RIPSAW

Recently, 2004 Toyota 4 cylinder would not start..(Read below for detail if you have time) The jest is what should you do if it cranks fine but will not start.
Know you push the accelerator to the floor and crank 15 seconds and then let up and try normally if it's flooded but this was not the problem. It had fuel pressure since the hose to the fuel rail was hard. However, it cranked us and has cold idle for 2-3 seconds and dies like no fuel. Then it wont do anything but crank strong. However if you have say a bad temperature switch, IAC valve or trash in the EGR. How do you get it to start till you really fix the problem?

My problem was but seems to have fixed itself after two days of checking and finding no problem. (PS, my quest went unanswered on the Toyota forums..way over anyone's head on there or my poor communication skills...)

Since this is a close match to my problem and need of understanding..Will present my thought and hope others can do some enlightenment.

Truck only has 50K bought new by me. First problem ever. Will start up but dies when you come off start side of key. 2004 4x4 Regular Cab Tacoma with the 3RZ-FE has the circuit opening relay under the drivers side fuse box. The relay is the same part number as the EFI relay and power supply in fuse box 2 under the hood. Relay is single control with only one coil. EFI relay supplies power to Circuit opening relay. The start side of the ignition supplies the control side of the circuit opening relay and the ground side of this control is the ECM.

So in a nut shell, the circuit opening relay closes and turns on the fuel pump when cranking. When motor starts, when you let off on the start, the running condition then makes the relay stay closed and keeps fuel pump on. If by chance, motor does not continue running, the normal on side of the ignition key does not keep relay on and the fuel pump does not run. (it's a safety switch to the EFI relay) Other cars use a timer to to run pump and do not have this extra relay. The running part that tells the ECM to keep the circuit opening relay closed is the Cam Position sensor. (it's OK in range)



Problem comes and goes. Driving me crazy and can no longer trust truck. Truck still has a airflow valve. Fuel pump pumps fine when you give it power to the blue wire on the circuit open relay. The call out for the fuel pump is .2-3 ohms . It reads 1.3 at the wire at the relay. Crank sensor calls for 1630-2740 ohms. It reads 2060.

This system does not have a fuel pump timer like most FI engines?

Another interesting fact is this motor has two 3 temperature sensor. One back by the ERG valve. One on the front right water housing (controls temperature gage) and the important one is hidden in back of motor on back side of valve cover at firewall. (need to lift protected wire harness on three hangers to see it). It is what reports to ECM for start and warm up fuel mixture. However, it reads in in range cold.

At first I thought it was ECM since when I grounded the signal wire to the ECM thru my meter to ground to make sure ECM was OK, motor started. So I figured the ECM was not getting a signal from the cam position sensor. However, since I did that, it always starts now. However, the truck was dead for two days of tinkering and I know there is a problem somewhere.

mac25

OK you really need to test things.

You do not guess fuel pressure by feeling a hose.

Get a fuel pressure gauge and hook it up, test it while cranking, running and driving, then, compare those numbers to OEM spec.



Second this may not be fuel related at all. It could be a faulty ignition switch which is cutting power to fuel, or some other electrical issue.

Hook up a volt meter to the fuel pump while you drive to monitor voltage.
If pressure looks good until voltage drops, you have an electrical issue.

if voltage always looks good and fuel pressure drops you have a fuel regulator/fuel pump/ or intermittent pressure issue.

RIPSAW

I tested everything to the oem service manual. Nothing appears wrong now. My question was more or less, say it was the temperature switch and the motor though it was warm and toasty and yet it was 40 degrees. In my mind the engine needs choke (on in the case a modern engines..fuel. Can you crank it and pump the accelerator to shoot more fuel to it? One fact I did not say in the first post was I had just filled it up that previous evening. Maybe I had got a trace of water. However, since that time, it has never missed a beat. PS.. On this engine with out a prime circuit timer, the pressure check on the hose with your finger replace listening for the prime circuit when you key on in most cars (and even my bike) It's in the service manual as a check since you cannot hear the fuel pump when cranking. I have check it now to make sure it is correct and the filter does not need replaced. (filter is a pain to get to under the intake curve) Thanks for the reply

sdaidoji

iTrader: (1)

Oh, c... You asking questions is rare...

Good luck, Ripsaw...

mac25

Sorry for being a bit cheeky there but I still believe using a fuel gauge is best.
fuel to the line does not mean operational fuel pressure.

If the fuel is the only thing you have changed since the issue started, perhaps drain the tank and add new fuel?