Pusher Pump
 

I'm thinking about a pusher pump for better start ups after a long rest, and maybe a little boost to my old fashioned mechanical pump (RobbMc 550). There are lots of options but I would want something that would not cause any additional flow restriction and in the event of failure would still flow. I'm running stock 3/8 fuel lines.

After a long rest so to speak why don’t you just prime the primary side of whatever carb you have thru the fuel bowl vent until the accelerator pump works some.?

It’s a lot cheaper way to go and besides your mechanical pump is already over kill volume wise.

Takes some effort to remove the air cleaner to prime the bowl vent, not very fun to do that every time the car sits for awhile to cause hard starting related to fuel evap or drain back.

A 550 mech pump is not overkill for a 500+ hp stroked pontiac...

jhein- Theres some threads on here about what pusher pumps will still flow when turned off or how to make a bypass set up that flows fuel around the pump when its off or failed. Do a search on here if you dont get the answers youre looking for.

For priming purposes only a diaphram style electric pump has more suction to self prime the fuel system versus most vane style pumps. A vane style pump back at the tank in series with the mechanical pump both primes and increase performance with the smaller fuel line. But after the car sits often you have to crank over the engine some for the mechanical to prime the electric pump in the back. It varies depending on where you locate the pump at the back of the tank. A Robbmc 550 with 3/8” lines is about a 450HP setup, for cars that are able to hook up off the line they don’t keep up really well, the 550 Robbmc even with 1/2” lines is really not overkill if your making much power.

Effort, like removing the air cleaner lid?

The vents always stick up thru the air cleaner base.

Yes effort... like popping the hood, removing the shaker on a TA, then the air cleaner/lid... then putting it all back together just to fill the carb bowl takes some effort that can be avoided by adding a pusher pump & flipping a switch when needed.

Doing that every time after the car sits for 4-6 days gets old real fast, I know because Im in the same boat as jhein & many others with a Q-jet that goes dry or fuel drains back for whatever reason in a relatively short time.

I find it easier to just use the starter to crank for a few seconds a couple times to fill the carb when needed, but an in tank elect pump is in the near future for me to remedy that as well as provide better fuel supply on hard launches at the track where mech umps have a hard time keeping a q-jet full. A pusher pump is a good option for this situation, plus can add a little extra flow.

I didn't like all that cranking to fill my tripower after a couple weeks between cruise nights I wanted to go to. I put in a low pressure pusher pump with a parallel check valve to use for priming, But it looked like the check valve was itself a restriction when it was running on just the mechanical pump.

So I got a switch over valve like gets used on truck saddle tanks. Then running through a momentary toggle switch I can change the valve from direct through to a bypass flow through the primer pump and run it for about 20 seconds. When I release the toggle it changes back to straight through flow and shuts off the primer. Pump the throttle once and it fires right up and uses only the mechanical pump.

With the availability of parts these days and options for electric pumps, if you're at the point where you need or want a helper, isn't it simply time to go to an electric setup completely?

Tanks Inc tank with a TI Automotive 255 lph pump and a bypass regulator to keep your pressure where it needs to be.

Yes, it's initially more expensive and a bit more work, but you'll never regret it afterwards.

Thanks for the replies. Doing a search I found that a few people have had good long term results using a Holley red or Blue pumps back near the tank so that's probably what I'll do. Simple, inexpensive and easy.

Yes, it's not the worst thing ever to have to crank for 10 seconds or so. And yes, on a car with the shaker it's too much of a PITA (to me) to prime the carb. This will solve the priming issue and provide a little support for the mechanical pump to overcome the 3/8 line restriction.

Just go Holley Terminator EFI... you'll end up there eventually anyway... just kidding :D

As JLMounce suggested, the Tanks Inc setup with the small internal pump is a nice set-up. You could actually eliminate the RobbMc pump entirely if you wanted.

I have the Tanks Inc 20.5 Gallon tank in my TA with dual Walbro 450lph pumps and a floatless fuel sending unit. It is super quiet. I have no complaints.

https://www.tanksinc.com/index.cfm/p...rod/prd411.htm

Those pumps are pretty noisy. If you go that route I'd suggest something quieter like a Mallory (or something similar)

Check out this carter pump, quite a bit less $$ than the holley pumps and Ive read it allows fuel to flow through it when off. Holey blue pumps are 14psi, the carter is more q-jet friendly at 4-6psi.

https://www.summitracing.com/parts/crt-p4070

10 seconds.

A couple 5 second cranking sessions and you’re there.

I personally don’t see an issue worth spending time and money on.

Carry on.

Great timing since I’m considering a new tank & sender to fix my fuel smell and inop gas gauge. So I could use a Tanks Inc tank with an electric in tank pump for my Quadrajet, I assume I’ll need a regulator and fuel pump block off?

The Mallory 110 looks nice. Thanks.

I don't mind a 10 second crank at all. Let's me see the oil pressure come up on the gauge first.

I've run a Holley black pump (vane type) in my race car and it was very loud. I run a Mallory 140 (gearotor) now and it's much quieter.

My Mallory 140 would not let the mechanical suck through it well-eventually pulled the mechanical and dead head the Mallory. It is even with the tank and sucks fine to prime.
I do believe the Carter will allow a mechanical. That is what I used in the 70s on my dual quad 409. Mechanical unless racing then used the Carter as a pusher.

This is meant as a joke obviously, but this is actually how it starts.

OP has already changed the wheel and tire setup for better handling and traction. He's stated that he's going to be doing some suspension upgrades next.

Everything he's doing is in service of actually driving the car more. Some sort of EFI system would be the next iteration of what he's trying to accomplish with a pusher pump.

By going to an in-tank pump with a bypass regulator and proper feed/return lines, that system would grow into an EFI system if he wanted it to. The pusher pump into a mechanical pump won't.

Here's my issue with the pusher + mechanical deal. If you're using the pusher only to help fill the bowls at start-up, then shutting it off, you degrade performance of the mechanical pump you are using, now that it has to suck through both hose and a pump. Now you have the possibility of fuel starvation at WOT, unless you turn the pusher back on. For the type of motor the OP is running, that's a real possibility.

Okay, so run the pusher at all times now. At that point, why have the mechanical pump at all? Now that you don't have a mechanical pump, you want your electric pump to be as reliable as possible. Well, the way to do that is to put it inside the tank with a proper sump.

The pusher pump may be "cheaper" and "easier" at first, but when you get to the point of having to deal with the limitation of that set up, you're going to end up doing the in-tank pump anyhow. Now you just added time and expense over doing it that way in the first place.

If it was me, I'd deal with the mechanical only setup while I saved for the in-tank setup, then go right to that. Bandaid fixes always cost more in the long run.

OK, both Mallory and Holey tech support say that their pumps (Mallory 110 and Holley red) will not allow the mechanical pump to pull fuel through them if they are off or if they fail. That seems to contradict what people have said here, at least for the Holley. I don't know which is correct but if they won't allow the mechanical pump to pull fuel through in the event of a failure then that's a no go. My intention would be to run it at all times, not just start up.

So now I'm back to either living with the limitations of the mechanical pump, which are not terrible, or going in-tank electric. I was on the verge of doing that a couple years ago but I soured on the idea. One of the reasons was because people advised that you should have the low oil pressure safety switch. I agree that seems like an important part of the system. But people said that the currently available switches were poor quality and not reliable. That really turned me off. But, when the fail, do they fail open or closed?