Low fuel pressure

Hunter

Hunter

Greenie N00B Member
Having low fuel pressure on 08 ms3 the car will start run for 5 secs then die fuel pressure reads 130psi and that’s it. New Fuel rail / sensor , new hpfp housing and internals , relief valve , spill valve , in tank fuel pump , Seals and fittings , injectors all been replaced brand new wiring harness as well. Car was just built and everything on the motor was just replaced with oem or aftermarket. Any body know what could be cause the fuel pressure to be so low


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There is a ground by the HPFP, make sure that is hooked up. It looks like a bunch of black wires that source to it.
 
Had almost same issue before, check your timing, our timing was off and hpfp pressure was off 100- then jumps to 900 then 100 again then shut off, then bent the valves,
And if it's the first start for new motor, my tuner told me to crank it 60 sec for the rail to build up pressure, check the ITFP too pull out the blue low side connector at hpfp then put bottle and check if it primes when key is on,
One last resort if still doing that, disconnect the rail sensor and start the car, we also had that problem when car dies after 1 sec turn out to be that sensor, car will run idle if the sensor is disconnected but shuts down the moment we connect it,
BTW that sensor everybody saying you have to buy with the rail with it? BS
Go vatozone/bro Reilly, part number is 800-900002 it's a fuel evap sensor for a cobalt which is same as that lol, I used it,
 
Timing is good checked 4 times it’s good done all the new motor start and prep stuff and still only getting 130psi the Pump inside the tank is brand new and the hpfp housing is brand new and same with internals. Check all electrical and it’s all good just seems that the hpfp is not building in any pressure and can’t figure out why


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Yeah not trying to be mean, not because brand new means it will work out if the box, the hpfp of my friend won't build pressure and stays at 76, turn out the Internals installation is wrong, over torque, so we swapped in stock one and it runs good until it's tuning time, he also have new built motor and is on break in

Up to you man what you want to do, you can sit and research and talk with people but swapping stock hpfp assembly isn't that half bad...

Btw my friend HPFP is also brand new....
 
Ok thanks I’ll pull part the HPFP and see if anything is wrong


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Eroler1 said:
Yeah not trying to be mean, not because brand new means it will work out if the box, the hpfp of my friend won't build pressure and stays at 76, turn out the Internals installation is wrong, over torque, so we swapped in stock one and it runs good until it's tuning time, he also have new built motor and is on break in

Up to you man what you want to do, you can sit and research and talk with people but swapping stock hpfp assembly isn't that half bad...

Btw my friend HPFP is also brand new....
Click to expand...

Checked the HPFP is all good nothings wrong with it


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Do you have anyone you can borrow a stock one? We had that too looks okay, started messing with the intank then gave up lol check your spill valve, and also forgot to mention your rail valve remove and check if you can blow thru it
 
I’ll check that and try to figure this shit out lol


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Yeah if the rail valve is stuck open, (can be manufacture fault) it won't build up pressure
[doublepost=1541823393][/doublepost]Lol you lucky your car fires up, mines won't even fire but cranks and my thread is dead LOL
 
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