Fuel pump won't come on

it sounds like the pump has failed which is common here is a guide to help walk you through the steps with instructions in the diagrams below to help you with your car.

https://www.2carpros.com/articles/how-to-replace-an-electric-fuel-pump

If the pump comes on and supplies pressure when you apply voltage then we most likely have a voltage issue. So we need to make sure the pump is not just coming on with no pressure.

However, I am including the wiring diagram below for this issue as well.

If you check the voltage at the relay you should have 12 volts on the red wire which is the voltage supply and then the PCM grounds that circuit on the Light Blue Orange wire which will close the relay. Then if the inertia switch is closed it will supply voltage to the pump. So we could have a relay or switch issue as well.

https://www.2carpros.com/articles/how-to-check-wiring

Check out the diagrams (Below). Please let us know what you find.

thanks, Tried the fuel pump relay and inertia switch reset wasn't tripped. What do I do if low voltage in the fuel pump power supply?

Usually, if you have a low voltage, it means there is a high resistance somewhere in the circuit.
'Somewhere' is the word here. It's impossible to tell which part is defective until you check all the components of the circuit for high resistance (wires, relay, fuse, etc).
Keep in mind that a component that 'looks' good is not necessarily working right.
DON'T check components by doing a continuity test; it will only tell you if there's current going thru the component but not if there's ENOUGH current going thru it...
You need to find what the normal resistance is for each component, and then do an Ohm test and compare what you have with what it should be.

I'll be honest, troubleshooting an electrical problem can be a pain in the butt.
I would not do this until I've rulled out any other possiblities.

If your voltage reading at the pump is normal when you turn your key to 'start', low voltage is probably not the problem.

I have the same problem and have been to two ford techs. So far we think that something is keeping the PCM from completing its functions. I fill like a anti thelf module is in the circuit somewhere but even the ford tech manuals will not show it in the diagrams. Good luck. I have replaced the PCM twice. Iwill let you know if I find the problem.

i have replaced fuel pump assembly , new fuel pump relay, all fueses are good .. if i bypass the relay the fuel pump cycles but truck wont start but with new relay in place and turning the key nothing happens i have been told that its in the ECM im kinda lost as of what to do now this is my only vehical and im about to loose my job because of this this has become very stressful so any help would be great

Problem Solved. Had a buddy who hooked it to a diagnostics computer. He was getting absolutely no readings from my ECM. so i replaced it and it fired right up and hasnt missed a beat since. Hope it helps. Thanks for all the help recieved from the forum.

Fuel pump not running, power to coil and injectors no power to pump. Engine light has also stopped coming on, used to come on at start and go off like normal. Replaced pump and relay, still don’t pump. Is this a ECM problem or something else?

Hi blademan7, Welcome to 2carpros and TY for the donation.

Check and test fuse no.4 30amp and fuse no.22 20amp in the engine compartment fuse/relay box, the PCM power relay in the center of left fender apron and the inertia switch at below right side of I/P below glove box

I have checked all that was mentioned. The truck did start once since this started, ran rough engine light flashing. Now nothing.

The truck did start once since this started, ran rough engine light flashing. Now nothing.

What is it doing now? Is it cranking over and will not start or just won't crank at all /nothing

Is it the check engine light that's flashihg?

Cranking over just does not start. Fuel pump not running. The engine light does not come on when key is activated.

Power the fuel pump direct from the battery and tell me what happened-this is beginning to be a nightmare. If the fuel pump comes on-have the computer tested-

Fuel pump does not come on, does not have power. The truck ran fine, shut it off one day and would not start up. Again fuel pump not running. All other things such as ignition coil, fuel injectors have power. The engine light always came on when the key was in the run position, but now does not come on at all.

If I jump the pump directly it runs.

Like you said the inertia switch, fuel pump relay, PCM power relay and the fuses been checked and tested good-last place will be the computer controlled of the relays one goes still has to be replaced

I have same exact problem

Have you performed any diagnosis on the vehicle yet? Checked fuses/relays and/or inspected the wiring to the fuel pump? Below is a wiring diagram for the fuel pump system on your vehicle. I've also attached a diagram of the under-hood fuse box showing the location of the fuel pump relay and fuel pump fuse(fuse 22). Let me know what you find.

i was driving to work and outta the blue the truck just stopped tried to start and just turns over come to find that fuel pump was not cycling so replaced the fuel pump w/ whole new assembly new relay all fueses are good inertia switch is fine still no cycle from fuel pump if we bypass the relay the pump will cycle but truck will not start w/ new relay in distrubition box fuel pump will not run could the problem be that i need a new ECM or should i bypass the inertia switch im very lost here and this is my only vehical so any help or suggestions would be very helpful my job is kinda hanging on this also no vechical no job and i cant have that happen

Sounds like the PCM control of the relay has gone bad. The power for the fuel pump comes originally from fuse no. 22 20amp, when the computer energizes the relay it powers up the pump thru the inertia switch this is how it works

Okay, checked PCM relay gets hot on yellow wire constant tan and black wire gets hot when ignition is on grounds. checked fine however pin 85 red wire at Fuel pump relay does not get hot ignition on .has New fuel pump and ignition switch. please help

so do you think that this pcm part has malfunctioned and a replacement one would fix this problem my boss is waiting on a update from me and ive missed a weeks worth of work cause of this i have put alot of time and money in this problem already

I see you're also discussing this issue with CARADIODOC on a separate thread. I would suggest you continue on that thread with this discussion. But yes, if the Yellow wire and the Black/Tan both have 12v with the key on, and your certain the Black/White wire has good continuity to ground, then it must be the relay or a poor connection at the relay. Measure the resistance between the Black/White wire and the negative battery terminal. It should be less than 1 ohm.

Times are tough -The PCM has to go-lacking the funds-power the fuel pump by using a toggle switch from the battery till you can afford the PCM

Good Luck and Happy Thanksgiving

can you please pm me or send me a e mail to [email protected] it sure would be appericated if you get me through this id be more than happy to make a donation in your name

what is the typical price on a new pcm for my truck i could prolly throw another 100$ at it but i just need it to run and if your saying this is the solution no sence in rigging it to make it work i want it to be right and last tgg switch sounds to dangerous

Disconnect the inertia switch and splice/tap into the pink and black wire make sure you use the same size wire with an inline fuse 10amp -install the toggle switch where you can reach it go thru the firewall straight to the battery positive terminal-your done

New/Refurbished PCM with Autoparts GIANT.com will cost about $165.00

looks kinda easy but wouldnt it be just as easy to replace PCM? where is PCM located and what kinda price am i looking at if its around 100$ i could see spending that rather than a switch knowing me i would forget to turn it off sounds kinda dangerous seeing as my lil boy loves to mess with everything in my truck lol what would you do in this situation sorry if im being a pain but you have been a big help thus far

PCM location -see below

that pic is it for the 1994 ford ranger xlt v6 3.0???
it looks like the pcm is close to the distrubition box under the hood would you just replace that or use the switch which would be better in my situation is the pcm just a simple unplug and plug in the new one

Its for a 3.0L engine-The PCM is an unplug and plug deal-The toggle switch method requires more time-But if its me lacking funds I'll go for the latter part just to buy time till I can afford a PCM.

so after i replace the pcm or put the toggle switch in will my gas gauge start working again also or is this a whole nother problem

The pink and black wire powers the pump and sending unit-No power at pink and black you'll lose both

Wow! you're definitely working me lol on that donation

Happy Thanksgiving from 2carpros.com

well if this fixes the problems im having you got a donation coming your way for sure ill let you know how it all goes after tomarrow i should be driving it if all of the info you gave me helps out are we missing anything or does this pretty much cover it thanks for everything your a great asset to this websiteim glad i found this site happy thanksgiving

I believe I have given you the very best of me on the fuel system circuitry as for your last comment being here the stars will tell you something about me-lol-Good bye for now Sir

ok as of now i tried to put a toggle switch in just like you had explained and the pump will run but truck still wont start i took the ignition control module off cause i thought it might be that and had it tested and it checked out ok so i was told maybe it might be the stator coil underneath the distrubitor cap for some reason i think it may not be getting spark i took off one of the plug wires and stuck a bolt in it and held it to a ground and no spark im tottaly lost now and the boos man is not happy where do i go from here i was also told that the pcms in the fords are pretty tough and it might not be that???im so lost

or do you think i should at this point take it to a professinal like yourself and let them do the work

Could be the crankshaft position sensor, distributor pick coil- or the coil/s itself-check for power input to the coil. My last suggestiion is take it in.

yea i so lost its not funny i went ahead and put the bed back on it since i know the fuel pump works but would these sensors have anything with the pump not working through the relay itsself or do you still recomend the toggle switch and checking all those things where is all those sensors located a pic would be of great help on this the last thing i want to do is take it in to get it worked on since i can do most of the work myself ive become mechanic inclined this past week lol please help

You got the fuel pump going now you need to find out what's causing the no spark.

Do you have a distributor or a direct ignition system?