OK, so I've done all the testing and replacements and this is where I am currently at. Cold Start Injector will spray ONE TIME when starting to crank, I can not test my fuel pressure and the way I see it there is only two options. My fuel pressure regulator is kaput OR my fuel pump can't keep up with the cold start injector. Which do I start with first? Could it be something else?? Suggestions? Just in case it isn't in my signature, 1987 Toyota 4Runner with tested ColdStart Sensor and replaced Cold Start Injector.

Thanks in advance.

Tim

 

When you say you've done all the testing and replacements, can you give us a rundown? Try jumpering the Fp to B+ in the diagnostic connector and see if you hear the fuel pump running with the key on. I have not read of too many fuel pressure regulator failures, not saying yours is good, but it does not seem like a common problem. Has your fuel filter ever been changed?

 

Like mentioned above, we need a list of what's been tested the general or exact result and what has been replaced. Because obviously you haven't replaced everything, or you'd be asking about a 2017 4runner now..

Cold start injector should only fire once, it will only fire again when the key is cycled and even then only if the timer is allowed to recool

87 has the pulse damper use it to verify the fuel rail has pressure (before cranking) it should push out the button to be flush with the housing face. If it's no good start with the COR checks. And then again after, if it's not pressurized after it's a VAFM problem possibly. Jumpering the test connector will by pass both, if it's no good then it's a supply issue(filter or pump, more likely than the regulator)

As a temporary work around of low starting fuel pressure cycle the key from off to on a few times before cranking, this forces the COR to operate and will bring up the fuel rail pressure to it's maximum as long as the fuel pump check valve is not sticking open.



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So... tested and changed cold start sensor and injector. Changed fuel filter in 2008 or 2009 along with fuel pump. I have jumper-ed the fuel pump and can hear it though to me is sounds weak (but I have a FASS on my dodge and it rattles the frame its mounted on), I did change the pre-filter when I changed the pump. This is inherently a cold starting issue, like I said before only an issue below 50 degrees.

 

So I thought the CS injector was supposed to continue to fire until the Cold Start Sensor warmed up. see response to prior post as to what I have done so far, any other ideas on cold start issues?? since the cold start injector is apparently functioning like it is supposed to?

 

no. the csi only fires when the ign switch is in the "start" position AND the temperature of the csits is below a specified temperature. it does not fire continuously.

 

So it could potentially fire more than just once.... at least until the cold start sensor gets up to "temp".... which brings me back to it ONLY fires once...

 

you've omitted an important detail. for a manual transmission 4r, to get the fuel pump to run and build fuel rail pressure without attempting to start the engine, turn the key switch to the "start" position without pressing the clutch pedal, and without pushing the "clutch cancel" button. this assumes that the clutch start cancel function is working correctly. this will cause the pump to run, but the starter will not operate. you can accomplish this by holding the key in the "start" position for a second, then while holding it in the start position, depress the clutch pedal to start the engine.

the pump will not turn on just by turning the key switch to the "on" position and then the "off" position several times. doing that, in a properly functioning system, the pump will never turn on.

edit: if you also jumper the B+ and Fp ports, then you only have to turn the key to the "on" position, you do not have to cycle it from on to off, and i see that your earlier paragraph lists this, and in this context, the last paragraph is correct.

wally

 

Too many humps not enough coffee? For some reason I saw a ground on the capacitor, which would prime the system with ig2

turns out even on a MT your still firing the CSI unless you don't have the starter relay (85 style start systems). Now I've learned something today I can go back to bed!

The point of cycling the key was to build pressure by charge and drain cycles of its capacitor. A moot point on AT or starter relay equipped vehicles..

I have to go back and quote the OP now and maybe make some coffee..

 

did you clean up the mounting hole really well, if not the timer doesn't have a proper ground which effects the CSI duration. Not a bad idea to descale the Ect sensor while you're there

Remember the cold start injector time switch is internally heated when active to prevent flooding, it needs a cool down period between cranking attempts to re-fire the injector.

By pass the COR like Corey(?) Said in the first response by jumpering the pump see if it starts. If that doesn't get it going it's not the COR issue

 

Second that.
The best brand-new CSI and CSI timer switch on 87's and earlier 22RE would not work without ground from the mounting thread. (In 88's and later, the ECU helps provide ground to CSI when ECU gets signal from the ECU temp sender that it is cold.)