Jos3ph

Quick question:

Is the fuel pressure suppose to slowly drop to zero psi once the car is turned off? or is it suppose to maintain pressure?

JT

The pressure will maintain for a while and then slowly drops to zero. When you switch on the ignition the next time, the fuel pump will energize for a couple of seconds to re-pressurize the fuel rail.


Modified by JT at 11:29 PM 10/19/2008

mattsnooz

exactly!

Otherwise it would be a mess when you bled the banjo bolt lol

A Blue Lude

If it's dropping off right away I'd be concerned, I think.

Jos3ph

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by A Blue Lude &raquo;</TD></TR><TR><TD CLASS="quote">If it's dropping off right away I'd be concerned, I think.</TD></TR></TABLE>

Mine doesn't drop immediately, but instead slowly goes down once the car is turned off.

I was asking because my car is hard to start period, especially when it's cold. I thought I had a fuel pressure leak because when I turned off my car, the fuel pressure was slowly dropping to zero.

<U>ANOTHER QUESTION:</U>

Is the fuel pressure from the fuel filter the same as the fuel pressure from the fuel rail?

I'm asking because I have a fuel pressure gauge installed on top of the fuel filter and even though the filter is connected by the fuel rail by a 1.5 ft fuel hose, i'm still questioning whether my rail is getting adequate fuel pressure.


Modified by Jos3ph at 12:48 PM 10/20/2008

A Blue Lude

Well, normal operation is as JT described it. Waiting for the pump to finish building pressure after key ON can probably help the engine start easier.

Jos3ph

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by A Blue Lude &raquo;</TD></TR><TR><TD CLASS="quote">Well, normal operation is as JT described it. Waiting for the pump to finish building pressure after key ON can probably help the engine start easier.</TD></TR></TABLE>

I would prime the pump multiple times (turn the key in the ON position, listen to hear when pump stops priming, turn the key to OFF position, and then repeat it multiple times) but still doesn't really help.

My car does start normally though if its already running and I turn the car off and a couple of seconds later try to turn it back on.

A Blue Lude

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Jos3ph &raquo;</TD></TR><TR><TD CLASS="quote">

I would prime the pump multiple times (turn the key in the ON position, listen to hear when pump stops priming, turn the key to OFF position, and then repeat it multiple times) but still doesn't really help.

My car does start normally though if its already running and I turn the car off and a couple of seconds later try to turn it back on.</TD></TR></TABLE>

That's not really going to make a difference unless you are having some kind of fuel pressure issue (like a leak or something). After the first key ON you should be at nominal rail pressure, at least in my experience.

Mervin

the fuel pump has a built in chack valve that will hold fuel pressure for a while, atleast not let all fuel drain out of the system and back into the tank......
If its faulty the last will happen and youll be cranking for atleast 5 seconds for the system to pressure and fire the engine up........priming for three/four times will do the same.......

try priming five or six times with a cold engine and if it starts up immediately, then the check valve is the culprit

Jos3ph

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Mervin &raquo;</TD></TR><TR><TD CLASS="quote">try priming five or six times with a cold engine and if it starts up immediately, then the check valve is the culprit</TD></TR></TABLE>

I just primed the fuel pump 6 times while my engine was cold and it started up immediately exactly like you mentioned.

So do you think I should plan on buying a new fuel pump?

Mervin

You could try to clean the check valve and see if it goes back to normal operation.

The check valve is located on the top of the pump body, where the hose that leads to the engine is attached....maybe try to get some compressed air into it and lube with a few drops of atf...

I also heard of inline check valves (between pump and engine) but dont know if these impair flow......Also some OEM fuel filters have the chack valve built in....

New fuel pump would be easiest guarnteed fix though, might want to look up a high flow one while your at it (keep in mind these will need a adjustable fuel pressure regulator)

Good luck & let us know how it turns out!!

Jos3ph

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Mervin &raquo;</TD></TR><TR><TD CLASS="quote">New fuel pump would be easiest guarnteed fix though, might want to look up a high flow one while your at it (keep in mind these will need a adjustable fuel pressure regulator)

Good luck & let us know how it turns out!!</TD></TR></TABLE>

I installed a brand new OEM fuel pump the other day (didn't think that I needed a high flow fuel pump and adjustable fpr since i only have the basic I/H/E).

Well, my starting problems are still there but not as bad. I wait for the fuel pump to prime once and then start the car. It takes about 2-3 cranks to start....not bad, but still going for the 1 crank start

Not sure what to check next though. any tests to see if my fuel pressure regulator is faulty?

NC.BB2

Yes, I can't recall exactly how you go about it so maybe someone else can finish this off for me but there is a way of hooking the pressure gauge onto the fuel rail, and a vacuum pump up inline to the regulator. As you increase vacuum pressure, the fuel pressure should go up as well. Like I said that's not very precise and I'm not sure how to do it on our cars, but I learned that in school a few semesters ago and that's how we did it on other cars. Good luck,

-Michael

civic8594

if you have changed the fuel pump it could be a falty reg or it could be an injector leaking this makes it hard to start because the fuel goes into your cly and floods out that one making it hard to start