Fuel Pump Control Module? Ground side circuit voltage drop

2011 DC 4x4 5.7 Flex, 68k miles, I've owned her since 62k miles.

No previous indications of a fuel issue, 100000% sure there is gas in the tank (I know, it's been said before), I drove the truck with no issues, parked it, came back a few hours later and now this issue:

Turn the ignition, starter cranks and nothing. I've eliminated key issues.

I pulled the fuel line off one of the fuel rails and cranked the engine, nothing coming out. I've checked every fuse that seemed to make any sense at all under the driver side dash and in the engine compartment. I've checked voltage at the fuel pump relays, I've switched some relays around to see if that helped (fog relay has same part number) and nothing so I don't believe it's the relay.

I checked for voltage on both sides of the fuel control module, the blue wire shows me a constant 12 volts, the red wire is only showing me 1.5 volts. I watched a video with a mechanic diagnosing this same problem and he was getting 12 volts on the blue side as I believe it's a ground side circuit. This is why I strongly suspect the control module.

When I have someone crank the starter I get zero volts at the blue which I believe makes sense since I'm measuring ground at that point...right?

I want to head back out to check current at the module when cranking the starter, Any idea how much I should be seeing assuming the fuel control module is good? Thanks in advance.

EDIT: On second thought, I'll have zero, or very very low, current given the pump isn't running.

EDIT: Now that I've been thinking about this more, since the ground side of the pump goes to zero when the pump is supposed to come on, that should indicate the module is closing the circuit to ground. The fact that there is a voltage drop across the pump is a problem, I think this should indicate there is something wrong with the pump, not the module.

 

So I dropped the gas tank to try to further diagnose.

The pump works fine. When i hook it up straight to a source it sprays like crazy.

I checked the resistance between sending unit terminals and get infinite, this seem odd to me because the varying resistance is what should be feeding my fuel gauge and i've never had an issue with the fuel gauge. I don't think a sending unit problem would keep the pump from running anyway.

The thing that's most suspect to me is that when I put a 12v lead to one side of the pump I get 12v on the other side. This is what I would expect, the wierd thing is that coming off the fuel pump control module I get 12v on the positive (blue wire) side and 1.4v on the negative side (red wire), yet the pump isn't running. This makes no sense to me unless that's some sort of default condition that the pump understands?

Or does this indicate the control module is not seeing the pump?

Any hints?

 

I want to see if I can confirm that all the ecm signals are getting to the fuel control module. I have this wiring diagram.

https://f01.justanswer.com/TECHPRO49/ca84c96e-df05-4cf0-863a-9a2bc4f88581_toyotafuel.png

The problem is I don't know what voltages I should be seeing and when. Anyone have any more documentation for this stuff?

 

So this is kind of crazy, I had to disconnect the battery to put it on a charger for a few hours. Probably 3 hours. I came back, spun the starter and watched voltage on the negative side of fuel control module without the pump plugged in. It dropped to zero from 1.5, so the control module was apparently doing something. So I thought hell, what happens if I plug it back in to the fuel pump. So I plugged the harness back into the fuel pump and spun the starter, fuel spraying out strong. So it evidently fixed itself? So this has me now thinking that it was a fuel pump harness and the plugging / unplugging somehow made a better connection OR maybe having the battery disconnected for that long let all the internals of the control module fully discharge and when I hooked the battery back up it "rebooted" so to speak.

The kicker now, and this is somewhat embarrassing, I left one of those little yellow hose holder clips on top of the tank and couldn't find it, so I pulled the tank back out from under the truck to look for it. Found it. Then saw the wires from the harness dangling without the harness...forgot it was plugged in and it's hard enough to pull that fuel tank around that I didn't notice it when I pulled. So now I get to go buy a new harness and solder it in before I know for sure if I'm all good to go.

Not a lot of action on this thread at the moment but I'll report back in case anyone else comes along with same symptoms at some point.

 

Truck is running. The two wires that I broke were for the sending unit so now my fuel gauge shows empty. I took apart the harness and managed to get the power wires back in there although they weren't particularly solid. Not a ton of confidence in them at the moment. When I get the new harness I'll drop the tank again and replace it, until then I'll only drive as needed and not far from home.

For anyone in a similar situation, assuming you've checked fuses and relays already, disconnect the battery for a good 2 - 3 hours. Maybe doesn't have to be that long but I don't think 10 minutes will suffice. I did in fact try disconnecting for 10 minutes before taking anything apart and it didn't change the situation. I can't say for certain whether this was a funky control module reset thing or if the connection at the fuel pump harness was the culprit but I know for sure that if this happens again I'll be disconnecting the battery for a few hours before I drop that tank.

 

Hey Eric. You sure didn't get anyone to replyon this one did you? Tell me if you have had any other problems since you got it running.I am having the same issue with my 2007.

 

Eric, question for you since you've had it all apart. What is the odd little 3 line/1 plug doohickey mounted to the frame above the flex fuel tank? Toyota calls it a fuel tank solenoid, but what does it do exactly? I ask because it seems the non flex fuel pump replacement videos I've seen don't seem to have it.

I am having rough running issues with my 2012 FFV crewmax. Trying to figure it out.

 

Same thing just happened to my wife's '08 Sequoia. About a week ago she got in it one morning and it turned over but wouldn't start. The very last thing she did before she got home was get a full tank of gas, so I thought she got bad gas or diesel on accident. Siphoned some out and it looked and smelled good, didn't seem like there was any water in it. Hopped on the internet and found a post about replacing the fuel pump relay, so I went out and swapped a similar relay into the fuel pump relay and boom, it started right up. It ran like normal for about 48 hours, but then, very luckily, it started sputtering as she pulled into the driveway. Wasn't the relay this time. Started disconnecting fuel lines and wasn't getting any output, but it sounded like the pump was going, so I figured the pump had spun out or something. Replaced the fuel pump a couple of days later, and verified that it worked with 12V. I also tried out the old pump in a bucket of water and it seemed like it had problems (although now I'm not so sure), because it had fuel spurting out the top of the pump where the electrical connector is. Unfortunately the new pump didn't fix the problem. Still wouldn't output fuel with key on. I spent the next few hours trying to troubleshoot wiring to the pump because it didn't seem like it was getting voltage when it should be. We tried jumping the ground wire to chassis ground and it would work. Anyway, nothing I did improved the situation, so before I went to bed I decided to disconnect the battery after reading this thread. I'm happy to report that when i woke up this morning and reconnected the battery, it started right up!!! It's been running normal all day today just fine. I hope it doesn't leave my wife on the side of the road some day.

Just to follow up with the OP, did the issues ever come back or is your truck still running like a champ? I'm leaning towards replacing the fuel pump control module for $300 just to have some peace of mind.

 

@onesun43, I haven't been on here in awhile. Any further issues? My control module wasn't my problem, it was pump. Once I put an OEM Toyota pump in it (after trying and failing with an aftermarket) it has run fine.

 

Same issues here, 2010 toyota tundra 5.7L, start for a few seconds and quite, sometimes it would run longer, like long enough to pull onto a trailer +. Put new fuel pump in, same issue, pulled fuel lines, no fuel moving but had power to connector, bigger blue wire had 12 volts and bigger red wire is ground, bigger red wire runs back to the fuel module/ecu that's on driverside rear of inside frame rail, hooked a wire to bigger red wire on fuel pump connector and grounded it to the frame.. fuel pump works, truck runs and fuel is pumping, but im not sure if this bypass will hurt anything else so I'm looking for answers on that now, anybody know if it would hurt anything by bypassing my junk fuel pump modules ground????

 

Subbed
My 08 5.7 is doing the same thing as OP
shut the truck off, came back 4 hours later, it started, I dropped it in gear then it died.
Nothing at this point, I sprayed starting fluid in breather tube, it fired, ran for a few seconds and died again, separated line on the fuel rail, nothing there while cranking....

 

This is probably my next step......



.

 

Check your fuel control module, it has two plugin connectors, find the biggest red wire, test it with a multimeter for DC voltage, it should show voltage when the pump is not running, when you turn the key and make your pump turn on it should not show voltage, the red wire is the fuel pumps ground connection, the fuel control module actuates it, if the controller is no good then the red wire has constant power and turning the key doesn't make it change.

 

Also the red wires voltage should match the blue wires voltage with my experience (12volts) but you can unplug both connectors and test the resistance. I do have the specs for this. (Jblack) you said you had like 1.5volts on the red wire and when cycling the key to activate the pump it went to zero, well the red wire should show more than 1.5 volts, it should basically match the blue wire voltage. If it doesn't then it's probably the issue but as I said you can test resistance on the two connectors to see if its the wires or if it's the module, if ya need help with that let me know and I'll give ya the specs to test.

 

Another way to test, maybe not the best way but can also be used to run the truck until you can repair it is to splice into that red wire either back by the fuel control module or at connector at the top of the tank, it doesn't really matter, and touch it to the truck frame to ground it, if the fuel pump runs when it's activated then it might be the fuel control module or ots the connection at the module, either way you could just splice into that red wire and ground it to the frame and run the truck but I'm not sure of how long you could do that without creating more issues, im sure it would create more wear on the fuel pump because that fuel control module is what regulates the fuel pump speed and without it the fuel pump would run at one speed all the time and probably would wear out sooner but it's something that could be done to get where you need to get to or until you can fix it if you have no other options at the time, could even use a toggle switch for the people that unplugged and then it magically ran fine later, splice into the red wire and run it to a toggle switch into the cab and ground it and if the issue comes back at a really bad time then switch the toggle and continue on, that way Noone gets stranded. Like that one guy that unplugged the battery on his wife's vehicle and later it ran fine and he said he hopes she don't get stranded, thats when the toggle switch idea would be a handy thing to add if ya didn't have the money to just buy a new module, you can also check the resistance on the wires to rule that out and if they check out ok and your module is just working and then not working (basically dying) then at least you weren't get stranded when ya least expect it.

 

I was 4 miles offroad hunting when it happened, went through some smallish mud holes, on the drive into the property, parked and hunted for 4 hours, got in the truck started it and dropped it in gear and it died.....
I had to use my sons tacoma to drag it out the 4miles to where I could load onto my trailer and pull it home with my sons duramax.

I've not tested anything to check the volts, I don't have a meter, but I can borrow one.
I called the local Toyota dealer and I'm suppose to have a new module in the morning, $310
he also said that if I didn't plug it up I could get a refund "wink wink"
If it doesn't fix it he'll take it back and refund me.
I've bought lots of parts from him over lots of years.



.

 

That's cool of him

 

Fuel pump was my issue.
Fixed now.



.

 

I too have this issue on a 2011 5.7L Crew Max, 255k miles. Just happened out of the blue this morning. Thought it might be my MAF but it doesn't appear to be. I have the Traction Control, CEL and blinking 4 Lo lights on so I'm tending to think it's the Fuel Pump Control Module as this has been mentioned in other threads I've found.
I'm going to try and decipher the wiring and voltages mentioned above to try and isolate if this unit is in fact the problem today.

As I've seen mentioned elsewhere, this is an odd unit to fail but something struck me - it's located in a spot that could get real wet if you launch a boat from a trailer like we do. We had an issue last summer where we had to get DEEP retrieving the boat. Highly likely that unit got submerged or close to it.

 

Chalk up another fix by replacing the Fuel Pump Control Module. I ordered a used Lexus part that had the same part number but was appended with an "-A". Seems to work fine. Once installed the truck fired up and runs normally again. I did put a new MAF in a couple days ago but the problem still persisted.
I also tried cracking open the old unit to see if there was an obvious failure point. I couldn't see anything. It's tough trying to pry the board up without wrecking it. The pins hold one end in pretty good. There was nothing I could see that should a burnt piece, corrosion or anything like that. Maybe it was just "time" for it to go?
Regardless, it's back on the road running normally. I'm glad there were a few threads out there with people discussing similar issues because this was an odd one. No codes, no lights, no issue starting over and over again but just that random fall-on-it's-face after about a minute repeatedly.
If you've got these symptoms, definitely consider replacing this box that sits inside the frame rail behind the rear drivers side wheel. 12mm bolt in the wheel well removes the bracket. Pry the gray plastic clip up until it snaps over the piece on the module that's stopping it. Once the clips is at a 45ish degree angle, pry it further back toward the module until it stops - this kicks the plug out enough so you can easily remove it. Two philips head screws hold the mounting bracket to the module. The Lexus bracket won't work so you'll need to reuse the old one if you go with a Lexus module. It's a very easy replacement with easy access that a novice can do with the bare minimum of tools.

 

This is an interested older thread, and have a question for the original poster or anyone else who did testing to those wires.

I want to install a kill switch that interupts the fuel system so the engine will still crank but not fire up.
I do not want to tap into anything under the hood , at the relay , or at the fuse box .

Its looking like interrupting one of the wires coming to the Fuel control module might be a good place to wire my kill switch to (run it from there up to a switch in the cab).
Am I correct to think when you turn the key , power is sent to the Fuel control module, and it send power to the fuel pump?

Can anyone tell me which wires are the incoming wires and which one I should cut into?

 

I’m having the same issue. 2007 Tundra with 5.7, drove it home in the morning, came out to move it later and it would crank strong but not start. Half a tank of gas, added fuel to be sure. Checked the fuel rail, nothing coming out while turning the key.

We tested the volts at the fuel pump control module, and believe this is the problem. Looks like it’s getting 12V but only sending around 2V to the pump while trying to start. Unless this is designed this way to control fuel use?

I am about to try disconnecting the battery, as suggested above. It looks like there are other ways to reset a fuel pump control module but I can’t find directions on how to do it for a Tundra.

 

I tried the disconnecting the battery trick and it didn’t fix my problem. I even tried doing it overnight, still no luck. I ended up jumping the power and ground around the fuel pump control module and the truck started up immediately. See attached photo for reference.

I have ordered the module… cheapest OEM I could find was $400. In the mean time, is there any harm in driving the truck while it is jumped around the fuel pump control module?

EDIT: Forgot to ask, for those of you who put a new module in, did you have to have it programmed at dealership? Is there any programming process at all?

 

Has any one been able to answer your last question? I'm dealing with a crank no start right now and I've gone through all the tests and I think I've narrowed it down to the control module or FP-ECU what ever you want to call it. I picked up a used one today for $73.00 cause the stealerships around me want $586. for a new one. If I can just plug the used on in and make sure it's the problem then I'll get a new one. But I need to know if it has to be flashed for my truck.

 

If I were a betting person I'd say no. PnP and see what happens I say this as the schematic shows it has no data lines thus no identification it's an I/O device.

Bolt it in and see if you isolated the problem.

 

thanks for the response that's what I was figuring as soon as I get of work in the morning that's what I was going to do the salvage yard kept insisting that it had to be flashed.

 

As far as flashing it goes, couldn’t you just jump from the power to the neutral on the uninstalled fuel control module to zero it out? Wouldn’t that drain any power or memory left in it?

 

NorthTexTundraFan
I'm not sure what that would do.

I hooked up the FPCM from the salvage yard and it sputtered on the first try. On the second attempt it started doing the exact same thing as the original FPCM was doing. If I strait wire the fuel pump it starts and runs like normal. What really makes this aggravating is it does not show and codes or faults. was running normal drove home from work and parked it and the next day went out to start it so it could warm up and all it did was crank no start. I have no clue as to why it just did this.

 

Have you tried disconnecting the battery for several hours? It looks like some of the guys above had luck with this.