'88 F-150 Fuel Problem !!
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New User
Joined: May 2004
Posts: 4
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From: BANGOR, MAINE
'88 F-150 Fuel Problem !!
I HAVE AN '88 F-150 5.0 EFI ! IT DID HAVE 2 GAS TANKS BUT PREVIOUS OWNER REMOVED REAR TANK ! ANY WAY, IT WONT START UNLESS YOU SQUIRT GAS INTO THE EFI INTAKE THEN IT DIES OUT ! WHEN I TURN THE KEY TO THE ON (NOT START) POSITION I DONT HEAR THE 3 SECOND ELECTRIC PUMP COME ON !
I REPLACED BOTH RELAY PUMP SWITCHES BUT ONLY ONE RELAY CLICKS ON AND IT STAYS ON, THE ONE THAT IS SUPPOSED TO COME ON AND OFF AGAIN IN 3 SECONDS IS DEAD, IT'S NOT GETTING POWER TO THE ELECTRIC PUMP RELAY SWITCH !! ANY IDEAS ?? INERTIA SWITCH IS FINE TOO !! THIS TRUCK RAN FINE TILL I HIT THE TANK SELECTOR SWITCH, IT APPEARS TO HAVE RETURNED TO THE CORRECT TANK AGAIN BUT I THOUGHT ID MENTION IT, YA NEVER KNOW !!
CAN ANYONE HELP OUT HERE ??
FUSTRATED,
I REPLACED BOTH RELAY PUMP SWITCHES BUT ONLY ONE RELAY CLICKS ON AND IT STAYS ON, THE ONE THAT IS SUPPOSED TO COME ON AND OFF AGAIN IN 3 SECONDS IS DEAD, IT'S NOT GETTING POWER TO THE ELECTRIC PUMP RELAY SWITCH !! ANY IDEAS ?? INERTIA SWITCH IS FINE TOO !! THIS TRUCK RAN FINE TILL I HIT THE TANK SELECTOR SWITCH, IT APPEARS TO HAVE RETURNED TO THE CORRECT TANK AGAIN BUT I THOUGHT ID MENTION IT, YA NEVER KNOW !!
CAN ANYONE HELP OUT HERE ??
FUSTRATED,
Senior User
Joined: Dec 2003
Posts: 354
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From: Memphis, TN USA
Check your CTS (Coolant Temperature Sensor). If the CTS is bad, either it gives out a too cold signal or too hot signal to the computer.
If it is stuck in too hot, it signals the computer and in turn it will immediately close the fuel injectors and not stay long enough.
If it is stuck in too cold, it signals the computer and in turn it will immediately open the fuel injectors for a long time and probably flood the engine.
During initial startup (cold engine), the Normal CTS sends a cold signal to the computer to open the fuel injectors longer and then gradually returns the fuel injectors to normal operation as the temperature rises.
I would try to by-pass the fuel pump relay and directly feed 12 volt battery source to the fuel pump and see if it works.
Get a fuel prssure gauge to determine pressure as well.
If it is stuck in too hot, it signals the computer and in turn it will immediately close the fuel injectors and not stay long enough.
If it is stuck in too cold, it signals the computer and in turn it will immediately open the fuel injectors for a long time and probably flood the engine.
During initial startup (cold engine), the Normal CTS sends a cold signal to the computer to open the fuel injectors longer and then gradually returns the fuel injectors to normal operation as the temperature rises.
I would try to by-pass the fuel pump relay and directly feed 12 volt battery source to the fuel pump and see if it works.
Get a fuel prssure gauge to determine pressure as well.
Thread Starter
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New User
Joined: May 2004
Posts: 4
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From: BANGOR, MAINE
would the cts sensor shut off just the high pressure (electric) pump and leave the in tank pump on ?? also, where is the cts located ??
today i hooked a 12v power source to both fuel pumps and they both shoot gas like crazy, i don't know if this info helps or not !!!
thanx for responding slade901, i really appreciate it !!!
today i hooked a 12v power source to both fuel pumps and they both shoot gas like crazy, i don't know if this info helps or not !!!
thanx for responding slade901, i really appreciate it !!!
