camaro1122

iTrader: (1)

Hey everyone i just pulled out my 305 tpi engine and im dropping in a 350 carb'd engine. When i removed the tpi i also removed the engine harness, do i have to have the engine harness to make this car start and run? Also ive been told that since i dont want to drop the tank and replace the fuel pump i could just buy a regulator, which i did. Now ive been told i need something to power the fuel pump relay since i dont have an ECM anymore. What should i do? If i buy an 88 and up TBI harness off a camaro will that solve my engine harness problem? Also will it solve my fuel pump problem? If not help is needed, thanks.

Street Lethal

iTrader: (16)

You need the harness on the fuse block side, the ECM wiring you don't need. If you already have your adjustable regulator installed, it is just a matter of hooking up your stock fuel pump with an independent relay; power, ground, and switched 12-volt source. You can even run an inline fuse if you'd like, whatever you feel comfortable with. Your also going to need a standalone e-fan control, very easy to hook up. Good luck....

camaronewbie

You need the driver side harness - if you yanked that out then good luck!

Most of the pass side harness can come out, but really - why does everyone insist on cutting wires BEFORE the swap is done? It's really about the dumbest thing to do, once you cut out a wire it's ten times harder to reinatsll it

Fuel pump relay - just add 12v+ to the green wire with white stripe - you want this to be a hot-in-run wire so the pump doesn't run 24/7.

You need a Mallory 4309 fuel pressure regulator to keep the intank pump.

You need to do some research on here - all these questions have been asked and answered at least 10 times a week.

camaro1122

iTrader: (1)

Thanks for the reply. Ive got the drivers side wiring harness understood. What im not understanding is the fuel pump wiring, when you say just add 12v to that green wire with white stripes what do you mean? Yes i have the mallory 4309 regulator, now if someone can help me with this. Is it possible to hook the fuel lines from the regulator up the the stock fuel lines from the car with a fitting? If not what will i need to do? Also what adapters will i need to use in order to get this regulator hooked up? Im new to carb so im starting all over again. All i know is i need three 6AN to 3/8NPT fittings to go into the regulator

BillyTheGoat

iTrader: (2)

Here you go https://www.thirdgen.org/forums/carb...installed.html

camaro1122

iTrader: (1)

Thanks for that. Now all i need help with is the fuel pump relay wiring

camaronewbie

You just connect a 12v+ wire to that green with white stripe wire at the fuel pump relay - that's all - what's so hard about that? You want a hot-in-run wire ... a wire that only gets 12v+ when the key is on ... tap into that and connect to the fuel pump relay green/white stripe wire.

The stock fuel lines can be connected to the carb and fpr via simple brass fittings from any hardware store - in the plumbing section. The fuel lines are metric, and you need hose barbs that are NPT for the regulator - so you get metric to NPT connectors, then run rubber fuel hose to the regualtor, then to the carb.

For the feed line, you need a metric to NPT connector on the stock 3/8 feed line, then a NPT hose barb that is 3/8 hose, then the 3/8 rubber fuel injection hose, then another 3/8 hose barb that is NPT that screws into the Mallory, then another 3/8 hose NPT out of Mallory, another chunk of 3/8 rubber hose, and the banjo fitting on the carb.

Same with the return line, except you need 5/16 hose and hose barb fittings.

All that available at local ACE hardware store, in brass, in the plumbing section.

yyz28

I've burned up two in tank pumps using the regulator in a carb'ed application. We are currently converting the pickups to remove the intank pump and will be installing either a mechanical pump or a frame mounted Holley.

...probably going to do the Holley, but there is something about doing it old school that appeals to me...

five7kid

iTrader: (14)

What kind of regulator, specifically?

yyz28

4039 3 port Mallory.

Nothing wrong with the regulator, I just think it puts too much back pressure, even with the 3rd port feeding the return, on the high pressure pump.

Like I say, we're going to junk the intank pump and go with a carb specific pump.

CHJ37

what do think is the best place to get this power from? dizzy? starter? i'd like to do it somewhere close to the relay...i'm also hooking up my electric choke so is there a place that you think would be good for both?
thanks!

camaronewbie

Really just any wire that gets 12v+ with the key on - just probe a few close to where you want to tie in at to find one that has 12v+ only when key is on.

CHJ37

thanks!

bluegrassz

iTrader: (3)

I tapped into the 12v source at the wiper motor.

CHJ37

another great spot. thanks!

Not'Jur Average

i know that this is an old thread but uh.... i see somebody mentioned the wiper motor 12v source. isn't this "hot in accy and run"? is that a problem? if so i was thinking of running the green fuel pump relay wire to the 25 amp htr-a/c fuse which is only "hot in run".

bluegrassz

iTrader: (3)

Yes it is hot in the acc position. Hot on run would be better, but run through the oil pressure switch would be best. That way if you wrecked the car, then it wouldn't continue to pump fuel, possibly feeding a fire.

But I have had no problem so far, but do intend on rewiring the 12v source.

Not'Jur Average

Being that the engine I have is carbed & out of a 79, it seems that I don't have an oil pressure switch in the block. Only a sending unit by the distributor.

bluegrassz

iTrader: (3)

Disregard the oil pressure switch as a safety that I posted earlier. It only turns the pump on after it sees 4psi of oil pressure. I doesn't cut the 12v to the fuel pump if it looses pressure according to several post on this board . I guess you learn something new every day. lol

I'm sure there is a way to wire up a safety switch, but that may be in a different thread.

Although this seems to say it does.
http://www.jegs.com/i/Holley/510/12-810/10002/-1

Directions on installation.
http://www.jegs.com/InstallationInst...510-12-810.pdf

napalm368

i realize that this is an old old thread..but were you able to get a gas gauge hooked up with your set up...i also went from tpi to carb..and a mechanical fuel pump...how do i get the gas gauge to work?

Not'Jur Average

Why not stay with the in-tank pump for now? That way ur guage wuld wrk.. & if it ever fails then go with mechanical..

Not'Jur Average

Use the in tank pump & a mallory 4309 fpr to drop the pressure.. search this site for mallory 4309 & you will find a thread with pikz of installation.

napalm368

i actually had no idea that you could adjust the pressure of the fuel coming out...lol. that would save me alot of headache! the PO told me that he went with the mechanical fuel pump..because the in tank pump that worked with the old tpi system would constantly flood out my carb. so i didnt know there was that option,,i wonder why the hell he would not have just done that to begin with..lol thanks!

IroczFan

so run power to the green/white wire and the fuel pump will kick in when needed automaticly?

Not'Jur Average

Run the green & white wire from the fuel pump relay to a "hot in run" source. I used the heater/ ac fuse under the steering wheel. Any time the key is in the run position the fuel pump will stay on.

drag10

My green and white wire that was one of 4 wires that went to fuel pump relay went back to the ecu..plze explain cause im confused. Lol

bluegrassz

iTrader: (3)

Use some type of connector to put 12volts power to the green and white wire at the fuel pump relay. I used one like in this video.

http://https://www.youtube.com/watch?v=YBxJmoXdBxk

The red wire would be the green and white and the black wire would be the wire coming from the 12v source. You need to tap into a wire or location that has 12v when the key is turned to the on position. Adding a switch between the 12v source is an extra precaution. That way you can have the key on without the fuel pump running.

92camarogm

I just converted my 92 camaro from 305 tbi to carbureted it has a 350 in it now.im running the intank pump that's brand new.It seems that when it is at idleing at a dead stop it runs out of gas and pump won't kick on for a minute or two while acasionaly cranking it over.it's got a fuel preasure regulator with return on it.I also noticed that when this problem occurs my oil preasure gauge starts flickering with the pump just a little bit.any ideas?

NoEmissions84TA

iTrader: (1)

1) How did you wire it?
2) From your description, it sounds like your engine has low/no oil pressure at idle.



https://www.thirdgen.org/forums/elec...it-wiring.html

If you are wired as in the diagram above, then power to the tank fuel pump gets cut off if your oil pressure drops too low. Look at the fuel pump oil pressure switch.

92camarogm

The motor was in a older truck it had a aftermarket oil gauge it read 40psi while driving and 20psi at idle I plugged the camaro oil preasure sender deal in on it and it and it will read 28psi on cold start and come down to 12psi at idle when the car had the 305 tbi the oil gauge would flicker and would usually bury its self in the red

92camarogm

So I doubt the motor has low oil preasure could it be the sender unit or bad wiring?

NoEmissions84TA

iTrader: (1)

1) Verify oil pressure with a known good mechanical gauge.
2) I don't know exactly how you are wired. You can jump the FP relay to see if it runs that way. Then investigate from there.

ZCanuk

Just to clarify..as I am doing this too. The plug that goes to the fuel pump relay is embedded in the ecu harness. I am removing the ecu harness. Did you just cut the plug off and run power to the green/white wire and tape/solder up the others? Or are these the wires that go back to the pump? I havent pulled the motor yet and havent cut anything off.

bluegrassz

iTrader: (3)

The relay is on the firewall next to the brake booster. The wiring harness going to the ecu through the passenger side fender is a separate harness. I cut the wire going to the relay and run a jumper to the 12v on the wiper motor. Looking back, it would be better to find a 12v source in the fuse box under the dash and not draw off another system. You can also wire in a switch for a theft deterrent.

ZCanuk

Thanks, I assumed this was the case. At first glance the plug/wiring from the fuel pump relay is routed into the same loom at the firewall as the ECU harness. It goes across the back of the engine and into the passenger fender well. It must split off before it gets to the fender well somewhere. I'm going to have to split that loom and sort it out.

TylerSteez

iTrader: (3)

Im facing this exact dilemma but the fuel pump relay wiring does in fact go into the ECM harness and into the fender making it impossible to get rid of the ecm harness without removing all fuel pump relay wires.

I've read just about every thread on thirdgen about TPI to carb swapping and they all say, "get rid of the harness and cut one wire and wire it to a key hot location" but I cant possibly do that when every single wire runs with the ECM harness.




as you can see in this pic, all of my fuel pump relay wiring goes into the ECM harness and gets entangled with the rest of the wires. this is making it impossible for me to remove this harness and still run the fuel pump relay

John in RI

iTrader: (167)

Save yourself the time and effort. Hacking apart an otherwise good ECM harness for a relay and a couple wires is, well,.... ruining a good harness for very little benefit; it's worth something intact - not worth much at all once it's hacked-up.

If your going to a carb than just use a block mounted pump,.... or custom wire a relay and aftermarket pump. ( Do the same thing for the electric fan too,.... then the only other thing the ECM harness would be removing would be TCC lock-up and there are aftermarket kits for that too. ) I prefer to remove the in-tank pump when swapping from FI to carb. Would rather use a FPR to keep the carb FP regulated down a few pounds rather than reducing the pressure from the 40lb range down the the 7-8lbs that the carb will want; ( just my opinion. )

TylerSteez

iTrader: (3)

John in RI

iTrader: (167)

As that VSS thread described, you don't need to go into the ECM harness AT ALL for the VSS. Just re-install it's ground and you're G-T-G. (the 2 speedo sending unit wires are inside the ENGINE harness,...... aren't they ?! )

No Block mounted pump - Got it !

You could use the exact same relay your car already uses,... just need a replacement relay and proper plug,... wire it exactly as the factory did. ( same thing for the electric fan )

From an 87 Camaro Shop manual:






P.S. Well - not "Exactly",..... Would need to wire the Green/White wire to an ignition source !

TylerSteez

iTrader: (3)

John in RI

iTrader: (167)

Got it ! Looks like they moved them to the C100 in the 87 Firebird. ( PIN 'M' on C207 is still VSS ground. )

In your 86 those 2 VSS wires run into a small 2 or 3 socket plug next to the big C207 connector. But; again,...... we're talkin' about just 2 wires and a plug, about as basic it gets.

TylerSteez

iTrader: (3)

So essentially I can just splice two wires and the correct pigtail connector for the VSS near that plug and run it down to the sensor itself instead of taking the two wires out of the harness, and I'd still have to ground the black and white wire, Correct?

and for the fuel pump relay, I'm wondering why they ran the wiring for that with the ECM harness. I tried following your schematic but I'm not too sharp with electrical.

John in RI

iTrader: (167)

Yup.... looks like 2 wires 1 plug and 1 ground for the VSS.


The FPR only has 5 wires
1 ground,
1 full time power
1 IGN power ( to ECM on schematic )
1 TEST ( ALDL )
1 Power to Fuel Pump


As for the Fuel Pump Relay wiring,.... C207 was a good way to get a circuit from 'here-to-there'. Over the years they have used it for lots of stuff that needed to get passed thru the car. ( reverse lights for example. ) Generally, most stuff @ C207 is ECM related - but not always. IIRC the 90-91 cars had a courtesy light running thru it !

TylerSteez

iTrader: (3)

John in RI

iTrader: (167)

Yup,.... That's pretty much it !

TylerSteez

iTrader: (3)

John in RI

iTrader: (167)

Feel free to send me a message anytime,...... I'm just over the CT line in western RI, so we might just end up meeting up over a drink at some point !

Good luck with your build !