[James408]

Hi I need some advise on wiring a Holley red pump as a helper to my mechanical pump with stock 3/8 lines. I want to set it up with a toggle and only run it on WOT runs. Can I run it with an inline fuse or do I need a relay set up. Do you guys run a oil pressure safety switch with a helper/toggle fuel pump set up? I want it to be safe. Excuse my ignorance, I just need some direction and a grocery list. Thanks

[dmac]

Relay plus inline fuse. You can wire other things in the future to the same relay- like electric choke, fans, etc, all with a single cutoff switch, or individual cutoffs One 20-30 amp relay wired kind of like a house breaker panel is probably cleaner than 4-5 separate 5-10 amp relays if you ever decide to upgrade

[carcrazy]

In my opinion using a relay and an oil pressure switch is a good idea. The wiring diagram is on the Holley website.

[lust4speed]

Anytime you use a vane or gerotor type pump on a standby basis, you should have a bypass plumbed around the pump. Sometimes the vanes will stop where fuel will pass, but other times the engine is going to starve out. Carter offers a bypass kit for this, but you can do better picking fittings out and putting together your own. the Carter check valve is a nice piece and necessary in the bypass to have things work correctly.

[James408]

Are those the check valves between the the tees and the elbows on the bypass lines

[lust4speed]

One check valve closest to the top right hand side of the photo. Here's the Summit listing for the unit: Carter Check Valve
I've installed two systems and both have worked excellent. We at first tried the system without the bypass line, and the car fell on its nose about the top end of first gear. After the bypass was installed (and the pump off) the engine ran totally clean through the gears. The pump will be used at the drags and other times when it's felt a boost might be needed. Here is the second system on a '66 GTO which is basically a carbon copy of the first in a '72 TA.

[Cliff R]

A mechanical pump is nothing more than a stumbling block for a good electric pump. I tried exactly what you are doing many years ago with my old engine making 455hp and it didn't work. If you are making enough power to where the mechanical pump can't keep up, a good electric pump, regulator, and return system will be a better way to go....IMHO.

Even with all that said, the biggest problem I've seen with using mechanical pumps on really fast cars, is that the fuel lines feeding them aren't large enough, so the pump never sees it's full capacity. Most of the HP mechanical pumps are PLENTY for these engines, but being fed with small lines and stock in tank pick-ups they will not work like they are supposed to, and fall way short of being able to keep the carb full on hard runs......Cliff

[James408]

Thanks guys, I've been thinking about what you said Cliff. I'm actually running a Robbmc 550 mechanical pump. with my stock fuel system. Would it be worth a try running 1/2 inch fuel lines with this pump. No way I'm making over 450 hp.

[Cliff R]

Are you experiencing fuel delivery issues? Even with large lines, if you don't have a sumped tank, or modified/larger in tank pick-up, the capacity of the pump still woln't be up to par.

Keep in mind that a factory 3/8" fuel line is only 5/16" inside diameter. Pretty difficult for any mechanical pump to work like it's supposed to unless it has unrestricted fuel delivery to it, at least from what I've seen here with those things.......Cliff

[James408]

yes, after first gear I nose over. You now have me thinking about going to get a Robmcc 1/2 in pickup and go that route with 1/2 inline to the pump. An my combo is not that radical. maybe knocking on 400 hp if that.

[James408]

Thanks Lust!

[James408]

Thanks Dmac and Carcrazy. Good information too.

[David Jones]

My Carter electric "pusher" pump (P4070) works flawlessly and has for years......since 2009. Without it the deep sump OEM mechanical can't pull fuel forward enough to keep the Qjets bowl full all the way through 2nd gear at full mat. Cruising around town, without it, all is well. Turn the Carter on and all is well as hard and fast as I want to go.

I run no bypass line around the electric for when it is off.

[goatman65]

My mechanical pump barely pulls thru the Holley blue pump if it is not turned on. I think that is the reason for using the bypass suggested.

[grandville455]

The carters are better for pulling thru cause of their design, I ran the 4594 into a carter mech, til I needed more fuel than I built my own mech and used two elec pushers for the Grandville

[James408]

Anybody have a pic or idea where to mount the carter on a 69 Firebird. Not much room with my exhaust.

[James408]

ok Dave I saw the angle iron you used on the tank strap bolts....nice!