2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

first start last night on new eng. got s couple of fuel issues. please help

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Old Aug 16, 2006 | 03:19 PM
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Exclamation first start last night on new eng. got s couple of fuel issues. please help

ok i have 2 issues.
finally got the new motor running in my 7 after must be almost 6 months of it being off the road.
issue number 1
My fuel pump seems to be cutting out when the car starts...

issue two
my malpasi reg

ok, so heres how it goes right and i think i may have a solution to one part so i wil put hat in bold adn maybe you guys tell me if im onto the issue or not.
87 t2 new motor. had to swap all the stuff from my last motor over as it was a bare block ( kinda unknown history
S5 inlet manifolds w s4 TB
S5 turbo
Malpassi RRFPR
no emission what so ever
still have BAC

so i go to start it up adn my fuel pump is goin fine and ive got 60+ psi fuel pressure and it turning over but not starting but firing a little bit here and there.
the fuel pressure starts to drop and goes down to like 20psi I think the fuel pump has stopped then it starts and runs for like 10 sec but as soon as it starts the fuel pressure disappears completely and it stops coz its out of gas presumibly.

so we have two thing i need to reconsile
1 how do i set my reg so it will start at low fuel pressure and rise as much as it needs to maybe i need to install the solenoid that i removed as part of the emissions **** that told the origional FPR to which from atmospheric pressure to vacume pressure
now this little solenoid may have something to go with my fuel pump cutting out.. i dont know
2 whats up with my fuel pump? its a walbro 255lph intank

so. what do you think guys. i know this may be a bit of and ear/eye full but if you could help that would be ace

nath

Last edited by NZ_87_TURBO; Aug 16, 2006 at 03:24 PM.
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Old Aug 16, 2006 | 03:26 PM
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The Wankler's Avatar
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Turbo Fuel Pressure should be around 36psi when idle. 60psi is way to much. Second, there is a little yellow coupler right next to the passenger strut. If you couple it, it will engage your fuel pump without having to start the engine. See if you pump cuts out then. It should just circulate the fuel. Yo uwill hear it run. To raise your FRP when driving is up to the vacum line attached to it. That is about all I can help ya with.
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Old Aug 16, 2006 | 04:13 PM
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long live the monster BP
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na your onto it mate. yea i know about the yellow clip adn use it to prime my system before starting (now anyway) i will adjust my reg to sit at 36psi to start with and we'll see how that goes. the pump works fine using that little plug to prime with. its almost like it there is a relay or something that swithes it off after a while of trying to start it.
hmmm
thanks for your help. im gona try and gather as many ideas during the day before i go home from work ( still 7 hours away )
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Old Aug 16, 2006 | 09:27 PM
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some one must have an idea of why my fuel pup is cutting out? is there some sort of built in system so when its turning over for to lon git cuts the fuel so it dosnt flood?
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Old Aug 17, 2006 | 01:05 AM
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The fuel pump's power is switched by the circuit opening relay. This relay closes only if the engine is cranking or if there's airflow through the engine, indicated by a switch in the AFM. It sounds like you might have a problem with either that switch or the relay.

Put a voltmeter on the pump and watch it when you start the engine. If the voltage cuts in and out then check the AFM and relay as per the FSM's instructions. When testing give them a shake and few taps to check for loose connections.
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Old Aug 17, 2006 | 01:31 AM
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it could also indicate a leak in the intake system, when cranking there is a surge of air through the AFM which closes the pump switch in the AFM momentarily to turn on the pump, once the engine is running and at a stable RPM then the airflow drops as it leaks past the leak in the intake system and bypasses the AFM and the fuel pump switch opens again which cuts off the fuel pump. if this is the case then usually a quick visual inspection of the intake system on the engine will reveal a vacuum line loose or disconnected or a line cracked and broken off, etc, etc, etc so a thorough inspection of the intake system is usually the first place i suggest looking when you have a stalling issue on a second gen 7.

oh, and yes, 60PSI at idle is WAYYYYYYYYYYYYYYYY too much pressure.

Last edited by RotaryEvolution; Aug 17, 2006 at 01:34 AM.
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Old Aug 17, 2006 | 03:34 AM
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::takes notes::
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Old Aug 17, 2006 | 06:28 AM
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Originally Posted by NZ_87_TURBO
issue two
my malpasi reg

Malpassi RRFPR
Who was the dumbass who told you to put that thing in a stock FC turbo???


-Ted
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Old Aug 17, 2006 | 11:09 AM
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Originally Posted by RETed
Who was the dumbass who told you to put that thing in a stock FC turbo???


-Ted

LOLOLOL....
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Old Aug 17, 2006 | 11:10 AM
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Originally Posted by NZConvertible
The fuel pump's power is switched by the circuit opening relay. This relay closes only if the engine is cranking or if there's airflow through the engine, indicated by a switch in the AFM. It sounds like you might have a problem with either that switch or the relay.

Put a voltmeter on the pump and watch it when you start the engine. If the voltage cuts in and out then check the AFM and relay as per the FSM's instructions. When testing give them a shake and few taps to check for loose connections.

I would try this.
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Old Aug 20, 2006 | 10:29 PM
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long live the monster BP
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yea im gona try this as i was all on the rewire the fuel pump mish ( which i will still do ) but then it dawned on me that cant be the problem. I'll have to have a look for vacum leaks.
now i heard a real good way to find these, using a compressor or something. Anyone remember the way to do this?
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Old Aug 20, 2006 | 11:03 PM
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NZ_87_TURBO's Avatar
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long live the monster BP
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the fuel pump wont even work now. not when cranking nor when using the yellow connector switch.
is this a relay issue? i can hear one clicking under the dash when i try and use the yellow connector
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Old Aug 21, 2006 | 12:47 AM
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Originally Posted by NZConvertible
Put a voltmeter on the pump and watch it when you start the engine. If the voltage cuts in and out then check the AFM and relay as per the FSM's instructions.
Do this!

If you get no power at the pump follow the wiring diagram to see where the power stops.
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