Who likes puzzles? She's a doozie!

[Stumped]

Ok, where to begin.... 1998 4Runner 3.4L.

It's my girlfriends old truck, it was parked several years ago after it wouldn't start. Got very little information on the symptoms that led to its parking. Did not die while in use, just didn't start one day.

It will turn over easily, and I do mean easily. It's wierd that it almost whines while cranking. Like most of the noise you hear is the starter motor, and that the engine doesn't seem to be resisting much.

I've checked relays and most electrical that is feasible. Has fuel and spark. Didn't check fuel pressure at the rails as there seems to be no easy way to do so, but the pump is on and fuel is coming out the return. Timing marked on the cams lined up. Won't fire with ether.

There's 100 other things I've pulled apart and checked but there doesn't seem to be a smoking gun.

My suspicions now are
-clogged cat not letting it breathe
-timing belt jump (hence ease of turning over due to lack of compression)
-a sensor malfunction (Crank, cam, throttle position, air flow, maybe even the ecm, ect)

Any ideas? I'd rather not start throwing parts at her until I know she can run.

 

[JayRolla]

Is the motor turning? Or just the starter motor whinning. If so it could just be bad starter motor that kicks the starter to hit the flywheel. Smack the starter with something metal like a rod or hammer or anything and see if it frees it up to start the car. The motor should not spin easily if it has compression. If it does than maybe it needs a compression check. You can pull a spark plug one at a time and turn and see if there is any pressure coming out at least to see if there is anything happening.

GOOD LUCK!

 

[jeremyc74]

When you're cranking it, are the cams actually being driven? It sounds like a broken timing belt, but you said the marks are lined up so I assume they are turning with the crank.

Have someone crank it and see if you're getting puffs out of the exhaust pipe (put your hand over it like you're trying to stop it).

If the valvetrain and crank are still coupled like they're supposed to be it should be making compression.

 

[kevin8629]

Ok, where to begin.... 1998 4Runner 3.4L.

It's my girlfriends old truck, it was parked several years ago after it wouldn't start. Got very little information on the symptoms that led to its parking. Did not die while in use, just didn't start one day.

It will turn over easily, and I do mean easily. It's wierd that it almost whines while cranking. Like most of the noise you hear is the starter motor, and that the engine doesn't seem to be resisting much.

I've checked relays and most electrical that is feasible. Has fuel and spark. Didn't check fuel pressure at the rails as there seems to be no easy way to do so, but the pump is on and fuel is coming out the return. Timing marked on the cams lined up. Won't fire with ether.

There's 100 other things I've pulled apart and checked but there doesn't seem to be a smoking gun.

My suspicions now are
-clogged cat not letting it breathe
-timing belt jump (hence ease of turning over due to lack of compression)
-a sensor malfunction (Crank, cam, throttle position, air flow, maybe even the ecm, ect)

Any ideas? I'd rather not start throwing parts at her until I know she can run.

Timing belt?

 

[IBallEngineer]

Ok, where to begin.... 1998 4Runner 3.4L.

It's my girlfriends old truck, it was parked several years ago after it wouldn't start. Got very little information on the symptoms that led to its parking. Did not die while in use, just didn't start one day.

It will turn over easily, and I do mean easily. It's wierd that it almost whines while cranking. Like most of the noise you hear is the starter motor, and that the engine doesn't seem to be resisting much.

I've checked relays and most electrical that is feasible. Has fuel and spark. Didn't check fuel pressure at the rails as there seems to be no easy way to do so, but the pump is on and fuel is coming out the return. Timing marked on the cams lined up. Won't fire with ether.

There's 100 other things I've pulled apart and checked but there doesn't seem to be a smoking gun.

My suspicions now are
-clogged cat not letting it breathe
-timing belt jump (hence ease of turning over due to lack of compression)
-a sensor malfunction (Crank, cam, throttle position, air flow, maybe even the ecm, ect)

Any ideas? I'd rather not start throwing parts at her until I know she can run.

Even a melted Cat wouldn't keep it from at least starting.

The timing belt is a definite possibility. A compression check is the first thing you should check.

Do you have a scan tool? You could get trouble codes like Cam Sensor if the timing belt is broken. So make sure you start with compression.

opcorn:

 

[Stumped]

Yes she is definitely turning over.

There is very minimal pressure at the tailpipe, as in my hand has no trouble sealing it off

Cams are turning with the crank, can't see the crank position though, but both cams are hitting their marks at the same time.

When I was checking spark (on 4 of the six cylinders) the drivers side front cylinder did let out a good blast of air with the plug removed on what I assume was the compression stroke. But the three passenger side cylinders didn't blow out like the opposite with plugs removed. Kind of leads me to believe the puff I got out the plug hole was back pressure of another cylinder coming through the exhaust valving on the open cylinder I was checking.

About to see about pulling the upstream O2 sensor and see if air will be forced out of there due to cat obstruction. I only need my arm to be about 7 feet longer to turn the key and also feel!

I'll also grab a scan tool and see about a compression tester

 

[Stumped]

UPDATE: pulled the O2 sensor and on the first crank got a loud pop, didn't have a visual since I was in the truck but on the following rotations I could hear each compression pulse... Still no real fire though. May possibly pull the cat/manifold joint next....? Any suggestions?

 

[jeremyc74]

Before you start tearing things apart, shove something like a coat hanger up the tailpipe and make sure nothing is in there. I backed into a bank one time in an old Buick and the tailpipe dug in at just the right angle to completely plug it and the car wouldn't run.

It's worth checking because its quick and easy, but I'd say you more than likely have something else going on.

 

[Stumped]

I stuck a hose up in there the other day and made it a good length. But knowing it sat for such a period means any number of things could have crawled in there and died.

But after breaking the exhaust joint I did get some real engine sounds, but it also made a small fire on that down pipe. So there's obviously ignition coming from somewhere, but it's pretty difficult not being able to watch the engine while its cranked.

More to come....

 

[Doc2012]

So you got a loud pop when you took the O2 off?

Gunshot type pop, or something breaking type pop? (Might be hard to tell the difference for some people.)

Did you smell fuel/exhaust when you did that?

What does it smell like when you're trying to turn the motor over at the tailpipe?

 

[Stumped]

Gunshot type pop, smells like fuel at the exhaust where I broke the flange. The fuel does smell a little old but not terrible. And still ether does nothing to get a cough or hesitation to compensate for old fuel

 

[02SE]

<iframe width="640" height="360" src="https://www.youtube.com/embed/a_1OVYsLqMU" frameborder="0" allowfullscreen></iframe>

 

[Grenvilleter]

Get rid of the old gas. Try a little spray of ether into the throttle body and see if there is more robust attempts at engine trying to start.

Old gas, especially if it is years old will not do modern fuel systems any good at all and may not have the volatility to explode when spark is applied at the right time.

 

[UnderFire]

Make sure you've got:

Fresh gas, new spark plugs, new oil, open exhaust and a new air filter.

Pull the intake boot off the throttle body, spray some starting fluid and pop the tube back on and crank it, if it doesn't start (or at least try to) your problem is most likely electronic.

 

[davidch]

I read nothing above about a compression test having been performed. Was the engine's original demise preceded, perhaps, by a very thorough soaking? Rusty rings not sealing? Rusty valve stems precluding their closing? (Being a non-interference engine, the piston wouldn't strike a stuck-open valve.)

Mechanics who've worked on motorcycle engines find things like this all the time on engines that have not run in years. Of course, a motorcycle's engine is more exposed to water in most any setting.

 

[Cree]

Toss a little Ether at it. If it doesn't start off of that, you've got compression or leak down issues.

 

[Stumped]

Big shout out to Doc2012 for all the offline help

She's got some injector issues because it's loading up with fuel. Will still drain the gas and get that compression tester on it (it's back at my place currently)

And as far as I know it never got in any water. It was parked after normal city driving and the next day it wouldn't try to start, like the starter wasn't engaging the flywheel or it was binding up (thinking a stuck injector could have flooded and locked up a cylinder?)

Whatever it is the is for all the ideas so far, it really makes me miss working on older cars without all the relays and switches and computers!

 

[Stumped]

Ok it's been a while since I've gotten to tinker with it but this last Saturday I drained the old gas, flushed the lines with fresh fuel and gave her the ole college try. Got a good bit of smoke that smells like proper combustion, but not in the places I want to see it. Mostly out the air box.....

So it seems like the valves are a big culprit, the compression test is next (I know it should have been done to begin with)

My question is are the valves spring loaded with roller cams? I really don't want to start digging at the heads on this thing but it may lead that way. I know it's a non interference engine as far as the valves and pistons are concerned so it would mean gunk and rust from sitting is preventing proper closing

On a side note, can these starters ever run backwards? That things was in about 6 pieces when it was pulled off to begin with, and I know it's mount is ground and it only has a hot wire from the battery but can the bendix or intermediate gear in there be positioned in a way to make her turn over in reverse?

 

[3bears]

sounds to me like the timing is off
have you confirmed the crank and cams are on the same marks of TDC

 

[TheDurk]

I'll take a wild-ass guess. Assuming you are correct that timing is set correctly, but compression is off on one side, perhaps you have a sludged up valve train on one side that is spinning in time but valves are unable to close when they should. We have seen sludge do that on here. How was the lady on her basic maintenance? What does the oil look like?

Again, compression test is badly needed here.