bitwise

Hey, new member and owner of a recently acquired 1990 pickup with the 22re engine. I've recently started having an issue where the engine will start then stall after a few seconds. The first time I had to add some more gas and it ran great (I knew the tank was low) but this time it stalled out on me while just moving it around in the driveway when it should have had a couple liters. I added 13L more to the tank just in case with no luck. Still cranks, starts, and stalls after a few seconds. I've spent a couple days on this without luck and followed the suggestions in all the other posts I can find and done the following:

* I've checked and cleaned my grounds on the intake and fender by the fuse box, cleaned up the battery terminals.
* Checked the fuses on the drivers kick panel and in the engine bay. If I jump the fuel pump in the diagnostic port I can hear it running but it doesn't improve the stalling. So that probably rules out the VAFM flap.
* checked for CEL codes and I have none. If I unplug something like the TPS or MAF sensors I get the corresponding codes (still stalls if you try to start unplugged) so I'm pretty sure it's reading codes correctly
* replaced all spark plugs since the old ones were really dirty the first time it was stalling. Ran very good after that. Right now it runs smooth with no vibration before gradually sputtering out within about 3s. Know I'm getting spark because when I disconnect the wires to one plug at a time you can tell it's not firing on that cylinder because it gets rough and the engine vibrates.
* Haven't tested fuel pressure with a guage, don't have the correct fittings right now to fit the guage, but I loosened the banjo bolt on the cold start injector and it sprays out when I turn the ignition on (fp still jumped) so I think I have decent pressure and flow rate.
* Don't see any leaks in the intake tubing and fittings are tight from a visual inspection.

Here are some other things I have noticed or considered:
* I have considered that the fuel filter may be getting clogged. I can order one if that might be the issue - will take about a week. Don't think it's fully clogged because the amount of fuel that sprayed out the cold start injector when I loosened it should be plenty for it to run.
* I also know the air filter is very dirty, a new one is on the way but I doubt that would cause it to stall on its own.
* It does smell like it's running rich.
* There is a small leak in the passenger footwell by the ecu but the leak is a bit lower ECU and wiring aren't wet and it just rained hard today.
* The EFI relay feels warm after I try to start, and I hear a repeating clicking somewhere on the passenger side right as it's about to finally stall out.

If anybody has any suggestions on what I can try beyond those things that would be really helpful. Thanks!

2ToyGuy

Fuel filter, COR relay. The COR relay has 2 halves. There's a half the functions during start, too run the fuel pump during the start up process. Then, there's the half that functions when the VAf vane opens, IE: the engine is running, pulling through the VAF, holding it's vane open, even just a little bit.

Did you check that the switch in the VAF? Does it close when the vane is opened? If the switch in the VAF is good, it could be the COR relay.

Does the engine run correctly with the jumper in the B+-Fp pins? That bypasses the VAF and COR, thus including, or eliminating them.

Check that the TPS is properly aligned, and that it's IDLe switch is set properly. It's all in the FSM on how to check it.

Check the IACV is functioning correctly. Check that there is no air leaks in the big air tube between the VAF and TPS. Check for vacuum leaks.

Good luck. Keep us informed on it goes!
Pat☺

scope103

If it jumpering FP to B+ doesn't affect your stalling, it probably isn't a VAF-COR problem.

Let's see if you have fuel flow. Replace the fuel return line at the FPR with a 1/4" (6mm) clear vinyl tube to a suitable container. Run the fuel pump with the jumper. There is no spec, but I get about 1/2 liter/min. Now start it (be VERY careful; you've got fuel splashing into a fuel-can and plenty of ignition sources). You should have a pretty steady flow out of the tube right through the engine dying. If the fuel flow stops, you're not getting sufficient rail pressure, and I'd replace the filter next.

The above test doesn't directly check fuel pressure. Yes, you need a banjo-whatever adapter for your pressure gauge (easier to find for the 3VZE with the 12mm banjo; you'll need a 10mm). Whatever you do, don't "crack" a fitting to see if fuel sprays out (oh. Too late.) You must replace both crush washers; they are one time use.

bitwise

Thanks for the suggestions!

I have not checked the switch in the VAF, because jumping the FP to B+ wires in the diagnostic port did not help. And I know the fuel pump was on because I could hear it with the key turn to on and fuel squirted out when I loosened the cold start injector banjo bolt. I didn't think it was necessary at that point to check the VAF.

I just went out this morning and tested the resistances of the pins in the TPS according to the FSM. VTA-E2 was within spec with no gap (1.05 k) and fully open (5.15k) and smoothly varied between the 2 values as you moved the throttle. Vcc-E2 was a solid 6.63k no matter the position of the throttle. IDL-E2 was out of spec though. Measured as open circuit if the feeler guage between the stop screw and lever was any bigger than 0.254mm (my thinnest guage) when it's supposed to be 2.3k or less at 0.57mm gap. Looks like the stop screw is adjustable and I might be able to loosen so that IDL-E2 is not an open circuit at a 0.57mm gap while keeping everything else in range. But I wouldn't think that's the issue with it stalling given it stalls when I'm not giving it gas and it looks like the IDL-E2 resistance is correct with no gap. One thing maybe worth noting is that it lasts a few seconds after starting, but if I press the gas pedal it dies immediately.

Also tested the battery at 11.87V but I didn't think that was the issue. Still doesn't start when connected to another vehicle.

I'll go and do a better inspection of the intake hoses to check for cracks later. Would a leak matter even with the fp jumped? As far as other vacuum leaks I'll see what I can do. I did test the fuel regulator vaccum hose when it was running a few days ago. Extremely weak vacuum from the hose. Again, that's probably not causing the stalling since you can normally run with that hose unplugged anyway. But I think I found where it's leaking from a connection so I'll probably go out and buy some new lines and replace what I can to be safe.

I'll go follow the FSM procedure for testing the IACV later. When I got the truck it was idling low around 400 rpm once warmed up so I loosened the screw to raise it to around 700-800. Maybe there's a problem there and I was just masking it by adjusting the screw.

bitwise

I'll give that a shot. Get some tubing tonight. I'll tow it out of the garage first before trying to start it. I've had enough bad experience with fire to take as much precautions as I can. Also found a specialty parts store nearby that could get me a new fuel filter next day for $11.50 CAD.

bitwise

Just finished trying this. Connected the return line to a tube and also a pressure gauge which I led away and turned the ignition to on with FP connected to B+. No flow whatsoever out the return line and no pressure on the gauge. I know I had the right line (the one under the FPR compared to vacuum line above) and it already had a bit of gas in it. I double checked I was getting anything at all by cracking the cold start line (I figure since I should already replace the crush washer, might as well try again) and fuel came out. Trying to start the engine had no impact on fuel coming out the return line. So it might be that I'm not getting enough pressure to exceed whatever threshold the FPR opens the return line. I'm going to try replacing the fuel filter tomorrow in case that's so clogged it's causing a pressure drop. I also contacted the previous owner who had recently replaced the fuel pump with a brand new pump. Hopefully that's not the issue but maybe I'll have to check that next if the fuel filter doesn't help.

bitwise

Update: replaced the fuel filter last night. Old one was extremely clogged. Held it vertically and put some fuel in it and it wouldn't come out the other end, compared to the new one which went right through. Ran the pump for a few seconds to clear the lines and the first bit had a lot of sediment but cleared up within a couple seconds. Still no fuel coming out the return line though. Does anybody know if there's some critical pressure that needs to be met before it opens? Might be low pressure still so maybe this weekend I'll drop the tank to have a look at the pump and sock. Given how clogged the filter was I imagine the sock is bad too.

But replacing the fuel filter got it running again. Strange thing is, I had to unplug the TPS and AFM which I didn't have to do before (I also tried that before changing the fuel pump and it didn't work). If I plug either the TPS or AFM back in it dies. So I guess besides taking a closer look at the fuel pump I'll have a look at the sensors.

bitwise

If anyone is still following this, I dropped the tank. The fuel pump sock / strainer was pretty dirty and clogged. I'll get a new one and see what that does. Hopefully the pump is not ruined but I'll test before putting the tank all the way back. Drained the tank and the bottom, especially in the pump pickup area was filled with a sort of rust sludge. Cleaned out the tank so if the new fp sock doesn't fix the problem that narrows bad fuel pressure down to the pump or a clog in the lines. Don't think the lines are blocked since nothing big would come through the fp and they looked clean when I took them off.

bitwise

So I found the problem. There is a rubber hose that connects the top of the fuel pump to the hard metal lines within the tank. I noticed when running the fuel pump outside the tank that hose had split. Pressure tested and I was only getting 5 psi, the rest came out and fell right back into the tank. So I replaced the hose and did another test and got 100 psi which is too high. Figured out the return line was clogged at the very end where it sticks at the bottom of the tank so I cleaned that out too.

Just stuck the tank back in this morning and after testing for leaks with the fp jumped it started on the first try. I would never have found that without taking out the tank, and it wasn't that hard to get the tank out. So if anybody is having any fuel pressure problems I wouldn't hesitate to drop the tank. Good chance to check out the frame behind it and see if the tank needs cleaning. Thanks everyone for your suggestions!

2ToyGuy

Glad you found the problem!

Tank dropped is a good chance to clean all around where it mounts up, and the tank's surface, and look for rust. There's enough room above/around the tank to hold "stuff", which can hold water. Rust city. Be careful before you put the tank back up permanently. Clean any rust off, and if it's just surface, take it off with a wire wheel, and paint the bare metal to try and keep it from happening again.

Sorry I wasn't more help...
Pat☺

bitwise

For sure. The frame is pretty good. I think somebody redid the whole frame at some point with POR or something. But I see it had a patch on the inside rail by the gas tank. I used a wire wheel on a bit of rust on the tank and painted it. I also sprayed some fluid film all around behind the tank before I put it back. The frame is bare right now, but living in a salty area I'd like to stop it from rusting away.