4g61t.org

so lets go back to 2004 when I had my talon.. I had a aeromotive fpr with gauge and when I turned off the motor it would hold pressure for a good 4-5+ hours...

now move forward to 2011 when I had my colt running.. same fpr and gauge setup.. but once car was off it dropped before I could even get around the door to view the gauge.. i didnt think much of it at the time.

but now I have a brand new (same setup fpr) and its dropping instantly also.. I have read it is suppose to hold pressure at least for a lil bit..(which could be why I ws having tuning issues on the colt..

so what does everyone think? is there suppose to be pressure after shut off.. and what would cause it to not hold the pressure? could it be the vent line that originally went to the charcoal canister? and if so is it dangerous to just plug it up?


thanks much.
Steve

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Steve 89 colt 2.3 stroker stock top end. evo3@20 psi 13.489@99.30mph 3/10 2012
On drag radials.auto trans.launching @ 5 psi and no traction thru 2nd.

My fuel systems never held pressure for 4-5 hours. Even using stock lines. They mostly behaved just as you are seeing now, immediate relief of pressure once the pump stops pumping. Fuel pressure should always be checked with the pump running and the hose to the pressure regulator removed from any source of vacuum.

It is technically okay to remove the charcoal canister, but you definitely need a vent for the fuel tank or the tank can explode or collapse. Removing the charcoal canister but leaving the vent in the engine bay could cause a smell of gasoline in the cabin.

yeah when I first got the colt running a few years ago I started it off with a tank of e85.and man did it smell when I boosted and let off.

I did have the vac hose off as I set the base pressure today.

maybe I will find some sort of 1 way filter or something like the check valve on the V/C.. and hook it to the line near the tank instead of letting it run back up front..and let it vent out by the rear tire somewhere..

thanks for the reply.


Steve

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Steve 89 colt 2.3 stroker stock top end. evo3@20 psi 13.489@99.30mph 3/10 2012
On drag radials.auto trans.launching @ 5 psi and no traction thru 2nd.

Probably the check ball in the fuel pump causing the instant drop in pressure.

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91 GSX - 511fwhp and 352 lb/ft 25psi 110 octane, 7.68 @ 95.9mph 1/8th 21psi 91 octane, 11.93 @ 112.9mph, 117.7mph best trap speed, 20psi 91 octane
98 Volvo S70 T5 - DD

http://www.facebook.com/captaintonus

My fuel system holds pressure in the lines when you shut it off, and yours should too unless something is leaking somewhere. Maybe where the fuel pump connects to the sending unit, or a bad check valve in the outlet of the pump. Simple process of elimination tests should narrow it down for you.

Either way, it has nothing to do with the canister or the vent. You should avoid plugging the tank vent though, and putting a check valve in the vent is a bad idea also.

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"A good day racing is better than a great day fishing!"

What those two said, and less likely a leaky injector. You would know if it spewed all the pressure in the rail into one cylinder.

im not sure what you mean by check valve in the pump?..

I just put in a brand new tank and fuel pump.. the pump pumps fuel out of tank..to front of car and back.. the return going back into the tank is just a tube about 3" long. and dumps directly into the tank.. so there only seems to be the fpr that is the only restriction in the system from the pump till return tube.

and as for the vent I see what you mean about it building up pressure and possibly exploding. so ill avoid that lol..


Steve

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Steve 89 colt 2.3 stroker stock top end. evo3@20 psi 13.489@99.30mph 3/10 2012
On drag radials.auto trans.launching @ 5 psi and no traction thru 2nd.

What kind of pump are you using?

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91 GSX - 511fwhp and 352 lb/ft 25psi 110 octane, 7.68 @ 95.9mph 1/8th 21psi 91 octane, 11.93 @ 112.9mph, 117.7mph best trap speed, 20psi 91 octane
98 Volvo S70 T5 - DD

http://www.facebook.com/captaintonus

wally 255 hi output

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Steve 89 colt 2.3 stroker stock top end. evo3@20 psi 13.489@99.30mph 3/10 2012
On drag radials.auto trans.launching @ 5 psi and no traction thru 2nd.

http://www.ls1gto.com/forums/archive/in ... 23614.html

I guess the HP doesn't have a check valve, and that's why the pressure bleeds off instantly. I ran 255HP's for years, and my pressure wouldn't bleed off immediately, but it wouldn't stay pressurized for 4 hours either. Usually it would gradually go down and bleed off within a few minutes.

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91 GSX - 511fwhp and 352 lb/ft 25psi 110 octane, 7.68 @ 95.9mph 1/8th 21psi 91 octane, 11.93 @ 112.9mph, 117.7mph best trap speed, 20psi 91 octane
98 Volvo S70 T5 - DD

http://www.facebook.com/captaintonus

ive been searching and i come across some threads that say its suppose to hold pressure for a few min.. or not at all...

if the fuel pressure drops off at key off.. I know it takes a bit longer to start up if left over night cause it needs to build the pressure back up...

my main question now is... will this be a issue? cause any problems.. or can I run it like it is?



thanks

Steve

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Steve 89 colt 2.3 stroker stock top end. evo3@20 psi 13.489@99.30mph 3/10 2012
On drag radials.auto trans.launching @ 5 psi and no traction thru 2nd.

It's not gonna hurt anything to drive it like that, but it's not supposed to do that...I would want to look in to it and fix the issue

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91 GSX - 511fwhp and 352 lb/ft 25psi 110 octane, 7.68 @ 95.9mph 1/8th 21psi 91 octane, 11.93 @ 112.9mph, 117.7mph best trap speed, 20psi 91 octane
98 Volvo S70 T5 - DD

http://www.facebook.com/captaintonus

kewl.. guess ill have to drop the tank again then. luckily its almost on E lol



Steve

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Steve 89 colt 2.3 stroker stock top end. evo3@20 psi 13.489@99.30mph 3/10 2012
On drag radials.auto trans.launching @ 5 psi and no traction thru 2nd.

That's not right about the 255 HP, because that's exactly what I have. The check valve is right in the outlet of the pump.

Here's a good picture of one broken off the pump:

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"A good day racing is better than a great day fishing!"

After a wally 255 and fuel lab fpr my pressure only holds for a couple minutes, the only side effect it seems to have is longer cranking to start, I've read it's a common issue and I have not dug into it yet but I agree it is still something that should be addressed.

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89 Mirage Billet 20g 63t 12.4@120 417whp 400wtq @ English Racing.
89 Colt GT E316g
06 Silverado SS
07 ZX6R