Merry Christmas everyone!

I noticed that when i prime the fuel pump, look at my Auotmeter fuel gauge and see that fuel pressure goes up to about 40psi and then drops off before starting the vehicle. After i start up the car, it runs well and maintains proper fuel pressure. Is it normal for this to happen with the fuel pressure before starting up the engine? Could there be something going bad on my fuel system? I am running a walbro 255lps fuel pump and AEM fuel rail/fuel pressure regulator.

I can also add that i just started up the vehicle, let it idle for a while and saw that fuel pressure was at 40 psi as set with no problems. I turned off the car and immediately took a look at the fuel gauge, it was already at 0.

We observed this same procedure on a honda civic and his fuel gauge goes up to the set fuel pressure and stays there with the key in but the engine off.

Thanks,
Mark


Modified by se93 at 8:11 AM 12/25/2003

 

anyone?

 

i had the same problem and i thought i had a leak. then i took a look at my neighbors hatch and it was at zero also. so i believe its normal for it to be at zero. but i dont think mine drops that fast tho. maybe check for a leak.

 

When you prime it my gauge also goes rather high until its done priming, then drops to the specified pressure.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 4bidden &raquo;</TD></TR><TR><TD CLASS="quote">When you prime it my gauge also goes rather high until its done priming, then drops to the specified pressure.</TD></TR></TABLE>

So, if you have your pressure set at 40psi for example, your gauge will stabilize at 40 psi and stay at 40 psi before starting the engine with the key in the "on" position before start-up? Mine goes up to 40psi and if i do not start up the engine, the fuel gauge will go back down to 0.

 

Go prime it more than once and see what you find out. See if it changes if you prime 2-3 times.

 

So, should pressure stay at the set pressure even after the pump is primed several times? I tried it a few times and it will go to the set fuel pressure, but drops off immediately to 0 psi

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by se93 &raquo;</TD></TR><TR><TD CLASS="quote">So, should pressure stay at the set pressure even after the pump is primed several times? I tried it a few times and it will go to the set fuel pressure, but drops off immediately to 0 psi</TD></TR></TABLE>

Think of a garden hose...

'priming' turns on the pump for about 2 seconds - so you build pressure AND you also put fuel inside you lines. After the pump turns off then the fuel is allowed to run back into the tank back through the fuel pump(i don't think hondas use positive displacement pumps - this is why the fuel can return back)... this happens very slowly but any built pressure will bleed off right away.. SOOooo...

pump on (tap on) (starts priming)
there IS pressure for a couple seconds- fuel system is being primed/filled..

pump off (tap off) (done priming)

there is NO pressure - fuel lines are FULL ready to go.. pump turns back on while the engine is running.

it's really quite simple..

Also, you should only worry about the 'set fuel pressure' when the engine is priming as much as you should worry about the pressure when the engine is running and there is vacuum controling the pressure regulator.

Hope this helps..

 

Thanks for your reply. You have answered my question. I will prime and have someone observe that the set fuel pressure is exactly where it should be and just enjoy driving the newly built H22a machine!!!!

I appreciate your information.