Technical Model A 4-Cyl. + Electric Fuel Pump issues

So I’m in the process of getting my fuel system installed and working properly as I didn’t go with the original cowl tank route.

Instead I have a RCI 15-gallon fuel cell, plumed with Fragola 6an lines and fittings to a K&N/Facet in-line pump 1.5-4 psi going into a pressure regulator hooked up to the fuel bowl for a nice concealed look.

Here’s the issue: with the regulator screw loosened counter clockwise (lowest psi setting 1-1.5) the pump still sends way too much fuel to the bowl, and eventually overflows. Yikes - the engine doesn’t even have the ability to keep up with the amount of fuel heading downstream.

I ordered a new Holley 1-4 psi regulator as I’m guessing the one I have from summit is is not regulating as designed? Gauge needle doesn’t even move… What else am I missing here Model A gurus? Here are some pictures to help show what I’ve done so far. Lines haven’t been fully attached to the frame rails yet as I’m still “in progress” but this first fire up today was a speed bump, as I had to essentially drain everything and sit there stumped trying to figure out why my system was sending so much fuel to the bowl…. The carb wasn’t even sucking it down the hard line either! Which is even more odd. It ran for a little bit on fuel I assume got pressurized and sent into the carb bowl, but it eventually sputtered and died, even know the glass sediment bowl was full of fuel? I did have the red cap off the tank (vent) fitting as well. Picture was taken before I ran it this afternoon.

Thanks to anyone who’s got some clues for me. I searched, read all the similar topics and couldn’t figure out what I did wrong…

 

Try asking the Model A guru's on www.fordbarn.com.Its Ryan's sister site.

 

Will do, great suggestion. Thank you.

 

I think you have a bad regulator. I bought the black QFT brand fuel regulator from same vendor you mentioned, 4.5 to 9 psi. I could not get it below 8-9 psi in fact if did not adjust at all. I then bought a Spectre 2518 Fuel Pressure Regulator, Inline, 1-4 PSI and I can run it down to about 3-4 psi. Maybe unrelated but my new pulse fuel pump died shortly after I installed the new regulator.
My other car has the Holly brand name regulator and it looks identical to the Spectre but I can adjust it from 0-5 psi with same pump setup.
Nice car and workmanship.

 

Thank you, I had a feeling it was bad too. Fingers crossed the Holley works as I’m eager to have this portion of the build sorted. Appreciate the feedback and compliment!

 

Try taking the fuel pump out of the equation, and feeding the carb from an auxilliary tank... I use a Briggs and Stratton small engine tank, clipped to the hood ledge on the firewall, or hanging on the radiator support rods to solve Model A fuel issues. The needle and seat still has to cut off the fuel at any pressure. You may find that the carb will not even hold back gravity!
It looks like an aftermarket carb you are using, they are often warped and leak furiously.
Get a Malpassi regulator and fuel bowl. You won't need any of that stuff on the inner firewall. Remember the A carb (Zenith) was gravity fed, so the float was only supposed to hold back a 10 gallon tank of fuel at about 18" of head when full.
The Malpassi is period correct , and delivers the goods.
Check out the monthly Banger meet
https://www.jalopyjournal.com/forum...ger-meet-thread-hows-your-4-cylinder.1231720/

there is a link posted at the end of each month to the next banger meet and on the first page of the new month a bunch of links to all the past banger meets and relevant Banger info.
It is "The online source " of hopped up banger info .
http://www.jalopyjournal.com/forum/showthread.php?t=161498

lastly I would recommend
https://www.jalopyjournal.com/forum/threads/building-my-first-roadster-in-san-francisco.1204990/

 

Appreciate all of this! I’ll look into that Malpassi! Thank you.

 

Get rid of that gauge... with the high range it has, coupled with the normal accuracy range, you actually have no idea what pressure you have! Get a high quality gauge with a max 20 or 25 psi range, then recheck what psi you THINK you have.
I don't know what carb you have, but most likely it won't take much pressure. Remember, it was designed to operate with gravity flow only, so proceed carefully.

 

http://www.officinamalpassi.it/en/

I like the FK 85 motorsport model for Model As, it has high flow but regulates right down. Includes a water trap and filter , and the parts are cheap and available.The Model A is a large capacity engine as far as Malpassi is concerned , Europeans tend to think 122 cubic inch (2000cc)engines are average.
I hasve seen them on Amazon for under $100, but they say none available at the moment. Pierce Manifolds in Gilroy California has them as does Redline Weber http://www.redlineweber.com

 

Hey Matthew,
IMO , you are fighting a fly with a shotgun !
In other words… you have an updraft carb that looks to be properly set up with a line… for gravity fuel feed !
However, you are trying to ‘force feed’ this carb with pressure.
Doesnt appear to be a zenith …is it?
I ask because zenith was stock and best suited. But even nos, the stock carb leaked notoriously. Thats why a shut off valve was connected(in line) on original equipment. WHY leaked ? This system used gravity feed, and fuel was sucked into carb/engine(via vacuum and atmospheric pressure. The needle/seat sorta did its job while engine was running, but often fuel kept obeying gravity… when shut off valve not shut off. Thats how ….um sensitive the system is stock !
Now you introduce positive pressure. Good luck. You do have choices. Go back to gravity and shut off valve, with your carb setup. Or use downdraft carb (s) with all the stuff you have hooked up.

 

Love your "A" Matthew !

 

Bleed off most of the pressure with a return line?

 

Thnak you, it’s a Marvel. My zenith flange broke that was on the vehicle unfortunately. I appreciate this information!

 

That’s something I was considering! So it cycles back to the tank.

 

So you think this will regulate enough to only send the Carb what it needs? Thank you again!

 

There is a Malpassi with a return line, but it depends on how your pump works. The carb itself should stop the flow when the bowl is full, as long as the pump pressure is regulated, however I do not know if the Marvel carb will do this. The Ford Model B carb (1932) is a bit bigger than an A carb, you can bore the A manifold out to match the slightly larger throat of the B carb for some performance improvement. The B has a fuel pump and the B carb is designed to work with it. A carb ( Zenith) should also be OK providing the needle and seat and the float and the float pivot are all in good nick.
BACK TO THE UNIT WORKING WITH YOUR PUMP!
Some pumps just stop when the flow stops, others have a return line with a restriction. I don't really like a pump that is running continuously just to circulate the excess fuel on a carburetor system...I realise that is the way a modern injection system works, unnecessary on a carb system. Those pumps with a return line built in and a restriction just bleed the pressure slowly and then pulse every now and then, instead of running continuously.If the pressure is set low, the needle and seat should just stop the flow and the pump . I tried to find a build thread for your roadster to discover what your ultimate intent is with the motor and carb...the Malpassi will still work if you are going with a downdraft carb(s) later on.
I don't think you will get the holley regulator to work any better than what you already have, they always creep up. I am sure the Malpassi will work better.
My reasoning is, the Holley diaphram is too small( surface area) to be sensitive enough to detect small changes in pressure.

 

Matthew, low pressure pump and no regulator ? I am presently using a Facet cube in a car with an SU. These pumps bypass internally when pressure is reached. You'll hear it at idle. Plenty of low pressure versions (some as low as on at 1 off at 2). See here: https://www.facet-purolator.com/tech-information/
I have also used Walbros. They stop when pressure is reached. You'll hear them going down the road. They come in low pressure versions too.
Both kinds are internally regulated, no external regulator or return. Both come in low enough pressures for carbs with lame needles and seats. More sano installation too. Mike

 

Looks like you are trying to build a period traditional, prewar style roadster. Here's a bizarre idea: Go Period Traditional. Back in the prewar days, people didn't use electric fuel pumps with the exception of some high end, European exotic cars.

For pumping gas from your rear mounted tank into a primitive, prewar style carburetor, the options were hand operated air pump or vacuum tank.

Shop around on the HAMB,, period air pumps turn up for sale often. These are simple to install, reliable and are actually fun to operate when they are set up right. All you need is a gas cap that will seal the tank and a tapped line into the tank that you pump the air through. The air line simply goes from the pump to a gauge (many people don't even use a gauge) and then to the tank.

The other correct route would be a vacuum tank which was used on thousands of cars during the 1920s and 1930s. Stewart Warner is the most common and these units turn up for sale regularly. They take some fussing to get right, but once they are right, they are predicable and reliable. There are also inexpensive rebuild kits available. They typically mount on the firewall on the same side as the carburetor.

The best part about a pressurized hand operated air pump or a vacuum tank is that they will never overwhelm and old carburetor.

 

I use a 1-15 psi gauge on the pump and for you that maybe too high for an accurate reading. K&N pumps from what I read are bought by gpm. Did you by the lowest available?

 

This is ideal, I was really not into the regulator setup as I was trying to hide it within the firewall as it's not very period correct, and unsightly. I am going to look into this option as well! Really appreciate your information.

 

I actually was reading up on this last evening, as saw some really neat systems using the hand pump. I even stumbled across one of Leno's pre-war monsters that had a crank that the passenger had to crank/pump while driving based on pressure on their gauge. Super interesting, and low-tech which I'm kind of liking since this setup is getting a little too "tech" for my speed.

 

I did, this model stated 1-4 psi. But I sure didn't stop pumping when the fuel bowl and carb were already maxed out on fuel level! It claimed it has some sort of internal regulation, but based on yesterdays fiasco I don't think it does?

 

I think I am going to return the K&N Pump as the range is too high in my opinion. I am going to attempt to run a Facet 1-2 PSI pump, as I know it shouldn't exceed 2 PSI. I unfortunately haven't found any Malpassi filter/regulators in the USA. All seem to be UK vendors which won't work unfortunately.

So I will run that Facet 1-2 PSI pump to the fuel bowl through the firewall. Should I still hook-up me new Holley regulator and set it to 1-1.5 to ensure I can slow down the flow to the bowl? Or is +/- 2 PSI low enough already to directly route to the carb without a regulator you guys think.

Really appreciate all your help! Loads of great information, and I'll be sure to post a comprehensive build/how-to when I get it working right so anyone in my shoes later will have a solid plan to run a similar setup.

 

Matthew, I think you will be fine without a regulator. A Facet cured my finicky carb issues, once and for all. I had a couple of "fuel everywhere" episodes before I tried it. A fellow with 50+ years under cars recommended them highly. All has been dry under the hood since. They are TINY too. You will have no problem stashing it out of sight. Keep us posted, Mike

 

They do make a couple of different type of float valves for the stock Zenith carb. The part numbers I'm giving you are from Bratton's 800-255-1929. The first is PN 14310, "modern float valve" $15.25. The second is PN 14330, "two ball Zenith float valve" $10.00. The top of the float on a Zenith carb should be 5/8" from the surface of the body. Since the Model A was gravity feed you might try to "trick" the float and get it to seal better by adjusting the float lower so the fuel level will push it up tighter. I have had several Model A Fords and have one now and even with gravity feed the carb tends to leak.

 

Not to start a what is traditional pissing match, but, Autopulse electric fuel pumps were available and common enough that I have documented multiple cars and period pictures of them. They're pretty easy to find now days, and robust enough that all of mine have been in working condition. They can be rebuilt and they run at 2 psi.

 

Great new Mike, I ordered through my local Napa. Should arrive early next week when we return from our fly fishing trip, just in time to give it another go!

 

Makes sense, after I install the new Facet 1-2 PSI pump, and give it a go. If it still has too much fuel in the bowl, I'll disassemble the carb and see where the float level is at and adjust, if that doesn't work I'll give the modern float valve a go! Just want to get this sorted as I thought it was the "easy part" of my build, haha!

 

Matthew, I think the Facets are better pullers and Walbros better pushers. Mine is at the firewall. Good luck ! Mike

 

Fantastic, I have mind on the inside frame rail, about middle way under the pass. seat area. So it's got a good run of hose to pull fuel from, and send up to the sediment bowl on the firewall. Hoping this works, I'll be one happy camper!