@hab

1986 4runner EFI SR5

This thread may seem redundant to others that have been posted, but after reading as many as I could find and performing various tests that were recommended, I'm getting no where.

Like many of these threads start, I drove it home from work & it wouldn't start the next morning. It will crank all day & at first would start then immediately die if given any throttle what so ever.

Checked fuses, they were good.

I suspected the fuel pump at first, as I had problems with it before. Not the pump, as I can hear the pump come on with either the diagnostic jump, or with the AFM vane flap manually held open.

Which brings us to what is confusing me.

When the AFM vane was propped open with a screwdriver, the truck would start & idle. As soon as I took the screwdriver out, the engine would die. Thus I concluded that either the AFM was bad, the ECU was bad, the main relay was bad, or the circuit open relay (COR) had burnt out.

So I tested the AFM using the oh-so-handy 4crawler.com cheap tricks write-up. It tested OK. So, I tested the COR with an ohm meter & also by listening for the "click". OK as well. Thinking it MUST be one or the other (AFM or COR), I swapped out both (one at a time) with used parts. Same thing with the replacement AFM. Would start & run with the vane propped open.

The reason I'm writing in the past tense is because now I can't get it to start at all.

My question is this: If it would start with the AFM vane held open, that would indicate a problem somewhere between the AFM & fuel pump, correct?

Am I way off on this? Should I be looking elsewhere, such as fuel issues?

This is my first Toyota. I've had the truck for a year & done various basic mechanical & electrical work on it, but am by no stretch of the imagination a pro at this.

ANY help, tips, or nods in ANY direction would be a tremendous help at this point.

Thanks

TNRabbit

Could be a short in the wiring between the VAFM & ECU, or an issue with the VAFM connector....

@hab

Was afraid of that, but hoping it wasn't true.

So, I know how to test the individual parts, but how do I go about testing the AFM connector itself? Checked the wiring diagrams in the FSM & they seemed to be written for someone who knows what they're doing...

1styota4X4

in the fsm it tells you how to test the sensors at the ecu to eliminate wiring problem start there.

YoderRunner

Or maybe u have a leak in your intake in between the afm and plenum. That happened to me and I did everything u did with same results then I actually time the tube off and saw a gaping hole in the bottom of it. I duct taped it and it starts now.

ChefYota4x4

iTrader: (5)

Yes, as 1st Yota said, ..you can read those things, (wiring issues between ECU and Sensor/Component) at the ECU. Some tests are done checking voltage, some for resistance. There is an entire section in the FSM that covers these tests, provides diagrams, and since you're testing resistance at the AFM, fuel pump jumper, etc., .... don't worry, you'll figure it out quick(Just a lil tight in there and a bit of a PITA having to lean over, etc. But you can remove the ECu from the firewall and lay it down, closer to the door, so you don't have to actually try and reach up in there! lol)

A couple other no start issues, where fuel is found, but seems to be getting "fuel cut"..... is the RPM Signal Code. Did you say you've checked for Codes? I would start there, no doubt. If you get an RPM signal code, it could be in the wiring between the connector from the main harness to the coil....that LONGGGGGGG wire with the green plug on the end. Just for the heck of it, make sure it's plugged in. I'm NOT saying this is likely your issue...it's just something to check that doesn't come up that often....but that does happen. A buddy, on YT, has just solved his no start problem by actually plugging that in.... Yep, it had either come unplugged or was forgotten, so a chasing of tail party ensued, and in the end, ....it was something unplugged. It happens to ALL of us, at least once! lol.

Yes, also, on the COR can often cause this. Mine slowly went bad, and it wouldn't start, often, after driving... Let it sit, 30 minutes, VROOM! lol. Then weeks later, it would just not start at all. Walked into Autobone, 40$, solved. Same aftermarket one is in there, 115K later, still working! I can see you've swapped in another COR(verified workinggggggg one, right? lol)... and no change. So that's not likely it. Mine was TOTALLY corroded inside due to a leaking windshield seam.

@hab

Thanks for the replies & suggestions.

Haven't had a lot of free time lately & ended up taking 'er to the shop. They've determined that there is no power going to the fuel pump when the ignition is turned to the "on" position, but the pump does get power when the ignition is turned to "crank". They're saying likely the ignition switch needs to be replaced.

Does this sound like a viable cause?

I never got around to testing the connections at the ECU, btw.

YoderRunner

They're wrong. The fuel pump in those 22re's only pumps when it cranks. Then the afm tells the circuit opening relay when to kick it on.

YoderRunner

I know this 100% for a fact. It sounds like u have an air leak or vacuum leak. Double check all your lines. Especially your PCV and your EGR.

YoderRunner

Take your intake tube going from throtle body to afm and thouroly examine it.

@hab

Seems like I've read on here somewhere that when the key is first turned to the "on" position, the pump will turn on briefly, then waits for the crank. I know I've taken off the intake tube and looked it over & didn't see anything obvious. I've also looked over all vacuum lines. Didn't see any thing.

ChefYota4x4

iTrader: (5)

Did you go to the "4Crawler, Cheap Tricks, FUEL PUMP" or "COR" section?.... And go through that thoroughly? Or just the AFM stuff's? lol.

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

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

Seems like you're reading up and such, ....just got yourself a lil Gremlin Hanger-on, eh? haha. BASTAGES! I hate them, and if I think of something else I will toss it here... Just been VERY busy, ya know?

myyota

Check the solenoid resistor, the one in my 86 4Runner went bad and my 4Runner wouldn`t start. Its mounted on the driver side inner fender and has two yellow plugs on it. I swapped it out for another one that i had, and it started right up. Another thing to check is the fuses behind the driver side kick panel, make sure there all good and not corroded.

RedneckBatmobile

iTrader: (2)

i had the same problem you had back when i bought my parts truck and before i gave up on it due to the wiring harness to the ecu being bad and me finding a new, running 4runner for not too expensive. all that means is i know alot about what can go wrong.

i absolutely second myyota on the selonoid resistor, but at the same time it should still turn over or sputter up. the reason i say that is because it controls the pulse to the injectors, but not the the cold start injector which means the engine could still theoretically start and sputter off of the fuel from the cold start injector.

as for the ecu, even if it tests okay sometimes they are junk. i'll quote someone else on here who once said "ecus going bad are extremely uncommon, but leaking windshields over ecus are not so uncommon." Even in this thread: Theres a little set of plug things that you can put into the injector plugs to test if the injectors are getting a pulse. I forget what they are called, but you should be able to get them from some local auto parts store, if not rent them from a store/shop. Also ensure your ecu has a good ground.

One of the first things i would try is pulling the line off your filter or off of the intake to make sure you have gas actually going through the pump to the engine. the fuel pump can run all it wants but it wont start if its not getting fuel.

I swear i thought the fuel pump was supposed to turn on in the on position because it needs to build up pressure in the fuel rail prior to ignition, but i honestly forget. If thats the case, you can hardwire it to your cigarette lighter port and see if it runs then, but i cant imagine that would make a difference because you said you can hear the fuel pump on. Again, check if you have fuel in your lines or a plugged line or something.

Last thing i can think of right now is do you have a spark? Pull one of your plug wires off the plug and have someone hold it near the head while you crank the engine. If it sparks, its good, but it has to be a good strong spark. Hope this helps....

ChefYota4x4

iTrader: (5)

Hhahaha.... yeah, I did say that, regarding the C.O.R., ...indeed!

Great input write up, BATMOBILE! .... And I believe you were referring to the "NOID" light kit they often rent at Autoparts stores(Not so often anymore! GRRR) ...lol. They are all Amer. Motor Noids... But some of those are import motors in them... So there is a Noid that worked for me in the GM/Ford/Dodge kit they offered. I believe it was the Probe(I know, ironic, eh? lol) You have to match them up to your connector. Also remember, due to the resistor they're talking about, your voltage is actually 5V at the injector.... (with 'whatever' resistance, depending on the year)... So CERTAIN Noid lights will not light up. There's another test using a top notch style Voltage/Ohm Meter, can't remember the brand they noted, but the kind electricians and mechanics often have..... it can read that.

@hab

Batmobile, thanks for the post.

The shop is putting a new ignition switch on now, but the more posts I read the more I'm afraid that's not gonna be the fix. If the ignition switch doesn't do it I'll be checking into the solenoid resistor next, along with checking for fuel at the filter & the EGR/PCV.

Btw, it has spark at the coil & plugs.

@hab

Thanks for the tips everyone, keep 'em coming.

YoderRunner

Try popping the hood. Disconnect the afm from the air box and hardwire your starter to the battery. When your motor is cranking your afm measuring plate should be flapping open and shut. If that doesn't happen then its time to start diagnosis there. Good luck and just another tip.

@hab

All right, got her back on the road last night, finally. Ended up being the damn fuel pump...sorta. Started pulling the sending unit out & the pump was just dangling there, disconnected from the the 1" hose that connects it to the line. Yeah.

Thanks for all the advice folks, if anything I now know what to check next time.
Cheers.

RedneckBatmobile

iTrader: (2)

It's always aggrivating, but relieving to solve things like this. I was definately in your shoes, and although I couldn't get mine running, I'm pretty pleased with the knowlege I gained through the months I tried and tried.

Congratulations! Hopefully she keeps runnin' good for ya!