No Start

[Johnny Cetane]

This seems to only happen after the truck sits over night. I don't know if engine temp or ambient temp have anything to with this. It might be just coincidence. It's in the teens right now and this has yet to happen after the truck is started for the first time after sitting overnight. It just cranks but doesn't fire. It's intermittent too. Sometimes you walk away for 5 minutes, come back and it'll fire instantly. Other times I can get up, go out there and it'll pop right off. I always look for something unplugged but everything is connected. I've checked for spark twice and both of those times it was getting spark so I take that to mean it's not getting fuel.

Is there a common cause I can look for? Seems like a stuck relay to me but I really have no idea......

It's an EFI with 225K on the truck. Almost all of my engine harness connectors are broken so they're missing the keepers but they seem to still be fairly tight.

[Johnny Cetane]

I'll add that this never seemed to be an issue before I rebuilt the motor. I only started it about 4 times before I pulled the motor but it always started.

Removing the motor I broke the water temp sensor on the front of the intake. I replaced it with one from Checker. (I know....) This might just be coincidence though.

I just tried to start it again. It's a little warmer out and it popped a couple times but never actually fired.

Cold start switch on the front of the intake?

[big d 85 yota]

turn the key to the run position and listen for the fuel pump turning on for a few seconds in the fuel tank. if it building up psi and turning off it is working properly. from there i would check to see if you got psi in the fuel rail. just loosen a fitting and see if fuel sprays out steadily. if you got psi there and still no gas in the cylinder your ingectors might not be working. dont know whey it would only be when cold though. or you might have valves out of adjustment that can make it hard to start when cold. got fresh plugs? what kind are they? new fuel filter?

[Johnny Cetane]

Ok, here's some more info. I went out to it and right now it's 21*F. It coughed and sputtered but it finally started. Now it fires right up and doesn't miss a bit.

I measured the water temp sensor that I put in and it measured some 7K ohms, which by the chart I have the temp sensor should be at around 10.2K ohms at 21*F. I don't know how big of a deal that is though? Thoughts?

I measured resistance across the terminals of the cold start thermo switch and it checked out at 30K ohms. ( But I still wonder if it maybe intermittently opens up internally when the temp drops below a certain degree.)

To add to things I also just ran out and bought a brand new battery for it. The old one only let me crank for about 5 minutes and it would die. I don't think that was the cause but it needed one.

TO answer your questions: My hearing sucks so I can't even hear the pump run when it does start good. I set the valves when I went through the motor. It has a new head assy from engnbldr.com, new pistons, etc. I got the whole kit. I put in new NGK plugs, cap, rotor, and wires from NAPA when I went through the motor. The fuel filter isn't brand new though.


Will the cold start injector stuff cause it to not start at all? Can someone give me the basic low down on how the system operates? I'm going to wait until this evening and try and start it again. If it doesn't start I think I'll hot wire the cold start injector with a toggle switch and see if that makes it start. Sound like a good plan?

[Johnny Cetane]

Oh and for full disclosure purposes my knock sensor isn't hooked up. There's no wire there anywhere. And that valve under the front of the intake that has coolant hoses running to it and to large hoses that run to the upper intake- that's not hooked up electrically either. Again no connector anywhere to be found.

I don't know if either of these will cause something like this but figured I better mention it.

[2ndGenToyotaFan]

The connection at the throttle might be an issue... As it could be temp related... The temp sensor being at 7k instead of 10 could be that the coolant wasn't all the way down to 21 like the air was.....

[KLF]

Originally Posted by big d 85 yota

turn the key to the run position and listen for the fuel pump turning on for a few seconds in the fuel tank.

No, this will not make the fuel pump run, not even for a second. You are thinking of the older Bosche EFI systems, like VW uses.

The fuel pump in Toyota (AISIN) EFI systems runs normally under only 2 conditions: the engine is cranking, and/or the engine is RUNNING and there is enough air moving thru the airbox to move the flapper in the MAF sensor. Otherwise, the pump does not run, this is a safety measure.

Take a paperclip, bend it into a U, congratulations you just made an SST (Special Service Tool). Now, take this SST, pop open the cover on the Diagnostic port, just behind the fuseblock under the hood (behind the battery). Put the paperclip across the B+ and Fp contacts in this connector. Then, turn your key to ON (but don't start the engine). Get back out, go back to the tank and listen, you should easily be able to hear the fuel pump running. Listen at the top of the engine, you should be able to hear fuel hissing thru the rail that feeds the injectors, and thru the pressure regulator. If you can hear it, then your fuel pump is fine. If not, then you either have a wiring problem or your fuel pump is dead.

But being an intermittent thing, I doubt this is the problem. It sounds to me like the cold start injector may not be working. Have you pulled it out of the intake? It make be REALLY dirty. You can put a test light across the terminals and see if it's open when the engine is running but still cold.

I would also take a close look at the EFI relay, it is under the pass side kickpanel, I believe above the engine ECU. If you listen carefully, you can hear it CLICK when you shut the engine off. At least I can hear mine every time.

[Johnny Cetane]

Thanks guys. Yeah I've been out playing with it a little this afternoon. I also removed and cleaned the cold start injector. It was pretty black and grubby. I jumped the pump terminal and I could hear the pump. As I said my hearing is bad. I can't hear the pump unless I'm standing next to it. I've rigged up a jumper for that to keep on the truck. If it won't start I'll jump that first. If that makes it start then I'm going to guess it's the control relay?

I rigged up a toggle switch with some extended leads with fuses. My plan is if it doesn't start by jumping the pump terminal I'm going to hot wire the cold start injector and see if it starts like that.

If it does with the injector hot wired then I guess I'm down to the timer switch???????

[Johnny Cetane]

I figured I'd update this a little bit because I can't stand searching for a repair to a problem that I am having and only finding semi-completed threads.

FWIW, I replaced the battery, cleaned the cables and cleaned the cold start injector and I haven't had any issues since my last post on 12/16/07.

So I don't know what exactly fixed it. Probably a combo of the battery and injector clean but hard to say.

[2ndGenToyotaFan]

Thanks Johnny!