North American Turbocoupe Organization



Questions about fuel pressure drop & fuel pump grounding
Ryan H Offline
Posting Freak
#1
Ladies and Gents, I need some help again! [Image: biggrin.gif]

I need to know if there is supposed to be a "draining fuel" sound coming from the fuel rail when you ground the pump??? Is that the fuel return line doing it's work, or is it a leak somewhere? Read below [Image: biggrin.gif]

After popping my hood today and smelling gas fumes.. I decided it was a great time to investigate that pressure drop I was getting on my gauge! So here is what I did. I went to the fuel pump diag. tech article and I grounded the fuel pump. The pressure rose to about 41 PSI and leveled off w/ the pump running. I noticed that while my pump was running, I could hear what sounded like a fuel leak that was internal??? I pulled the upper intake manifold off and sure enough, really strong gasoline fumes! Well, I pulled the injectors and none of them were wet at ALL. Which brings me to ask where all of those fuel fumes are coming from?!

I changed my Aeromotive reg out for the Kirban. Put everything back together and ran the pump. The Kirban made an odd squeaking noise for a brief second, like it was filling up with fuel or something. I ignored it and kept running the pump until my gauge said 40 PSI. The pressure bled back down to 10 PSI almost instantly when I removed the pump ground. I unlocked the pressure adjustment screw on the Kirban and ran the pump and turned the screw. The pressure on my gauge slowly increased as I turned the screw, so I know the regulator part is working. This time, I removed the pump ground and the pressure dropped about 5 PSI and stuck [Image: smile.gif] I tried a few more times to make sure it kept staying and it did.

I think I'm still going to send my injectors off to get them serviced just in case they are leaking a tad bit. So anyway, does it sound like I need to inspect anything else before I go back together?

OH and something I forgot to mention. The last time I grounded the fuel pump and ran it, the needle on my gauge was "ticking" around 40 PSI. Is this good/bad?

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Ryan Harris

88 TC, 5 spd, B&M Ripper Shifter, Walbro 190 LPH, Aeromotive FPR, K&N, 3.73 rear, KS disconnected, BCS bypassed, 89K miles, shattered clutch, new muffler bearings, Mobil 1 blinker fluid

[This message has been edited by Ryan H (edited 09-04-2005).]
'88 TC Smile Walbro 255HP, Stinger FMIC, PIT BOV, Pro 5.0, Kirban, RR cam, FRPP strut tower brace, T3
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trashline Offline
Posting Freak
#2
pretty sure kirbans allow fuel pressure drop fairly quick mine does and im not really worried about it i know my injecters dont leak so the fuel is going back into the tank. I can see the intakes smelling like fuel as fuel is sprayed in there. and there might be a residue. as long as your injecters dont leak and you dont see any visual leaks then i wouldnt worry about it. but your saying you can smell fuel so there must be an external leak somewhere.

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1966 mustang
1988 tbird
Finally have mods that I can post... 373 gears with a brand new t5. K&N cone. Gillis set to 15 psi. Walbro 255 lph. Kirban afpr. Kelly Evo Z tires. Energy suspension front swaybar bushings. Rebuilt topend with stock components.

Working on a FMIC w/ the stock IC.
Brian

www.BCPCustom.com

06 Cobalt SS
66 mustang 289 C4 handfully modded

Stingers IC install and tbird photos
http://community.webshots.com/user/trashline
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Ryan H Offline
Posting Freak
#3
I am 100% positive the fuel is on the inside of the intakes. The fuel that I smelled was coming from the charcoal box and from my K&N cone. The fumes traveled back up the intake, through the IC/turbo, and into the air filter. I confirmed this by sniffing my IC just now.

I'm going to tie my injectors into the rail really securely and run the pump with them out of the car to try and spot leaks.

Oh and as far as leakdown goes... this just recently started. The pressure used to hold steady w/ the Aeromotive FPR for about 30-45 minutes after shutdown. The system never leaked down. I've also noticed "rougher" starting, as in it used to just start right up and idle, but now the engine sputters a bit when it's cold before the idle holds at 1000. Even then, the idle hasn't been holding at 1000 lately eiter. It's been a little rough and fluctuating from 1000-1250 or so at a slow, steady rate, up and down. Maybe the fuel leak was causing that?

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Ryan Harris

88 TC, 5 spd, B&M Ripper Shifter, Walbro 190 LPH, Aeromotive FPR, K&N, 3.73 rear, KS disconnected, BCS bypassed, 89K miles, shattered clutch, new muffler bearings, Mobil 1 blinker fluid
'88 TC Smile Walbro 255HP, Stinger FMIC, PIT BOV, Pro 5.0, Kirban, RR cam, FRPP strut tower brace, T3
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Ryan H Offline
Posting Freak
#4
I found the source of the "ticking needle". I had air in the line going to the gauge [Image: smile.gif] I bled it out (loosened the gauge in the line and ran the pump until the air bled out and tightened it back down) and the needle stopped jumping.

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Ryan Harris

88 TC, 5 spd, B&M Ripper Shifter, Walbro 190 LPH, Aeromotive FPR, K&N, 3.73 rear, KS disconnected, BCS bypassed, 89K miles, shattered clutch, new muffler bearings, Mobil 1 blinker fluid
'88 TC Smile Walbro 255HP, Stinger FMIC, PIT BOV, Pro 5.0, Kirban, RR cam, FRPP strut tower brace, T3
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Pete D Offline
Administrator
#5
There is a routine in the "Diagnostics" for testing for leaky injectors.

Injectors leaking from the pintle into the intake might not be wet. From what you say I think testing them in some way would be a good idea
Pete Dunham


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Jeff K Offline
Administrator
#6
When running the pump by grounding the FP test terminal of the EEC TEST connector, there is a "water rushing / squirting" sound that mostly comes from the FPR. Perfectly normal.

Fuel pressure should not drop fast after engine shut down. If it drops fast, either the FPR is leaking, or the anti backflow valve in the pump is leaking. In my experience, the most common of these is the valve in the pump. It is NOT a normal characteristic of the Kirban to leak fuel back down the return line.

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Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 23 psi, forced air intercooler, water injection, bypass valve, Ranger roller cam, subframes, etc., etc.. // 86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP nitrous, ignition, gears, suspension, etc., etc.... // 91 Escort: Bone stock winter car // 04 Taurus Duratec (wifes car) // 91 Topaz (daughters first car)
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
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trashline Offline
Posting Freak
#7
Quote:Originally posted by Jeff K:
It is NOT a normal characteristic of the Kirban to leak fuel back down the return line.


I swear I read that on turboford, or maybe it was the walbro pump.



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1966 mustang
1988 tbird
Finally have mods that I can post... 373 gears with a brand new t5. K&N cone. Gillis set to 15 psi. Walbro 255 lph. Kirban afpr. Kelly Evo Z tires. Energy suspension front swaybar bushings. Rebuilt topend with stock components.

Working on a FMIC w/ the stock IC.
Brian

www.BCPCustom.com

06 Cobalt SS
66 mustang 289 C4 handfully modded

Stingers IC install and tbird photos
http://community.webshots.com/user/trashline
Reply

Ryan H Offline
Posting Freak
#8
Yeah, I think I read that post too, something about high flow pumps letting the pressure bleed down.. I'll know for sure once I get rid of the 155 and install the 255HP [Image: smile.gif] As of right now the pressure bleed down is fixed although I am still going to get my injectors serviced. Thank you for the input everybody and I will update this with more findings later [Image: smile.gif]

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Ryan Harris

88 TC, 5 spd, B&M Ripper Shifter, Walbro 190 LPH, Aeromotive FPR, K&N, 3.73 rear, KS disconnected, BCS bypassed, 89K miles, shattered clutch, new muffler bearings, Mobil 1 blinker fluid
'88 TC Smile Walbro 255HP, Stinger FMIC, PIT BOV, Pro 5.0, Kirban, RR cam, FRPP strut tower brace, T3
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