Josh2002z28

91 RS, I did an engine swap recently and have run into some troubles. I pulled that ratty 305 throttle bodied engine out and put in a nice 355 with a Road Demon Carb. on top. I wanted to know if I can hot wire the "in'tank" fuel pump to run all the time while the ignition key in the ON position. The reason I ask is since I'm running a carb. now, the ECM does not know when to turn the fuel pump back on, I only get that little bit of fuel at the begin when turning the car on and then the pump never comes back on. I also wanted to know if this would be safe? I dont know if the pump will get to hot and cause a fire in the tank and I know that wouldn't end to well for me. Anyones insight would be helpful.

Thanks

Josh

PS, i already have a pressure regulator and if works fine.

DarthIROC

You could probbaly do that, I think it would jsut stop working before it caused a fire. But its probbaly easier to just buy a mechanical pump. And totally eliminates risk, of blowing yourself up

StealthElephant

I did a 305 TPI to 355 Carbed swap...oh wait, I'm still working on it.

I kept the stock inline pump and ran a 3 port regulator. I've been having hell. The idea was to avoid dropping the fuel can, in doing so I think I caused myself more heartache and work.

Tapping and retapping off of power sources that get 12v when the key is in the "ready" position. First spot I had it, gave you 12v with in in "ready" position. My problem? Somehow the power I tapped into turn completely off when I use the brakes...meaning, voltmeter read 12.98v with key in, put foot on brakes, power goes to nothing, result, I finally figured out why the car kept stalling in idle at stoplights.

Retapped the power, used the voltmeter to make sure the power never cut out no matter what electrical devices or other things were doing. Result, when I hit the brakes, my battery gauge hits 0, my tach freezes, my buckle up warning lights up, and my headlight left on sound rings constantly, oh yea, the damn thing still stalls even though the voltmeter read full power at all times no matter what, even with brake down, even though gauge cluster was down. Can't figure it out, I'm working on it tomorrow, we're going to directly tap off the battery and use a manual switch, if it's still stalling, we're going to fill up a gas can, put a mechanical fuel pump on, hook the mech fuel pump to the carb, run aline from the mech pump to the gas can, and see if the son of a bitch will idle in gear. If it still won't idle....then I guess it's not a fuel delivery problem, and I'm throwing my car into a lake. I started this swap like August 20th, it's November now? Yea....this is the first and last time I ever do a motor swap. There's a black 2000 Camaro Z28 with 34k miles sitting on a Chysler Jeep dealer lot 1 mile from my house for like 12k....just calling my name, I'm so pissed at my car I almost want it not to work tomorrow.

Josh2002z28

I feel you on that one, I have been working on this thing since May 2001. Anyways, I have a mech. pump too, my question is are you gonna use the same lines the electric pump uses or make new ones? If you make new ones, how are you gonna do it. I know the Mech pump with work fine but i'm worried about the delievery of the fuel when I'm road racing.

90rocz

The signal to fire the Fuel injectors and coil originates in the distributor's "pick up coil". It's the reference signal sent from the factory distributor to the ECM then back to the coil & injectors. If the oil pressure switch and the factory distributor are used, I don't see why the fuel pump would shut off.....
If you want to hot wire the pump just short the 10 gage orange wire(from keyed power source) to the 14gage tan w/white stripe(from fuel pump) wire...at the "fuel pump relay"... by the firewall, drivers side. The orange wire is fused by a 20amp inline fuse, and this should bypass the inputs needed to trigger the pump at the relay.
I had a similar problem before and used this as a "band-aid" fix, until I figured out the distributor was the problem.
Oh, yeah, don't forget to regulate fuel pressure down to 6-7psi, I'd install an inlet gage to keep an eye on it, you don't want to blow the needle valve off it's seat and flood out.

Josh2002z28

OH MY GOD, someone with the insight that I'm looking for THANK YOU THANK YOU THANK YOU!!!!!!!!

But i have to know a few things.... Did you keep your pump running like that for a long time and did it cause you any safety issues? Or would the fuse protect from that? Which orange wire did you use for the fix? Did you completely cut it or did you splice in the tan relay wire to the orange wire and let it give power to both(the oringal connection of the ORG wire and the "band aid" the pump)?

Thanks for you help I hope this works maybe even today /me crosses fingers

c1989rs

i swaped from fuel injected to carbed and found it best to use an external pump instead of the tank pump that way u can remove the computer altogethor

Josh2002z28

But if i do that, i will have to remove the in tank pump, right? How did you do it? Some Details please..

c1989rs

i didnt touch the pump in the tank and it flows fine, u will have to plug ur return line that is used with the tbi though if u dont u will have fuel spillin out of it i found this out the hard way it took me about three months to get my car back on the road when i did my swap most of it waz because i waz waitin till i had all the stuff i needed. let me know if u have ne other problems.

Josh2002z28

ok let me get this straight....you used a mechincal pump and you connected it to your original fuelline(line on the drivers side) and capped your return line and did nothing to your intank pump and it flows just fine with no problems???????? what about wires, did you disconnect any of them from the intank pump?

DarthIROC

Wait a minute, I just did a swap to a mechanical pump, but I havent ran all the lines yet. WHen I use a mecahnical pump I dont need the return line? Just the line going to the pump, and then from the pump to the carb?

AutoRoc

Stock in-tank pump easily wired to run with the Key ON Thanks to a friend it works flawlessly. Holley 600 carb, Mallory 3 port, Edelbrock intake.

Josh2002z28

thats what i want to know DarthIROC

Josh2002z28

AutoIROC, if its so easy then how did you do it? Come on br0 share the wealth, I have been working on this car for 2 years.

c1989rs

thats right all u got to is plug the return and conect the in line to ur mec pump. u can remove almost all of the wires in the motor bay i have at most 10 wires left in the bay i also went with mechanical guages for everything i have pics of my car if u want to see what i have