Start, idle, and shutdown. Engine cuts out when driving.

[bamp]

Hello LC enthusiasts,

I have a 93' FZJ80 with +300kmi. A couple of weeks ago it started, idled at 600 rpm, then died after about 5 seconds. Popped the hood, checked connections, and tried several more times. After about 30 minutes I gave it another try, this time revving high, and the engine held.

After a week of letting it sit due to work scheduling, the fuel filter was replaced. I drove it to a nearby park that night to walk my dogs, but it stalled out just before getting on the freeway.

This time, the engine wouldn't hold an idle, even after giving it full throttle. I tried quickly putting it in reverse then drive without luck. After thirty minutes and checking the bay over, it turned over and kept on churning.

I suspected the fuel line might've been plugged, especially with the fuel filter just replaced, and the bumps at the park might've jostled something loose.

I put in some star tron tank cleaner and let it sit for another week. This weekend, the LC ran fine on some errands. Then I hit the freeway for maybe 15 miles, parked, and the start/idle/die problem reappeared. I revved high and got it going. I headed back hole and noticed the LC engine cut out doing 65 a couple of times, but the engine came back in.

Reading on these forums, I first thought it might be the fuel filter, then then fuel line, and recently the volume AFM/MAF. The filter is new, an organic solvent has been added to a full tank, and the resistances of the AFM/MAF checked out per the FSM. I looked over the air filter to engine boot/duct, but didn't spot any obvious cracks or leaks. Could it be the TPS? Maybe the fuel pump and filter? Fuel pump relay? I thought maybe debris/sludge could be blocking the line from the filter to the engine. I really don't know.

I chanced driving my LC to work this morning and it exhibited every problem. It hiccuped on the freeway, stalled on a turnoff, died after idling 5 seconds, held after revving hard, and honestly died just as I pulled up home this evening after driving it gingerly as hell the 17 freeway miles back home.

Do you enthusiasts have any suggestions? I've read people here have had similar problems, but the solutions often are very different. Water in connections, bad MAF, etc. I don't want to give up on my LC.

Best regards and thanks in advance.

 

[voodu3]

Have you checked the throttle cable? They do wear out and get stretched. It can be tighten up at the top of the throttle body. I would take it loose and see if it moves smoothly. I had a similar problem and adjusting the cable fixed it.

 

[BILT4ME]

Do you have a CEL?

If so check.it and advise what number.

 

[93yotasr5]

Have you checked the throttle cable? They do wear out and get stretched. It can be tighten up at the top of the throttle body. I would take it loose and see if it moves smoothly. I had a similar problem and adjusting the cable fixed it.

I had very similar issues and this was my issue.

Another time I had managed to get water in my engine compartment (dumbass move on my part I also hydro locked the engine) but afterwards it ran funky like this. I had water in the VAFM connector and the harness itself.

Lastly I had the ECT sensor on the block go bad and it caused a funky idle and had weird issues.

 

[bamp]

Have you checked the throttle cable? They do wear out and get stretched. It can be tighten up at the top of the throttle body. I would take it loose and see if it moves smoothly. I had a similar problem and adjusting the cable fixed it.

I checked the throttle cable and there's only about an eighth inch of give, so it's pretty taut. The action is also pretty smooth.

 

[bamp]

Do you have a CEL?

If so check.it and advise what number.

There isn't any CEL when it starts, idles, and dies. When it did shutdown on the freeway, I did see the CEL, along with the other lights, but I wasn't able to check it as I wanted to get off ASAP.

 

[bamp]

I had very similar issues and this was my issue.

Another time I had managed to get water in my engine compartment (dumbass move on my part I also hydro locked the engine) but afterwards it ran funky like this. I had water in the VAFM connector and the harness itself.

Lastly I had the ECT sensor on the block go bad and it caused a funky idle and had weird issues.

How tight should the throttle cable be?

It hasn't rained here much at all, so I don't think it's water. I did check the VAFM connection and harness, which were dry.

I'll check the ECT sensor tomorrow. Besides resistances and integrity of connections, is there anything I should be looking for?

Thanks!

 

[BILT4ME]

At any time did you remove the screws from the wiring harness on the AFM/VAF/MAF doohickey and tug on the harness?

If the answer is yes, open your wallet and find a way to used one. It won't run without it.

 

[SmokingRocks]

Your ECM has likely stored the code. You need to pull your code. Engine off, find the data connector on the passenger side firewall under the hood, jump terminals TE1 and E1 with a paperclip, get in the driver's seat and turn the key to on. Count the number of blinks, code 25 would blink like this ____--__--_______--__--__--__--__--____________--__--_____--__--__--__--__--______ one second on, one second off, two seconds between first and second number in the code then like 3 or 4 seconds between codes and 5 seconds or more when it finishes and starts over again.

If there are more than one codes stored it will blink each of them one after the other then repeat itself. If it blinks fast and consistently at like .5 seconds on/off/on/off then there is no code stored.

Toyota OBD/OBD2 Codes – TroubleCodes.net

www.troublecodes.net

Also if you don't have your Factory Service Manual then get it now, follow the link in my signature. You need the 1994 FSM and the A442 Transmission FSM

 

[SmokingRocks]

This section will help you

 

[SmokingRocks]

There are several common issues that come to mind but I don't want to throw those out yet because it's never a good idea to fire the parts cannon at the problem without having an idea of what's up.

 

[bamp]

At any time did you remove the screws from the wiring harness on the AFM/VAF/MAF doohickey and tug on the harness?

If the answer is yes, open your wallet and find a way to used one. It won't run without it.

Haha, oh no. I've read a few threads about people messing with the screws on the wiring harness of the AFM/VAF/MAF. I only unplugged the connector to perform the tests on resistance. The air flow sensor was my guess originally, but its resistances check out.

 

[SmokingRocks]

I immediately suspect the FPR (Fuel Pump Relay) as they get old they cause the exact symptoms you described and it's very common. The FPR If you want to pew pew the parts pistol at this culprit it's not a bad idea, even if it isn't the root of the issue it's worth having a spare on hand. I have one in my trail kit. Toyota Part Number: 28380-66010

If the engine dies for an extended period (the issue is persistent and remains present) you can easily diagnose if it is the FPR by removing the relay and hotwiring two of the pins in the connector on the harness. The FPR is on the driver side fender adjacent to the brake master cylinder. It's bolted on an L bracket that tucks it in one of the fender holes IIRC. It's black and looks like this.

Here is what the pins on the F4 Fuel Pump Relay are doing in the diagram above:

Pin 5) 12v should be present at this pin/terminal when the key is in the ON & START positions

Pin 1) ECU calls for High Flow when it senses enough throttle position, internally it closes the circuit to ground (most all of the circuits in our rigs are ground switched).

• This can be seen as continuity between Pin 1 and chassis ground, which energizes the relay and switches the flow of power from Pin 5-->Pin 2 TO Pin 5-->Pin 3

Pin 2) With a functioning FPR pin 2 will be energized with 12v with the key in the on the position under low throttle applications

• This 12v then is reduced to roughly 9.5v by the Fuel Pump Resistor before being routed to the pump

Pin 3) With a functioning FPR Pin 3 will be energized with 12v when the ECU closes the switch to ground for Pin 1

• This sends the full 12v to the fuel pump

Next time your rig shuts off jump terminals 3 & 5 and try to restart the engine immediately if it lights up the FPR is faulty.


The contacts in these relays get corroded over time and eventually the relay will not function 100% of the time, sometimes seemingly at random.

I've written up a detailed procedure on how to diagnose a faulty FPR here: 1FZ-FE Cranks but won’t turn over without starter fluid, then drives fine.
And here: Possible Voltage Drop Issue?

I've attached the specific section of the FSM's electrical wiring diagram to give you the full picture. Page 2 explains how/what the FPR does, page 6 shows the FPR in the EWD.

 

[bamp]

Your ECM has likely stored the code. You need to pull your code. Engine off, find the data connector on the passenger side firewall under the hood, jump terminals TE1 and E1 with a paperclip, get in the driver's seat and turn the key to on. Count the number of blinks, code 25 would blink like this ____--__--_______--__--__--__--__--____________--__--_____--__--__--__--__--______ one second on, one second off, two seconds between first and second number in the code then like 3 or 4 seconds between codes and 5 seconds or more when it finishes and starts over again.

If there are more than one codes stored it will blink each of them one after the other then repeat itself. If it blinks fast and consistently at like .5 seconds on/off/on/off then there is no code stored.

Toyota OBD/OBD2 Codes – TroubleCodes.net

www.troublecodes.net

Also if you don't have your Factory Service Manual then get it now, follow the link in my signature. You need the 1994 FSM and the A442 Transmission FSM

Thanks for the link.

I jumpered the TE1 and E1 terminals and checked the CEL. I had two codes stored, 24 and 41. I do have a FSM downloaded from the Toyota Technical website. I'm on to check the FPR per SmokinRocks.

Thank you very much for your help.

 

[bamp]

Do you have a CEL?

If so check.it and advise what number.

Thanks BILT4ME. I saw your post this morning and checked the CEL after jumpering it. 24 and 41, so intake temp sensor and TPS signal.

 

[SmokingRocks]

I absolutely hated setting the tps per the fsm’s procedure. It never seemed to work right. I just gave up on mr. T’s method and just dialed it in by hand and multimeter.

That said a failing TPS can certainly cause the symptoms you have

 

[bamp]

I immediately suspect the FPR (Fuel Pump Relay) as they get old they cause the exact symptoms you described and it's very common. The FPR If you want to pew pew the parts pistol at this culprit it's not a bad idea, even if it isn't the root of the issue it's worth having a spare on hand. I have one in my trail kit. Toyota Part Number: 28380-66010

If the engine dies for an extended period (the issue is persistent and remains present) you can easily diagnose if it is the FPR by removing the relay and hotwiring two of the pins in the connector on the harness. The FPR is on the driver side fender adjacent to the brake master cylinder. It's bolted on an L bracket that tucks it in one of the fender holes IIRC. It's black and looks like this.

View attachment 1990051View attachment 1990050
Here is what the pins on the F4 Fuel Pump Relay are doing in the diagram above:

Pin 5) 12v should be present at this pin/terminal when the key is in the ON & START positions

Pin 1) ECU calls for High Flow when it senses enough throttle position, internally it closes the circuit to ground (most all of the circuits in our rigs are ground switched).

• This can be seen as continuity between Pin 1 and chassis ground, which energizes the relay and switches the flow of power from Pin 5-->Pin 2 TO Pin 5-->Pin 3

Pin 2) With a functioning FPR pin 2 will be energized with 12v with the key in the on the position under low throttle applications

• This 12v then is reduced to roughly 9.5v by the Fuel Pump Resistor before being routed to the pump

Pin 3) With a functioning FPR Pin 3 will be energized with 12v when the ECU closes the switch to ground for Pin 1

• This sends the full 12v to the fuel pump

Next time your rig shuts off jump terminals 3 & 5 and try to restart the engine immediately if it lights up the FPR is faulty.


The contacts in these relays get corroded over time and eventually the relay will not function 100% of the time, sometimes seemingly at random.

I've written up a detailed procedure on how to diagnose a faulty FPR here: 1FZ-FE Cranks but won’t turn over without starter fluid, then drives fine.
And here: Possible Voltage Drop Issue?

I've attached the specific section of the FSM's electrical wiring diagram to give you the full picture. Page 2 explains how/what the FPR does, page 6 shows the FPR in the EWD.

SmokingRocks,

Thank you very much for the thorough walk through and help. I'll need to follow up again as I tried testing the voltage across terminals 2 and 5 of the connector and saw 0.4V with the key in the On position. I then jumpered terminals 3 and 5 and the engine fired right up (after stalling out earlier on idle within 5 seconds) and stayed on.

Although you pointed the above as positive verification of a faulty FPR, I turned off the engine so that I could have another try at it to see whether I could just run the LC with the jumper in place. The second startup failed miserably with the engine sputtering out within 5 seconds. I know you mentioned jumping 3 and 5 immediately after an engine idle die case, but I was curious. I did not go through all voltage testing cases due to time, but I'll be back tomorrow. In the meantime, I'm ordering an OEM FPR tonight.

Best regards.

 

[SmokingRocks]

Cool man glad I could help, hold on to the old FPR as an emergency spare (there is a rehab/cleaning method outlined in this forum that can extend the life of a dying FPR)

If this doesn't fix it then we need to listen to what the OBD system is telling us which means investigate the TPS.

. I'll need to follow up again as I tried testing the voltage across terminals 2 and 5 of the connector and saw 0.4V with the key in the On position.

I'm glad you didn't measure any voltage across those two terminals with the relay removed! The relay in its de-energized state basically is a jumper between pin 5 and pin 2, then it goes to the fuel pump and ground.

So instead of measuring voltage the regular way with one probe on the + source and the other on common ground you were essentially trying to measure voltage by placing the probes both on the + side of the circuit, this won't give you much of a reading. Now if you wanted to measure current flow that is how you would configure the meter.

 

[bamp]

I absolutely hated setting the tps per the fsm’s procedure. It never seemed to work right. I just gave up on mr. T’s method and just dialed it in by hand and multimeter.

That said a failing TPS can certainly cause the symptoms you have

I ordered a TPS just in case since the ODB did give the error. I'll have it on hand in case the FPR doesn't fix the issue.

Thanks for all of your help. This place is great.

 

[SmokingRocks]

any updates?