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Fuel Pump testing


BronKitis

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Replaced fuel filter last night and started truck this morning. Cycled the key 2-3 times to prime fuel system, cranked it over and it fired. I was letting it warm up, went inside to get garage clothes on, cup of coffee etc. Came back out and it had died, wouldn't start back up. Been having intermittent issues and this was my chance to check spark and I have it. Bumped the pressure tester on the fuel rail and got a slight squirt with key off. Cycled key and attempted to start again with no luck. Squirt test failed miserably as no fuel came out. I hear the relay click off after a few seconds but don't hear either pump and this morning only heard HP pump I think. How should I test these? Unhook fuel lines from HP pump and see if tank pump is working? Voltage? Tricks and tips? Thanks!
 


RonD

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There should be an OBD test port in engine compartment, usually passenger side.
Look here for diagram:
http://www.therangerstation.com/tech_library/OBD_I.html

The Fuel Pump port is shown, if you ground that port with key on, the power to fuel pumps will be on full time.
This port grounds the fuel pump relay, which is how the computer turns on and off the relay.
Check if you can hear both pumps

If not test for 12v on both sides of the inertia switch(in passenger footwell under glove box or in kick panel).
This switch passes fuel pump power from relay to pumps, it will turn off fuel pump power in case of an accident, sudden stop, but they can fail when older.

Under the truck by the high pressure pump follow the wires from the pump, there will be a Factory splice where they tied in to the original wire to the low pressure pump in the tank, this splice can fail.
Test for 12v on that splice, also test the ground for the pump.

Pink/black wire should be the 12v to fuel pumps,
black is the fuel pump ground

Yellow/white is the fuel gauge sender
Orange is the sender ground
 
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BronKitis

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Okay, tested fuel port it HP pump out and I can hear the in tank pump. Tested HP pump with 12V and it works, but seems to sound a little wimpy. Pink black wire? Funny....

I found a plug on driver side fender that was all beat up, replaced plug and found 2 pink/black wires connected in the same port that went no where to other side of plug. When I replaced plug, I soldered them together since it was the same thing.... I wonder what that's all about???

I will reinstall HP pump and the run test to see if I hear them both. Thanks for the help!

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BronKitis

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OK..... Tested pumps by jumping relay from port and got 40 psi at rail. Tested spark. Have spark. With relay jumped, both pumps ran but engine wouldn't fire. No jumper, key cycles do not make relay click.... No fire still. So, I have spark, constant fuel pressure and it will not start... Any ideas???
 

RonD

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EEC relay(brown base), next to Fuel Pump relay(green base), supplies power to Fuel Pump relay, fuel injectors, and most engine sensors and controls, also powers the EEC(computer).

Is the EEC relay clicking when key is turned on?

With spark and fuel pressure but no start I would suspect fuel injectors are not opening.
Pull a spark plug after cranking and see if tip is wet with fuel.

Fuel injectors should have 12v when key is on, computer grounds them to open them.
If no 12v then look at the EEC relay, it passes the 12v supplied by a 30amp fuse, so EEC relay could click but if fuse is blown there is no power to pass, to injectors, FP relay, computer, ect......

Here is an electrical diagram for the 2.9l:
http://www.therangerstation.com/tech_library/EDiagrams/files/Diagrams_ElectronciEngControls2_9_1of3.JPG

It shows the EEC relay and FP relay wiring.
And if you look at the inertia switch................pink/black wire connects to Fuel Pump..........lol, so I didn't make that up
 
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BronKitis

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Relay is clicking. After squirting some starter fluid, it fired. After starter fluid and bypassed fuel relay, fired and ran normally. After running a few minutes, would even start without starter fluid. As soon as ground for pump relay was pulled, it instantly died.

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BronKitis

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To clarify, EEC relay is clicking on with key.

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RonD

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Relay is clicking. After squirting some starter fluid, it fired. After starter fluid and bypassed fuel relay, fired and ran normally. After running a few minutes, would even start without starter fluid. As soon as ground for pump relay was pulled, it instantly died.

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It shouldn't have die instantly with no fuel pump on.
40psi of pressure at idle should last awhile.
 

BronKitis

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But it did.....? I also disconnected inertia switch while it it was idling, it sputtered and ran out of fuel like it should have when I disconnected the bypass for relay....

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BronKitis

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What would cause the relay NOT to work without bypassing it?

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RonD

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Well it looks like the FP relay ground is grounding other things, so as long as it is connected to ground engine will start, yes it will die without fuel pumps(inertia switch disconnect, but it will start back up)

Wondering if the computer grounds are the issue here, that would explain why computer can't turn on FP relay, no ground, also why spark and/or injectors die as soon as ground is lifted, these are both controlled by computer grounding them to fire or open.

I guess look around the EEC for ground points, also check ground strap from engine head to firewall, that is the main ground for the cab electronics.
 

BronKitis

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EEC itself has one major ground running to body behind passenger kicker panel and it seems fine. I'll have to look at the other grounds you mentioned.

I believe it is killing the injectors because without relay grounded I was still receiving spark.

I always seem to get the odd ball issues.... If only it were as simple as a pump or relay.

Adsm08, can you put together any of this with the issue we've been speaking of here recently?

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RonD

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Well according to the wiring diagram EEC relay is grounded at G101 via splice S108, and EEC(computer) should also have two ground wires there, at splice(s108) that grounds pins 40 and 60
At S108 it is showing Black/white wires for all 3
 
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