Secondary fuel pump dead? - ZR-1 Net Registry Forums

Subfixer · 04-05-2023

Car runs fine, except when at full throttle going through the gears. Then acts like fuel shutoff. For short bursts of full throttle, everything is ok. I'm thinking the secondary pump isn't keeping up, or only the primary is working.

Sent from my Pixel 4a (5G) using ZR-1 Net Registry mobile app

Young1 · 04-05-2023

Most likely yes. To confirm perform the fuel pumps amperage test on the red pigtail at the wiper motor. Your meter will read 7-9 amps if both are running. 3-4 amps if one is running. Details in the Stickies.

A26B · 04-08-2023

Do you still have the Secondary Port Throttle (SPT) system still in place?
If so, test the vacuum pump and each of the vacuum actuators. A failure of any 1 of those 3 items can cause the same symptom.

Subfixer · 04-08-2023

Secondary Port Throttle (SPT) system is still in place. Entire system was checked by Marc when my 415 was built less than a year ago. Vacuum pump doesn't cycle at all. Pretty sure its a pump. Will be replacing both today.

Subfixer · 04-08-2023

My first check was the current draw. Current reads 9.3 Amps, so it seems both pumps are running.
Next check will be fuel pressure.

Subfixer · 04-08-2023

Fuel pressure check.... not good.
Only 42psi at cold idle.

Subfixer · 04-08-2023

I really am disappointed in aftermarket Chinese parts.
After replacing both pumps with Delphi FE0039 units, I now have a combined fuel pressure of 20psi.....

A26B · 04-08-2023

Quote:

Originally Posted by Subfixer

Secondary Port Throttle (SPT) system is still in place. Entire system was checked by Marc when my 415 was built less than a year ago. Vacuum pump doesn't cycle at all. Pretty sure its a pump. Will be replacing both today.

If the vacuum pump doesn't cycle at all, how do you know if it is still working?

Subfixer · 04-08-2023

Vacuum pump does cycle, just not excessively. About once every 45 seconds after initial pump up.

Put old (original) fuel pumps back in for now.
After removing and replacing the assembly 3 times, I'm now an "expert".

Subfixer · 04-08-2023

Any recommendations for "good" fuel pumps?

04-05-2023	#1
Subfixer Join Date: Sep 2018 Location: Groton, CT Posts: 384	Secondary fuel pump dead? Car runs fine, except when at full throttle going through the gears. Then acts like fuel shutoff. For short bursts of full throttle, everything is ok. I'm thinking the secondary pump isn't keeping up, or only the primary is working. Sent from my Pixel 4a (5G) using ZR-1 Net Registry mobile app __________________ 1992 ZR1 #442, 2 tops, White, White, Haibeck 415, 3.90 gear, Coilovers 2018 Audi RS5, 2.9 V6 Twin Turbo, Auto, Black, Black 2021 Audi Q3, 2.0T, 8 spd Tiptronic, Navarro Blue metallic, Pearl Beige

04-05-2023	#2
Young1 Join Date: Sep 2016 Location: Ocala, FL Posts: 899	Re: Secondary fuel pump dead? Most likely yes. To confirm perform the fuel pumps amperage test on the red pigtail at the wiper motor. Your meter will read 7-9 amps if both are running. 3-4 amps if one is running. Details in the Stickies. __________________ 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.

04-08-2023	#3
A26B Join Date: Dec 2003 Location: Arcadia,OK Posts: 3,394	Re: Secondary fuel pump dead? Do you still have the Secondary Port Throttle (SPT) system still in place? If so, test the vacuum pump and each of the vacuum actuators. A failure of any 1 of those 3 items can cause the same symptom. __________________ Jerry Downey JERRYS LT5 GASKETS & PARTS http://www.jerrysgaskets.com 1994 *ZR-1*, Black/Black, Lingenfelter Aerobody, 416cu in, 3.91 gears, coil-over susp, Brembo brakes, etc. 2016 Black-Red, 3LT-Z51 Auto 8-speed.

04-08-2023	#4
Subfixer Join Date: Sep 2018 Location: Groton, CT Posts: 384	Re: Secondary fuel pump dead? Secondary Port Throttle (SPT) system is still in place. Entire system was checked by Marc when my 415 was built less than a year ago. Vacuum pump doesn't cycle at all. Pretty sure its a pump. Will be replacing both today. __________________ 1992 ZR1 #442, 2 tops, White, White, Haibeck 415, 3.90 gear, Coilovers 2018 Audi RS5, 2.9 V6 Twin Turbo, Auto, Black, Black 2021 Audi Q3, 2.0T, 8 spd Tiptronic, Navarro Blue metallic, Pearl Beige

04-08-2023	#5
Subfixer Join Date: Sep 2018 Location: Groton, CT Posts: 384	Re: Secondary fuel pump dead? My first check was the current draw. Current reads 9.3 Amps, so it seems both pumps are running. Next check will be fuel pressure. __________________ 1992 ZR1 #442, 2 tops, White, White, Haibeck 415, 3.90 gear, Coilovers 2018 Audi RS5, 2.9 V6 Twin Turbo, Auto, Black, Black 2021 Audi Q3, 2.0T, 8 spd Tiptronic, Navarro Blue metallic, Pearl Beige Last edited by Subfixer; 04-08-2023 at 06:22 PM.

04-08-2023	#6
Subfixer Join Date: Sep 2018 Location: Groton, CT Posts: 384	Re: Secondary fuel pump dead? Fuel pressure check.... not good. Only 42psi at cold idle. __________________ 1992 ZR1 #442, 2 tops, White, White, Haibeck 415, 3.90 gear, Coilovers 2018 Audi RS5, 2.9 V6 Twin Turbo, Auto, Black, Black 2021 Audi Q3, 2.0T, 8 spd Tiptronic, Navarro Blue metallic, Pearl Beige

04-08-2023	#7
Subfixer Join Date: Sep 2018 Location: Groton, CT Posts: 384	Re: Secondary fuel pump dead? I really am disappointed in aftermarket Chinese parts. After replacing both pumps with Delphi FE0039 units, I now have a combined fuel pressure of 20psi..... __________________ 1992 ZR1 #442, 2 tops, White, White, Haibeck 415, 3.90 gear, Coilovers 2018 Audi RS5, 2.9 V6 Twin Turbo, Auto, Black, Black 2021 Audi Q3, 2.0T, 8 spd Tiptronic, Navarro Blue metallic, Pearl Beige

04-08-2023	#9
Subfixer Join Date: Sep 2018 Location: Groton, CT Posts: 384	Re: Secondary fuel pump dead? Vacuum pump does cycle, just not excessively. About once every 45 seconds after initial pump up. Put old (original) fuel pumps back in for now. After removing and replacing the assembly 3 times, I'm now an "expert". __________________ 1992 ZR1 #442, 2 tops, White, White, Haibeck 415, 3.90 gear, Coilovers 2018 Audi RS5, 2.9 V6 Twin Turbo, Auto, Black, Black 2021 Audi Q3, 2.0T, 8 spd Tiptronic, Navarro Blue metallic, Pearl Beige

04-08-2023	#10
Subfixer Join Date: Sep 2018 Location: Groton, CT Posts: 384	Re: Secondary fuel pump dead? Any recommendations for "good" fuel pumps? __________________ 1992 ZR1 #442, 2 tops, White, White, Haibeck 415, 3.90 gear, Coilovers 2018 Audi RS5, 2.9 V6 Twin Turbo, Auto, Black, Black 2021 Audi Q3, 2.0T, 8 spd Tiptronic, Navarro Blue metallic, Pearl Beige