iiyama
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| posted on 10/5/26 at 01:04 PM |
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Gen 1 Hayabusa fueling issue
It's been a while since I posted anything on here for many reasons; so to those that remember me, hello! To those that have no idea then hello
too!
The fuel system in the car seems to have developed a pressure issue. System is straight forward, tank supplies an Aeromotive pump via a Sytec filter,
pressurised fuel is then fed to the rail via another Sytec filter. An Aeromotive FPR is sited on the far and of the rail and all this is connected
together with -6 tube.
System has been faultless up until recently. Pressure has been set at 43psi with vac tube disconnected and has remained steady with it connected.
Now all of a sudden the pressure seems erratic. Figured the diaphragm may have perished due to the car being stood for a while, so I have changed this
and visual inspection of the old brought no joy and the replacement has made no change.
Pump is delivering 43psi at idle but yesterday after a drive to a charity gig in Bournemouth the car barely made it home; pressure at one point
dropped to 35PSI at a steady 4500 RPM.
I've checked the plugs this morning to see if one was showing signs of over fuelling, (i,e, injector stuck open), but there is nothing obvious.
There is no sign of a fuel leak.
I haven't had a chance to take the car for a run with the vacuum line of the FPR, but considering it's meant to be connected I'm not
sure if this would reveal anything?
Any ideas out there in the think tank?
Cheers,
Mouldy
If its broke, fix it. If it aint broke, take it apart and find out how it works!
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adithorp
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| posted on 10/5/26 at 05:33 PM |
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Givrn uour description it could be the pump is able to deliver the pressure (hence ok at idle) but isn't delivering the volume to keep up with
fuel use at higher revs and the pressure drops as a result. I'd change the filter and check the supply pipe from the tank for a blockage.
You could also check the specified delivery rating of the pump (in lt/min) and then run the pump into a container to see if it matches.
"A witty saying proves nothing" Voltaire
http://jpsc.org.uk/forum/
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iiyama
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| posted on 10/5/26 at 06:03 PM |
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Thanks fella.
I should have added that I removed the post pump filter element and that has made no difference, pre-pump filter element is still in place however.
I'll give the other suggestions a crack tomorrow. 
If its broke, fix it. If it aint broke, take it apart and find out how it works!
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adithorp
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| posted on 10/5/26 at 10:11 PM |
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The pumps don't suck very well so any restricting in the flow to them has,a bigger impact than anything after them. So the pre pump filter is a
suspect.
"A witty saying proves nothing" Voltaire
http://jpsc.org.uk/forum/
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iiyama
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| posted on 11/5/26 at 08:26 AM |
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Pre filter was indeed an issue; it's certainly done it's job!
I could probably clean it as it's a metal filter but I think I'll order up a replacement.
It will be interesting to see if this is the only issue, (I hope it is!).
I'll report back when I've got it all back together.
Mouldy
If its broke, fix it. If it aint broke, take it apart and find out how it works!
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iiyama
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| posted on 13/5/26 at 01:43 PM |
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As it was a metal filter, I decided to clean it.
It is a 120micron filter but due to all the crap in there I think it was down to nearly 0 microns!
Anyway all back together and a run in the garage shows things appear to be back to normal.
Just need to road test it now.
If its broke, fix it. If it aint broke, take it apart and find out how it works!
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