READ! tbi 2.5L wont start

[Comanche_Fanatic]

Turn the the knob counter clockwise to the 20V position. Make suer the black lead is in the com hole and the red lead is in the Volt hole.

DCV 20?

[jimoshel]

Yes.

[mnkyboy]

 

I'm not too bad with electricity

:dunno:

[Comanche_Fanatic]

this is the first time ive had to check a fuel pump, and returned 0 volts. batterys pumping out 12.73 volts, and everything else working even the lights. I'm thinking the fuel pumps just dead and ppl are telling me I'm checking it wrong

[Comanche_Fanatic]

turned the key on, pulled out the sending unit, and checked the voltage by red on red and black on black. returned 0 volts on the meter.

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[jimoshel]

You could just take a long wiree and hook one end to the bat pos and run the other end back to the pump. I would go to the FP relay and check voltages there. Check the voltage on the red wire, input, and the orange wire, output direct to FP. Should be 12V with key on.

[mnkyboy]

If you have 0v at the pump the pump is not the problem. You need to find out where in the curcuit you are losing power.

[Comanche_Fanatic]

tried testing the voltmeter from the wires that lead to furl pump, the one u plug in.

 

then tried from the fuel pump itself

 

anything I'm doing wrong or anything wrong with this pump?

[Comanche_Fanatic]

You could just take a long wiree and hook one end to the bat pos and run the other end back to the pump. I would go to the FP relay and check voltages there. Check the voltage on the red wire, input, and the orange wire, output direct to FP. Should be 12V with key on.

 

ok i wanna try checking relays but can u be more specific

[mnkyboy]

So your testing the pump with no wires hooked to it? How could it have more then 0v?

 

4v isn't enough you have a volt drop some where,Did you get the cranking problem resolved?

[Comanche_Fanatic]

all the wires are connected. i even rewired one section of it cause it had been laying over the hot cata converter. and yeah 4v isnt nuf i agree, theres something screwy going on with the flow.

 

the car cranks, it just won't get any gas. ill post a vid soon

[jimoshel]

On the front of the left hand inner fender is 2 relays, 3 if you have AC. If I remember correctly the front one is the FP relay. there are 4 wires to it, yellow, red, orange and orange with black tracer. The yellow and red wire should be 12V when the key is on.The orange/black is from the ECU, activates the relay when needed. The orange wire goes direct to the FP and be 12V.

[Comanche_Fanatic]

here, sorry its dark but you should be able to hear. i put VERY LITTLE gas in the tb

[mnkyboy]

On the front of the left hand inner fender is 2 relays, 3 if you have AC. If I remember correctly the front one is the FP relay. there are 4 wires to it, yellow, red, orange and orange with black tracer. The yellow and red wire should be 12V when the key is on.The orange/black is from the ECU, activates the relay when needed. The orange wire goes direct to the FP and be 12V.

:agree: this should tell you where you losing power.I would also test from the fuel pump + wire to the frame and see if you have the same 4v,put the red lead on the + terminal of the plug and the black lead to the frame of the truck

[Comanche_Fanatic]

On the front of the left hand inner fender is 2 relays, 3 if you have AC. If I remember correctly the front one is the FP relay. there are 4 wires to it, yellow, red, orange and orange with black tracer. The yellow and red wire should be 12V when the key is on.The orange/black is from the ECU, activates the relay when needed. The orange wire goes direct to the FP and be 12V.

 

yeah from my point of view thats just 100% confusing. am i gonna be working under, in, over, aside, or in front of it?

[jimoshel]

Anytime directions are given, front, rear, left, right,above, below it is from the drivers seat for reference. You will be, or should be, standing on the LEFT hand side and towards the FRONT of the truck. You will be leaning over the fender, With the hood raised, and the pre-mentioned components will be directly in front of you.

[mnkyboy]

On my 89 2.5l MJ they are on the right side. On my 4.0l they are on the left

Image Not Found

See the 2 little cubes those are relays

[Comanche_Fanatic]

i got tired of messing with the wiring, i just took the damn pump out. in my honest opinion, the wire pointed in the second picture is probably the problem, cause thats been burnt and retaped. the pump is also the wrong size, its being held down by a tie.

 

[Comanche_Fanatic]

found the relays, they were on the right side of the jeep. now what

[mnkyboy]

Its not uncommon to see a pump held in with a zip tie.

 

If your worried about the wires take the meter and check continuity on each end. Or you could hook 12v to the plug and see if the pump runs

 

If that harness is the problem you should have 12v where the harness plugs in.

 

Now that you found the relays pull out the one Jim said to check and test the terminals where it plugs in

[Comanche_Fanatic]

will do, give me a sec

[Comanche_Fanatic]

ok I'm wanting to text the pump, i can take the tape off and put it on the battery to see if it runs. but ive got 3 wires, red black and purple. do i leave out the purple wire or..?

[mnkyboy]

2 should go to the pump motor,one should be for the fuel gauge. See if you can follow the wires and see what goes where.

[Comanche_Fanatic]

ahh the purp must be for the fuel measurement. ill hook up black to neg and red to pos to see if it runs

[Comanche_Fanatic]

tried it, pump didnt come on, was alot of sparks from the wires that came to contact with the batt tho