Fuel Pump Problems

Here's the deal: My 1996 Bronco 5.8L will not start. It will turn over, but not start. I can't hear the fuel pump kick on at all. I have replaced the fuel pump relay, but it still doesn't start. My Haynes manual says I can test the fuel pump through the data link connector, but for the life of me I don't know how to do that. I posted the same thing on fullsizebronco.com and was be-littled. I know a little bit about cars, but don't usually try and fix things myself, but I can't really afford the $350 my mechanic wants right now. Could somebody please help me without treating me like crap?

Have you checked the inertia switch? It's function is to turn the pump off in the event of an accident. However, they often go bad or are activated by a large bump.

Good luck,

>-

The switch is in the down posistion. I have popped it up and reset it to no avail. Should I wire around it as my dad did in his 1988 Ranger once?

hms79 said:

Here's the deal: My 1996 Bronco 5.8L will not start. It will turn over, but not start. I can't hear the fuel pump kick on at all. I have replaced the fuel pump relay, but it still doesn't start. My Haynes manual says I can test the fuel pump through the data link connector, but for the life of me I don't know how to do that. I posted the same thing on fullsizebronco.com and was be-littled. I know a little bit about cars, but don't usually try and fix things myself, but I can't really afford the $350 my mechanic wants right now. Could somebody please help me without treating me like crap?

Click to expand...

There are various Fuel System Trouble Codes that may lead you to the problem area; Do you have a check engine light on?

Anyway, I believe some non-emission faults won't light it off; so beg or borrow an OBD II Code scanner and run the test.

Some DTCs are

Poor fuel pump Ground

Open/shorted ckt in pump

bad pump (Locked fuel pump rotor)

Fuel Pump control out of Self-Test range

or;

Plugged fuel filter

By Ford for 96 OBD II:

As fuel system components age or otherwise change over the life of the vehicle, the adaptive fuel strategy learns

deviations from stoichiometry while running in closed loop fuel. These learned corrections are stored in Keep

Alive Memory as long term fuel trim corrections. They may be stored into an 8x10 rpm/load table or they may be

stored as a function of air mass. As components continue to change beyond normal limits or if a malfunction

occurs, the long term fuel trim values will reach a calibratable rich or lean limit where the adaptive fuel strategy is

no longer allowed to compensate for additional fuel system changes. Long term fuel trim corrections at their limits,

in conjunction with a calibratable deviation in short term fuel trim, indicate a rich or lean fuel system malfunction..."

& FYI on the CEL'

Occasional flashes show momentary malfunctions. It stays on if the problem is of a more serious nature, affecting the emissions output or safety of the vehicle. A constantly flashing MIL is a sign of a major problem which can cause serious damage if the engine is not stopped immediately. In all cases a "freeze frame" of all sensor readings at the time is recorded in the central computer of the vehicle

hms79 said:

The switch is in the down posistion. I have popped it up and reset it to no avail. Should I wire around it as my dad did in his 1988 Ranger once?

Click to expand...

NO, that sets up a potentially hazardous situation. It is there to prevent you from getting fried in the case of an accident and/or fire. Do the checks Miesk5 talked about. Get a EVTM http://cgi.ebay.com/ebaymotors/1996-Ford-B...sspagenameZWD1V from ebay and use a voltage meter to troubleshoot the problem. Use a voltmeter and see if you have 12V at the pump, if not go back to the inertia switch and check either side, if none there go back to the fuel pump relay. I'll try to post a picture of the circuit later today, if you need it.

God luck,

>-

My check engine light is on, but that is because I have a bad O2 sensor. Someone suggested that I remove the fuel line and crank the engine to see if fuel comes out, but that sounds insane. The bronco isn't my daily driver, but I did just fill it up the day before this occured. That's what is funny, I parked it one day, in which it ran fine, go out the next, it started and died, and hasn't started since. I thoght that if the fuel pump was going bad it would act up a little?

Now, I can swear I just heard the fuel pump kick on. I am at a loss here, it still won't start!

Actually, my fuel pump went bad in the corse of about 4 hours. I went to lunch, parked it, and went to go home and BAM! Nothin'. Ran when I parked, but nada when I got back in, so it's a fickle thing I suppose.

HMS,

beg or borrow an OBD II Code scanner and run the test; Test connector is mtd under dash between ashtray and glove compartment; under radio and climate controls

may have to do a wiggle test too; turn the ignition on (dont start the engine), then you go into wiggle test mode and the flash will occur is a connection fails while you go around shaking the connections

for pump and related parts;

The computer turns on the fuel pump relay 1. For about 2 seconds when you first turn the key to ON and 2. when it senses rotation in the dizzy from the pickup.

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You should test your relays (in power distribution box, under hood, aft of air filter box; should have a diagram inside cover) by applying 12 V across the small terminals, listen for the click and check continuity across the large terminals. This will rule out the relays themselves being a problem. Usually they ARE the problem, so hopefully you can stop there. They absolutely HATE moisture so if you are missing your cover Im sure some moisture got inside the relays themselves.

Source: by Will H

Power Distr. Box Diagram in a 96 Source: by our good guy Roadkill see Realy 2 and

Fuel Pump Relay Socket Corrosion Info; ... if you had corrosion in your relay socket, then you probably have it other places. one at a time unplug all relays and connectors on that fender and spray them down with contact cleaner. then after you let that do it's job for about 30min-1hr, go back and unplug each relay and connector again (one at a time) this time put them together with di-electric grease. you can buy a tube of it from any electrical/electronics supply or auto store. make sure you get everything plugged back in

Source: by datrimm

GL!