View Full Version : Upgrades to fuel system

09-13-2005, 09:27 PM
I am new to the world of GNs and TTypes, but recently acquired a 1985 GN. It is stock at the moment, but I plan on improving it. From the little I have read here, everything points to improving the fuel delivery system first. Looking for recommendations on the following:

Fuel pump- Walbro 340, where can I find one and is this appropriate for the 85? Any other recommendations?

Fuel pressure regulator- Dont even know what they look like, where it goes, where to get one or how to install it.

Fuel injectors- Is it possible to get to big of a fuel injector? If so what would be the reprocussions? If it was too rich wouldnt the ecm compensate?

From some of the discussions on here, it looks like most of you guys have advanced degrees in math and I am waaaay behind the powercurve when it comes to these new fangled thingamubobs. I am used to wrenching on SB 350s, 327s and 400s. Please help me out here as I feel like the lowest common denomenator. Seems like a great forum though, thanks for any help.

09-13-2005, 10:10 PM
All of these sound good depends on how fast you are intending to go just bought a 255 pmp. and was told it can support 600 hp., your regulator while facing the engine is to the right of your plenum on 86-87 model and is black mine is a black bosch unit looks like a little vacuum canister, good luck but changing these things are a good idea. :bye:

09-14-2005, 10:54 AM
Fuel pump - the Walbro is pretty much the standard and works really well. Racetronix, Full Throttle, Cotton's, Quad Air all sell kits that will get you going. While you are in there, buy one of the "plug 'n play" Hot Wire kits from them as well. It ensures good voltage/current at the pump and bypasses a lot of the 20 year old wiring in the cars.
Adjustable regulators are basically a little barrel shaped part on the fuel rail that has return line to the tank. Same vendors should be able to get you a nice adjustable for $120 or so.
Fuel injectors - it comes down to what your plans are. If you are planning to run alky or if your goals are something like a high 13 second hot air street car, you might want to consider just a mild "step up" to something like a 36# injector.

With properly calibrated chips, most can comfortably accomodate up to the MotoTron 60s without any sacrifice in reliability, gas mileage, or idle performance. Once you go much larger than that, you are starting to look at low impedence injectors, which need updated drivers in the stock ECM (and are really designed for peak and hold, not saturated drivers) and you can start having issues with rich idle and off idle transition problems. They are more finicky to calibrate and become more sensitive to combination in the lower RPM range.

You might also consider upgrading to an 86-87 ECM for more choices in chips and calibrations.

09-14-2005, 12:46 PM
Thanks for the info. Well what I thought was a bone stock 85 GN, apparently is not. It already has a cold air kit on it. In the trunk I found an ECM and a chip. Just tinkering around I put the chip in, whoa, big difference in idle quality, much more aggressive, rougher. Take off seemed the same, but top end would beg for more throttle.

Chip info: GM emblem, BLO in bold black letters, 882614 on the label on the chip sticker, 16022614 4067 etched on the outer surface of the chip. Any ideas where I can find info on this chip?

ECM info: serv. no.1226459

The box the ecm was in has cardone (manufacturer?) engine control computer 77-6459

Its possible the chip and ecm both went bad at one point and they were replaced, dunno? Hopefully they are upgrades. Any insight would be appreciated.

09-14-2005, 01:09 PM
Did some searching on the internet ecm is a stock replacement.