s.c.i.e.n.c.e

Here's what going on.

The fuel pump and the "other thing" on the top of the gas tank, that tells how much fuel there is, are not working. The gas guage reads empty all the time, and the fuel pump well.... isn't pumping fuel.

When I hook the fuel pump up directly to the trucks battery, it runs. It does not run hooked up to the truck though.

I tried to jump it according the the FSM, and the fuel pump does not work then either.

I have read the FSM but can't figure out what to do next.

I am tired of my truck sitting in the driveway, and I am too cheap to take it to someone downtown that probably knows less about how to fix it then I do, and I don't know much.

I know there are quite a few people on here who know what could be going on, so thanks for your help in advance!

Hophead

I had the same symptoms-fuel pump would not run using the factory circuit- but when I jumped it directly off the battery ( used the power supply from my sub amp) it ran -this got me out of the bush and home. I ended up replacing the fuel pump. My theory was that the pump was old and it required more current to get it turning over than the factory circuit could provide. After replacing the pump - no problems. Changing the pump was dead simple too.

PS. Obviously check for power at the pump before replacing....

desert-rat660

well u need to invest in a digital multimeter or at the very least a test light. check for power and ground to the pump

abecedarian

so you've jumped the FP and B+ terminals and no worky
do you have battery voltage at the B+ terminal?
if you jump from the battery to the FP terminal, does the pump come on?

bipolarandproud

I replaced my main relay . and it solved my prob . $12 I think . When you turn the key to the on position do you heard a buzzing sound ?

By buzzing sound I don't mean fuel pump .

GenXr

Like mentioned above, check for voltage at the B+ terminal and at the wiring harness. Also check the relay.

Those are a whole heck of lot cheaper than a new pump. If you can get the pump to run when you jump, I doubt the pump is bad.

s.c.i.e.n.c.e

Hey all,

I will use your suggestions tommorrow and let you know what I find.

Hophead and desert-rat660 - I will check for power at the pump and ground at the pump.

abecedarian - I haven't checked for voltage at B+ yet but I will. I will also jump from the battery to the FP terminal, and see if the pump comes on.

bipolarandproud - I do have a buzzing noise when I turn the key to on.

bipolarandproud

ok Buzzing is a good thing, When my relay went bad it stopped buzzing . : )

GSGALLANT

For your gas guage, it is fused off the same fuse (10A guage) as the rest of your instruments, so if they work, then the fuse is fine. It will read empty if your connector is disconnected, or if you have a break in either the "power" wire or the "ground" wire to the fuel level sender.

For your pump, if the B+ to FP jumper in the diagnostic connector with the ignition key to "on" isn't making your pump run, and the pump runs fine when you bring 12V directly to it, then the only possible problems (assuming everything else in the truck works well) could be:

1. The 15A EFI fuse - this is easy to check. Verify that you have 12V on both sides of the fuse. If you do, it's good... if you don't, well... easy fix.

2. A break in the positive (blue) wire between the fuel pump and the junction where the wire from the FP terminal of the diagnostic connector joins the wire coming from the circuit opening relay. This is not as likely, but you can check this by connecting 12V directly to the FP terminal of the diagnostic port. If the fuel pump starts, that section of wiring is OK. You do not need to have the ignition "ON" to do this test.

3. The EFI main relay could be bad. Take it out and check it using this.

4. A break in the wire between the battery and the circuit opening relay (and the diagnostic connector terminal b+). To test this, after you've confirmed that your EFI main relay works and your 15A EFI fuse is good, turn the ignition to "ON", and check that you have 12V at the diagnostic connector terminal b+. If you don't, it's either a wiring problem, or the 7.5A IGN fuse is gone... which is again easy to check.

Post up some results of these tests then we'll go from there.

PS... the other part of the circuit is the fuel pump switch (in the AFM) and the circuit opening relay, but these are out of the picture in the tests I mentioned above.

scuba

s.c.i.e.n.c.e

Hey all, I tried a few things and here are the results.

abecedarian - I do have voltage at the B+ terminal. When I jump from the battery to the FP terminal, the pump does NOT come on.

GSGALLANT - I will read through what you wrote and try start trying things out.

Thanks for all your help so far everyone. I hope I can fix this myself and get my truck back on the road.

s.c.i.e.n.c.e

GSGALLANT - Are the fuel pump sending level unit and the fuel pump connected in any way? The fuel guage stopped working first, then the truck (fuel pump) would run sporadically when it wanted. Then the fuel pump stopped working as well.

Also, I stuck the leads of the multimeter into where you plug the fuel pump harness. I was not getting any voltage there at all.

abecedarian

so with voltage to the B+ terminal, you can assume there is a problem in the wiring to the fuel pump.
follow GSGALLANT's direction

desert-rat660

check for corrosion in the connector to the pump. what state do u live in

s.c.i.e.n.c.e

Hey all, trying to do some test but I have some questions.

1. I'm assuming that the EFI main relay is the round one in the fuse box under the hood that says "toyota relay M4." I'm not sure because the picture in GSGALLANT's link, shows the relay as being square and this relay is numbered 1,2,3,4 instead of 1,2,3,5. Do they test out the same way? Just curious, how much do these relays cost?

2. I checked the 15A EFI fuse and had 12V on both sides before I pulled the "main EFI relay". Then I pulled the supposed "EFI relay" and reinstalled it. After this none of the fuses had any power (12V). These included: the 15A EFI, 15A dome, both 10A head (LH and RH), 7.5A charge, and 15A haz-horn.

I feel like I'm making progress but I am confused and learning as I'm going.

GSGALLANT

That is correct. The top of the EFI main relay is round. Not sure about the pinout numbers being different, but if you had 12V at the b+ in the diagnostic connector with the key to "ON", this would also confirm that your EFI Main relay was fine.

Now this is very strange. Pulling out and re-installing the EFI main relay would not blow any fuses. It sounds like you shorted something out while doing troubleshooting. When you say the fuses above have no power, do you mean both sides (i.e. the fuses are not blown but there is no power getting to either side of the fuses?) If that's the case, something has been shorted out. If the fuses are blown, replace all the blown ones, and we'll start over. You have to get back to the point where you have 12V at the B+ terminal with the key in the "on" position first.

The 15A dome and 15A haz-horn fuse connect to the battery (on one side), without going through any other component (except wire, of course). If there's no power to either side of these two fuses, your battery is not connected, or there's a short somewhere, or you melted wires.

The two headlight fuses, I wouldn't worry about right now. They should only see power if the headlight relay is energized (i.e when your headlights are on).

When you say the 7.5A charge fuse, do you mean the 7.5A IGN fuse? The 7.5A IGN fuse and the 15A EFI fuse share a common supply. They both get power from the AM2 30A fusible link. Can you check if that's blown (remove it and check for continuity through it)? It is located in the same fuse block as the EFI main relay and the EFI fuse.

Now, I'm not trying to be a smart a$$ here. I just want to know if I'm oversimplifying or undersimplifying things here or not, because you mentioned you're starting to get confused. How proficient are you in electrical terms and the functioning and proper use and settings of multimeters. Are there any terms that we're using that you need clarification on? If there are, then make sure you ask questions before probing things with the multimeter. It is a good diagnostic tool, but on the wrong setting, it can cause more harm than good. If you already know all this, then disregard this paragraph and again, I'm not trying to be condescending... I just want to make sure we don't make things worse here.

GSGALLANT

No, they are not connected (electrically) in any way, except for being powered by the same battery.

GSGALLANT

I must say I should have asked this sooner. I guess you hadn't mentioned it, but I assumed you had the 3VZE. I just did a search of all your posts, and realized that we're dealing with a 22RE here (You still have the same truck, right?)

Now the basics of what we've already discussed are probably very similar on both engines, but some of the specifics (like relay pinout numbers, or details of the power supply fuses and wiring and such) might certainly be different.

Please consider putting your vehicle info into a signature so that it gets posted for you everytime you put a post in so that this doesn't happen again.

s.c.i.e.n.c.e

GSGALLANT - the truck is a 22re.

I understand a multimeter enough to get by. I know how to use DC V to see if something has 12V, how to use the ohms setting to see if a wire has continuity, ect.

Unfortunately, right now my progress is going backwards. When I originally started to work on the truck, I used the battery from my s10 because the toyotas was dead. This morning I had to use a different trucks battery, that was fully charged, and when I turned to the key to "on" I had no power whatsoever. I don't know whats going on now, but I am getting frustrated.

GSGALLANT

I wonder if you have a short somewhere giving you a parasitic load on your battery which is causing your batteries to drain. This new battery from this morning... is it dead now? or you just have no power at your fuses? Check the voltage across the battery posts and let us know.

To test for parasitic load, start with the ignition in the "off" position, with all accessories (the ones that you can run with the ignition "off", such as dome lights, headlights, etc...) selected "off". Basically, have everything the way you'd leave your truck if it was going to be parked for a week.

Take a known charged battery (check it for 12V), connect the positive lead of the truck to the positive post on the battery, set your multimeter to measure current (start at the highest setting... up to 10A or whatever your meter allows... make sure you plug the hot wire in the correct hole on the multimeter to measure the current range for the setting your meter is set to), connect one wire from your multimeter to the negative post of the battery, and the other wire from your multimeter to the truck's negative lead, then decrease the setting of the meter progressively until you get a reading.

Let us know what that reading is, so we can tell if your truck is killing batteries.

This will only be fully effective if all the fuses in the truck are good. Have you checked them like I mentioned a few posts up?

I can understand the frustration, but you have to systematically go through checking things out to solve something like this.

If you find a high parasitic load in the test I mentioned above, we'll have to isolate which circuit it's coming from. That part is easy... you just remove the vehicle's fuses one by one and see when the current drops off. When it does, you've found the problematic circuit. Let's start with the first test to see if you're even having that problem to begin with, though.