Fuel pressure bleed down time?

Reply Subscribe

Thread Tools

Search this Thread

Nov 20, 2007 | 06:47 PM

davidnclearlaketx

Thread Starter

Racer

Joined: Jan 2006

Posts: 473

Likes: 7

From: Houston Texas

Fuel pressure bleed down time?

I've read all the hard start when warm posts and used searches but cannot find my answer. This issue is on my '88.

How many minutes on average would you guys think it would take for the fuel pressure to bleed down if I had any leaky injectors?

I put my gauge on the fuel rail fitting and after cranking then shut off the key my pressure gradually/slowly bleeds down to zero after about 55-60 or so minutes.
No check engine codes, runs good but sometimes a hard start when stop/start when warm. Pulled/checked the vacuum line at the adj fuel pressure regulator and no gas leak there.

I've replaced the factory injectors once several years ago (10+yrs) but don't remember the type. I think they were replaced with the newer (post GM crappy ones) style gray OEM. Guess it's time again!

I've not checked the resistance yet with my ohm meter.

So I would assume I have one or more leaky injectors since they won't hold pressure more than an hour or so?

Thanks in advance for the help!

Nov 20, 2007 | 07:05 PM

geogolf

Drifting

Joined: Jun 2005

Posts: 1,426

Likes: 1

From: brookville pa.

injs.

just ohm them, should read around 16/17 if you have one or more that is way off that is your problem lot of guys go with ford 22or24# injs.

Nov 20, 2007 | 07:06 PM

CFI-EFI

Race Director

Joined: Sep 2000

Posts: 17,298

Likes: 33

From: The Top of Utah

Quote:

Originally Posted by davidnclearlaketx

How many minutes on average would you guys think it would take for the fuel pressure to bleed down if I had any leaky injectors?

That would depend on how many injectors were leaking and how badly. Pressure can be released from three primary points without ending up visible or able to be smelled. Leaky injectors, a leaky regulator, and back into the gas tank. Generally the regulator will leak into the vacuum line. Gasoline in the vacuum line will find it's way to the intake manifold and cylinders. It can cause the hard starting of a flooded engine. Gasoline can also leak back into the gas tank through a defective check valve in the fuel pump or a leaking hose or pulsator inside of the tank. You can test to see where the pressure is dissipating by alternately blocking the supply and return line and observing the pressure.

RACE ON!!!

Nov 20, 2007 | 07:26 PM

davidnclearlaketx

Thread Starter

Racer

Joined: Jan 2006

Posts: 473

Likes: 7

From: Houston Texas

Thanks!
I'll try ohming them and blocking the lines and do the pressure checks.

Nov 20, 2007 | 08:48 PM

redrose

Melting Slicks

Joined: Feb 2006

Posts: 2,753

Likes: 15

From: backwoods upstate ny

10 psi after 12 hr sit is ok...a few do better...zero in a couple minutes is trouble.

Nov 20, 2007 | 08:57 PM

davidnclearlaketx

Thread Starter

Racer

Joined: Jan 2006

Posts: 473

Likes: 7

From: Houston Texas

I'm going from around 42 psi key on/no start, shut off key and watch my gauge slowly go to zero in about an hour or so +/- a few min.

Nov 20, 2007 | 09:27 PM

yoitsmatt

Advanced

Joined: Sep 2007

Posts: 50

Likes: 0

From: lexington nc

The fuel system should actually hold pressure overnight, there is no spec that I know of however when the fuel pump relay energizes it has to reach full fuel pressure almost instantly for quick startup so the system usually holds residual pressure, your leak could be in the fuel tank as well, when testing for leaking injectors its nessasary to pinch off the pressure and return lines after priming the fuel system to see if the leak is in the fuel rail or fuel tank sender.

Dec 11, 2007 | 10:56 PM

davidnclearlaketx

Thread Starter

Racer

Joined: Jan 2006

Posts: 473

Likes: 7

From: Houston Texas

I replaced the injectors with 24lbs Accel from Summit ($279.95 set + $10.95 ship/handling) and she's running great again! I have the adj fuel pressure reg. and a street/strip stage II EPROM so I figured the 24#'ers would be OK. So far so good.

It's been some time since I replaced the fuel pump so I think that is the next project.
What would you guys recommend? What is the stock pumps GPH?
I see Summit has a 67 GPH Edelbrock kit-pump, strainer, etc. for $143

Thanks for everyone's input!

>edit<
** I forgot **
Thanks Sam Lamb for the great procedure so I didn't have to remove the runners! It took some time but all was tight, no leaks and started up on the first crank!

...so after some more searches and reading I see the Racetronix kit. It sounds good. But which one? 190L/Hr or 255L/Hr

Thanks again!

Last edited by davidnclearlaketx; Dec 11, 2007 at 11:36 PM. Reason: thanks!

Corvette Stories

The Best of Corvette for Corvette Enthusiasts

2027 Chevrolet Silverado 1500 First Look: Everything You NEED to Know!

Michael S. Palmer

5 Best & 5 Worst Corvette Daily Drivers

Joe Kucinski

The Headlights of Every Corvette Generation Explained

Joe Kucinski

5 Best & 5 Most Overrated Corvette Track Packages of All Time!

Joe Kucinski

Every 2027 Corvette Engine Explained

Joe Kucinski

Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette

Verdad Gallardo

10 Ugly Corvettes That We Still Kinda Love

Joe Kucinski

Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer

Brett Foote

10 Things Every Corvette Owner Needs (2026 Edition)

Michael S. Palmer

8 Most "Only Corvette Owners Understand" Quirks and Problems

Pouria Savadkouei

Dec 12, 2007 | 08:47 AM

DVNCI

Melting Slicks

Joined: Jun 1999

Posts: 2,949

Likes: 23

From: Bowling Green KY

Go with the Racetronix, their kits are great.

I'd probably go with the 190 unless you are planning on making more power in the future.

Dec 12, 2007 | 02:18 PM

#10

CFI-EFI

Race Director

Joined: Sep 2000

Posts: 17,298

Likes: 33

From: The Top of Utah

Quote:

Originally Posted by davidnclearlaketx

It's been some time since I replaced the fuel pump so I think that is the next project.
What would you guys recommend? What is the stock pumps GPH?
I see Summit has a 67 GPH Edelbrock kit-pump, strainer, etc. for $143

I'd wait until you see some signs of a problem. There is nothing to be gained by replacing a fuel pump that is meeting the demand. At the very least, if you have suspicions, you could test it.

RACE ON!!!

Dec 13, 2007 | 02:03 AM

#11

prism_kiter

Instructor

Joined: Jul 2007

Posts: 117

Likes: 0

how do you check the injector OHMS ??

hello there,
sorry to but in on your thread .
i have 30 lb ford motor sport injectors i want to test.
do they still require 16-17 ohms ?
how do you check them please ?
what setting do you put the multi meter on please ?
i have a Void light test kit,will this help at all ?
hope some one can please help/advise.

Dec 14, 2007 | 01:03 AM

#12

davidnclearlaketx

Thread Starter

Racer

Joined: Jan 2006

Posts: 473

Likes: 7

From: Houston Texas

Quote:

Originally Posted by RUKWKR

Go with the Racetronix, their kits are great.

I'd probably go with the 190 unless you are planning on making more power in the future.

Racetronix on the way!

Since my car is a daily driver, I take lots of road trips and the fuel pump is at least 10 years old I figured $100 bucks is cheap insurance!
Plus with brand new injectors and fuel filter I figured what the heck!

The last time my fuel pump went out was on a road trip. Lucky for me it died in a hotel parking lot when I was trying to leave so I didn't get stuck out on the road. I just got a ride to the local auto parts and got the pump and installed it in the hotel parking lot. I always keep tools in the car!

Thanks everybody for the input!