Jonathan Lynn

HELP!
I've got a 22re 4runner, 1990, with a rebuilt engine with 12k miles on rebuild. 2 weeks after I bought it, head gasket blew.
I towed it to my buddies house and we fixed the head gasket, no huge issues, used OEM parts from 22reperformance.com, including new injectors
all back together, fires up, runs for 5-10 seconds and dies.
I have tried numerous fixes, including:
jumper between +B and fp to test COR,
tested Air flow sensor and TPS, both check out according to specs.
No air leak in intake tube from air box to intake.
Took efi back off and undid wiring harness looking for shorts between positing and negatives of injectors, no bad wiring found. Literally checked every wire in that whole section.
no check engine codes showing
put it all back together and no changes, starts, runs 5 seconds (sounds great while it's running) and dies.

If i disconnect the cold start injector electrical connection, it won't start at all.

fuel pump is audible when +b-fp jumper is in place.

i cannot figure out why the injectors are not working. Wiring looks good, no blown fuses and appropriate volts measured through injector wiring.

If it was was a bad AFM it would run when jumper is in place, bypassing COR, if I understand all the research.

Ive read a lot of forums, tried everything I can, and I'm back at square one. This is my daily driver and I'm on a motorcycle till I get this fixed, and 50 mile commute is getting cold fast.

What am am I missing?
Thanks

scope103

Welcome to YotaTech. Kudos for a careful step by step investigation.

I'd still suspect fuel pressure. You can actually measure it. You'll need a gauge, and probably a banjo-schraeder adaptor. If you want to go that way this tester has what you need (and is the one I use).

But before you do that, disconnect the fuel return line from the fuel pressure regulator, and plumb a piece of 6mm (1/4") clear vinyl into a suitable container. With just the jumper, I get about 1/2 liter/minute. Once it starts, you should still get something close to that at idle. If your fuel pump is wheezing, once you start the engine the flow may stop completely, and that will lean out the injectors.

RAD4Runner

Like Scope says^^^

AND... You verified the ECU is properly grounding the negative side of injectors? Terrys87 has a "noid light" setup to check that. The ECU pins (10 & 20 on 1986 to 1988 22R-Es) connect to negative side of the injectors through wireS AND SPLICES that have been known to get brittle, corroded, and easily break... enclosed in red below. You double-checked those?




To help us see fuel pressure readily, Wallytoo, et al and I installed fixed liquid filled fuel pressure gage piggybacked on CSI (https://www.yotatech.com/forums/f199...l#post52312190)

Jonathan Lynn

Thanks for the replies guys.
I checked the negative splices and entire wire length in the wiring harness, but not at the ECU, thanks for that tip, I'll check that out, and I'll double check fuel pump. Fuel pumped never wavered as far as sounds go.
Frustrating thing is, before the head blew, this thing was running beautifully. So I'm trying to figure out if something I did when I repaired the head gasket has caused this, or if it was just poor timing with something else happening at the same time.
Its been stored in doors, and only been 3 weeks since the head blew. Not like it's been neglected for years and I'm trying to get it running.

Jonathan Lynn

Is it possible the inectors are the wrong kind and that's why they aren't working?

They fit, but I'm wondering if that's the problem

Jonathan Lynn

I know I know, parts from amazon. Learning that lesson the hard way I bet

scope103

Well, you took the whole fuel system apart, so sure.

I would suspect that something got into the fuel line and you no longer have enough pressure. I gave you a very easy test for (most of) that.

Visually inspecting the wiring is taxing at best. Before I did that (and risk damaging more wiring) I'd listen for the injectors opening. You'll need some sort of stethoscope (cheaper than dirt at the favorite tool store of YotaTech devotees, or you can try using a dowel) because you'll need to crank the starter to run the injectors. If that leads nowhere, the "noid" light is the next step (a "12v" LED (has an integral resistor) is the easiest/cheapest, but don't forget the LEDs are polarized). If you've getting a flashing light the wiring is (almost certainly) good.

abecedarian

Check your ignition wiring too, from the distributor, through the igniter and to the ECU.

If the ECU isn't getting IGt from the igniter, it won't trigger injection. Cold start valve and stuff is separate from the primary injection system.

scope103

"IGF." IGT runs from the ECU to the igniter, IGF goes back to the ECU.

Missing IGF should throw a code, though.

Terrys87

iTrader: (1)

I have never gotten a code for a bad AFM and I have had some bad AFMs. The only time I have ever gotten a code for a AFM is if I left the cable disconnected. Take a Haynes Manual and do the resistance checks listed in the manual and that will tell you if your AFM is good or not. The numbers will be in tolerance if it is good and make sure the flapper moves freely. If it is bad, your resistance numbers will be way off in one or two of the test..

The 90 wiring harness seems to be built better then the earlier generation. I have experienced non firing injectors. To see if the computer is sending the signal, I use a $3 noid light to see if it is working. The computer is a solid piece of equipment so I doubt it is the culprit. https://www.yotatech.com/forums/f199...l#post51897320 The Injector Circuit may seem complicated but is actually an easy circuit once you get into it and this is coming from an electrical dummy such as myself. The links above have several pieces of information that may help.

I would see if I was getting a signal from Pins #10 and 20 for the injectors. There a 3 different injectors for these trucks. 85-87 is one style, 88 is a one year only and the 89-95 is all the same. A 9 volt battery, syringe, cleaner, and a hose can tell you if the injectors are operating. Google on how to test and clean an injector. You asked earlier if you had the wrong injector. The injectors do have tabs/keys to keep you from installing the wrong injector into the wrong year of truck. I have seen wrong injectors in these trucks. When I say wrong injector, I mean the wrong year of injector.

Jonathan Lynn

I got her running tonight guys. It was the injectors. Put refurbished OEM ones in it, and it started up, idle was kind of all over the place, pulled the ecu fuse for a minute to reset it, and now it starts and idles great. Hoping that's all it is. No vacuum leaks, triple
checked them all tonight. Thanks for all the tips and help guys, seriously, I really appreciate it all.
Hoping the test drive tomorrow works out as good as it was running tonight.