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How do you set fuel pressure?
littleman - 23/7/10 at 07:21 AM

I recently bought a fuel pressure guage to go with my regulator. I have been told that i must set the maximum fuel pressure to 2.3psi, the car is a ZX9R engined Tiger B6.

I set the pressure to 2.3 psi at idle, is this correct? Just when the car is running and i blip the throttle the pressure guage goes down to zero. This further shows when driving it because when i go full throttle or over 8k rpm it stutters a lot and wont go any faster.

Am i right to think that the fuel pressure is set too low? And if it is how do i set it properly?

BenB - 23/7/10 at 07:25 AM

That doesn't sound right! It shouldn't matter what RPM you set the fuel pressure at the regulator should maintain it..... Infact even if you set the regulator with the engine off (but the fuel pump running) it should still work.

littleman - 23/7/10 at 07:34 AM

quote:
Originally posted by BenB
That doesn't sound right! It shouldn't matter what RPM you set the fuel pressure at the regulator should maintain it..... Infact even if you set the regulator with the engine off (but the fuel pump running) it should still work.


Yeah i thought so, i guess thats the whole point of having tha damn regulator there in the first place!

Its stable with just the pump running and also at idle and with a little throttle but once the throttle is opened a lot it drops. Could be that the regulator is faulty i suppose.

BenB - 23/7/10 at 07:42 AM

Could be the pump isn't able to keep up / restriction in line flowing to regulator etc etc.

l0rd - 23/7/10 at 07:53 AM

Did it start stuttering after the pressure regulator installation?

Work backwards to find the problem.

omega0684 - 23/7/10 at 08:02 AM

is it running carbs or injection?

tonym - 23/7/10 at 08:07 AM

2.3 psi is hardly the pressure you would find in an injection system.

minitici - 23/7/10 at 08:17 AM

Is your fuel pipe from tank to pump collapsing?

littleman - 23/7/10 at 08:19 AM

quote:
Originally posted by BenB
Could be the pump isn't able to keep up / restriction in line flowing to regulator etc etc.


What do you think is the best way to test for this? I'm thinking to take the pressure regulator out and see what readings i get without that in, then i can eliminate that. But as for seeing if the fuel pump is up to the job i'm not sure how i would find this out.

littleman - 23/7/10 at 08:22 AM

quote:
Originally posted by l0rd
Did it start stuttering after the pressure regulator installation?

Work backwards to find the problem.


I havnt had the car very long and it was fitted when i got it so i cant say.

quote:
Originally posted by omega0684
is it running carbs or injection?


Its on carbs mate

quote:
Originally posted by minitici
Is your fuel pipe from tank to pump collapsing?


I'll check, it will only be a small pipe though as the pump is fitted next to the tank.

daviep - 23/7/10 at 08:28 AM

What type of pump are you using?

The bike pump is the easiest option and doesn't require a regulator.

Davie

littleman - 23/7/10 at 08:56 AM

quote:
Originally posted by daviep
What type of pump are you using?

The bike pump is the easiest option and doesn't require a regulator.

Davie


Its a facet pump, not sure of the max pressure of it but i think its about 7psi.
Would the bike pump be up to the job do you think? just thinking about the extra distance its required to pump over.

daviep - 23/7/10 at 09:28 AM

The bike pump should work perfectly, I've got mine mounted on the scuttle "sucking" from the tank but it is preferable to have them mounted at the tank and "pushing".

We used to run a Facet pump and Filter King regulator on a race car and changed to the bike pump after a lot of problems.

Davie

littleman - 23/7/10 at 09:39 AM

quote:
Originally posted by daviep
The bike pump should work perfectly, I've got mine mounted on the scuttle "sucking" from the tank but it is preferable to have them mounted at the tank and "pushing".

We used to run a Facet pump and Filter King regulator on a race car and changed to the bike pump after a lot of problems.

Davie

Thats the same setup as i have currently, facet pump with filter king regulator.

Dingz - 23/7/10 at 12:54 PM

It sounds like a flow problem, nothing to do with the pressure. Check the fuel lines are clear and not kinked, is there a blocked filter in the system somewhere?

britishtrident - 23/7/10 at 01:07 PM

Pressure regulators that fit into the fuel line between the fuel pump and the carb restrict flow are a liability.

On injection systems it works differently the regulator reduces the pressure by bleeding off fuel from the fuel rail back to the tank.

Better to use a lower pressure pump either a bike pump or Facet road solid state pump (2.5 to 3psi 12 GPH) or an SU style pump with solid state switching.