Fuel pressure dropping off - Honda Prelude Forum

se93 · 12-25-2003, 10:59 AM

Happy holidays to all at preludeonline.com.

I have a question regarding fuel pressure when the ignition key is in the "on" position and after you turn off the engine.

Is it normal for:
1- with ignition key in the "on" position, the fuel gauge will register the set fuel pressure and drop off immediately to 0

2- after starting up the engine, and letting it sit at idle for a while, you turn the engine off and the fuel pressure reading will go from the set fuel pressure to 0 in a matter of seconds.

Is this how it should be or do i have something in my fuel system that is not working properly? Engine starts up immediately, no hesitation and it has a new fuel pump main relay (installed a few months ago) and a new fuel filter as well. This inquiry is due to my tech's observation of the fuel gauge and we thus documented what was done and the results.

My H22A fuel system setup includes an AEM FPR/fuel rail, Walbro 255lph fuel pump, stock OBD1 H22A injectors and an Autometer 2 inch fuel gauge connected to the fuel filter.

The engine was started up yesterday (christmas eve, yes we worked until about 10:30PM while everyone else was partying!!)
and took it for a very short ride in which all seemed normal.

Any feedback will be appreciated.

NXLude · 12-27-2003, 08:30 PM

I have the same setup as you onlly I run the weapon R FPR. My car behaves somewhat similar, but when I run it and turn it off the pressure takes a long time to bleed off.....but remember you ran the guage to the filter and I ran mine to the riser......that would explain your faster drop times......I would say your car is fine, especially with that pump you have no fuel worries as far as enough volume or pressure. Try running the guage offf the rail, you may see different results

se93 · 12-28-2003, 12:45 PM

Hi NXLude:

Thanks for your reply. What you indicate is true. My fuel system is perfectly fine. No problems whatsoever, thank god!!!!!!!!!

marcucci · 12-29-2003, 07:19 AM

The fuel pressure should take a long time to bleed off. When you turn the key "on" and then off again the pressure should not bleed off beyond what the regulator is set at. I'm not familar with the Weapon R FPR or what AEM regulator we are talking about, but if it is working properly the pressure should stay at the setpoint with the key off. The only reason it would drop is if something is leaking (out or past the regulator). This should lead to low pressure when running.