DM91RS

Does anyone know how to plumb a fuel pressure guage under the hood to a 670 Holley TBI unit? I remember seeing Dan's 4bbl. having one.

scauffiel

Well, I plumbed one into my OEM TBI and it should work pretty much the same. Just splice it into your rubber lines. Piece of cake, taking all of twenty minutes.

Steve

badbird88

I did the same thing right where the rubber lines run into the steel lines near the steering pump. It works great and had no problems for 3 years now.

------------------
1988 TA 300+hp 350 w/ TBI and Holley TB unit,
WC T-5, 3.42 gears w/ Auburn posi. MSD 6A, edelbrock TES headers, dynomax 3" cat and cat-back system, ACCEL coil, polyurethane bushings all around, aluminum driveshaft, Mr. Gasket open air cleaner.

1993 S-10 w/ 4.3L V6 TBI, slightly bigger cam, Mild polish job and 3 angle valve job on heads, Edlebrock TES headers, Dynomax cat back, MSD 6A, ADS chip
(bought from my dad)

2000 GMC Sierra Regular Cab Stepside
285hp 5.3L w/ 3.42 gears and locking diff. (sold to my dad..no!!)

DM91RS

If the guage is installed in the feed line will that not give you the fuel pump pressure and not the regulated pressure going to the injectors?

Scott C

I believe that since the TBI system is a pressurized setup using a supply line and a return line, you will see the "system" pressure at the guage.

When I adjust the AFPR on my Holley TBI, the gauge reads the correct pressure as I increase or decrease it (8-15psi).

------------------
'92 RS, ZZ4 10:1 350, Edelbrock 6085 heads, Crane 208/214 467/482 cam, GM 1.6 true roller rockers, Holley Projection TBI intake, Holley 670 TBI, SLP/Jet-Hot 1-5/8" headers, Catco 3" cat, Flowmaster 3" catback, Hughes 2500 stall converter, stock 700R4, Auburn Pro posi w/3.42, 17x9" SS rims w/BFG tires, Medium Quasar Blue w/white SS stripes, 48,000 miles....

badbird88

same here, here is a pic of where I installed mine at...kind of dirty and I've since replace the rubber hose since the time of the pic but you get the idea. Also the air intake tube isn't there anymore so I can see the gauge a lot better. I'm eventually going to use braided lines on my next engine swap.

it may take a little bit to open up..
http://www.geocities.com/badbird88/t...pressgauge.jpg

Get Blown ?

What brand gauges do you guys recomend? I've been considering doing that to mine.

badbird88

I don't think it really matters too much that gauge I have isn't an el'cheapo model but it isn't an expensive one either. To be honest I don't know what brand it is. It is only shows up to 15 or 20 psi. I would spend the extra few bucks for a nicer model because if they are anything like cheap air gauges they won't read properly.

I just looked at mine and it is a Summit Fuel pressure gauge so it should be pretty decent, didn't pay for it though so I don't know how much it cost.

[This message has been edited by badbird88 (edited September 26, 2000).]

Dan W

On the 4bbls, there is a little port on each side of the TBI unit. These ports are there for fuel pressure gauges. The one on the drivers side is the fuel feed pressure, the passanger side has the fuel return port. Havent messed with the 2bbl so cant tell you if it has the same ports.

BTW, Summit sells a fitting that goes into a rubber line that has a port for a gauge.

FastBroker

FYI, the fuel pressure will be the "same" (regulated) from the pump outlet all the way up to the regulator diphragm seat... Once it gets into the return line (past reg seat, now "unregulated") fuel pressure instantly drops.

snflupigus

instantly drops to what? Wait, would anybody really care how much pressure the return line had?? Would there be a way to measure pressure inside the tbi after the diagphram? im thinking it would have to do with an ugly and machined port into the injector pod's top plate. money for nothin acheived?


------------------
ENGINE SPECS:
305 TBI
Open Element
K&N 14x3
Hypertech Stage I
160 Deg. Thermostat
454 GM TBI

STEREO SPECS:
JVC Kalmeleon kdlx3
Infinity Kappa 2way 6x9's
PPI 4x6 Coaxials
PPI PC2400 AMP @ 2ohm
DEI Studio 12" 4ohm DVC
Custom Box,
Exactly 1 Cubic Foot

Scott C

Don't complicate the issue. Buy a 15 or 30psi gauge, mount it inline on the rubber supply line before it turns into the hardline at the engine, read it and adjust it accordingly. You should see between 7-18psi depending on your TBI setup.

The gauge and adapter should be around $25. I chose a 30psi Holley, but others will do just fine.

Twin_Turbo

iTrader: (25)

Always use a liquid filled gauge!!

Dan W

yes you care about return line pressure. if return line pressure is too high it will affect fueling. Holley has parameters for this and I'll post them later.

UnderDogRS

i'm going to install a guage today, what size is the fuel line?

thanks,
RS

------------------
(A.K.A FireBird88)
AOL SN: Zander0710
1992 Camaro RS 25th anniversary edition Adopted Feb,14 2000

Mods:
14x3 Open element w/ K&N filter, MSD GM blaster Coil and 8.5 SC wires, AFPR, 60psi. Fuel Pressure gauge, 3-Row Al rad. , 180* t-stat, Hooker 1 5/8 headers, 3" Catco cat, 3" Hooker Aero Chamber cat-back