legojego

Hey guys, new to the forum here. I bought a '91 Pickup last summer. Such a fun little truck. I've taken it off road a few times and I can hardly believe what it'll get through.

Anyway it was running great until recently. It developed a misfire for a few weeks and before I could diagnose it, it stopped running completely. It turns over fine but doesn't fire at all. I checked for spark and that's good. Also checked VAF resistance and that's good. I'm assuming fuel pressure is good because otherwise it wouldn't spark (according to this comment).

As far as I can tell the engine is getting fuel, air, and spark. So I'm not sure what to try next. Any ideas?

EDIT: forgot to mention what engine it has. It's the 3VZE.

scope103

Welcome to YotaTech.
If you read further in that post, you'll see eddieleephd also says: "note the ECM looks for fuel pressure and air intake before giving a spark as well it needs a signal from the cam and crank sensors so I would suggest testing for the cam and crank signals at the ECM as well as at the sensors and be sure the ECM is getting the intake and pressure signals it is looking for." Unfortunately, there is no fuel pressure sensor, no cam sensor, and no crank sensor in your truck. I can't tell you what vehicle eddieleephd was thinking of, but it's not a 2nd gen Toyota.

Yes, it sparks even if the fuel pump is not running. So you'll need to check that. While I'm not a big fan of starting fluid, you can try a small spritz here. Don't forget that all the induction plumbing (VAF, air cleaner) needs to be connected, so you'll shoot the starting fluid through the tube that connects to the valve cover. If that causes your truck to fire, you'll need to get serious about checking the fuel pressure.

A possible cause of misfire (and no start) is loss of compression. Rule that out; get a $30 gauge https://www.autozone.com/test-scan-a...ece/273352_0_0 and check it.

legojego

Thanks Scope. I'll check compression and try some starting fluid. Really appreciate the tips.

While I was checking for spark, I noticed that if I removed the EFI fuse there was no spark. Any idea why that would happen? I found an ignition system diagram and I'm not seeing any connection between the EFI fuse and the spark plugs.

scope103

See any power to the ECM in that diagram? BATT is through the EFI fuse, +B and +B1 are through the EFI Main Relay, also downstream of the EFI fuse. The igniter does need the IGT signal from the ECM to fire.

legojego

Ah, I see. Thanks for explaining.

legojego

I tried some starting fluid today and the engine fired. So I guess it is a fuel issue after all. Thanks a lot for the tip, Scope. I'm going to test the relays next. Really hoping it's not the fuel pump. Dropping the tank seems like it'd be a bit of a nightmare.

scope103

Not likely a relay. Here's what I know about the fuel system: https://www.yotatech.com/forums/f116...-quits-312747/

legojego

Thanks, Scope! Great write-up, very helpful. I've also started going through the troubleshooting chart in the FSM.