Sniper fuel pump with existing EFI pumps

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Joe1shoe

Junior Member
Joined
Jul 7, 2020
Posts
8
Reaction score
3
Location
Wernersville
First Name
Joe
Truck Year
1987
Truck Model
1500
Engine Size
383
Truck us 1987 GM PU. Dual Tanks. I removed the TBI Carb and ECM some time ago for a classic carb. I want to install a Sniper EFI Carb. I have existing EFI pumps that run continuously with ignition on to a regulator for the carb and return line. The Sniper Master kit has an inline HP fuel pump. I doubt it will pull fuel through the existing pump if they do not run.

Can I use the blue wire from the sniper EFI to the original fuel relay, AND to the Sniper fuel pump to control fuel flow? The original pump runs when the sniper pump runs?

Replacing the original tanks or in tank pumps is a lot of expense I'd prefer to avoid.
 

Frankenchevy

Proverbs 16:18
Joined
Jan 3, 2018
Posts
5,905
Reaction score
7,252
Location
USA
First Name
Jeremy
Truck Year
Square
Truck Model
CUCV
Engine Size
Small
Sniper needs 58 psi. Your TBI electric pumps aren’t much over 10 psi. I don’t know that running the in tank pumps to an external high pressure pump would work well.

If you don’t want to drop your tanks and put a pump like an ACDelco ep381 in, your best bet is a sump system. These are fed by your existing pump, then turn that low pressure into high pressure with a submerged pump in the engine compartment.

By the way, the correct in tank pumps that will work with the sniper aren’t expensive. They’re somewhere around $50. They replace the pump you have in your tanks and it’s super simple. With two tanks, you have a switching valve and that will need replacing due to the increased pressure. Again, maybe the easiest for you is the sump system.

As for running the high pressure pump off of your existing relay: the sniper harness has a built in relay with a 12ga blue wire that you run directly to whatever high pressure system you choose.
 

75gmck25

Full Access Member
Joined
Oct 13, 2016
Posts
2,018
Reaction score
1,811
Location
Northern Virginia
First Name
Bruce
Truck Year
1975
Truck Model
K25 Camper Special TH350 NP203
Engine Size
5.7
As mentioned, you can buy fuel sump or surge tank systems from Edelbrock and other places, and they are about $400. You connect your low pressure line as input to the reservoir, and the built in pump jacks the pressure up for your EFI. The small tank mounts in the engine compartment and the pump is activated by the EFI. I like this solution because I can leave all my existing dual tank setup as factory.

Surge tanks are also common for racing if you have issues with the in-tank pump sucking air during high speed turns, so there are many articles on how to build your own.

Bruce
 

SquareRoot

Full Access Member
Joined
Mar 18, 2017
Posts
3,659
Reaction score
6,602
Location
Arizona
First Name
Mike
Truck Year
85
Truck Model
K20
Engine Size
350
I have a Edelbrock remote tank in my 85 k20. Its fed from the factory mechanical pump around 5-6 psi. It works great except I've recently discovered it doesn't like the engine compartment heat. I never had an issue until summer when outside temps got up around 95 and higher.

It will be coming out and done correctly with baffled tanks and in tank high pressure pumps. If I would have done it right the first time I would be time and money ahead.
 

Joe1shoe

Junior Member
Joined
Jul 7, 2020
Posts
8
Reaction score
3
Location
Wernersville
First Name
Joe
Truck Year
1987
Truck Model
1500
Engine Size
383
Thanks for the advise. I’m going to try feeding the new pump with the factory pumps. It that does not work. I’ll replace the factory pumps with Walbro 5CA400HP Direct-Fit Fuel Pump Kit 255 LPH GM In-Tank.
 

Texxxan

Full Access Member
Joined
Dec 2, 2019
Posts
66
Reaction score
60
Location
Hooks, TX
First Name
Jose
Truck Year
1978
Truck Model
C10
Engine Size
350
Thanks for the advise. I’m going to try feeding the new pump with the factory pumps. It that does not work. I’ll replace the factory pumps with Walbro 5CA400HP Direct-Fit Fuel Pump Kit 255 LPH GM In-Tank.
Just curious if it worked.
 

Joe1shoe

Junior Member
Joined
Jul 7, 2020
Posts
8
Reaction score
3
Location
Wernersville
First Name
Joe
Truck Year
1987
Truck Model
1500
Engine Size
383
It does look like it worked. We have it up and running. We drove it 4 times for the learning process.

BUT...... I'm not ready to recommend this just yet.

I could use some further guidance on this. when I used the stock TBI pump to the Sniper pump (connected after the fuel valve) the pressure was too high. I was getting around 100psi. So I removed the original fuel relay so the tank pump would not run. The sniper pump does pull the fuel. But I can't switch tanks. Can someone tell me how to power the Fuel switching valve via the fuel switch in the cab without energizing the pumps? And if the tank pump does not work will the fuel gauge work?
 
Last edited:

Marcoman

Junior Member
Joined
Oct 12, 2019
Posts
23
Reaction score
6
Location
California
First Name
Marco
Truck Year
1982
Truck Model
Scottsdale
Engine Size
305
It does look like it worked. We have it up and running. We drove it 4 times for the learning process.

BUT...... I'm not ready to recommend this just yet.

I could use some further guidance on this. when I used the stock TBI pump to the Sniper pump (connected after the fuel valve) the pressure was too high. I was getting around 100psi. So I removed the original fuel relay so the tank pump would not run. The sniper pump does pull the fuel. But I can't switch tanks. Can someone tell me how to power the Fuel switching valve via the fuel switch in the cab without energizing the pumps? And if the tank pump does not work will the fuel gauge work?

Hey, can you give us an update on your EFI dilemma?
 

Joe1shoe

Junior Member
Joined
Jul 7, 2020
Posts
8
Reaction score
3
Location
Wernersville
First Name
Joe
Truck Year
1987
Truck Model
1500
Engine Size
383
Ok. Here is the update. The tank switch problem was the switching valve. Replaced it and my tanks switch. The Holley pump is connected about 4” after the valve. I do not run the in tank stock pumps. I do get a consistent 61 psi at an inline gauge. I drove it on 2 hour trip and back and did not have an issue.

I’ll say the pump is on the noisy side as others have said. I can hear it in the cab while still but not while driving. But the truck is not exactly quiet. I could hear the original pumps at ignition but not while running. Many comments that the noise is due to some cavitation. I cannot prove or disprove that.
I’ll also say that my install is not officially sanctioned by Holley. They recommend replacing the tank pumps with approved pumps.
 

Latest posts

Forum statistics

Threads
41,857
Posts
903,628
Members
33,370
Latest member
mitchell1128
Top