ztweny8

Truck won't run. Turns over constantly. Checked for spark by removing a plug and grounding to block, and it has spark.

I've checked all the fuses, and made sure the ecu connections were snug.

Just removed the access panel under the back seats for the fuel pump (talk about convenient), and with the key in the on position no noise at all. I read all this info about b+ to Fp etc., after looking around under the hood I'm thinking my 1986 doesn't use that system, and rather uses those green and yellow plugs on the driver side behind the air box.

My Question.

I want to know how to give power to the fuel pump, bypassing the relay (which is located above the ECU on the passenger side correct?), because I want to rule that out.

If I rule out the relay, what other diagnostics should I do before buying a fuel pump?

I've searched for the past hour and I'm not finding the answers to my questions being that my truck is an 86. Its -30 out and I don't have a garage, so I can't be wasting time lol.

ztweny8

Reading some more of the FSM and its starting to make sense a bit, atleast I think so. The Fp and +b are located on the relay on the passenger side by the ECU? I'm going to do a bit more reading and then head back outside.

4Crawler

iTrader: (3)

http://www.4crawler.com/4x4/CheapTri...shtml#FuelPump




http://www.4crawler.com/4x4/CheapTri...CheckConnector

ztweny8

HA HA HA VIIIICTORY!!!!!! I was having such a bad day, this is really sweet lol.

I jumped the fuel connector circled in red in the 2nd picture and I heard the fuel pump start humming, turned the key and YEAH!!! lol.

Alright. First of all thanks, theirs lots of good info on here, its just hard to put it all together sometimes.

By inserting the wire where I did, I'm bypassing the relay right? Are their any consequences to just leaving the wire in place? I had the key in the on position when I connected it, so I guess it could be running the pump with the key off too in which case it would have to remove the wire obviously. I'm just letting it run to charge the battery currently.

Everything is closed here at this time, so I'll have to try and track down a relay tomorrow I suppose.

4Crawler

iTrader: (3)

No. See the full discussion on the web page. In short, you are bypassing the auto on/off relay control via the AFM.

See the full discussion on the web page. In short, jumper in, pump runs with key=ON, stops when key=OFF. Only down side is if you run out of fuel or otherwise kill engine, pump will run until you turn the key off. I ran w/ mine jumped for a few years w/ no issue.

ztweny8

Yeah I just read some more on the website and I get it now. Well going along with the budget theme of this truck I'll just leave the jumper in.

I've been itching to drive it too as we just got about 15cm of snow lol.

scope103

If you have an accident that breaks a fuel line, do you want the pump to keep running? What if you're trapped in the vehicle?

The purpose of the relay is to assure the fuel pump shuts off when the engine stops running. I'd get it fixed if it were mine.

ztweny8

Point taken. Theirs probably a 1% chance I'll ever get in an accident with this truck that incapacitates me enough that I can't turn off the key, but better safe than sorry.

scope103

Good call. The bad news is that 910-35010 - Circuit Opening Relay is over $100 at ToyotaPartsZone.com. RockAuto has an aftermarket part (that they think is the right fit) for $40. The good news is that even $100 is 1% of only $10,000.

4Crawler

iTrader: (3)

Yes, that is correct and a consideration. There are fuel injected vehicles that do not have the auto fuel shutoff built in. I know my old '78 VW Rabbit fuel pump turned on when you turned the key to the ON position, whether the engine was running or not.

Funny thing is in my '85, after having the fuel pump jumper installed for a year or so, I thought that that jumper would make a handy anti-theft device if I were to replace it with a switch. With the jumper/switch open, the engine would be very hard to start since the fuel pump was not running. So I pulled the jumper (that had been there for that year or so), put in the switch and for some reason, the CO relay started to work normally again. So now it starts fine without the jumper . So I was happy that the "problem" fixed itself, but bummed since my anti-theft device was rendered ineffective. But I left the switch up in the engine bay, "just in case" it acts up again: