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Fuel Pump no Pressure----- GAWD-super lost

General technical discussion and troubleshooting
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Topic author
rpmnava
I am merely driving my van
I am merely driving my van
Posts: 2
Joined: Fri Jan 15, 2021 7:13 pm

Fuel Pump no Pressure----- GAWD-super lost

Post by rpmnava »

Hi Everyone,
I AM STUMPED.....Van was running fine... parked it overnight and wont start.

First thing I did was listen for FP to prime ( 2 seconds ) and nope! after that swapped relay and Nope!

Knew it was time for new fuel pump. Here's where I get lost. Went to local parts store and picked up the only anyone had in stock
(MasterPro MPA30043) O'reilly brand. Dropped the tank, installed as usual and noted this new pump requires minor rewire for supplied plug (see pic).

Rewired as specified and did a power test prior to reinstalling the tank... got my 2 second prime, figured all was good and reinstalled the tank. I went ahead and replaced the inline fuel filter just because and tried to start.... no go. Below is what I did after that:

1. 5 prime cycles (keys off and on).... no start.
2. Starter fluid to check spark and motor started for 10 seconds. (good spark)tarted
3. Removed dog house and checked for pressure at schrader valve (NO Pressure).
4. Checked for fuel at inline fuel filter (dry).
5. Removed gas tank again to check electrical connections and for correct wiring per spec (see pic)
6. started the whole mess all over again and still no pressure.
7. Replaced oil pressure sending unit just in case.
8. I spliced into the pump power wire direct to battery, ran it for 60 seconds... no pressure and filter still dry.

I did crack the return line and it was wet.
Is it possible for the motor to run backwards?
Is it possible to swap the return and fuel hoses?
Could the evap hose at top of fuel pump be suspect?

Hopefully the pic goes thru:
IMG_3460.JPG
IMG_3458.JPG
Existing fuel pump wiring:
Grey
Black
Purple/white stripe
Black/white stripe

New plug color code:
Orange/black
Grey
Purple
Black

Side Note;
when I tested the existing fuel pump wiring I found:
Black and Black/white stripe had continuity to chassis ground
Grey was the 2 second prime signal
Purple/white stripe - unknown.

Van Specs:
2003 GMC Safari
2WD
159K Miles

Topic author
rpmnava
I am merely driving my van
I am merely driving my van
Posts: 2
Joined: Fri Jan 15, 2021 7:13 pm

Re: Fuel Pump no Pressure----- GAWD-super lost

Post by rpmnava »

*****Update******

My issue was the wiring to the new connector... the diagrams in the pics (6 of them) were all incorrect. They had the grey and orange/black switched.

Up and running.... grateful for this forum.
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okie1
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Re: Fuel Pump no Pressure----- GAWD-super lost

Post by okie1 »

Thanks for the follow-up, this will help others & glad you solved the problem. :supz:

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Re: Fuel Pump no Pressure----- GAWD-super lost

Post by Captn. Crunch »

rpmnava wrote: Sat Jan 16, 2021 3:33 pm *****Update******

My issue was the wiring to the new connector... the diagrams in the pics (6 of them) were all incorrect. They had the grey and orange/black switched.

Up and running.... grateful for this forum.
Wow that would burn my biscuits!! Bad enough doing that job once but having to do it more than once due to poor directions is rough.
Glad you got it
Captn. Crunch
"I don't beat my rig-I use it to it's maximum potential"
1994 Safari conversion (sold) and miss'n it!
1999 Safari SLE AWD junked
2003 GMC Safari AWD SLT
cast iron Torsen equipped front diff
S-10 leafs-G80 rear w/3.73’s
2” body lift w/Falken Wildpeak AT’s
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