a1jasong

Long time reader - first time poster.

I own a 91 4runner with the 3.0 and it won't start. Engine turns over fine - I have fire/spark, timing verified, compression (140psi), and plenty of fuel pressure. The cold start injector is not sticking open and the MAF tests OK. Will not fire even with starting fluid. I'll list everything I've done/checked/replaced first.

Distributor, Cap, Rotor, Coil, Igniter, Plugs, and Battery all replaced.
Double-checked all grounds and ground wires for continuity.
Ohm'd out G1, G2 and NE - G1 and G2 = 226 ohms, NE = 225 ohms (at ECU harness) - NE just a tad high (+~25ohms) according to manual and temperature.
Cleaned all connectors at igniter, coil, distributor and battery.

Check engine light comes on when ignition is turned on. No codes, but CEL light flashes quickly and infinitely when jumper is installed.

Now here's what happened prior to the breakdown: Came out one morning and the truck wouldn't start. Checked for spark and there was none - pulled the cap and found one of the signal generators had blown apart (copper winding unwound and perhaps shorted (to ground) the rotor button (and anything else hooked to it). Went to the junkyard and replaced distributor - reinstalled exactly how the old one came out...I've since verified TDC/Compression stroke and reinstalled it again. Still no fire, hence the purchase of the coil and igniter.

Common sense says I got a bad distributor from the junkyard...but maybe someone here has a different idea.

My working theory is that the NE or G signals are not telling the igniter when to fire the coil...or the signals are making it into but not out of the ECU...but I don't own an oscilloscope to absolutely verify those.

At this point, I'm looking at everything so closely, that maybe someone will comment that maybe it's something simple.

Anywho, any help/ideas would be great...!

scope103

Which is it? Do you have spark now? Put your timing light on each plug wire and verify that the light flashes (if not, suspect the plug wire). If no flash on the plugs, back up and look for flash on the lead from the coil. There is a reason why they are called "junk" distributors. But trashing the distributor could have shorted (and wrecked) the coil.

If you managed to get the distributor in 180° out of phase, you will read correct timing off the harmonic damper, but the plugs will be firing at the end of the exhaust stroke (and do you no good).

Pull a plug or two. Are they wet? If not, your injectors may not be opening (but the starting fluid test, as bad as it is, will usually show that up.)

Good luck!

a1jasong

Thanks Scope.

I do have fire now...sorry for the confusion. The no fire situation was right after I found the signal generator looking like a copper birdnest. I set the rotor button by removing the timing belt cover, moving the crank to TDC and checking my cams were on their marks (to make sure I was on the compression stroke)...I also wanted to make sure I didn't have a slipped timing belt.

The plugs have gas on them, but still fire.

I guess my next steps are to check the air gaps on the distributor and perhaps make another trip to the junkyard on Monday. I know where there is another distributor. This problem has been beating me up for a month now...you may be right and I pulled a bad distributor from the junkyard...it was from a truck that was not wrecked...so it could have ended up there with a bad dizzy...fun, fun.

I'll try to repost here when I solve this problem...I haven't found any other threads covering this issue, yet.

RSR

Well if the wire unwound on that signal generator and got sparked by the ignitor, it's possible it fried the ECU -- but I think that'd be a catastrophic failure that'd kill you on the road, not a failure to start. Same if it fried one of the other ignition components. Did you limp home before the failure to start?

With bad signal generators even in a replacement distributor, I think your truck should still start, but would just get really bad fuel economy as the computer would overpump fuel to protect the engine, since it doesn't know where the cams/cranks are in the cycle...

Mine ran fine but rich with the NE (crank) signal not working at all (measured infinity). Others have run but gotten bad mileage with one or both of the G (cam) signals not in spec: https://www.yotatech.com/forums/f116...estion-241202/.

Don't know what Gs not working at all will do, but don't think you're likely to get two that don't work in entirety.

FWIW, Amazon sells new richporter distributors for the 3vze for $130. Sure beats Toyota's $700.

RSR

Also, if you installed one tooth off your truck may not start either despite spark. Important that the groove on the teeth lines up with the groove on the distributor body that lines up with groove above the distributor slot on your engine...

scope103

I may have created some confusion. By "fire," you mean that the plug is throwing a spark, but the fuel is NOT igniting? If the plugs are sparking (which you can easily check with the inductive pickup of the timing light) then your problem is probably not the distributor.

If the G signals are absent, there is no spark. http://personal.utulsa.edu/~nathan-b.../7descript.pdf Just because the coils are slightly out of resistance-spec doesn't mean they won't generate the G signal. (But if they are far enough out of spec they probably won't; so go ahead and do the easy diagnostic.)

One tooth off just introduces 28° of ignition timing error. He said his is timed correctly, which tells me that it is NOT off by one tooth, and the distributor is causing the plugs to spark.

a1jasong

Thanks again for the input!

I've got some more to report...

The crank sensor air gap was 0.017" (just out of spec). I moved it to 0.010".
I took the battery to Autozone and got a new one since it wouldn't take a charge...probably from me cranking on it for a month.
I placed the crank on TDC (compression stroke) and reinstalled the distributor with the aforementioned marks all in place...I'm fairly confident the distributor is installed correctly.

An interesting bit of trivia: after installing the distributor by the marks, the rotor button is definitely further to the left (CCW) than it was...so I may have misjudged where #1 was on the cap...I noticed the metal cam no longer lines up with the G1(?) signal generator...the book's unclear where that should all line up. I'm tempted to cruise Walmart's parking lot and pull someone's cap to find out. lol...you may read about me in the news.

One spot of semi-good news: Upon removing the battery for load testing, I found someone had tried to splice into the wire feeding the fuse box in the engine compartment and it was loose...real loose. I've replaced the battery terminal and correctly spliced into the fusebox..so no more intermittent power loss (was never a problem, but glad it's fixed)

I do have spark at the plugs, but noticed it was orange in color...I was expecting blue. I tried two spare plugs from my stash, laid them on the intake and turned the engine over...both times it was an orange spark...kind of anemic spark so to speak. I've ohm'd out the plug wires and they're all within 5K to 21K ohms depending on length...should be fine.

I think I'm at a standstill until I get a timing light.

a1jasong

Upon more thought...I may have been overconfident on how the distributor goes in.

Here's some pics of the distributor...there's a huge difference between lining the rotor up with the marks and lining it up with cylinder #1 on the cap...my Haynes book says it should do both...no way...!

Below pic shows the gear mark is about two teeth off when the rotor points directly at #1. The next two show different views of the same thing.




The next two pics are when the gear mark lines up with the mark on the body.



I was able to get a timing light off CL...so I'll know more tomorrow...I hope.

Team420

Orange (weak) spark could be cause by a bad coil or igniter. I would lean more toward the coil, as I dont think there would be any spark at all if the igniter was shot.

scope103

And why do you think that is? The drive gear is helical, so as you slide the distributor in it turns. So if the marks are lined up (ready to install), the rotor better not be pointing at No. 1. Once it is in, the rotor will turn to the right direction (which isn't actually at No. 1, but about 10° before.)

But all of this is a waste of time without a timing light. Even if you follow the instructions carefully, it is pretty easy to get it off by one tooth. That produces about 28° timing error, which you will see instantly with the timing light. No guessing.

RSR

Yes, like scope says. LIne up the marks and the rotor will move as it's inserted. I've found, and maybe b/c that's how I usually aim, that if you look through that screw hole, it's pretty much in line with the marks you need to line up. Put first put the gear in line w/ dist mark, and then use that screw hole to keep the line on the engine in line with the line on your dist. And if you have a hard time seeing, just add a little white out or something similar to the lines your lining up.

a1jasong

Interesting development...wanted to share before I run off and start researching:

The resistance between G- and ground is 2.5 ohms when the key is OFF and 500 ohms when the key is ON (Run position). The schematic I have shows G- connects directly to the ECU so I'm under the assumption there is something in there interrupting the ground circuit when it's powered up.

So off I go to see if this is important.

a1jasong

Oh...and the timing light showed that when I was cranking the engine and had the test connector jumped, the timing was 10 deg BTDC....when the jumper was removed, timing was at 0 deg. I've had to turn the dizzy all the way CCW to make this happen.

a1jasong

Quick update, I've now replaced the coil with a new one from autozone...same weak spark...then I suspected the ECU...so replaced it and got the same weak spark.

It did start for about one second and then shut off immediately and cleanly; it won't even try to start again.

So, here I am bumping this thread to see if anyone has some new ideas.

Chickenman

Just so you know...
You cannot accurately measure resistance in ohms with the component tuned on and in the vehicle. The reason is because the multimeter sends out a small voltage charge (I think around 9volts) and reads what it receives on the other end. If the component is on then there is voltage freely flowing through the component and it will skew your results.

a1jasong

Thanks Chickenman...I get the feeling I'm missing the forest for the trees at this point.

Chickenman

I think we've all been there before. So back to the basics you know 100%
Spark plugs are sparking.
Timing is ok?
Are the injectors injecting fuel? Are cam and crank sensors okay?

a1jasong

I've ohm'd out the G1, G2, and NE sensors and they are within spec...fuel pressure seems adequate and will squirt to the hood if I loosen the banjo bolt at the cold start injector (so at least the fuel pump seems to be working and holding pressure), the timing has been religiously checked, and compression is good.

lol...so I've got (albeit weak) spark, compression, fuel, and timing...and it won't fire/start for more than one second. It may be fuel related...I'm going to pony up for a pressure tester and check the fuel pressure to absolutely be able to remove it as a concern. After fuel testing, I'm going to buy a brand new Cardone distributor...since the one in it (though tests OK) came from a junkyard...sure wish I had an oscilloscope to see the NE and G1/G2 signals.

If it sits for another two months...I'm going to fix it with a gallon of gas and a match...maybe throw in some s'mores, too...!

Chickenman

Since you've replaced the ignition components will it start with starting fluid?

a1jasong

Sorry for the delay...at the pool hall all night. It won't start with starting fluid either. I just got off the phone with the local all-star toyota guy (according to the lady at autozone) and he said I may have gotten a bum distributor...so off the junkyard again for another...we'll see.