troubleshoot fuel (help)

bmlu37 · Nov 23, 2010

what a pain, i have a 86 2.9 4x4 bronco ll. my kids would use it, they grew up, and it sat. tried to get it running for a toy and of course, poop. got it running holding my hand in front of the throttle body, youngest boy drove it forward and back while i was under hood. then it quit, got frustrated and it sa :dntknw:

t a little more. bored yet? heres the point got back motivated and started piddlin. turns over but wont start. no fuel pump noise so i droped the tank. wow full of crap and pump was shot. so i started making sure everthing works before i buy the 100 dollar pump. checked the relay and its good, high pressure pump works when i jump it with 12 volt but not with ignition switch what can i do to check that the high press pump works with key switch not sure about a fuse cant identify location i ohms the inertia switch it beeps so i guess its good. send the posse......any feed back i great if you last long enough to read the post lol thanks :dunno:

Shran · Nov 23, 2010

Check for broken wires and bad grounds, only other thing you can do is start at the pump, and follow the wires back with a test light or multimeter and find where you start seeing voltage.

bmlu37 · Nov 23, 2010

i have a meter but not sure how to read......it shows numbers but not sure what number is my benchmark to start with i know the battery is 12.50 or something but what should it read at the pump????? and also will the high press pump even come on with the other pump removed?

Shran · Nov 23, 2010

Your meter needs to be on the DC volts setting. Should read 00.0 or something like that with the leads not touching anything. I assume you should have full battery voltage at your fuel pump but don't know for sure. You will also need to ground your fuel pumps at the ECM test connector (red plug, passenger side, near the firewall) - one pin on this grounds the fuel pumps so they run constantly for troubleshooting purposes. Otherwise they will run for a second or two when you turn the key to "on" and then shut off and you'll see zero voltage.

Either pump will run with the other removed. They are both powered through the same relay.

Shran · Nov 23, 2010

Here's the pin you need to ground out... just run a piece of wire to your negative battery terminal

bmlu37 · Nov 23, 2010

cool i will try that.......yea dc volts but whats the number ? will it be 12 v or less ? the battery full charge BY THE WAY HOW MANY RELAYS ARE THERE I KNOW 1 FOR SURE AND IT CHECKED OUT OK THANKS FOR THE FEEDBACK oops sorry hit the button

Shran · Nov 23, 2010

There are two identical relays. One is for your ECM and the other is for your fuel pumps, although if either relay is bad or missing, the fuel pumps will not work.

Read the voltage of the battery and that is probably what you should be seeing further down at the fuel pump. I don't think there is anything in the circuit that drops the voltage down.

bmlu37 · Nov 23, 2010

if the ecm relay is bad will the motor still turnover?

Jmthunderbird · Nov 23, 2010

maybe, but you wont have spark. grab your timing light and check spark while turning over. still though, if your HP pump isnt coming on, thats your issue. also, check to make sure your fuel filter is clean, cause if the tank was full of crud, then so in your filter, and it may have clogged up the pump too.

-J0N

Shran · Nov 23, 2010

Yes it will still turn over but you will have no power to any of the engine electronics.

xr75er · Nov 24, 2010

The hp fuel pump is powered off a fusible link off the hot side of the starter relay. no fuse. If you changed or disconnected the battery cable you might have missed putting the ring terminal back on. I have made this mistake before.

kimcrwbr1 · Nov 27, 2010

measure the batt voltage first it should be aroun 12.8 fully charged. you should get that or a little less depending where you are measuring. You should get batt voltage up to the pumps.

troubleshoot fuel (help)

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