cracker1

After checking everything I could, I am stumped. 1989 4runner 3.0, was running. albeit poorly-low idle, before I had my son change the valve cover gaskets. Now it turns over but won't run, I have fuel in the rails and spark. Will fire initially on the cold start injector, but won't run on it own. I can spray fuel thru the throttle body and can keep it running... Checked the fuel pressure at the pump, 55psi. Checked fuel rails and fuel at the banjo fittings. Changed injectors with another set I had, no change. I have 12v at the injectors with the key on. Have jumped the fuel pump, swapped the AFM and ECM with another I had from a running 4runner, still nothing... Checked and even swapped the injector relay. All grounds are attached and good on the engine. Did notice the EFI fuse was initially blown, now its good.... What am I missing??? What would have blown the EFI fuse? Checked all wiring, everything looks good...

scope103

These usually mean a problem in the VAF-COR circuit -- the fuel pump runs with key to STArt, but the COR is not getting (or acting on) the signal from the VAF. Of course, the easiest way for this to happen is to try to run the truck with the induction (air cleaner) plumbing disconnected, but you wouldn't do that.

You can connect a fuel pressure gauge at the FPR to watch the pressure as it starts up. Even easier is to jumper FP to B+ on the diagnostic connector to force the pump to run with key-on only. If it runs now, you've identified the area of the problem.

cracker1

Tried jumping the FP/B+. Pump runs but engine won't.

cracker1

Doesn't anybody have any ideas on this problem???

akwheeler

[QUOTE=cracker1;52399405]After checking everything I could, I am stumped. 1989 4runner 3.0, was running. albeit poorly-low idle, before I had my son change the valve cover gaskets. Now it turns over but won't run,QUOTE]

Yeah, something didn't get connected back up when the gaskets were replaced or a wire was broken or pinched. check all your grounds and connectors. Is the intake completely reassembled all the way to the air filter?

RAD4Runner

Look at C.O.R. aspect as mentioned above^^^
Also...
There will always be 12V at injectors when IGN is on. Also 12V at the negative side of the injector connector at rest. However, are they getting grounding pulse from ECU in order to fire them? See Injector to ECU wiring schematic, and inspect wiring. Sorry I only have 22RE schematic.

scope103

Well, it COULD be a broken wire to the injectors. There is 12v constant with key-on; the ECM opens the injector by grounding the other side. All 6 injectors open at the same time, but they are WIRED in two banks (making it a little less likely to take out all 6 injectors, but wadda I know?)

The injectors make an audible click when opened, which can be heard with a stethoscope, but you'll have a hard time picking that up over the sound of the starter. A "noid" light will tell you if you are getting the grounding pulse. (a noid light is just an LED with a 1k series resistor. What you PAY for is all the connectors. You can build one yourself if you can connect three wires.)

Have you tried cranking, then pulling a plug? If the plug is dry (and you've REALLY confirmed you have adequate fuel pressure in the rail), then the injectors may not be opening.

cracker1

As stated, I have 55psi at the pump and it is running. I don't hear the injectors thru the stethoscope. The intake plenum is off currently, haven't found any broken or pinched wires anywhere...
Also, what would have caused the efi fuse to blow? Found that initially, figured my son grounded something out... fuse is good now.

Saturn

You mentioned an EFI fuse, but have you checked the 4-pin relay in the box in the engine compartment? I had that go bad and stop it from running. And check the ground on the back of the upper intake manifold near the firewall, it has a connector going between two bolted grounds, I've left it unplugged before and gotten no start issues.

cracker1

Where is the 4 pin relay located? Grounds are all good and connected.

scope103

The spec for fuel pressure at the rail is 38-44psi http://web.archive.org/web/201003261...87fuelpump.pdf Since you think you have NO fuel flow, there is insignificant pressure drop from the pump to the rail. So 55psi at the pump means you could be flooding the engine. I suggested pulling a plug to see if it is wet.

cracker1

Plugs are dry. I am going to replace the COR and recheck all wiring.

RAD4Runner

Check wiring, yes, but do not replace COR unles you are absolutely, positively sure it is defective and that replacing will fix the problem. See signature.

cracker1

I haven't found any damaged wiring or anything else for that matter that would prevent the injectors from working. So, I think I have an extra COR relay on my shelf, so won't cost me anything to try...

scope103

Ah, the switch and pray. Do you have any reason to think your "spare" COR is any good? Easy to test, but you seem to be allergic to testing.

What happens if you plug in the spare, and the truck starts working? That means you were right, doesn't it? Well, unless the problem was a bad relay socket; cracked wire, or something else you bumped into blindly switching parts. And a few weeks from now the relay will wiggle out of the bad socket and the truck won't start anymore.

This test, if done correctly, positively tests the COR.

Why don't you now check for fuel flow. No special tools needed; just run the fuel return line into a suitable container and run the pump with the jumper. You should get about 1/2 liter/min. If you get nothing, there may be no fuel pressure in the rail.

cracker1

I am going to check the gas flow tonight and see if the gas is flowing or not. Then onto whatever else... I know there is gas in the rails, as I have cracked them and got sprayed...

wallytoo

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wallytoo

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cracker1

No fuel out of the pressure regulator on the left fuel rail. So, not enough pressure or? Again, I cracked the fuel log below it and fuel sprayed out. And checked the cold start injector, fuel there also. Fuel pump failing under pressure?

RAD4Runner

Thoroughly check ECU to injector wiring. That is usually in very extreme environment so wires / crimps go bad.

And consider installing fuel pressure gage like Wallytoo, I and others have done (on our threads).