gwat

My truck refuses to start. Seems like it is getting spark. Air filter looks good. Fuel filter was new last fall. Could it be fuel pump? How to check? Other ideas??
Its a '92 22RE. It fires and gets up to 2K RPM for about one second then dies. I can hit the gas when it fires and it will stay running a split second longer, but still dies. It seemed to be running fine before this, no hesitation or sluggish starts. Help please!?

spanish-road

test for spark and see if it is getting a good one. To test to see if your fuel pump is working:

1. CHECK FUEL PUMP OPERATION
(a) Turn the ignition switch ON.
HINT: Do not start the engine.
(b) connect terminals Fp and +B of the DLC1.
HINT: The DLC1 is located near the No. 2 relay block.
(c) Check that there is pressure in the fuel inlet hose. (feel the rubber fuel line for pressure)
HINT: At this time, you will hear fuel return noise from the
pressure regulator.
(d) Remove SST from the DLC1.
(e) Turn the ignition switch OFF.
If there is no pressure, check these parts:
• Fusible links
• Fuses (EFI 15A, IGN 7.5A)
• EFI main relay

sb5walker

https://www.yotatech.com/forums/f116.../#post51266212

iamsuperbleeder

I'm willing to bet the AFM is either unplugged, or faulty

gwat

The fuel pump seems good.
Checked the AFM. Took a voltmeter to it and here's what I found:
E2 to Vs was good at 190
E2 to Vc was good at 180
E2 to Vb, super low readings (40--60ish) that flashed on the display for a split second. I assume that`s not normal.
Does this confirm the AFM is faulty.

sb5walker

It's the fuel pump switch - E2-FC - that would prevent it from running; do you get continuity when vane is open?

E2 to Fb being out of range might make it run poorly, but I don't think it would prevent it from running.

Have you checked for codes?

gwat

I didn't check with vanes open vs closed but I will do that.
The check engine light is burned out. That's the only way to get codes, right??

sb5walker

Yes, FC has to be grounded to E2 when vane is open to trigger the fuel pump relay (circuit opening relay). Otherwise the relay will only be triggered while ignition switch is in the start position and motor will stall as soon as you release the key.

Re: the CEL, first check the Gauge fuse that supplies power to the CEL (the ecu grounds it), but if the fuse is good & has power when ignition is on then yes, either replace the bulb in the cluster or you could identify the grounding wire from the ecu and rig up your own bulb to get the codes.

gwat

OK, latest developments. AFM seems to be fine. I replaced the fuel filter and voila! she fired up. Had her idling but after about a minute it died again. Now I can fire it up and get it going, but it will sputter and die unless I've got it revved over 3K and even then it dies after a short while. It will hold a nice steady idle for a few seconds, then sputter and barely be hanging on, then will get back to a normal idle again. Sometimes when I hit the gas it cuts out, sometimes it will rev up.
I thought it was bad gas or water in the tank (its been pissing rain for the past few days) but with fresh gas the problem is still the same. Is it worth trying another fuel filter (thinking the one I just put in could have got clogged with the old gas if it was indeed bad) or are there other things I should be looking at. This sucks, I just want to drive!
I will try riging up some sort of bulb to the ECU.

sb5walker

If you still have the old filter, grab a hacksaw & cut it open.

Possible to have water in the gas, but with all the alcohol in gas these days I would think that a moderate amount of water would be absorbed. A larger amount would of course be a problem.

May be time to get a fuel pressure test.

gwat

Ok, so fuel pressure test reads 6psi. Doh. Is there any reason, other than a faulty pump, why it would read so low. I'm not sure of the function of the fuel pressure regulator, could that be causing a problem? Also, the wiring on the sending unit looks old and corroded, if the pump isn't getting proper power could that cause it to pump low pressure?

sb5walker

The way it's supposed to work is the pump runs continuously and is capable of developing much more pressure than the 38-44 pound design pressure. The pressure regulator is essentially a spring-loaded relief valve that spills excess pressure/fuel down the fuel return line (the rubber line that comes off the side of the regulator), and the fuel runs down that line and back into the tank.

There's a vacuum line that runs from the fuel pressure vsv to the top of the regulator. The ecu triggers the vsv to open at idle, causing vacuum to lower the pressure to 33-37.

So, low pressure could be due to a bad regulator, or failing pump, or yes, a corroded connection to the pump can also cause the problem. I know, big help, huh?

If I had to guess, I'd say most likely to be bad pump or pump wiring. If you need a new pump, get a Denso - the best deal that I know of on them is from autohausaz.com, which sells the denso pump, sock, and a kit with all the fittings for $180. Thanks to the friendly foreign owners of our federal reserve bank who have devalued our currency by printing up an extra 2 trillion in the past three years, this price is $30 more than it was 6 months ago.

EDIT: Oops, in my ranting I forgot to add that you should get a new pump bracket gasket and screws (I think there are seven - not 100% sure) from the dealer. May also want a new gas tank drain plug gasket if you plan on draining the tank before removing it.

gwat

Faulty COR! I'm back in action.
Thanks everyone for the help!