Sgt_Sizzle said:
So I have been and will continue to read this stem to stern and was wondering if you would mind giving some details and maybe going over some of the intricacies of the hybrid electrical/mechanical fuel system. What all went into making the electric fuel pump play nice with the big hanking carb? Thanks, keep up the good work
Certainly. Its all electrical to begin with. The pump in tank has been removed and a pick up tube fabbed to the same level as the prior pump pick up level was. The fuel line from the modded pick up is plumbed with 3/8 line all through. The line goes into the Holley Micro Mite which is electrical. From that point it goes up front to a filter to a regulator and then to the carb. Pressure is regulated to 5 psi. Its all electrical running on one fuse. I used the existing ecm and ignition set up and tapped into it for key on engine on power. Key is turned on and power is given to the pump which pressurizes the system. The carb as noted is too big for my setup, but its not large. Its pretty common size actually.
By keeping the stock ecm and all that, I was able to retain the full function of the stock gauges and keyed functions.
Kept it simple. I may if money permits change it all up at some point.
Thanks!
Highest recommendations to reconfigure your fuel pump circuit to run through a relay. Asking a key-on power wire to run your pump is ambitious.
Cousin_Eddie (Forum Supporter) said:
Highest recommendations to reconfigure your fuel pump circuit to run through a relay. Asking a key-on power wire to run your pump is ambitious.
Understood. Benefit of doing it my way is this. I am using a relay. The factory relay exists for the actual circuit. The key on power source is a dedicated (removed circuit) with is own relay and power IIRC. Either way with a low draw pump it works. I cant see it being an issue now, but larger pumps and higher draws I see it being an issue.
bonylad said:
Sgt_Sizzle said:
So I have been and will continue to read this stem to stern and was wondering if you would mind giving some details and maybe going over some of the intricacies of the hybrid electrical/mechanical fuel system. What all went into making the electric fuel pump play nice with the big hanking carb? Thanks, keep up the good work
Certainly. Its all electrical to begin with. The pump in tank has been removed and a pick up tube fabbed to the same level as the prior pump pick up level was. The fuel line from the modded pick up is plumbed with 3/8 line all through. The line goes into the Holley Micro Mite which is electrical. From that point it goes up front to a filter to a regulator and then to the carb. Pressure is regulated to 5 psi. Its all electrical running on one fuse. I used the existing ecm and ignition set up and tapped into it for key on engine on power. Key is turned on and power is given to the pump which pressurizes the system. The carb as noted is too big for my setup, but its not large. Its pretty common size actually.
By keeping the stock ecm and all that, I was able to retain the full function of the stock gauges and keyed functions.
Kept it simple. I may if money permits change it all up at some point.
Thanks!
Thanks for the explanation, I like to think I'm pretty capable mechanically but once there's wires involved my eyes cross real quick. I'll definitely be referencing this setup when/if I start my own similar build. Thanks
In reply to Sgt_Sizzle :
Absolutely. Simple is always best. I am sure the setup could be analyzed and found weak by those who know. Though for me I just tapped into what worked already and modded to my needs. Please feel free to ask any questions. Im here for you!
Initial rev the E36 M3 out of it in the garage results are amazing! No bog. No hesitation or delay. Just runs! Amazing. Will report back when I get to drive it.
So Im thinking I may have a restriction. I do have 3 fuel filters and I am using 3/8 line. I no longer need that many filters as originally I ran that due to possible contamination. As such I noted even with the regulator all the way in (increase) I still couldnt get any more than 5 psi. This is Holley Might Mite running 5-7 psi. I need 7. So I will do the following. I am removing the 3/8 line and going to 5/16. I will be removing all restrictions and see what pressure I have just dead headed at the pump outlet at the end of a 12 ft section of hose. Will see what that gets me.
Just do like I did on my '72 Charger, strap your dad to the roof with a water bottle of gas and have him dump it straight into the carb under load. (not intended for highway use.)
In reply to Sgt_Sizzle :
BUHHAHAHHAHAHAHAAHA......maybe my 11 year will do it?
I have 7-8 psi fluctuating at the head on the pump. So I think I will replace the excessive number of filters with unions for now (replace all line later) and see if I cant get a steady 7 psi at the output on the regulator. Stay tuned!
Removed the regulator as it was pointless. I am getting a smidge over 5 psi with 5/16 line. This is with the line just being one piece and no filters. At the pump with a short section it got over 7. With the 3/8 line and unions and no filters it was 5 psi. Idk.
Maybe the Mighty Might doesn't have the hootchpah to maintain that 7psi all the way up the firewall and to the carb? Not sure what all I can suggest here, since its not a restriction issue maybe its a supply issue.
Are you sure of the pressure rating on your pump?
In reply to solfly :
According to the specs, and according to the pressure read at the pump with a gauge?
I am going to try another pump. Pressure loss on that run of hose is just too much. Assuming 2 psi pressure drop from a 7 psi pump. That gives me 5 psi. Going to a 12-428 Holley.
Mighty Mite 12-428 34 GPH Holley Mighty Mite Electric Fuel Pump, 7-10 PSI
Which should go as high as 10 psi. I may have to run the regulator again. Given Holley recommends 7.5 psi at idle, I am way under! Could be the issue I have been having all along!
Ordered and on the way! Man I hope this is the issue!
Installed! Fuel pressure is now steady at 7 psi @ idle. I cant speak to what it is as it gets nearer to redline. Either way, another improvement. Seems to run better, now I need to tweak the secondaries. I need to delay the opening of the secondaries as they open too quick and without the airflow its no happy. With the fuel pressure upped its better, but not perfect. I picked up a spring set to tweak it. Need to pull it off at lunch and see which one I have already and go with a stiffer spring.
Nice, slowly but surely chipping away at it. When you get it all dialed in I would love to see a 1/4 mile time.
bonylad
HalfDork
8/14/21 10:35 a.m.
In reply to Sgt_Sizzle :
I don't think it will be fast. It's peppy. Sure. Over the winter. I'm slapping in that 700r4 with a stall and the maybe a drag run. Thanks!
So as far as I can decipher. This is a 91 700R4 from an F body. So it's a 305/350 unit. The trans has fluid in it and it's not burnt. Afaik it had low mileage. I'll just clean it up and probably paint it. Along with a fresh filter and gasket.
To support the goals of a better performing truck. I also ordered a 2200-2500 stall converter and a lock up kit for the 700r4. Once it get all this I will probably start the swap. I'll need a tv cable as well. It has one but they are cheap and I have heard issues of them stretching.
I'd recommend a Corvette servo for the 700r4 as well - it's a $65 part and I thought it made my 700 way less 'lazy'. Took about 25 minutes to install with the trans in the truck.
I believe this is the one I got. https://globaltransmissionparts.com/performance-2-4-corvette-servo-assembly-700r4-4l60e/
Keep up the good work!
Ooooo, now I'm even more interested in this build. This is exactly the setup I'll be running on my '53 Bel Air. I'll be watching to see how you set up the TV cable
In reply to Gunchsta :
I have considered a shift kit, but the truck is a cruiser. I am not sure I want that level of hell.
In reply to Sgt_Sizzle :
Dope! Yeah. So far as the TV cable goes, I have a bracket to adapt the tv linkage to the Holley. Should be no issue. I will fit it and see how far the cable it came with goes. Then order a new one, as they stretch and wear out. The stall is the biggest thing, will really wake it up! The lock up kit, is basically a pressure switch that closes the circuit on the lock up in 4th. Thanks!
In reply to bonylad :
The corvette servo will be way tamer than a shift kit.
