Fuel Pump Options Mechanical

[Frankenstang]

I have tried 3 of the 4 different mechanical fuel pump options that I'm aware of (didn't include the very early vacuum/fuel pump/wiper model cause she's an odd duck)...and not really interested in electric at this time.



The first one I ran for the past several years was the airtex. Although I know they don't have a great reputation for a quality part, it performed well until about 6-8mos ago when I thought I heard some new lifter noise. Turns out it was the airtex making racket that kept getting louder and more consistent, so I switched to an NOS carter (2nd pic above) not wanting to risk a major purge of fuel into the crankcase or damage to the cam eccentric.

The problem I've run into with both 1100's using the carter is that when trying to start the car after 1 week (sometimes less), I've had to crank the engine excessively and steadily pump the throttle to get her to start...like she has lost all prime.
With the airtex I could go 1-2 weeks easily without having to give more than 2-3 pedal strokes (often just the recommended 1) and she'd fire right off.

I recently picked up a NOS 'Motorcraft'(?) pump like the one I had on the car about 8 years ago (and that was on the car since '88 till I switched to the airtex). My lines are in good shape so I got this one to see if it eliminates the issue.


I've not seen nearly as many of the above pumps around, and they look like they might be a 'mid-year change part' : They look alot like the '65 and earlier pump with an adapted top portion to remove the filter body.


So its got me wondering :nono: which bring up questions :roll: ...

1. Could my 'bleed off' issue be an internal issue with the Carter not holding line pressure, causing it to lose prime?
2. It's curious that when the Carter bled off, that there would still not be enough fuel in the bowl to fire her up, could the bleed off be draining the fuel bowl in the carbs? (siphoning the fuel bowl?...that would seem wierd)
3. Anyone know if there are any major differences in these pumps? (psi rating, etc).
4. Also it seemed that later on the carter became standard, but didn't the eccentric arm or the whole pump change at some point on the 200 in the late 70's or so?
5. Anyone know the timeline for the various pumps?
6. Anyone have any strong preferences in their selection(other than electric)? Resons why?

I'm swapping back carbs so I'll change to the NOS '66 at some point and see what it does, after some mpg and plug readings. I like the idea of going back to the '66 'Motorcraft' pump (the one that looks like it was an adaption of the '65 pump) in part cause it was original (which for me is nice when it works) and it appears to be serviceable, which raises one last question...

7.Anyone know if the bladder assembly for the '65 'filter on' pump would work with the '66 'Motorcraft' pump?

Thanks in advance for any and all input!

 

[Frankenstang]

Well it gets wierder...after removing the old manual choke 1100 and leaving her upside down all day...not a drop of fuel came out of it :

That's absolutely bizarre cause this carb has been running fine other than the long cranking starts after sitting for a few days and less than desirable mpg's. No flat spots, smooth acceleration, and smooth idle. The one thing I noticed when switching to the carter was the fuel filter never filled, but I've seen that before on occasion and it not effect running.

I think the poor mileage was partly affected by a non-optimum manual choke cable setting...doesn't look like the choke has been opening quite all the way...linkage could use some refurb and tweaking.

Anyway, I don't know how it was running so well if the bowl was never filling...or was it filling and somehow siphoning down after shutoff...that would be a new one on me :

 

[rbohm]

8) sounds to me like the carb has in internal leak somewhere. as for the fuel pump, you could take a V8 pump and swap the arms for the six cylinder one.

 

[CZLN6]

Howdy Back Robert:

THis sounds like a good research survey. It would be good to know the factory psi rating on each, as well as the actual pressure each one generates in application. To be honest, I don't recall seeing this data anywhere, but I'm going to relook- again. I hope you post what you find. This will be interesting.

Happy 4th!!!

Adios, David

 

[Explorer]

8) sounds to me like the carb has in internal leak somewhere. as for the fuel pump, you could take a V8 pump and swap the arms for the six cylinder one.

X2 Has to be a crack or something. That would mean it's possibly washing down your cylinder walls.

 

[Frankenstang]

Thanks for the replies guys.
rbohm & explorer, I'm pretty sure I checked the outside base of the bowl or would have noticed fuel there, but I hadn't really thought about an internal leak especially one that might be letting it bleed off into the throttle bore :idea: That might also help explain the poor mileage. Choke was probably part of it, but it was opening over halfway just not full open and 14-15mpg avg on a couple tanks is fairly low versus past history with my mostly stock setup. While I've got the manual choke 1100 off I'll pull the top fill the bowl and see what I can see, thanks again.

David, I haven't plumbed a pressure gauge inline as yet, but it definitely seems worthwhile now. I'm still concerned the pressure could be sub par on this carter, haven't compared volume rate either come to think of it...might as well.
EDIT: By the way my '66 FSM says 4-6psi @500rpm for 'all' pumps (6&8), so it will be interesting to see how these compare. I will be trying the one I'm calling a '66 for comparison relatively soon, and believe I've still got the old noisy airtex I could pop on for a quick test as well, so I'll plan on sharing what I find eventually.

I've heard some folks like the modded bent8 model with the i6 arm, so if I find one for cheap I might even give that a shot. I'd like to be sure the one I settle on is running close to specs and holds up...that airtex was a disappointment.
...and a Happy 4th of July to all the good folks here at FSP

 

[FalconSedanDelivery]

A little heads up on fuel pump pressure and Autolite 1100/1101 and 1904's , the do NOT like fuel pressure over 4-4.5 lbs , Ive used a pressure regulator on my 62 Falcon 170 combo set at 3 and the fuel economy was way up , on my race setup , 4.5 was as high as i could use safely , higher and the carbs would flood on occasion , I have a regulator with every vehicle I have , well worth the money .Oh and I got high 20's in town and 31 on a trip of 20 miles or more , and I didnt spend 400+ on a so called Improved carb

 

[chad]

the modded bent8 model with the i6 arm
didn't we see a Thread yrs. ago bout switchin out the arm to fit a higher capacity carter on this site? Had pic AND 'instructions'.
Was it from a chebby? (a carter StreetStrip or some such model?). Seems just switch the arm by pull/replace the pin in the arm that is the holder/fulcrum for it? Uses same bolts and gasket, just a lill higher rise on the top and fatter (don't have the nomenclature) "barrels".

 

[Frankenstang]

A little heads up on fuel pump pressure and Autolite 1100/1101 and 1904's , the do NOT like fuel pressure over 4-4.5 lbs , Ive used a pressure regulator on my 62 Falcon 170 combo set at 3 and the fuel economy was way up , on my race setup , 4.5 was as high as i could use safely , higher and the carbs would flood on occasion , I have a regulator with every vehicle I have , well worth the money .Oh and I got high 20's in town and 31 on a trip of 20 miles or more , and I didnt spend 400+ on a so called Improved carb

Thanks for the tip FSD I'd heard of some of the other 1bbl's being particular about pressure, but guess I hadn't either run into yet on 1100's or heard of them being as sensitive to the issue. It's good to get the inside dope from you perfomance guys. Rich has recommended the pressure regulator on several occasions too...and given the cost of the carb, that added component is a minor additional expense at this point I do suspect the airtex had gotten out of specs (not just loud...maybe developing more lift than intended through wear/malfunction)...heck it might have been high from the get-go, and ultimately my goal is to milk the highest mpg/efficiency from an essentially stock setup.

Chad, yep I've read about the mod here as well at least once IIRC...best I can remember it is supposed to be as simple as a pin, arm, spring change as you said. Not sure if the bent8 carter used was from a particular era, model etc.
I was thinking the 'street/strip carter' is still sold as a modern iteration of that same bent8 base carter FP...modded for street/strip and sold by summit or some such...but don't start me lyin

Thanks again fellas!

 

[69.5Mav]

Well it gets wierder...after removing the old manual choke 1100 and leaving her upside down all day...not a drop of fuel came out of it

Once upon a time----

One of my sons freinds came over on a saterday and rebuilt the 2V on my sons 73Mav 302. They were at it all day and still din't get it quite right.

On sunday I went out and started checking their work. They couldn't get the car to idle and it was hard to start. After checking it and finding the fuel bowl empty I realized that any fuel I put in was quickly draining away. I toke the carb off and watcked as the fuel leaked out the "new" power valve. I reinstalled the old one reassembled the carb and reinstalled it, Problem solved.

Moral: while I don't know if you have a power valve or not, don't think so, you might try filling the bowl up with the carb off and see if anything leaks. It should noy sinse this is a vacuum draw system. Might leak a little out the idle hole.

I can not see any way for the fuel to be siphoned off by the fuel line.

Good luck.

 

[chad]

Not sure if the bent8
Just (another of my) a quick Qs.
What is this bent8 referred to so often around here, thanks.

 

[rbohm]

Not sure if the bent8
Just (another of my) a quick Qs.
What is this bent8 referred to so often around here, thanks.

8) bent 8=V8

 

[woodbutcher]

Thats a V8 such as the 302 ect.
Good luck.Have fun.Be safe.
Leo

 

[chad]

DOH!
(or in my time Duh!) So the V is the 'bent' (from a straight line) as above - any make 8 cyl (again @ some vee configuration). Comprende`.
Gotcha, thanks
BTW: who'd want THAT? esp when they could have an I6, not a pancake, not a slant, not any other kind but a real, true, honest to goodness I6?

AND NOW back to your regularly scheduled fuel pump posts....

 

[Frankenstang]

BTW: who'd want THAT?

:rolflmao: Exactly! Who'd want a bent engine when you can have a nice straight one...and all that implies

I can not see any way for the fuel to be siphoned off by the fuel line.

Yeah, I gotta admit that was a stretch. The seal on my tank cap is very tight so I was wondering if it was possible for the cap vent to be blocked sufficiently to develop some neg pressure/or vacuum back at the tank with the pump running that could be draining, or 'siphoning' the fuel back once the car shut off...eh, slightly overthinking it maybe :duh:

I'm guessing it's gotta be a relatively small leak not to have seemingly affected performance (well apart from mileage)...hopefully I'll get a chance to fill her and do some rooting around one evening this week, or at least by the weekend. :thanks:

 

[wsa111]

Robert, i have run several mechanical pumps in the last couple of years.
I use a holley electric pump as a pusher to the mechanical pump.
The airtex seems to run about 4-5# while the carter pump runs in the 6-7# area.
Needless to say i never have fuel starvation at the top end.
I run holley carbs using braswell floats which have a longer fulcrum dimension than the stock holley nitrophyl floats.
Before ethanol fuel i used the duracon plastic float which controlled fuel pressure.
If you run any other carburetor other than a holley 7448 or 4412 & even them without the right float a fuel pressure regulator is necessary.
If you purchase a carter i have had 4 of them where the arm contact area with the camshaft eccentric only contacts on the edge.
What i'm saying the contact surface is not parallel with the pump mounting bolts.
The contact lever is twisted causing just the edge of the arm to make a partial footprint on the camshaft eccentric.
Check all pumps for this problem. Carter is the best pump, but if the arm is twisted that is a no no. Bill

 

[64 200 ranchero]

was111 i think i might have a fuel starvation problem, I run a modifyed 4412 holley and i notice that at high rpm, my temp starts to rise slightly, i get no pinging or anything

 

[Frankenstang]

Thanks Bill, especially for the pressure stats on the airtex and carter as well along with the tip about the pump arm. I was hoping for some comparative stats. I've got the carter on there now with an auto choke 1100 with a brass float (just swapped over from a mechanical 1100 with brass float). As I understand it, if the pump pressure is too excessive it can still force the needle off its seat causing rich running or flooding.
Wondering if over time that could permanently affect the float level (bending it slightly over time)?

EDIT: I'll be interested to see what my noisy airtex puts out... I think the wear might be around where the pump arm pin seats (could be causing overstroking), and I'll check the contact pads and alignment on the arms as I go as well.

Can y'all recommend a good/affordable pressure regulator?
I seem to recall a pic posted of one...I'll see if I can track it down.

Also, any thoughts on combo fuel pressure/vacuum gauges?
I noticed some of the old snap-on kits go fairly cheap on fleabay, and the other couple choices out there in the same price range seem to be the Mr Gasket or a cheap import fuel pressure only. Like the idea of a double duty gauge.
Thanks again!

 

[oldtown]

My Airtex fuel pump also began making lifter type noises. I believed it was the lifters. Then there was a puddle of gas under the car from the fuel pump. As it was dying, it self distructed and clogged up the idle circuit in the 1100 carb. I had to send it back to Pony Carbs to clean it out.

I replaced it with the Carter fuel pump, and added a Fram G2 inline filter. No more Airtex for me. Now everything works great.

 

[bubba22349]

I have used to use the Airtex (they are rebuilds of factory type pumps) fuel pumps on many cars and seldom had a problem with them. With a NOS part (they would have used old style diaphragms and parts) I wonder if what you’re seeing is not caused by the fuel we now have? Alcohol can deteriorate the rubber parts quickly some areas have more added into the fuel than others.