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  1. #1
    FEP Super Member cb84capri's Avatar
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    Default Edelbrock 1725 mechanical fuel pump

    The car I'm working on is an 84 Capri with a 347 stroker. It has a 750 Edelbrock afb carb, ported Typhoon dual plane, ported World Windsor Jr heads, custom roller cam, 1-5/8" long tubes, dual 2-1/2" full exhaust. Has 3/8" tubing and -6 braided hoses from in the tank to the carb. To clarify, the hanger in the tank is essentially stock with a 3/8" tube.

    Is anyone running this pump



    on a hot small block with any level of success? That is the newer style (Carter?) 1725 fuel pump. Started having a fueling issue with my old 1725 pump which looks like this:



    It wasn't keeping up with the fuel demands at wot, and the bowls were emptying out. I could stay in it for a little more than a gear and the fuel bowls would empty and the wideband would swing dangerously lean as the car fell on its face. Get out of the throttle for a couple seconds and get back on it, it would take of screaming again. This seemed to coincide with a hard starting issue that was worsening to the point of me having to pour gas in the carb to start it after a couple days sitting. I disconnected the pressure line and no gas came out, so I was led to believe there were some bad check valves in the pump. I'm going a little out of order here, but before I changed the pump I tried putting the larger needle and seat kit in my 750 and readjusting the float levels thinking that was perhaps a bottle neck. This did nothing. Inspected my fancy fuel filter at the carb as well, it was pretty clean. I wanted to rebuild this pump, but the rebuild kit is discontinued as well so my hand was pretty much forced into buying the new pump. The carb is performing very well in all modes aside from my wot running out of fuel issue.

    I bought the new pump in the first picture, and nothing changed. Edelbrock tech support told me there should always be fuel in the pressure line or a valve is bad in the pump. I had the pump warrantied and got a new one. Pulled the valve assemblies off of both new pumps. Pump #1 that was on the car definitely had a check valve on the fuel inlet side that was not sealing up properly. Pump #2 seemed to be good. Got #2 on and gained a little more time in wot, but still emptying the bowls...

    So I dropped the gas tank out, and replaced the strainer. Everything looked pretty clean in there. The new strainer is a lot longer than the original, was hoping this would fix the issue but so far there seems to be absolutely no change. Comparing my disassembled old model 1725 to the original, the old one looks like it's a much nicer piece. I'm going to do what I can with the old one, maybe I'lll get lucky and find a rebuild kit for it... but I'm not really sure where to go from here. The lowest portion of the new style pump is the inlet, and my 3/8" fuel lines all the way there feed into a 1/4" passage to the inlet chamber. The bottom floor of the pump outlet chamber (upper hole) is a poorly supported gasket, with the only support coming from a cube of foam stuck by the cast in inlet passage. This is both hard for me to describe and I'm sure hard to comprehend. I may have a picture on my phone...

    Have I reached the limitations of this carburetor with this engine combination? Are these fuel pumps just junk and I should try for a refund in full? Does anyone make a good inline fuel pressure gauge I can leave on there? Does anyone think I need to go to a higher pressure pump with a regulator? Should I got to an inline electric pump? Should I dig hard and try to find a rebuild for my old pump? Is it worthwhile to enlarge to aforementioned 1/4" inlet passage up, and epoxy or somehow fill the cavity below the unsupported gasket in the pump outlet chamber in the new pump? Edelbrock claims these 110gph pumps will support 600hp, I'd estimate I'm at least 150hp less than that brake...

    I know this is long, and if you're reading this thanks for staying with me. I've been banging my head against the wall trying to figure this out and could really use some help.

    Thanks,
    Cale
    Last edited by cb84capri; 09-21-2017 at 11:51 PM.

  2. #2
    FEP Member brianj's Avatar
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    I'm running the older style pump, and it feeds a mechanical Holley 750DP on a blower with 0 issues. I'd consider a rebuild on the old one, but I think you are having other issues.
    1983 Mustang G.T. No-option stripper- I like strippers.
    5.0, GT40P heads, Comp Cams XE270HR-12 on 1.6 rockers, TFI spring kit, Weiand 174 blower, Holley 750 mechanical secondarys, Mishimoto radiator, Edelbrock street performer mechanical pump, BBK shortys, T-5 conversion, 8.8 rear, 3.73 gears, carbon fiber clutches, SS Machine lowers, Maximum Motorsport XL subframes, "B" springs.

  3. #3
    FEP Super Member erratic50's Avatar
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    ^ this

    I would get an aftermarket fuel assembly for the tank. I would consider a low pressure high volume electric boostapump inline which should be adequate but realize that there is only so much fuel is going to flow by being sucked.

    If I was going to go off on it I would skip the boostacrap and I would switch to an intank pump assembly (86+ style fuel) and put in a return style loop up to a fuel pressure regulator right by the carb and eliminate the mechanical pump.

    Good luck!

  4. #4
    FEP Super Member cb84capri's Avatar
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    Did some digging... this looks familiar:



    https://www.summitracing.com/parts/q...50-1/overview/

    Does that look a lot like the old Edelbrock pumps, or what?

    I can't find the discontinued Edelbrock 1799 rebuild kit online for my old pump, but I could probably sacrifice one of these Quick Fuel Chevy pumps to save mine.

    Cale

  5. #5

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    "It wasn't keeping up with the fuel demands at wot, and the bowls were emptying out. I could stay in it for a little more than a gear and the fuel bowls would empty..." ... unless verified somehow (I'd imagine not easy with an Edelbrock carburetor), are assumptions, understandably supported by, "... the wideband would swing dangerously lean as the car fell on its face."... but, widebands are only a tool, that can be fooled, and indicating lean can and will be the wideband indication when there is rich misfire as well, because that sends all sorts (usually much more) of oxygen out the exhaust.

    What do the spark plugs and the insides of the tail pipes look like?

    That, and your bowl emptying after a time sitting, having to manually add gas to get it started, would send me looking for an internal crack or defect or defective part or casting porosity or bleed blockage or something in the carburetor, allowing the draining and/or a rich WOT condition. I think bowl emptying is incredibly rare. The instant the float/s begin to drop, the fuel starts getting added, if of course the pump is allowed to supply...

    "I disconnected the pressure line and no gas came out..."... When? After sitting some time, or just after running? Has the feed line between the tank and pump been verified to not have some blockage?...
    Mike
    1986 Mustang convertible ---> BUILD THREAD
    Past Fox-chassis "four eyes":
    1983 Mercury Cougar LS
    1986 Ford Thunderbird ELAN
    1980 Capri RS Turbo

    Work in progress website ---> http://carb-rebuilds-plus.boards.net/

  6. #6

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    Quote Originally Posted by cb84capri View Post
    Did some digging... this looks familiar:



    https://www.summitracing.com/parts/q...50-1/overview/

    Does that look a lot like the old Edelbrock pumps, or what?

    I can't find the discontinued Edelbrock 1799 rebuild kit online for my old pump, but I could probably sacrifice one of these Quick Fuel Chevy pumps to save mine.

    Cale
    Actually, they were Holley pumps before they were Edelbrock pumps, and I see now that Holley abandoned that design too. Things that function right and with longevity don't seem to be in the marketing ploys anymore.
    Mike
    1986 Mustang convertible ---> BUILD THREAD
    Past Fox-chassis "four eyes":
    1983 Mercury Cougar LS
    1986 Ford Thunderbird ELAN
    1980 Capri RS Turbo

    Work in progress website ---> http://carb-rebuilds-plus.boards.net/

  7. #7
    FEP Super Member cb84capri's Avatar
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    I just tried to start the car to go for a drive. It wouldn't start. Last time I drove it was Wednesday night. So I disconnected the pressure line to the carb and fed it into an old water bottle. No fuel came out yet again when I disconnected the line. I am getting little to no fuel coming out of the line after cranking it for several seconds. I disconnected the fuel filter and did the same and it made no difference. I think there are now 1 of 4 things potentially going on here.

    1. Blockage in fuel lines somewhere. When I have some more time, I will check and blow out the lines.

    2. This pump is bad.

    3. Issue with the fuel pump eccentric. The engine has a Ford Racing 1 piece fuel pump eccentric required for the timing set I'm using. Maybe I got a bad one? Possibly not pushing the pump arm enough? Is it possible I could have screwed up the install of this?

    4. Issue with timing cover. It has an aftermarket replacement timing cover on it. Maybe the fuel pump mounting pad is not in the proper location?

    I don't know the probability of 3 and 4, but I'm hoping to figure this out before I get to that point.

    Cale

  8. #8

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    Don't rule out the lines having a hole or a crack and sucking air
    84 LX Vert. 5.0 5speed canyon red on white
    99 cobra, electric green on medium parchment, vortech s-trim

  9. #9
    FEP Member brianj's Avatar
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    Curiosity - has this setup ever run for any length of time, or are these new motor problems? Do you have access to a fuel pressure guage?
    1983 Mustang G.T. No-option stripper- I like strippers.
    5.0, GT40P heads, Comp Cams XE270HR-12 on 1.6 rockers, TFI spring kit, Weiand 174 blower, Holley 750 mechanical secondarys, Mishimoto radiator, Edelbrock street performer mechanical pump, BBK shortys, T-5 conversion, 8.8 rear, 3.73 gears, carbon fiber clutches, SS Machine lowers, Maximum Motorsport XL subframes, "B" springs.

  10. #10

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    "1. Blockage in fuel lines somewhere. When I have some more time, I will check and blow out the lines."

    Check to see that the tank is venting too.
    Mike
    1986 Mustang convertible ---> BUILD THREAD
    Past Fox-chassis "four eyes":
    1983 Mercury Cougar LS
    1986 Ford Thunderbird ELAN
    1980 Capri RS Turbo

    Work in progress website ---> http://carb-rebuilds-plus.boards.net/

  11. #11
    FEP Super Member erratic50's Avatar
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    Loop a clear line up to the windshield then back to the carb. Then you can see if the line goes dry.

  12. #12
    FEP Super Member cb84capri's Avatar
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    All good suggestions, thanks. I found a suspect area of my fuel hardline in the right rear of the car. Looks like the tailpipe got in contact with the line somehow. I'll keep this updated. I'm hoping to find a small hole in the line.

    Cale

  13. #13
    FEP Super Member cb84capri's Avatar
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    Finally had a chance to tear into the car, examine and fix the problem tonight. Boy was I ever relieved to see a rather large crack in the fuel line! Lowetlx hit the nail on the head with this one. Thank God the car never caught on fire. It was in the right rear where the fuel line bends around the bottom of the rear frame rail, right near the beginning of the fuel line. The tailpipe was rubbing on it. If this car had an in-tank pump this would not have hidden from me this long, but it may have started on fire. I guess this area of the fuel line was high enough up that gas didn't pour out, likely any drips evaporated on the hot exhaust. I cut the line back and ran stainless braided hose up higher into the floor away from the contact area altogether.

    After the fix, the car even started on its own without pouring gas down the carb! And the pump is keeping up beautifully! Thanks for all the suggestions guys, this one really had me pulling my hair out. So happy to finally have this fixed!

    Cale

  14. #14

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    Good to hear that you were able to get it fixed.
    84 LX Vert. 5.0 5speed canyon red on white
    99 cobra, electric green on medium parchment, vortech s-trim

  15. #15

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    Quote Originally Posted by cb84capri View Post
    Finally had a chance to tear into the car, examine and fix the problem tonight. Boy was I ever relieved to see a rather large crack in the fuel line! Lowetlx hit the nail on the head with this one. Thank God the car never caught on fire. It was in the right rear where the fuel line bends around the bottom of the rear frame rail, right near the beginning of the fuel line. The tailpipe was rubbing on it. If this car had an in-tank pump this would not have hidden from me this long, but it may have started on fire. I guess this area of the fuel line was high enough up that gas didn't pour out, likely any drips evaporated on the hot exhaust. I cut the line back and ran stainless braided hose up higher into the floor away from the contact area altogether.

    After the fix, the car even started on its own without pouring gas down the carb! And the pump is keeping up beautifully! Thanks for all the suggestions guys, this one really had me pulling my hair out. So happy to finally have this fixed!

    Cale
    I have a 79 with the bottom of the tank fitting that I want to upgrade to 3/8" line up to the engine bay. Did you just bend your own lime or did you have a source for a prebent line?

    My car is carbed and I was thinking of using the upr top of the tank pickup for down the road efi setup. What are you using for the to the tank comnection?

    Sent from my SM-G892A using Tapatalk

  16. #16
    FEP Super Member cb84capri's Avatar
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    I bent my own 3/8" lines in place of the stock 5/16" stuff. The tank hanger line is also 3/8", I made this hanger like the stock 84. I have some Russel compression fittings that adapt from 3/8" to -6an to connect braided hose wherever it is. No fuel pressure in the line and no plans for it.

    Cale

  17. #17

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    Quote Originally Posted by cb84capri View Post
    I bent my own 3/8" lines in place of the stock 5/16" stuff. The tank hanger line is also 3/8", I made this hanger like the stock 84. I have some Russel compression fittings that adapt from 3/8" to -6an to connect braided hose wherever it is. No fuel pressure in the line and no plans for it.

    Cale
    So the mechanical pump does not have an issue pulling from the top of the tank?

    Sent from my SM-G892A using Tapatalk

  18. #18
    FEP Super Member cb84capri's Avatar
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    Not at all now, the hanger does go to the bottom of the tank. I don't ever let the car get below a quarter tank of gas so the thing not being baffled or sumped shouldn't really be an issue with what I do. It's the same way the car was set up from the factory, just with nicer, bigger lines and fancier hardware.

    Cale

  19. #19

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    Quote Originally Posted by cb84capri View Post
    Not at all now, the hanger does go to the bottom of the tank. I don't ever let the car get below a quarter tank of gas so the thing not being baffled or sumped shouldn't really be an issue with what I do. It's the same way the car was set up from the factory, just with nicer, bigger lines and fancier hardware.

    Cale
    Do you have any pictures of your setup?

    Sent from my SM-G892A using Tapatalk

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