Slant Six Forum :: Mechanical Fuel Pumps

can you tell us some things you did to come to the conclusion your running out of fuel? also if you are driving at sea level with the car to the floor does she stammer or surge then?

How old is the foam? Have you (or any one) ever run race fuel in it. I ask since foam has a limited life and more exotic fuels will really attack the foam. If this is a used cell, I would look at that closely.

Have you been able to cause the same problem by crusing at, say, 90-100 MPH on level grades to simulate the same fuel use? And how is your cell vented?

Putting a bbm pump in the slant 6 is fairly straight forward.

It is just break the sweges that hold pump arm pin in the body and replace the pump arm with the slant six one. Reswedge the pin and mount the pump upside down.

I used a hp replacement for 440/hemi. This pumps flows 33gph at 7psi. The 7psi is to much pressure for an edelbrock which shouldn`t be run over 5psi.. So you need a pressure regulator. Also the fittings on the pump expects 3/8 fuel line, so you should replump the fuel lines. Also the pump can overpower the floats in a deadhead configuration, even at a 5psi limit. So I am going to try a return style system this year.

Right about now Dan is saying, see I told you so...

Way I see it I'm asking a factory pump is designed to feed a 1bbl with half the power I'm making, so it could be a bit deficient under heavy/constant load.

If I can whack one of these together before I go, swap it on and then take the stock stuff and tools with me, worst case I can always change it back.
Thanks for the tip!

I used a hp replacement for 440/hemi. This pumps flows 33gph at 7psi. The 7psi is to much pressure for an edelbrock which shouldn`t be run over 5psi.. So you need a pressure regulator. (...) Right about now Dan is saying, see I told you so...

We dyno-tune all of our stuff an haven't had/seen any issues on the dyno. It's such a minor issue i always forget until I'm getting on my way up the hill.

Flatdecked Block, .060 over
Comp 264 .440 lift cam
Ported head
Supersix
3-1 Headers

Author:	terrylittlejohn [ Fri Jan 16, 2015 6:27 pm ]
Post subject:
can you tell us some things you did to come to the conclusion your running out of fuel? also if you are driving at sea level with the car to the floor does she stammer or surge then?

Author:	nm9stheham [ Fri Jan 16, 2015 6:30 pm ]
Post subject:
How old is the foam? Have you (or any one) ever run race fuel in it. I ask since foam has a limited life and more exotic fuels will really attack the foam. If this is a used cell, I would look at that closely. Have you been able to cause the same problem by crusing at, say, 90-100 MPH on level grades to simulate the same fuel use? And how is your cell vented?

Author:	Dan-o [ Fri Jan 16, 2015 6:44 pm ]
Post subject:
Quote: can you tell us some things you did to come to the conclusion your running out of fuel? also if you are driving at sea level with the car to the floor does she stammer or surge then? Nope, fine then. We dyno-tune all of our stuff an haven't had/seen any issues on the dyno. It's such a minor issue i always forget until I'm getting on my way up the hill. Quote: How old is the foam? Have you (or any one) ever run race fuel in it. I ask since foam has a limited life and more exotic fuels will really attack the foam. If this is a used cell, I would look at that closely. Have you been able to cause the same problem by crusing at, say, 90-100 MPH on level grades to simulate the same fuel use? And how is your cell vented? No, i generally don't exceed the speed limit by more than 5mph driving around and don't have anywhere local to leagally get over 75mph. I get my speed fixes at race tracks. And with this car I don't really feel comfortable with some of the older/haven't serviced yet components on anything more than commuting and the occasional autocross. Modding a fuel pump will cost 40 bucks and I can try it tomorrow. Anyone got the link?

Author:	kesteb [ Fri Jan 16, 2015 8:06 pm ]
Post subject:
Putting a bbm pump in the slant 6 is fairly straight forward. It is just break the sweges that hold pump arm pin in the body and replace the pump arm with the slant six one. Reswedge the pin and mount the pump upside down. I used a hp replacement for 440/hemi. This pumps flows 33gph at 7psi. The 7psi is to much pressure for an edelbrock which shouldn`t be run over 5psi.. So you need a pressure regulator. Also the fittings on the pump expects 3/8 fuel line, so you should replump the fuel lines. Also the pump can overpower the floats in a deadhead configuration, even at a 5psi limit. So I am going to try a return style system this year. Right about now Dan is saying, see I told you so...

Author:	Dan-o [ Sat Jan 17, 2015 5:27 am ]
Post subject:
Quote: Putting a bbm pump in the slant 6 is fairly straight forward. It is just break the sweges that hold pump arm pin in the body and replace the pump arm with the slant six one. Reswedge the pin and mount the pump upside down. I used a hp replacement for 440/hemi. This pumps flows 33gph at 7psi. The 7psi is to much pressure for an edelbrock which shouldn`t be run over 5psi.. So you need a pressure regulator. Also the fittings on the pump expects 3/8 fuel line, so you should replump the fuel lines. Also the pump can overpower the floats in a deadhead configuration, even at a 5psi limit. So I am going to try a return style system this year. Right about now Dan is saying, see I told you so... Gotcha. I was thinking about seeing if the part numbers varied between something like you got and maybe a 383 with a 2bbl, and see if that tones it down enough. Plus the possibility of keeping everything 5/16 would be great too. Way I see it I'm asking a factory pump is designed to feed a 1bbl with half the power I'm making, so it could be a bit deficient under heavy/constant load. If I can whack one of these together before I go, swap it on and then take the stock stuff and tools with me, worst case I can always change it back. Thanks for the tip!

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Author:	nm9stheham [ Sat Jan 17, 2015 11:00 am ]
Post subject:
Quote: Way I see it I'm asking a factory pump is designed to feed a 1bbl with half the power I'm making, so it could be a bit deficient under heavy/constant load. If I can whack one of these together before I go, swap it on and then take the stock stuff and tools with me, worst case I can always change it back. Thanks for the tip! All depends on the load you are askng it to take. Is the grade so steep that you think a 1 BBL and stock motor would not pull same the hill at 70 mph? The load is primarily weight lifting and air pushing this case, so total load won't vary much regardless of peak engine HP (if you are not near or at the peak). If the stock engine woud not pull the grade, then your idea makes snese; if it would, it is likely a delivery issue. But if you have the stuff to put it in, why not? Sometimes just trying tells and teaches a lot.

Author:	SlantSixDan [ Sat Jan 17, 2015 12:13 pm ]
Post subject:
Quote: I used a hp replacement for 440/hemi. This pumps flows 33gph at 7psi. The 7psi is to much pressure for an edelbrock which shouldn`t be run over 5psi.. So you need a pressure regulator. (...) Right about now Dan is saying, see I told you so... Naw....right about now Dan is saying If you want to eliminate the potential problems of a fuel pressure regulator, get the Carter bolt-together fuel pump for the 440/Hemi (this one), disassemble it and send the diaphragm/spring assembly to these folks along with a note requesting an exact-fit diaphragm with a 3-to-4 pound spring (such as the one on the diaphragm for the Carter M2996s pump) instead of the original 7-to-9 pound spring. Receive it, install it, and voilÃ , a high-volume pump with slant-6 pressure rating. (tho also smart to run a 3-nipple fuel filter with return plumbed back to the fuel tank)

Author:	Dan-o [ Sat Jan 17, 2015 7:59 pm ]
Post subject:
Not a terrible idea Dan. I did some control tests today on the drive. If I didn't move my foot at all RPM's dropped about 400 and I got a total loss of about 20 mph, no issues. If I depressed the accelerator (about 1/2")to my known "good speed" of 2250 RPM's and about 55mph she climbed fine with no issues. If I gave it enough gas to accelerate up hill it at any time (waited for clear traffic) She would pull great unlit it began sputtering (time varied on aggressiveness of acceleration 10-18 seconds), and then tit gets a bit hairy because it seems the bowls have to fill back up and with the lost momentum plus engine braking (PB Trans) speeds can get dangerously low and then the car has to be VERY gingerly babied back up to a safer speed. I gave it about three goes for confirmation and counting of calibrated Mississippi's. The return drive tomorrow is a bit shallower of an ascent and only has 3 sections where this issue comes up. Anyway, fun tinkering! Looking forward to trying this pump mod since I'll be making the same drive in a about a week and a half.

Author:	SlantSixDan [ Sat Jan 17, 2015 8:20 pm ]
Post subject:
Reading back thru the thread, I don't see specs on your engine and carburetor. Unless you have a really big carburetor, I'm having trouble imagining a stock pump in good condition being unable to get the job done unless it is not being fully actuated because the fuel pump eccentric on the camshaft is worn, or there's something else the matter (internally swollen hardline-to-pump inlet hose, clogging in-tank fuel strainer...).

Author:	emsvitil [ Sat Jan 17, 2015 10:36 pm ]
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Have you replaced the fuel filter?

Author:	emsvitil [ Sat Jan 17, 2015 10:56 pm ]
Post subject:
Take the gas cap off to see if the venting is restricted.

Author:	Dan-o [ Sun Jan 18, 2015 6:54 am ]
Post subject:
Flatdecked Block, .060 over Comp 264 .440 lift cam Ported head Supersix 3-1 Headers Car runs really well for what it is everywhere else except in extreme hill climbs apparently, haha. Fuel pump/filter are a year old and have displayed symptoms since new; and tank has 3/4" vent to atmosphere.

Author:	DusterIdiot [ Sun Jan 18, 2015 9:14 am ]
Post subject:	I would...
I would get a different tank and bypass the fuel cell and see if that improves things (then you can eliminate the fuel cell and/or clogged hard lines from the list of issues). I know that the BBD had issues with the floats on extreme grades requiring some modifications and has been noted in some 4x4 publications, but I doubt you are running that kind of grade. Quote: We dyno-tune all of our stuff an haven't had/seen any issues on the dyno. It's such a minor issue i always forget until I'm getting on my way up the hill. Here again, the dyno cannot 100% simulate the real world...you might be able to get the load on the rollers, but you won't be able to simulate a 10% uphill grade physically on the car... I really think your issue has something to do with the tank, lines, filter or the pump is defective....I have run more engine build/carb, heavier car, and some nice Oregon mountain passes with the stock pump (even when it was a CC252 engine with the BBD and 2.94's, I never had fuel delivery problems)

Author:	SlantSixDan [ Sun Jan 18, 2015 9:54 am ]
Post subject:
Quote: Flatdecked Block, .060 over Comp 264 .440 lift cam Ported head Supersix 3-1 Headers None of this is even close to needing a bigger-than-stock fuel pump. Before you go to the expense and trouble, diagnose the existing system, find and squash the bug.

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Author:	terrylittlejohn [ Sun Jan 18, 2015 3:31 pm ]
Post subject:
where is the pickup in the cell? bottom or top with internal tube?