EFI fuel pump

[79monzaman]

I have a 79 monza that I planning to put a TBI 4.3 V6 in. What is the best fuel pump to use and where do I mount it?

Thanks

[cosvega76]

I would suggest one from, say, an '88 S-10. With a little tweaking, it should fit right where your old electric pump is now in the tank.

Chuck

[Jitterbugdude]

I would suggest one from, say, an '88 S-10. With a little tweaking, it should fit right where your old electric pump is now in the tank.

Chuck

OK, I'll bite... what is "a little tweaking"?............ Randy B

[cosvega76]

There may be a slight difference in the length or girth. In other words, it may not drop right in. It should be close enough to fit with a little bending to the bracket on the bottom, and it may use a different "sock" on the fuel inlet. Match it to the old one as best as you can.

Chuck

[cozwurth]

There may be a slight difference in the length or girth. In other words, it may not drop right in. It should be close enough to fit with a little bending to the bracket on the bottom, and it may use a different "sock" on the fuel inlet. Match it to the old one as best as you can.

Chuck

If the S-10 pump is the same size as a V-6 Fiero pump, it will take a little more than bending the bottom bracket. I used a V-6 Fiero pump in one of my Cosworth Vegas, and I had to add about 1/2" in length to the bracket. It was a very simple mod to make. The girth was fine. I don't remember if I used the Fiero sock or a Monza/Vega sock. I made that mod over 15 years ago, so the memory has faded a bit. I took some pictures of my modded bracket, but I'm not home to get them right now. I'll try to remember to post them when I get home this weekend.

[ColinOpseth]

You can also use a TBI pump from a thirdgen F-Body. Just make sure it's from a TBI car and not TPI.

I have a three-port TPI pump setup I'm going to run with my LT1 (if I ever get the exhaust done). It looks like it'll fit with minor bending of the fuel pickup assembly.

[TimMcCabe]

Don't forget you will need some kind of reservoir to prevent fuel starvation while cornering and braking.
The Cosworth has a little tray the fuel pump sits in to keep the pump submerged in fuel at all times.

I have the fuel pump for my TPI mounted in the center opening of the fuel tank with a new 3/8” line coming out the top of the tank. I used the original fuel line as the return line. (I don't even know if the Monza has the flange in the center of the gas tank like the Vega)

The fuel pump sits in a plastic can with a small jet pump in the bottom that keeps the can full of fuel all the time. I was running a TPI pump, but now I have a Suzuki Hayabusa pump (over 255 liters/hr@ about 90psi , no fuel shortage for my stock TPI)

Cheers,

Tim

[cosworth0135]

For those interested, I replaced the stock in tank(low pressure), with a 86 fiero tpi pump on the cosworth, should have the same pickup/sending unit as the other vegas,as the tank it self is different on cosworths not the pickups or in tank pump. I had to cut the end off that holds the sock(and the pump) and extend it about 2.5 inches because the fiero pump is longer, its easy and would work great on any tpi motor. simple cheap and do it yourself, I am also pretty sure other intank gm pumps are the same as well,, P.S. the fiero pump is only $15 on ebay, sure beats a $130 walbro, or equivalent, with some research you could do the same mod for a TBI system as well(using a gm TBI pump they have a pressure of 18psi , A very wise elderly friend of mine taught me to spend time thinking, before spending money with my wallet. I came up with this fix because of the high cost of a replacement secondary(high pressure) pump on a cosworth,,,TImmy

[75Monzta]

GM TBI systems utilize 9-13 psi and have set regulators (brazed) so they are non adjustable. 18psi will cause a different fuel spray pattern and you may have to "turn down" the pulse width to make sure you don't get rich readings on your INT (Integrator) reading on your scanner and on your BLM (Block Learn Multiplier) readings. Custom chips can take care of having to modify your regulator.

[cosworth0135]

That may be true but GM TBI pumps push 18 psi This I am sure of I also know for a fact they work for a Holley projection system , been there done that it's how I am sure of my prior post and that it will work they are also the same dimension as the high psi pump like the 1986 fiero that I have in my cosworth tank right now and if I can get on in there with the factory slosh baffle of the cosworth tank then regular vega owners should have no problem. and on the regulator the GM system has it's own regulator so you won't have to turn anythting down be cause the rgulator will bypass any unused fuel and unnecessary presure back to the tank just make sure you don't use to small a return line or it will hike up the pressure and cause problems but if your installing a tbi system you have read that somewhere already

[MonzaRacer]

GM pump may deadhead 18 psi but all gm TBI use a return system with regulator in TBI unit, if you use it with a carb , use a return style adjustable regulator

[78spyder]

Is there any reason you cant use a return style regulator at the pump near the tank and run the return line right there back into the tank ? I realise it may not be as sensitive to changes, but I can imagine its really splitting hairs, But the oems run the line the whole way back for some reason. I was planning on using a short return on a carbed set up but I wonder how that might work on an efi setup like a Powerjection 3 or Holley?

[bill1978v8]

I'm using the Corvette fuel pressure regulator/filter with a short return on mine. It is mounted under the back of the car with a short return line. Mine is set at 58 psi from the factory and reads 59-60 psi on my gauge. I don't know why you couldn't use a regulator back there set to the correct pressure. It would make adjustments a lot harder but you could set it and forget it.

BIll

[Rickracer]

One of the major benefits to a return style regulator is that they keep cooler fuel near the carb, returning back by the tank instead of near the carb negates this benefit,

[bill1978v8]

I do agree with that statement. I should state that my system is a returnless set up but that I built a bypass regulator into it for convienence of plumbing.