high fuel pressure at startup (should be moved to electrical

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Re: high fuel pressure at startup

Postby spencerforhire » Mon Jun 04, 2012 9:01 pm

I presume that you have the Summit relay in the back of the car between the battery and the pump; are you using the car's original blue wire to hook to the yellow "ignition" wire on the relay? I still have no idea what relays you hear clicking under the hood and under the dash. The only relays I can think on the firewall near the heater fan would be for the A/C compressor and A/C high fan. For now maybe disconnect the blue and just run a dedicated wire from a spare ignition terminal in the fuse box to the yellow on the Summit relay. If that solves your strange clicking noises the problem could be in the harness.
The "fleet"-
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77 Vega Estate wagon- project(someday)will have TPI305/T-5, S-10 spindles/axles
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01 Saturn SC2- son's project
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Note- the very act of listing all of these has made me realize I have some kind of problem.....

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Re: high fuel pressure at startup

Postby rtm » Tue Jun 05, 2012 7:48 am

spencerforhire wrote:I presume that you have the Summit relay in the back of the car between the battery and the pump; are you using the car's original blue wire to hook to the yellow "ignition" wire on the relay? I still have no idea what relays you hear clicking under the hood and under the dash. The only relays I can think on the firewall near the heater fan would be for the A/C compressor and A/C high fan. For now maybe disconnect the blue and just run a dedicated wire from a spare ignition terminal in the fuse box to the yellow on the Summit relay. If that solves your strange clicking noises the problem could be in the harness.


thanx spence,
I will try that as time permits.
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Re: high fuel pressure at startup

Postby rtm » Sun Jun 10, 2012 5:13 pm

rtm wrote:
spencerforhire wrote:I presume that you have the Summit relay in the back of the car between the battery and the pump; are you using the car's original blue wire to hook to the yellow "ignition" wire on the relay? I still have no idea what relays you hear clicking under the hood and under the dash. The only relays I can think on the firewall near the heater fan would be for the A/C compressor and A/C high fan. For now maybe disconnect the blue and just run a dedicated wire from a spare ignition terminal in the fuse box to the yellow on the Summit relay. If that solves your strange clicking noises the problem could be in the harness.


thanx spence,
I will try that as time permits.


question;
If I want the oil pressure switch to be functional, could I run a 'dedicated' wire to the summit relay , yet hook it to the oil pressure switch (in place of the blue wire, which will be abandoned )?
I'm pretty sure the pink and purple wires are functioning normally.
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Re: high fuel pressure at startup (should be moved to electr

Postby spencerforhire » Sun Jun 10, 2012 8:37 pm

That will work; it will bypass all the OEM fuel pump wiring( including the fuse in the fuse box) yet still be safe.
The "fleet"-
72 Vega HB Drag Car -383/'Glide/9"(9.35@146.19)(5.94@117.28 1/8th)
77 Vega Estate wagon- project(someday)will have TPI305/T-5, S-10 spindles/axles
76 Vega GT- 400/4spd/9" retired from active duty(rusty)
06 Silverado 2WD ex.cab daily
03 Silverado 2WD ex.cab (retired)
06 Haulin' 20ft enclosed car transporter
06 GMC Canyon Shop truck
07 Colorado project( 5.3 4L60e swap)
99 Saturn SL1- wife's car
01 Saturn SC2- son's project
07 Saturn Ion Redline project
and 4 more Saturn "parts cars"
Note- the very act of listing all of these has made me realize I have some kind of problem.....

Visit http://www.spencerforhire.ca
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Re: high fuel pressure at startup (should be moved to electr

Postby rtm » Thu Jun 21, 2012 4:19 pm

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Re: high fuel pressure at startup (should be moved to electr

Postby chevyart » Fri Jun 22, 2012 1:33 pm

any pics of burnouts or donuts in the parking lot? art
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Re: high fuel pressure at startup (should be moved to electr

Postby rtm » Fri Jun 22, 2012 4:27 pm

no burnout pics yet art.
I'll start a new tire roastin thread soon :th:
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Re: high fuel pressure at startup (should be moved to electr

Postby chevyart » Sat Jun 23, 2012 11:17 pm

rick if you can get the tires heated up enough i would like to send over some marshmallows to roast up art
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Re: high fuel pressure at startup (should be moved to electr

Postby rtm » Mon Jul 09, 2012 5:43 pm

here we go again :bang:
has anyone ever heard this ? (from a fuel pump site online)

problem-Lower Fuel pressure when engine is warm:

answer-Fuel pressure gauges mounted in the engine compartment will indicate a lower pressure when the GAUGE gets warm. The fuel pump and regulator don’t change

my original post:
I am trying to set my fuel pressure by using the guage I installed at my carb inlet line.
it is installed after the bypass regulator I am utilizing.
the problem I am having is occuring when I start the engine cold, the guage is reading 10 or 12 PSI.
I adjust the pressure immediately at the regulator, (I have tried anywhere from 6 to 4.5 PSI ),then when the engine warms up, the pressure will drop to almost zero.
every time I start the car cold this occurs.
I have a mallory 140 gph pump mounted below my fuel cell.
all lines, including the return, are 1/2 inch diameter.

today I got my rebuilt carb to idle well,
but the engine only builds power to a certain point , then falls flat on its face (at launch ).
This is in the limited space of my driveway, as the car still remains unregistered, and has no glass or paint yet
I know there are a lot of variables I am leaving out here,but, anyone got any ideas

UPDATED INFO
(after rewiring the pump,)

if I run the pump by itself, with the engine off,
the pressure stays the same.
as the engine warms up, I lose approximately 1/2 PSI per minute
could it be the fluid in the guage getting warmer ?

the free flow pressure is a steady 3PSI without the engine running (and cold), adjuster turned all the way out.
should I set it @ 5PSI cold. and forget about it ?
:?: :rolleyes: :x
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Re: high fuel pressure at startup (should be moved to electr

Postby rtm » Mon Jul 09, 2012 6:58 pm

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Re: high fuel pressure at startup (should be moved to electr

Postby chevyart » Mon Jul 09, 2012 7:25 pm

rick not sure if i asked you about the type of regulator you used. if you just used a 2 port regulator, it could be a problem. a regulator for a bypass system should have 3 ports, 2 for fuel lines into carb(holley type carb) and one port that is dedicated to returning fuel back to the cell., and of course an intake port to let fuel in. im pretty sure this is the way it works. is there any way you could block off the return line and run the car., just to see if this would make a difference.. my buddy used the wrong one(2 port and he wound up disconnecting it and car runs fine. just a though. i think i had discussed the return line with you a long time ago.cant believe all those guages could be wrong. i have to replace my guage at the regulator every few years in the race car, but i have my main pressure guage in the car so i can see what kind of pressure i have at the traps when i am racing.. anybody else have any input about what i just mentioned here. art
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Re: high fuel pressure at startup (should be moved to electr

Postby chevyart » Mon Jul 09, 2012 11:44 pm

rick. one other thing and its probably not so, but is there a chance that the pump is mounted upside down. it can be mounted this way and you may not even realize it, and the pump will work but it will aeriate the fuel and you will loose pressure, and it will eventually burn out as the pump will overwork and fuel will eventually get into the electronics. just something else i saw happen to another friends car. art
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Re: high fuel pressure at startup (should be moved to electr

Postby chevyart » Tue Jul 10, 2012 8:15 pm

rick guess i just thought you still had the problem. didnt realize you were running good. you didnt post the reasuls of running a dedicated fuel pump electric line as suggested by spence. guess that bypassed a bad oil pressure safety switch? let us know what worked for you art
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Re: high fuel pressure at startup (should be moved to electr

Postby rtm » Tue Jul 10, 2012 8:44 pm

chevyart wrote:rick guess i just thought you still had the problem. didnt realize you were running good. you didnt post the reasuls of running a dedicated fuel pump electric line as suggested by spence. guess that bypassed a bad oil pressure safety switch? let us know what worked for you art


no, I still have my oil pressure switch.
I'd rather not run without it.
it seems my problem was twofold
one: I had intermittent power to the fuel pump relay.
two: the cheap summit guage (liquid filled) is reading different PSI @ different temperatures as the engine warms up.
I almost started re- routing fuel lines (thought the fuel was boiling)
I would like to find a reliable underhood pressure guage.
but, for now the car runs good.
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