Rbinder88

I have an 88 Toyota Pickup. I got it last year and well... I haven't got to drive it much. The engine grenaded and it seemed everything I took apart had to be replaced. So after some time it has a new engine, Every single thing has been redone. and every time i put it back together something else went wrong. This engine has about 10 miles on it... if that
to the point, I just finished replacing the head gasket and got everything back together, I drove it for about 15 minutes then parked it re torque the head bolts and re adjusted the valves.
Then it wouldn't start.... after putting some gas in the tank and replacing the fuel filter, which was new. it still would not get any fuel pressure in the line when it turned over.
I tried testing the fuel pump from the diagnostic check and it didn't power on. So i took the bed off to get to the fuel pump, I know I could have dropped the fuel tank but I had my reasons. anyway. I replaced the fuel pump and still the same thing, it just wont turn on. I decided to run a positive lead from the ignition to the pump.
When I turn the key the pump turns on, and when I try and start the engine it starts right up and dies in an instant, then just turns over as i try to start it. If I let it sit for a minute it will start and die again. It kinda seems like It's flooding out.

My buddy says that every fuel pump is suppose to turn on as soon as you turn the key, but I spoke to an old Toyota master mechanic and he said it wont. So I'm lost

I figure I just need to run a new wire from the fuel pump to wherever that blue wire hooks into, I don't know if it's to the relay, or the diagnostic box. Is there some kind of sensor that adjusts the voltage to regulate the fuel pressure. I found wire diagram but i really just can't follow it.

I also Spoke to my other mechanic and he said it could just be the main relay switch. but when I went to the parts shop to buy one they said it couldn't be the relay because the it was turning over.

anybody have any ideas?

mt_goat

The AFM (air flow meter) should have a switch the cuts power to the fuel pump if it senses no air flow. My 93 3VZE had one, sounds like you have a 22re, but its probably the same. I'd check there first, maybe the flap is stuck closed. Did you by any chance mess with the 2 screws in the AFM connection?

BTW lifting the bed is the best way to get to the FP, so you did good.

Rbinder88

are you talking about the airflow screw on the throttle body? i did mess with those quite a bit trying to see if that helped anything before but it didnt.

Rbinder88

ok nevermind, I see what you are talking about. I didnt try adjusting anything in the air box. I never messed with it when I was changing the head gasket so It shouldent be the problem. any other ideas?

mt_goat

No the wiring connector that plugs into the AFM looks like its held in by 2 screws but its not really. Do NOT ever remove the 2 screws (it rips the inside connections off the circuit board), Toyota never should have even put screws there, they should be rivets or something. The proper way to disconnect the AFM wiring harness is to remove the clip.

Anyway "rant off" I was just asking because you may have destroyed the inside of the AFM while trying to remove it if you did remove those 2 screws. If not just check that the little flap door inside the AFM intake is opening ok.

Rbinder88

ok well i never even knew those screws were there, I used the clip to remove it, so im good. thanks

4Crawler

iTrader: (3)

Figure out what is up with the power not getting to the pump:
- http://www.4crawler.com/4x4/CheapTri...shtml#FuelPump

Should only run with the starter cranking or the engine running (or with the jumper installed and the ignition on):

Rbinder88

ok great, that actually helped alot. So I got my mechanic to hook me up with the 2 main relays at cost so I have those to put in. but i still have my pump wired to my ignition, and Im waitin for a buddy to help me lift the bed so I can get to it again. but hopefully those relay switches fix it.

if that dosent work, what else could cause that?

4Crawler

iTrader: (3)

Wiring issues?

Rbinder88

ok so I replaced 3 of the relays, the main relay under the dash on the passenger side, one of the relays under the steering wheel ( a round metal one), and the other main relay in the relay box under the hood. Sorry didnt remember the exact names of the switches. still the same issue... So yes it is a wireing issue. the main relay clicks when I turn the key so it's getting power and working. but I got a tester and found i was not getting any power to the positive line of the fuel pump.

So i guess what I have to do is run a new wire from the main relay to the fuel pump...
I dont think the wire passes through anything else from the realy to the pump, right?

4Crawler

iTrader: (3)

Before throwing money at new parts, I would have first found where the problem is. If those other relays are out, the fuel pump not running is the least of your problems

You can see the circuit above. If you have power at the CO relay and not at the pump, that gives you two data points. Now, see if you can find a point in between those two points to test for power. Then use that data to narrow down the source of the problem. That is if you find power halfway to the pump, then the problem is between that point and the pump, likewise if no power, then problem is between the CO relay and the halfway point. I think that wiring harness runs inside the cab for a while and there may be a connector in between. CO relay is in the cab, pump is below in the pump, so wires must pass though cab floor at some point, might be a good test point.

Rbinder88

Ok, so I lifted up my seat and the carpet on the passenger side and found where the harness goes through the floor, There is a connector there. I tested all the ports for power and they are all good. From there the harness goes to the back tail lights and a section splits off that hooks to the fuel pump.
So i guess what I need would that a new harness for that section. I could just run a positive lead from the connector under the seat to the pump right?
any other ideas?

mt_goat

Yes, but if your problem is on the ground side it wouldn't help you much. I'd probably run new positive and ground wires to the pump. It might be a break in wiring right at the fuel tank cover though, check for that.

Another slightly more complicated option is to use the existing good harness under the seat to trigger a relay on-off, and run new wiring straight from the battery (or another good high amp source) to the relay and on to the pump. The advantage to this way is you will no longer be running lots of current through the old weak wiring harness because triggering the relay uses very little amps. Those fuel pump wires were very small to begin with and over the years they just get worse and worse at handling the load (voltage drop to fuel pump is not good).

Rbinder88

OK so WOW.... Hard lesson learned.
So I did everything that I said i was going to do. I tested connections for power every where. I ran a new wire from the relay to the fuel pump. I got a blown up image of the complete wire diagram and figured out my trucks entire electrical system. In the end I still had the same problem. no power to the fuel pump. But I had power into the cross over relay.
So I went back to stage one and pulled out the fuses under the dash.
IT WAS A STUPID 7.5 AMP FUSE!!
this fuse looked like it was fine, I had to look really close to notice it was bad. I replaced it and it solved all my problems. In my defense, my buddy is the one who checked them the first time.
Now I just gotta put it all back together, The bed is off and the dash it taken apart. all that work for nothing.. plus the 200 bucks i spent on a new pump and relays.

mt_goat

Tuition to the college of hard knocks can get expensive sometimes.

Moco2448

Thank god for this thread I had already replaced my fuel pump and efi cyliniod and after closer look at my ing. Fuse found that it had blown witch was crazy cause my truck had been sitting for about 9 months With the fuse in place she started right up runs like she used to

theduck21

I'm having the same problem. Ran a wire from the battery to pump and the pump ran fine but no power from the stock harness. I'll be sure to check that fuse before spending a fortune on relays!

Badger62811

Yall don't feel bad for overlooking the little stuff. When I rented a uhaul trailer to go pick up my truck the trailer turn signals weren't working. The guy said most likely a fuse. I looked in the owners manual for it and found nothing related to trailer lights. After an hour he grabbed a tester and went through all the fuses till he found the bad one. I looked up the name and number in the manual, and it was "trailer turn signals"

Plus your simple mistakes help others to remember to check the little things first.

Christian.hipps

Im having the same problem but I have checked my fuses many times my pump want work unless I run a power cable straight to the pump from my battery and the truck will start and barely run that's if the cable from the wireing harness is still connected to pump if I separate the cable and run power to just fuel pump and it want start it's like it has to have power sent back up the wiring harness to power my injectors or something idk I have spent $1000 on parts trying to figure this crap out and it's driving me crazy plz does anyone have any idea what it could be plz anyone

scope103

Christian -
Welcome to YotaTech. Didn't you just post that your fuel pump is working fine? https://www.yotatech.com/forums/f116...l#post52444005

Whenever you post, be sure to include the year/make/model/engine/transmission/trim. Put it in your "signature" so you don't need to keep repeating it. What works for a '94 3VZE may be no help at all for someone with an '86 22R.

And most importantly, use punctuation. I know you're posting from a phone, but phones have periods and commas and paragraphs just like everything else. Your long, run-on sentence is beyond what I can figure out. And if you want help, you'll want the most people to figure out your post.