rabbit and it just died again been messing with this for about a month and a half now don’t know why scratching my head looking fo put it in everything worked fine let it idle and warm up then went to rabbit and it just died again been messing with this for about a month and have Gotten very frustrated with it. I don’t want to go and get a new $250 sending unit and am at a roads end any help is greatly appreciated
 

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The regulator is sealed with plastic cement if I remember right.

Also, the fuel pump relay could be failing not passing full power to the pump under load.

You might want a new sending unit.
 

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Discussion Starter #4
I’ve tried swapping some of the 4 relays that are all sitting there and changing them didn’t make a change

I’ll try testing the battery this weekend although I doubt it will get a bad reading because I’ve tried hooking up a battery charger to the battery while it’s running to make sure it wasn’t from low voltage yet the problem was not fixed

I’m trying to avoid getting the whole sending unit but if that’s what it comes to then so be it

Only reason I can think of needing to replace the sending unit is because the plastic is cracked
 

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I’ve tried swapping some of the 4 relays that are all sitting there and changing them didn’t make a change

I’ll try testing the battery this weekend although I doubt it will get a bad reading because I’ve tried hooking up a battery charger to the battery while it’s running to make sure it wasn’t from low voltage yet the problem was not fixed

I’m trying to avoid getting the whole sending unit but if that’s what it comes to then so be it

Only reason I can think of needing to replace the sending unit is because the plastic is cracked
If the plastic is cracked, the regulator is bad or the o-rings around the regulator are bad or missing..then the fuel is recycled back into the tank..thus the loss of pressure...

Here's the cheapest sending unit I found on Ebay.. https://www.ebay.com/itm/08-14-KAWASAKI-KFX450R-KFX-450F-FUEL-PUMP-GAS-PETROL-SENDER-UNIT/401689532371?hash=item5d868fd7d3:g:Da0AAOSwXAxcQk21:rk:26:pf:0
 

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Discussion Starter #6
I would agree however does not explain why it holds perfect pressure till revved that’s why I’m so confused on this problem
 

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I would agree however does not explain why it holds perfect pressure till revved that’s why I’m so confused on this problem
When a fuel pump/regulator goes bad it's starts losing pressure around the higher RPMs (usually) causing lean fuel mixtures and gets worst from there...idle pressure usually remains good throughout the ordeal...!!
 
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