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77 fuel regulator???

287 Views 2 Replies 3 Participants Last post by  johnh240
My 77 280 has been sitting for a year and I just got it running tonight. When I crank it up it takes awhile because it's not holding fuel pressure.It will run fine for a minute then it starts skipping. All plugs are firing(they are new) all injectors are working but when I pull the plug wires to see where the miss is, it seems to be that the first three are weak and the back three are fine. Then it will clear out, then go back to skipping. Could the fuel pressure regulator not be letting the first three get enough gas?
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Drain all of the old fuel from the tank and replace it with 5 gallons of fresh high octane gas with 2 ounces of fuel injector cleaner / fuel conditioner. Change the fuel filter. Put 1 ounce of fuel injector cleaner / fuel conditioner in the filter before you reinstall it.

Put a fuel pressure gauge between the fuel filter and the top fuel rail. Disconnect the small gauge wire at the starter solenoid and turn the key to the "start" position and hold it there for 5 seconds. The fuel pressure should jump to 42 PSI and hold at that pressure when the key is returned to "off".

Replace the small gauge wire on the starter solenoid and start the engine. At idle the fuel pressure should be 32 PSI. Now pull the vacuum hose off from the Fuel Pressure Regulator and the pressure should jump to 42 PSI. Put the vacuum hose back on the FPR and the pressure should drop back to 32 PSI. Crack the throttle open quickly and the pressure should jump to 42 PSI and then return to 32 PSI.

So far so good, then the fuel delivery system has been checked out.

Since the ECU fires the injectors in "Batch Mode", that is three at a time, and you are having problems with the first three, do the following.

Disconnect the negative battery terminal. Disconnect the harness connector from the ECU and carefully clean the terminals. Put some silicone die-electric grease on the connectors of the harness plug and reconnect it to the ECU. Reconnect the negative battery terminal.

Start the engine. Does the problem still exist?

Yes? Then remove the connectors one at a time from the injectors and clean them and apply a small amount of silicone die-electric grease on the connectors and re-assemble.

Use Brake Parts Cleaner to flush any crud out of electrical connection. It evaporates very quickly.

Wayne Monteath
Masham, Quebec.
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Check fuel pressure, check for vacuum and air leaks. Do a complete tuneup including cap, rotor, fuel filter, air filter, and plug wires. Make sure firing order is correct. 153624 counterclockwise at distributor. Regulator controls pressure to ALL injectors simultaneously. If car has been sitting for a while it wouldn't hurt to run some 'HEET' through it or other alcochol based water removal treatment.
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