North American Turbocoupe Organization

fuel pressures
oldone Offline
A buddy of mine just bought an 87 TC. The car is completely stock and the problem
is the idle is very erratic and sometimes during acceleration the car will
fall on its face as if its starving for fuel. I pulled codes but there was nothing unusual there. I ran fuel pressure cks last
night and with the key on engine off the pressure goes to 40 but falls off
to 10-15 within a minute.(I thought it should maintain the pressure) With the
engine running the pressure is 34 and will jump to 40 with the regulator
disconnected. Any help is appreciatted.
88 Maroon TC 5 speed
K&N Filter
Gillis boost valve
220,000 Miles

Jeff K Offline
The drop off indicates either a bad regulator or a bad check valve in the fuel pump. All that will do is probably make hot restarts harder, and cranking after sitting a day or so may be longer before it starts.

You really need to check the fuel pressure under high load conditions, like WOT at 4000+ RPM where fuel demand is high.

Do a COMPLETE tune up with Motorcraft parts (wires and plugs especailly) and see what happens.

Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 20 psi, forced air intercooler, water injection, bypass valve, Ranger roller cam, subframes, etc., etc.. // 86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP nitrous, ignition, gears, suspension, etc., etc.... // 91 Escort: Bone stock winter car // 00 Windstar (wifes vehicle)
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized

Keith Nubel Offline
Posting Freak
Fuel pressure should remain constant at idle around 35 psi and increase as your boost increases. Stalling or stumbling can be caused by the regulator or tune up.

85 TC 5 speed, K&N filter charger, Ranger Roller cam, 3" exhaust system, manual boost valve, large VAM, SVO PE computer, front mount intercooler, underdrive pulley, ported upper and lower intakes,flow matched injectors, ported E6 manifold, 245/45/17 wheels & Tires
1985 TC

Pete D Offline
I sent your friend (roufneck) the diagnostic routines last night. Leaking injector(s) can also be a cause of rapid pressure bleed down.

88 TC X 2, 86 SVO, Main TC with K&N, 3"DP to 2.5"duals through Dynamax, Ric valve at 17+ and disconnected KS.
Elite Bodega 16" chrome wheels. Autometer pod w/ A/F and Vac/boost gauges. New engine: Total Seal rings and TRW pistons, ported and polished head w/ cc'd chambers,1.59"exhausts, SS valves, gutted upper, knife edged lower, A-230 cam, Race Engineering Adj Cam Sprocket, Crowlers, ARP head studs, and rod bolts. Walbro 255 HP pump and T-3. Centerforce II, KB subs and jack rails.
Pete Dunham


zora_d_1991 Offline
this might sound retarted, but you checked the fuel filter isn't clogged, right? if you did, please disregard this statement.
"thank you for flying red bird airlines....enjoy the flight."

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