1FZ-FE Cranks but won’t turn over without starter fluid, then drives fine.

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Jan 3, 2018
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Hey mudders,

Having what I believe is a throttle position sensor issue, but I’m not sure...

Here’s what’s going on:

My car started and was running fine per usual, then I hopped on the interstate and floored it hard until I reached about 85mph. I turned off of the interstate and floored it again, and my RPMs dropped immediately almost like I turned off my car. I backed off the pedal and my RPMs went back up. I floored it again and it cut out again.

Then I drove normally and all was fine unless I floored it. I stopped at the store and when I came out, it wouldn’t start. It cranks but won’t turn over. I sprayed some starter fluid in and had my friend crank the starter until it turned over and it ran fine from there. While in park, I floored it and it revved up for a second and then cut out and the engine died. I tried starting and it wouldn’t turn over again so I sprayed starter fluid in again until it turned over, then I drove it home just fine.

Basically, I can’t start it without fluid and the engine cuts out when I put the pedal to the floor.

If I push the pedal down lightly in park, I can get the RPMs to redline but if I push the pedal down too far, the engine cuts out.

Is it my TPS sensor? I adjusted the sensor placement both ways to no avail.

Other things, I keep getting EGR insufficient flow errors but no symptoms.
 

SmokingRocks

I bought a Cruiser to keep miles off my Cruiser
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Any CEL?

It sounds like your Fuel Pump Relay, if not that then something else fuel related. Try pulling your codes.
 

jonheld

 
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I agree with @SmokingRocks. This doesn't sound like a TPS issue, especially if you can't start the motor normally. There are diagnostics for the TPS.
The ECU runs the fuel pump by firing the circuit opening relay which in turn powers the fuel pump relay. Both are run by the ECU. The ECU will get +12 from the starter circuit and fire both relays to power the fuel pump during engine start.
I would make sure the logic is correct before swapping parts.
 

Proven

RTFM, STEP 6, POST
 
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Could you put 12 volts to the fuel pump and test it that way?
 
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Could you put 12 volts to the fuel pump and test it that way?
I would make sure the logic is correct before swapping parts.
It sounds like your Fuel Pump Relay, if not that then something else fuel related. Try pulling your codes.


Sorry for the delayed response fellas,

Reminder on symptoms:
  1. I cannot start the car without manually energizing the fuel pump, but after it starts, the vehicle drives normally unless I floor it.
  2. I cannot engage the throttle fully (pedal to the metal) or else my fuel cuts out until.
  3. After I get the engine started and warmed up a bit -- Sitting at idle in P/Neutral --
  • If I floor the gas, it'll rev my engine to 3000rpm and cut out the gas flow until my RPM's drop down to 1000rpm, then it gives it gas again until 3000rpms and drops back down to 1000rpms -- All without me lifting my foot off the gas.
  • Basically, with pedal to the metal, my engine will rev to 3000rpm and cut out until 1000rpm before it receives gas to rev again.


I replaced the Fuel Pump Relay and the Throttle Position Switch, both OEM Toyota parts, and neither one of them fixed it. No codes are being triggered.

looking down at the connectors. There are two rows of connectors in the socket. The top row has 3 connectors (numbered left to right 1, 2, 3) and the bottom row has 1 connector in the middle position. Like this:
--------
|1 2 3|
|x 5 x|
--------

If you then hook a jumper wire from +12v on the battery to connector #3 in the relay socket, the fuel pump will run and you can easily hear fuel running through the fuel rail on the motor. Then at least you know the pump and the wiring from the relay to the pump are okay.
I did this ^^ test to check if the fuel pump was working by jumping a connection from the battery to terminal 3 on the plug of the FPR, which activated the fuel pump and I could hear fuel rushing into the rail.

  • I also checked:
    • Every connection I could and couldn't figure out the problem.
    • The Fuel Pump Resistor was within the correct ohm range specified as well.
    • Circuit Switching Relay behind the US driver-side kick-panel under the dash
    • All of the fuses on the interior fuse board
    • EFI Relay under the hood
    • Every single other fuse under the hood

Temporary Solution:
I ended wiring a connection from the battery to a switch in my car, then to the terminal 3 on the FPR relay plug so I can manually send power to the fuel pump when trying to start the car. Then after the car starts, I turn off the switch and it drives like normal unless I try and floor the vehicle. If I turn on the switch and then floor it, the car accelerates and no fuel is cut off.



Possibly Related?
A few weeks ago while I was on the the interstate, my cruise control randomly began cutting out but the cruise light was still illuminated and it would kick back into cruise on its own. Then about 20min after the first couple cutouts, it completely cut out and the cruise light on the dash went out and wouldn't come back on. Then I went to dinner and came back out to the car and it worked fine the whole way home.

Near the CC unit, there are a few wires to the antenna motor that were slightly wet and had quite a bit of corrosion in the plugs. The Fuel Pump Resistor happens to be in the same area. I filled all visible connections on the entire vehicle with dielectric grease 4-months ago.
 
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Hi, Wires in these trucks are getting old. Go back in there pull plugs and check for broken or loose wires. Mike
Do you have any recommendations on where to start looking or specific junction points? I've checked all the connections I can visibly see under the hood and under the vehicle.
 

jonheld

 
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Like I said, I would check the logic before swapping parts. The fuel pump logic is run by the ECU.
Is the ECU getting +12 from the starter circuit?
Is the ECU sending +12 to the COR?
Is the path between the COR and the FPR good?

Get the schematic and a multimeter and have at it.
 
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Like I said, I would check the logic before swapping parts. The fuel pump logic is run by the ECU.
Is the ECU getting +12 from the starter circuit?
Is the ECU sending +12 to the COR?
Is the path between the COR and the FPR good?

Get the schematic and a multimeter and have at it.

1) (Blue) I know the low-speed circuit is working completely as it should because the car runs fine after it gets started.
2) (Purple) I know the high-speed circuit wiring between pin 3 on the FPR plug, through the fuel pump, to the battery is good because I hooked up a jumper to bypass the relay
3) I know the relay is working because the relay has to be energized in order for the low-speed circuit to run (which it does because I can idle and drive normally after car is started.) Which means that the wiring from the COR to Tr2 on the board is good because the relay would be in high-speed mode all the time otherwise.
4) So, the only thing I can think of is that something failed in the ECU which is causing the Tr2 to send power to the relay AT ALL TIMES, thus not allowing the FPR to disconnect from the low-speed circuit and the low speed circuit can't send enough fuel to handle start-up or full-throttle?

Orrrrrr, is it possible that my fuel-pump just stops whenever it tries to run at high-speed, but it runs fine at low-speed?
Screen Shot 2018-08-15 at 8.52.03 AM.png


Screen Shot 2018-08-15 at 8.09.47 AM.png
 

jonheld

 
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You're jumping too far ahead.
#1. Is the ECU getting +12 from the starter circuit?
This is telling the ECU that you're trying to start the engine and that it needs to fire the fuel pump circuit. If the ECU is not getting the starter logic, then it won't fire the fuel pump during cranking. You need to verify this FIRST.

#2. If the ECU is getting the starter logic, is the ECU putting out +12 on the FC (fuel control) terminal during starter cranking?
 
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You're jumping too far ahead.
#1. Is the ECU getting +12 from the starter circuit?
This is telling the ECU that you're trying to start the engine and that it needs to fire the fuel pump circuit. If the ECU is not getting the starter logic, then it won't fire the fuel pump during cranking. You need to verify this FIRST.

#2. If the ECU is getting the starter logic, is the ECU putting out +12 on the FC (fuel control) terminal during starter cranking?
Ahh, I see what you're saying now. Thank you for being patient with me haha.

I'll check this evening after work and will let you know. Thanks again, Jon!
 

SmokingRocks

I bought a Cruiser to keep miles off my Cruiser
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@jonheld is on it listen to him closely.

That said I've had FPR's that seemingly are fine and pass every bench test yet still cause the problems you are describing. Also had a circuit opening relay do the same thing. If you didn't replace with brand new oem parts you should. If the problem persist then you now have trail spares for both those relays, which are common failure points.
 
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@jonheld is on it listen to him closely.

That said I've had FPR's that seemingly are fine and pass every bench test yet still cause the problems you are describing. Also had a circuit opening relay do the same thing. If you didn't replace with brand new oem parts you should. If the problem persist then you now have trail spares for both those relays, which are common failure points.
I haven't replaced the COR or EFI Main relays, but they tested good electrically per FSM directed tests.

I did replace the TPS and FPR with new OEM Toyota Factory parts.
 

LINUS

Waiting for the Great Pumpkin
 
 
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Many of us keep a spare EFI relay in the glovebox just because they run so hot & are cheap insurance - maybe grab a new one & swap to confirm constantly good over time, and if so just toss it in a ziploc in the glovebox.

Also, did I miss you changing the fuel filter?

If you did, my bad - if not, it’s probably due no matter, and it’s cheap insurance.

The power to the fuel pump has a socket connector underside the body from the floor harness about at the rear DS door / B-pillar - that could use a pull open & make sure the gasket hasn’t failed / salt corrosion on the terminals.

If nothing else, a hit of dielectric or lithium grease all in that socket will keep it good for another 20 yrs.

All 3 will cost you <$25, even buying the grease.
 

SmokingRocks

I bought a Cruiser to keep miles off my Cruiser
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If jumping the pin at the FPR with 12v runs the fuel pump at full steam the issue likely isn't between the FPR connector and the fuel pump.

Rather that indicates the issue is the FPR or something upstream; CO relay, EFI main, or ECM control.

Based on this:
Temporary Solution:
I ended wiring a connection from the battery to a switch in my car, then to the terminal 3 on the FPR relay plug so I can manually send power to the fuel pump when trying to start the car. Then after the car starts, I turn off the switch and it drives like normal unless I try and floor the vehicle. If I turn on the switch and then floor it, the car accelerates and no fuel is cut off.
I suspect the FPR as faulty but would conduct this exact test with a multi-meter to verify.

#1. Is the ECU getting +12 from the starter circuit?
This is telling the ECU that you're trying to start the engine and that it needs to fire the fuel pump circuit. If the ECU is not getting the starter logic, then it won't fire the fuel pump during cranking. You need to verify this FIRST.

#2. If the ECU is getting the starter logic, is the ECU putting out +12 on the FC (fuel control) terminal during starter cranking?
Capture.JPG
Although I would start my test at terminal 1 on the FPR connector, stick the multi meter + probe in there and clip the - prob to a common ground then crank the engine and see if you are getting voltage at this terminal.

I can't remember if the ECU provides 12v or a ground to terminal 1 to trigger the FPR. If the above test shows no voltage then turn the multi-meter to continuity test and leave the probes as is. Crank the engine. If there is continuity then the ECU is providing the ground to terminal 1 which triggers the FPR to go into high flow mode.

If either of the above test pass the issue is with the fuel pump relay itself or circuit opening relay
 
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I suspect the FPR as faulty but would conduct this exact test with a multi-meter to verify.
It isn't likely that the old FPR and the brand-new OEM Toyota Factory FPR in it now would be faulty in the exact same way, right? I guess it's possible... but not likely.
 
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Hi, Are you sure those fuseable links are sound ? If they are not codes will throw up and the car will run poorly, not start, or randomly die. Don't keep throwing parts at it. In all the cruisers I've had Ive never replaced the computer,they are almost bullet proof. Almost always a wiring issue. Even on the Efi once you replace the wires going in under the panel to 12 gauge the problem goes away. Mike
 
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