Jump to content
SAU Community

Recommended Posts

Hey guys wondering who could help me out running at idle only has 30psi fuel pressure at idle, and only goes upto around 35psi engine off

Has walbro fuel pump running on full 12v from battery

new fuel filter

stock injectors

stock regulator

using a turbosmart fuel guage setup on the line from the filter to the back off the injector rail

R33 gtst rb25det

thanx any help would be great !

Link to comment
https://www.sau.com.au/forums/topic/352837-low-fuel-pressure/
Share on other sites

I think the filter would be on the intake side before the injectors, well thats where i put mine on both our cars, but just check that all the lines are on in the correct order it should go from the fuel pump to filter, then to fuel rail, out of the rail into the fuel regulator, then back to tank. Maybe this could be a problem if the fuel regulator is hooked up back to front.

You need to check fuel rail pressure with the air/boost signal hose disconnected and blocked

Fuel rail pressure is around 2.5bar at zero manifold vacuum. That's about 37-40psi.

If you haven't removed the air/boost signal to the fuel reg, at idle it may be pulling around 20" vacuum or the equivalent of around 10psi.

So with the signal hose connected, you'd only see a fuel pressure of around 27-30 psi.

I think the filter would be on the intake side before the injectors, well thats where i put mine on both our cars, but just check that all the lines are on in the correct order it should go from the fuel pump to filter, then to fuel rail, out of the rail into the fuel regulator, then back to tank. Maybe this could be a problem if the fuel regulator is hooked up back to front.

the incoming fuel is going through the filter into the rail then out the reg to the fuel damp back to the tank thats right isnt it?

You need to check fuel rail pressure with the air/boost signal hose disconnected and blocked

Fuel rail pressure is around 2.5bar at zero manifold vacuum. That's about 37-40psi.

If you haven't removed the air/boost signal to the fuel reg, at idle it may be pulling around 20" vacuum or the equivalent of around 10psi.

So with the signal hose connected, you'd only see a fuel pressure of around 27-30 psi.

disconnected the air hose to the reg and blocked the feed, it went from 29 to 35 psi.

also could try and pinch the fuel return line and if rail pressure increases, then your fpr is stuffed. fuel filter is on the intake line. no good filtering fuel thats already gone through the system

i pinched the return line from the reg and the fuel pressure was rising all the way upto 60 psi if i left it there does this mean my reg is gone?

Low fuel pressure, it is difficult to run the country. If you are worried about the pressure on oil prices, the installation of a Mei Ling M55A is a pump with a high volume pump std spring. When all fails, do a fuel pressure, fuel quantity test, could save you from chasing your tail and throwing good money at the wrong problem.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • Unfortunately haven’t taken pics yet after it was finished. All the edges are hemmed nicely, just had to cut holes for the gear shifter and seat bolts and seat belt bolts in the rear. The molds seem like they’re done with steam and a layer of glue on the underside to hold a bit of shape but still soft enough that it’s a good fit when it’s all pressed down.
    • When's the rear mounted turbo kit coming? Needs dose and V8 chop idle lol.
    • I was very unimpressed with how the car came up from the A pillar forward, before I hit things (twice). It all has to go. It had to go, but now it has to go... more. So we finally found the very first Shennanigans with the entirely perfectly setup engine that had no problems being pulled apart to improve on 'was perfectly fine'. Cam bearings looked a bit... stock. Which isn't entirely bad given they were stock and this is a ~20 year old engine. So new cam bearings are on the way because it's somewhat difficult to get to this stage to do it later, and it will trash the block. It was quite unusual that it wasn't done when the perfectly new-looking VCM cam was originally installed by [unknown] What IS unusual is the cam that was installed there was advanced SIX degrees. As to why there is no way to know.. however it could have been @Dose Pipe Sutututu's mate who wanted a larger cam sound but also wanted it to come on earlier to be more usable. This is my dyno sheet with the previous setup - This cam is not supposed to peak until 7000+ RPM, according to VCM. This is what lead me down the whole 'my heads/intake setup is running out of puff and can't support the cam' line of thinking to begin with. Anyway too late now - New cam is in! It could be rather funny if this smaller cam acts like a larger cam because it isn't advanced six degrees. In the spirit of everything is working amazingly - the COMP cam required no dialling in whatsoever. It was about 0.5 degrees advanced, which seems pretty bang on. Any adjustment either way would be further out. I'm told as a chain breaks in it ends up regarding back about 0.5 a degree as the chain breaks in, making it bang on. In the spirit of everything was previously working amazingly - The timing gear that was taken out turned out to be was an N-Motion double timing chain kit, with adjustable cam gear (which is how it was 6 degrees advanced) and all looks entirely perfectly new. It also had a Torrington bearing, which was one of the reasons I ended up getting the Cloyes kit which they used in the C5R 24 hour racecar - Because I couldn't confirm what was in the engine when talking to Tony Mamo. I did believe however it was a Double chain kit of some kind... but found no supporting documentation or evidence for it.
    • I recently did this to my R33 with the full set from Car Mats Direct, they can't do the vinyl anymore that's advertised on the website due to a supplier issue so I ended up with the Black Loop Pile which looks great. I went all out with rubber sound deadening sheets from Repco and also added the sound deadening foam layer option with the carpet. Makes a world of difference and got rid of all the weird smells in the 29 year old interior. It was a bit of work but I'd 100% recommend it, Car Mats Direct had awesome customer service and quick postage. Replaced my seats with some sporty ones from Autotechnia while I was at it, feels like a new car.
×
×
  • Create New...