yo,
Pull the red vacuum line & check for gasoline...There shouldn't even be the ODOR of gas in it
W/engine idling, carefully disconnect the vacuum line going to the fuel pressure regulator. Fuel pressure typically jumps to 40 PSI ± 3 PSI (4.9L typically is 15 PSI higher).
A high pressure fuel tester must be connected to the fuel Schrader valve on the fuel rail.
First relieve fuel system pressure, then attach the tester. Next, turn the key on (engine off) to prime the fuel system. There should be about 36-42PSI of pressure.
Fuel Pressure During KOER Self Test for 92; 4.9 (45-60 PSI), 5.0 (30-45 PSI), 5.8 (30-45 PSI) & 7.5 (30-45 PSI);
Start the engine. The pressure at idle should remain within the same range. Rev the engine a few times to ensure fuel pressure remains constant.
Excess pressure usually determines a faulty FPR. Too little pressure could be the FPR, fuel filter, fuel pump(s) or relay, or a leak.
Eng vacuum affects fuel pressure; ck for vacuum leaks and get a vac gauge;
Mount it inside and use to also help increase MPG by keeping needle in Green Zone (steady speed and acceleration)
"I have a vacuum gauge mounted right in the dash of my truck. I use it to also help determine the load my engine is under while driving, and to estimate fuel economy..." by unknown
Vacuum Leak Test; On an idling engine check for vacuum leaks using a mechanic's stethoscope with the probe removed, or a ~3' garden hose section. Don't spray flammables on a running engine. MIESK5 NOTE; Also check: vacuum hoses; intake manifold gasket & throttle body; PCV line; vacuum reservoirs: EGR Sys Vacuum Tank & 2ndry air (coffee can); AC, heater, defroster, vent control ckt & vacuum tank (plastic ball type), under dash & lines to heat/blend/etc. doors; power brake booster; cruise control ckt, etc.... where applicable; BEWARE OF BELTS/PULLEYS, FAN AND HOT ENGINE
Vacuum Gauge Diagnosis - BEST!; Normal engine; Steady gauge 18"-20" at all speeds..." READ MUCH MORE
Source: by Craig U at
http://www.classictruckshop.com/clubs/earlyburbs/projects/vac/uum.htm
---------------
for more info on FPR, & System see;
Ford Fuel Injection and Electronic Engine Control: How to Understand, Service and Modify, 1988-1993; & Ford Fuel Injection and Electronic Engine Control: How to Understand, Service, and Modify All Ford-Lincoln-Mercury Cars and Light Trucks, 1980 to 1987 by Charles Probst
avail @ BARNES & NOBLE, AMAZON, E BAY, ETC.