In-tank carb fuel pump?

[Broncojunkie]

Is there a pump available that fits the efi in-tank setup, but produces pressure/flow closer to carburetor requirements? I have a holley inline pump on my pace car. The noise is annoying and mounting it down low isn't ideal. I understand I can use an efi tank and pump, and use a regulator that reduces the pressure. It seems to me that this method, although it will work, isn't the best way to go about it. Reducing the high pressure is probably tough on the pump and puts unnecessary strain on lines and fittings.

Is there a better option for running an electric pump for carb setup?

Edit: I see there is another Aeromotive regulator for around $165. Still pretty spendy, but definitely better. I still don't care for the idea of sending unnecessary pressure through the system when it's not needed.

[Walking-Tall]

The pump I used (since 2016) is able to be fit into an '86-up EFI pump hanger. It's slight smaller diameter can be made up with rubber/other spacers of your choice, and I secured it into the hanger with zip-ties. See post #158 on page 7 of my car's build thread... a link to it is in red capitals below...

Don't believe their listed pressure range of 5-8psi, lol. They never did give me a straight answer when I asked what it would produce if "dead-headed". Initially, as you'll read, a 1/32" return line restriction I added to my homemade regulator resulted in 9-10psi, so it would have been 10+psi if "dead-headed"... so even with this earlier '80's low-pressure in-tank "lift pump", it's a good thing you're planning to also run a regulator. Best of luck with it.

[306gt]

I ran a stock 88 lph C.FI. pump to a stock e.f.i fuel filter. Then stepped up the factory line up to 3/8" hard steel. Up the car to a Mallory Regulator with the original 5/16" feed line as the return back to the tank. Worked for over 20 years. Ran mid 11's with my stroker motor. Last year I installed a 190 lph pump. Still same combo. Going to up grade my return line to 3/8"

[Broncojunkie]

Great info, guys. The thought of using a cfi pump cruised my mind. I haven't owned and driven a cfi car since the 90's, but I thought maybe they used a lower-pressure system. Evidently, they have 2 pumps. In-tank pump is low pressure and inline pump is high pressure.

Now, I'll need to research the situation for the fuel level sending unit/gauge. Not sure if the 79 sending unit will fit the later tank or if a later sending unit will work with my 79 gauge.

[Broncojunkie]

Found an older thread concerning the sending units (thanks to Trey and his wealth of knowledge).

"1979-1986 Mustang/Capri fuel level sending unit Ohm Readings are approximately 73 ohms empty and approximately 10 ohms full. So you could use a meter and apply current to the gauge to test if it is operating properly."

http://vb.foureyedpride.com/showthre...l+sending+unit

So it looks like I can use a later sending unit and tank, if that's what I'm reading.

My pace car is pretty rowdy and the exhaust drowns out most of the inline fuel pump noise. My 82 capri and 79 cobra will be more for cruising and junk, so a quieter fuel system will be a better fit. I may go with a mechanical fuel pump on one of these cars, but it will need to have a return line. I want to avoid any problems with ethanol and vapor lock.

[darkd0r]

FWIW, I had a 1969 Buick Riviera that was factory equipped with a low pressure in-tank electric fuel pump that fed the carb. There was an access plate in the trunk for pump replacement.

Probably too much work to adapt to a Mustang.

[Broncojunkie]

FWIW, I had a 1969 Buick Riviera that was factory equipped with a low pressure in-tank electric fuel pump that fed the carb. There was an access plate in the trunk for pump replacement.

Probably too much work to adapt to a Mustang.

Interesting that Buick had that setup in 69. Regardless, it doesn't look like it's being produced these days, so that pretty much rules it out. If I go this route, it will need to be something that's readily available.

I believe I'm going to try the pump listed above, for the cfi cars. Everything seems to fit the bill, except for (possibly) the flow rate. If I were to take the car to the track, I'm not sure the pump would keep up with fuel demand. Most of the info is lacking, concerning gph. I may have to buy one and do some bench-top testing.

[massacre]

Interesting that Buick had that setup in 69. Regardless, it doesn't look like it's being produced these days, so that pretty much rules it out. If I go this route, it will need to be something that's readily available.

I believe I'm going to try the pump listed above, for the cfi cars. Everything seems to fit the bill, except for (possibly) the flow rate. If I were to take the car to the track, I'm not sure the pump would keep up with fuel demand. Most of the info is lacking, concerning gph. I may have to buy one and do some bench-top testing.

I have one of those pumps (86 LTD wagon pump) brand new. I can tell you that it does not flow much at all. I swapped a 255lph pump into that sender assembly, had to cut down the supply tube a little bit but not very difficult to do.

[Broncojunkie]

I have one of those pumps (86 LTD wagon pump) brand new. I can tell you that it does not flow much at all. I swapped a 255lph pump into that sender assembly, had to cut down the supply tube a little bit but not very difficult to do.

Where did you get the 255lph? Is it still a low-pressure pump?

[teal95]

The 83, 84 and 85 2.3t cars used the dual fuel pump setup. I always thought that the in tank pump was low pressure suitable for a carb and the second pump boosted it to EFI levels.

steve

[quickshift]

I've got an 84 cougar (originally 302 CFI auto) with the stock 2 pump system. I'm running a carb on a 90 5.0 HO with mild mods (RPM manifold/Holley 725 VS/ 1.7 RRs / shorties / T-5 / 8.8 with 4.10s etc) and routinely turn 6200 through all the gears. The fuel pressure NEVER falls from my pre-set 6 psi controlled by a Mallory 4309 regulator. IF my memory serves me correct, when I built this combo years ago, I did a flow test on the fuel system running a battery charger connected to the car to duplicate running/charging conditions and it worked out to 33-34 GPH @ 6 psi. NOT free flow. Free flow would be higher! Just saying this works good for me without over thinking and not having to drop the tank.

[306gt]

When I had the c.f.i. 88 lph pump in my car. I was running 11.40's at 120 mph. Had a 337 stroker in it. The cfi pump was fine. Never ran out of fuel.

[quickshift]

When I had the c.f.i. 88 lph pump in my car. I was running 11.40's at 120 mph. Had a 337 stroker in it. The cfi pump was fine. Never ran out of fuel.

......exactly!

[massacre]

Where did you get the 255lph? Is it still a low-pressure pump?

It is a Walbro 255
I think it is high pressure, this motor is EFI.
Teksid block with Terminator heads and Mach1 intake.

[dynodon64]

You can run a stock high pressure in tank fuel pump with a regulator to drop it down to 6PSI. Just use a return line and it will work just fine. The high pressure pump will run just fine at the lower pressure, with the increase in volume as well.

[Broncojunkie]

You can run a stock high pressure in tank fuel pump with a regulator to drop it down to 6PSI. Just use a return line and it will work just fine. The high pressure pump will run just fine at the lower pressure, with the increase in volume as well.

It's my understanding that there are only a few regulators that are rated for this big of a drop in pressure. The aeromotive one is what most people use. Unfortunately, it is $300. I think I would put that money towards an efi conversion before spending that much just to run a basic carb setup.

Am I missing something? Is there a less expensive way to do this without overtaxing a basic carb regulator?

[quickshift]

It's my understanding that there are only a few regulators that are rated for this big of a drop in pressure. The aeromotive one is what most people use. Unfortunately, it is $300. I think I would put that money towards an efi conversion before spending that much just to run a basic carb setup.

Am I missing something? Is there a less expensive way to do this without overtaxing a basic carb regulator?

Mallory 4309

[Broncojunkie]

Mallory 4309

That looks like it could work. I'm reading that it is good up to 200 gph. However, it appears Mallory has discontinued it. When I did a search on Summit's site, a couple (nearly identical) Mallory fpr's popped up. I'm guessing there was a change that prompted a different part #.

A lot of the info I'm reading about pumps, carbs, fuel lines, and pressure are contradicting. For example, most people are suggesting you should install the regulator after the carb. That makes sense to me. If you're running a return line for circulation (to prevent vapor lock/boiling of ethanol fuel), returning the fuel before it reaches the carb isn't going to be as effective. I get that. What I don't understand is why the same people are also saying you have to run a return-style regulator in this scenario.

I have a return fpr on my pace car. It's carbed with a Holley Blue pump. It is returned, via bypass port in the fpr, just before entering the carb's fuel log. Fuel comes in through the inlet port and out through the outlet and bypass ports. Here's the kicker: the instructions from Holley state that either outlet port can be used as a return line or as your main feed to the carb. If you look at it, you'll find that one outlet port is on the side and the other outlet is on the bottom, but they're basically just the same outlet split into two ports.

I watched two different videos showing this setup and explaining how it works with the fpr installed AFTER the carb. In both instances, the bottom outlet port was used as a return and the side outlet port had a psi gauge installed (no line). It seems to me, other than having a convenient location for a pressure gauge, a regular non-bypass-style regulator would literally serve the same function.

[Broncojunkie]

I have a good grasp on how pumps and pressures and flow work. I may just be putting too much trust in people who claim to have experience and know-how when it comes to cars. I know a high-pressure pump will never be "high pressure" unless you restrict the pressure side (with a regulator, smaller line, clogged/pinched line, etc).

My concern is mainly with a clogged/pinched line or a possible failed fpr. A pump that's only capable of producing 12 psi will only make 12psi in one of the scenarios above. With a pump rated for 60 psi, a pinched line could cause a massive spike in pressure, thus overloading the needle & seat or just blowing out a fuel line. This is the main reason I'm not a fan of using high-pressure pumps when they're not needed.

I will ultimately choose one of these setups mentioned here in the thread. I'm not in a big hurry. I won't reach that point for at least a couple more months. I'm enjoying the conversation on this subject, though. You guys have some very good insight!

[Walking-Tall]

Apologies for some blatant tooting of one's own whistle, lol... but...
Ain't nuthin' functionally simpler, or plumbing-aisle prices cheaper, than my DIY fuel bypass-return "T"...



One of the horizontal barbs is fuel from the pump in the tank, and the other (inline) is to an inline fuel filter and to the carburetor, and the downward barb is for to the return line. This is mounted on the passenger side strut tower, connected up with the original CFI fuel lines on the car in that area.

To create this ridiculously simple and inexpensive dead-nuts functioning fuel return "regulator", I internally tapped the return barb's big end for a 3/8-NCx3/8" brass socket set screw, and drilled a 1/32" restriction in that for starters... I later went to a 1/16", and then finally to a 1/8" restriction to get a non-varying rock solid 5-6psi.



The return barb assembled with the restriction. The final internal restriction size is determined based on the resultant fuel pressure that your carburetor sees.



I have yet to experience any sort of lack of fuel issue with my ~300hp 306 SBF revving beyond 6000rpm.


* Important side note, and my fuel pump electrical circuit below... if present, replace any sort of resistance fuel pump ground wire (mid or later '80's CFI/EFI) with a regular non-resistance ground wire.



Best of luck with your situation

[Broncojunkie]

Mike,
I have been reading up on your setup and just haven't got around to mentioning it yet. I'm glad you chimed in, though. I love the simplicity of it and have been considering doing a slightly different version of it. Same principle, but I found some multi-port fuel manifolds (I believe they actually refer to them as "logs") at Summitt and Jegs. I run Holley 4150 carbs... the basic double-pumper with two fuel inlets. I could have the fuel line coming in from the pump and filter, into one end of the manifold. With 3 ports along the side of the manifold, I can run both fuel lines and a gauge. The port at the opposite end could serve as a return line, with a restriction like yours has.

My only hesitation is the idea that an actual regulator will auto-adjust to deal with anything that may spike pressure. On the other hand, use of a regulator is another device that is prone to failure and could cause spikes in pressure.

Can you tell me what type of fuel pump you are using?

Here is the fuel log I'm looking at:

[Walking-Tall]

The fuel log is a nice idea, and with a restricted return connection will work the same as the "T" I created, plus adding a gauge.

I'm with you on minimizing components in a system... let's face it, if a kinked line or a pump itself is spiking pressure, it's probably time to examine the fuel lines or time for a new pump...

The choices are few for the low-pressure internal pumps (and truthfully they all look like the same pump)...
https://www.rockauto.com/en/catalog/...fuel+pump,6256

I got mine (the first listed at that ^ link under "Daily Driver" at RockAuto), a Spectra Premium SP1152...



Like I mentioned above, it's diameter is a little smaller than a high-pressure CFI/EFI pump, so ya gotta get creative (I used split lengths of rubber fuel line to take up the space) fitting it into the hanger.