1991 fj80 crank but no start.. Will start the next morning ...?!?!??!??

[thex1231]

When did this issue start?
Was it good one day and bad the next?
Does the cold start injector and the cold start injector time switch work?

I stopped using the truck for about 2 months and it sat on the driveway then it started after that. The cold injector and time switch are also up to specs.

This has been going on for about a year now, since I have other vehicles is not a problem but I do want to get her tip top shape again.

I have checked tons of things up and down, I upgraded the efi wiring since it was giving me grief and it the relay overheating but this was due to an aftermarket fuel pump.


I installed an OEM denso pump about 2 months ago when I upgraded the wiring and the relay is no longer an issue, I can run it for as long as I need to.

I also removed the intake manifold, fuel rail, throttle body etc, cleaned everything. Changed the connectors on the injectors since were very brittle and the wires were gone. Cleaned everything, new gaskets and reinstalled it all back in but no improvement.

New injector filters and o rings.


I will check the timing a little later today to make sure it hasn't moved.

 

[jonheld]

Please don't take this personally, but that is the worst sounding 3FE I have ever heard.
A good running 3FE is certainly not quiet, but yours sounds really bad.

You say you have spark during cranking.
You say you have fuel pressure during cranking.
Are the injectors firing during cranking?
Because if you're getting fuel and fire into the cylinders, the next test would be compression. I'm making the assumption that you're getting good air flow into the throttle body.
I mean this is essentially a tractor. Fuel, fire, air, and compression is really all you need here.

 

[thex1231]

It sounds like this because there is not catalytic converter, I haven't tested compression but as I said before once running and up to temp it doesn't misfire nor it looses power at any time.

I do need to adjust the valves, this truck was quite neglected when i got it, I've had it for about 10 years now and used to be my daily driver.

Regular maintenance on everything has always been a priority, this truck was taken to a Toyota specialist before I had it, they charged an arm and a leg but the always did a very lousy job (I wasn't the owner then).

It belonged to my wife's godmother and they've had it since it came out of the showroom, they were diligent with maintenance but since they don't know about cars they only paid and trusted the people who were doing the job so I received it in poor shape.

The motor was supposedly rebuilt about 130,000 miles ago but I doubt it.

I won't give up on her and will be at it until I figure out where the gremlins are.

The only other thing I can think of is that it might be the computer, I say this because water came in once through the windshields seal on the passanger side once but it wasn't a large amount, I just don't recall if the issue manifested right after or not.

Again thanks for your help, I'll keep at it.

Not like I have anything better to do right now with all this madness.

 

[thex1231]

I am thinking the injectors aren't firing when cranking, the engine will start with external fuel source.

 

[thex1231]

Please don't take this personally, but that is the worst sounding 3FE I have ever heard.
A good running 3FE is certainly not quiet, but yours sounds really bad.

You say you have spark during cranking.
You say you have fuel pressure during cranking.
Are the injectors firing during cranking?
Because if you're getting fuel and fire into the cylinders, the next test would be compression. I'm making the assumption that you're getting good air flow into the throttle body.
I mean this is essentially a tractor. Fuel, fire, air, and compression is really all you need here.

I adjusted a few more things that were pending ( NOT ENGINE RELATED), the screw on the distributor was loose. I adjusted the timing a bit without a light and the hesitation went away.

I will get my timing light tomorrow and time it, do you know how many rpm does the ecu needs to see to open the injectors?

 

[jonheld]

I adjusted a few more things that were pending ( NOT ENGINE RELATED), the screw on the distributor was loose. I adjusted the timing a bit without a light and the hesitation went away.

I will get my timing light tomorrow and time it, do you know how many rpm does the ecu needs to see to open the injectors?

The injectors should start to fire as soon as the motor starts to crank. The ECU uses the pick up coils in the distributor as the crank position sensor.
On a 3FE, the injectors are fired in 2 banks of 3, not individually as on later models. A constant +12 is fed to all injectors and the ECU grounds each bank to fire them.

 

[BILT4ME]

The injectors should start to fire as soon as the motor starts to crank. The ECU uses the pick up coils in the distributor as the crank position sensor.
On a 3FE, the injectors are fired in 2 banks of 3, not individually as on later models. A constant +12 is fed to all injectors and the ECU grounds each bank to fire them.

2 banks of 3 or 3 banks of 2?

 

[jonheld]

2 banks of 3 or 3 banks of 2?

LOL. 2 banks of 3.

 

[BILT4ME]

LOL. 2 banks of 3.

Wouldn't it fire 1 and 6, 5 and 2, 3 and 4? All on the up stroke (compression and exhaust)? Actually a serious question. Does the 1FZ do this also?

 

[jonheld]

Wouldn't it fire 1 and 6, 5 and 2, 3 and 4? All on the up stroke (compression and exhaust)? Actually a serious question. Does the 1FZ do this also?

The 1FZ is 2nd/3rd generation EFI. Each injector is controlled individually.
The 3FE is 1st generation (again 1986 technology). According to the EWD, 1, 2, and 3 are bank 1 and 4, 5, and 6 are bank 2. That said, the EWD might be in error regarding the injector numbers, but there are only 2 terminals on the ECU that fire the injectors.

 

[BILT4ME]

The 1FZ is 2nd/3rd generation EFI. Each injector is controlled individually.
The 3FE is 1st generation (again 1986 technology). According to the EWD, 1, 2, and 3 are bank 1 and 4, 5, and 6 are bank 2. That said, the EWD might be in error regarding the injector numbers, but there are only 2 terminals on the ECU that fire the injectors.

View attachment 2313933

Is the firing order on the 3FE: 153624? (Too Young, Too Old, Just right)

 

[jonheld]

Is the firing order on the 3FE: 153624? (Too Young, Too Old, Just right)

Yes. 1-5-3-6-2-4.

 

[jonheld]

Wouldn't it fire 1 and 6, 5 and 2, 3 and 4? All on the up stroke (compression and exhaust)?

The injectors would fire on the intake stroke. Spark would fire on compression.

 

[jonheld]

This information is also confirmed in the FSM.

 

[BILT4ME]

The injectors would fire on the intake stroke. Spark would fire on compression.

Just trying to get my head around this, that's why I'm asking. There would be one in each stage when firing the injectors.
The cylinders are 120° apart.

1 Power (TDC) (Beginning) 0° Injector
5 Compression (Upstroke) (Middle) 120°
3 Intake (Downstroke) (Middle) 240° Injector
6 Intake (TDC) (Beginning) 360°
2 Exhaust (Upstroke) (Middle) 480° Injector
4 Power (Downstroke) (Middle) 600°

That means you have an injector firing on the exhaust stroke every time, effectively wasting 1/3 of your fuel.

I know the GM V6's I've worked with fired the spark plugs only both cylinders at the same time, so 1/6, 2/5, 3/4, but not the injectors.

I'm gonna have to ponder this more. What am I missing?

 

[jonheld]

I'm gonna have to ponder this more. What am I missing?

OK, you're making me read through a bunch of technical documents on Memorial Day weekend.
So far, the best explanation is it all comes down to valve timing, but I'm going to need more coffee.

 

[ppc]

The motor is not a direct injection setup. The fuel is injected into the intake manifold. Only the cylinder on the intake stroke will have the intake valve open drawing the fuel in. The other two cylinders in in that bank will have the intake valves closed at the same time so there is no unburnt fuel being expelled. Each injector supplies 1/3rd of the banks requirements but does it three times as often.

 

[BILT4ME]

The motor is not a direct injection setup. The fuel is injected into the intake manifold. Only the cylinder on the intake stroke will have the intake valve open drawing the fuel in. The other two cylinders in in that bank will have the intake valves closed at the same time so there is no unburnt fuel being expelled. Each injector supplies 1/3rd of the banks requirements but does it three times as often.

That makes more sense!

 

[thex1231]

OK, you're making me read through a bunch of technical documents on Memorial Day weekend.
So far, the best explanation is it all comes down to valve timing, but I'm going to need more coffee.

So here´s an update, she is alive and well.

I went back and and checked all the electrical connectors that had to do with the engine and made sure they were clean and connected correctly, the computer was removed and checked.

Adjusted the valves, reset the timing and tightened a few things here and there. She is now running pretty smooth without any sputters at the start, the cold start injector must be gummed up because now it starts better when it is hot then cold ( it takes two tries when cold).

I mentioned I chanced the EFI wiring to a larger caliber, yesterday it would suddenly stop running, it had all the symptoms of a bad efi relay or connection. Wiggled the relay while running and she would cut off. I will tidy everything up today but it seems she finally lives.


The old gal was upset she was placed on the sidelines but I plan on using her at least twice a week now so everything stays smooth.


So it ended up being a long list of issues with fuel spark and bad connections but I see the light at the end of the tunnel.


I need to replace my starter, mine is now tired. Changed the plunger and contacts about two years ago but it seems the brushes are gone now, does anybody know if a starter for an FJZ80 will fit my 91?, I ask because these have larger motors.


Again thanks for the input.

 

[pizzajohn]

I have some information that people in this thread might find helpful. But please read to the end!

I have been reading about similar problems on here for months now and finally figured it out. Sorry if I have given too much info, but want to make sure I include everything.

Whenever the LC is cold she starts with no problem. If I have been driving around and stop then try to restart her within up to 2 hours of sitting ‘sometimes’ she does not start. She will crank indefinitely. Usually if I keep trying to start by reinserting the key and cranking it will start after a few minutes and a few tries (usually). The moment the LC starts cranking, I can tell whether it will start based on the sound of the cranking, but I couldn’t tell you the difference in sound, it is so small. When she is running and driving, everything is well...she runs perfect! Where I live the outside temp is constantly in the 70’s and 80’s. I have desmogged her and removed the cooling fan under the hood to add a battery for my solar setup. When I take off the gas cap to refill, there is a huge pressure release that happens.


--Yes, the CEL is on when key is in start position. (I have moved the EFI relay into the cab with higher gauge wiring)
--No CEL codes
--I have tried turning the key to the start position three times before starting and letting it sit in this position for 5 seconds before starting and sometimes this helps and sometimes it does not.
--Pushing on the gas pedal does not help to start.
--I have tried shorting the B+ and FP contacts in the diagnostic box and it does not help.
--Replaced the starter with a WAI branded starter.
--Replaced the alternator with a WAI branded alternator.
--Replaced the Fuel Pump and both Fuel filters with OEM parts.
--Replaced both the FPR and the Damper. Neither are OEM because I could not find OEM parts. I also made sure the screw on the damper is all the way tight.
--Battery tests good with multimeter.
--Replaced Cap, Rotor, Wires and Plugs all with OEM.
--Replaced fusible links and checked grounds.
--No leaks on the intake boot.
--Spark is fine.
--Replaced the Igniter with a used OEM one.
--Replaced Ignition Coil with new, but not OEM. When I use a multimeter to test the Coil, I get the following for both the new and old coil. (Coil Primary Resistance is usually .4, but occasionally reads erratic other numbers. The Secondary Resistance reads 12.75k)
--I bought a ‘used but tested’ Circuit Opening Relay and both my old and the ’new’ COR have the same readings which do not match the FSM. The Continuity for one was in the 20’s and one was in the 100’s.

In the end it turns out the brand new FPR I installed was bad. I replaced it with a new one and all is well. This was a lesson for me that just because I installed a new piece of equipment it does not mean it is good!

I hope this helps, good luck!