fuel pump question - which is primary - ZR-1 Net Registry Forums

EvanZR1 · 05-05-2021

Going to be swapping out the failing primary pump tomorrow with a buddy using a spare OE pump I have. Which pump is the primary and which is the secondary? I'm sure I can figure it out by the wiring, but I'm guessing you can also tell by the position (one is lower than the other).

Young1 · 05-05-2021

The lower one is the primary. The upper one secondary.

EvanZR1 · 05-06-2021

Quote:

Originally Posted by Young1

The lower one is the primary. The upper one secondary.

Thanks! That's kind of what I figured.

Ccmano · 05-06-2021

Why not replace both while your taking trouble to pull it all out. Pumps are cheap.
H

EvanZR1 · 05-07-2021

Quote:

Originally Posted by Ccmano

Why not replace both while your taking trouble to pull it all out. Pumps are cheap.
H

Both pumps were changed in in 2017 and have less than 6K miles on them, and 2nd pump definitely works good (had pulled pin from ECM so it was running full time when I realized primary was acting up). Swapped the primary with a used one I had on the shelf and reinserted wire to return 2nd pump to normal (4K+ only operation), and unfortunately it looks like I should have just ordered a new pump (replacement pump runs ok at idle and light throttle but sputters at anything more than maybe 1/4 throttle).

Oh well, changing the pump is actually pretty easy. And you're correct, they are cheap (didn't realize how cheap). So I guess I'll order a new pair of pumps and go ahead and change both. Anybody try the Autobest HP2251 before? Found it on Rockauto and it's supposed to flow at least 15% more than stock:
https://www.rockauto.com/en/moreinfo...sn=908&jsn=908

jss06c6 · 05-14-2021

Evan, make sure you also check the harness where it connects to the bulkhead. I've had numerous issues with corrosion there which will shut down the pump(s).

Steve

Sent from my SM-G950U using ZR-1 Net Registry mobile app

05-05-2021	#1
EvanZR1 Join Date: Nov 2010 Location: Omaha Posts: 403	fuel pump question - which is primary Going to be swapping out the failing primary pump tomorrow with a buddy using a spare OE pump I have. Which pump is the primary and which is the secondary? I'm sure I can figure it out by the wiring, but I'm guessing you can also tell by the position (one is lower than the other). __________________ Evan 2024 Z06 SOLD - 1991 Admiral Blue ZR-1 SOLD - 2012 Carlisle Blue Metallic ZR1 - 800HP SOLD - Steel Blue 91 391cid ZR-1 #391 SOLD - Black 91 ZR-1

05-05-2021	#2
Young1 Join Date: Sep 2016 Location: Ocala, FL Posts: 898	Re: fuel pump question - which is primary The lower one is the primary. The upper one secondary. __________________ Steve Young 1991 ZR-1 Quasar Blue Metallic/Black #729 Second Owner 1991 ZR-1 Dark Red Metallic/Black #2040 SOLD 1990 ZR-1 Dark Red Metallic/Saddle #1670 SOLD Double your happiness.....complain half as much.

05-06-2021	#4
Ccmano Join Date: Jun 2006 Location: Sparks, NV Posts: 2,852	Re: fuel pump question - which is primary Why not replace both while your taking trouble to pull it all out. Pumps are cheap. H __________________ 90'ZR-1 #1461 Red/Black Ported Intake, Degreed Cams, OBX Headers & Exhaust, Fidanza FW, Secondary Delete, Custom tune, C6 GS Wheels. Sold 08 C6 Z51 Crystal Red Metallic Sold Vararam Intake, Tune, Sold 05 C6 Z51 Red/Black Sold 90'ZR-1 #1723 Black/Gray Sold but not forgotten 91' Z51 L98 White Vert. My First, you always remember your first. Sold.

05-14-2021	#6
jss06c6 Join Date: Aug 2015 Location: Magnolia, Texas Posts: 884	Re: fuel pump question - which is primary Evan, make sure you also check the harness where it connects to the bulkhead. I've had numerous issues with corrosion there which will shut down the pump(s). Steve Sent from my SM-G950U using ZR-1 Net Registry mobile app