Alright this is a tough one. I'm out of ideas.

I ended up changing my engine in my 1997 limited 4runner. I was burning coolant on the old engine only on start up for about 10 seconds after the engine sat for awhile, it was running perfectly fine otherwise. Long story short I end up putting a used engine it in with 300,000 less km. Got everything back together and no start. The engine I put in has been in for 3 weeks now and still unable to find the reason why it wont start.

Things I've checked:

Compression 160 on all cylinders other than cylinders 1 and 2 they are 170
Spark at all cylinders
Fuel at all cylinders (also has a fuel pump in it that only about two months old)
checked all fuses. and switched around the EFI relay with the Tail Relay with no luck than switch them back
Check power at the EFI fuse
checked power at the fuel injectors and that it was firing but turning over the engine with the starter.
Checked timing with the crank Pulley and the timing marks on the cam pulleys (has a new timing belt that I did not install came with it)
Checked all the grounding wires
checked multiple times everything is plugged in and unplugged and re plugged every sensor.
Its in Park tried neutral as well.
same wiring harness that was in there with the old engine running
new spark plugs but also tried the ones out of the engine that was running.
The used engine came with cam and crank sensor on it. after it did not start I changed them out for the ones that came off the old engine even though all the Sensor had the right Ohms according to the service manual and it.
my year doesn't have a chip in the key and I'm using the same key as before. using the same ECU as the the running engine it never left the vehicle. I've took the return line off for fuel from the fuel rail and it is spraying lots of fuel. ( and has a pump that was in there only two months old that was used for the engine that was running. I have tried quick start spray as well. OBD2 reader reads no codes and shows rpm when cranking the engine. its cranks fine to me.
When I pull the spark plugs the seem wet with fuel also they are properly gapped.
It has spark fuel and air. and wont start seems like its not evening trying. I've had mechanics over who did not understand why it would not start as well. I've ran out of things to check any help or ideas would be awesome.

So with the plugs out. Are you seeing the spark when cranking over with the plugs grounded ?

I really sounds like you try to cover everything. It sure seems like the ignition is not letting the plugs fire being the plugs are wet when you pull them. :-)

Did you remember to plug in the igniter on the passenger side of the engine compartment?

Hey! yes with the plugs out ill ground them with the valve cover and see spark. the plugs did seem wet when I took them out. the engine is not even back firing or anything. Also tried leaving the spark plugs out over night to air the cylinders out. As well I tried turning over the engine with the starter removing all the spark plugs and removing the EFI fuse to air out the cylinders. that did not work, after it not starting for a bit I than removed the spark plugs and put in a propane torch into the spark plug holes to ignite everything to make sure it wasn't flooded.

Hey! thanks for the reply. yes its plugged in and unplugged and re-pluged to make sure its seated properly

Oh boy. There's so many things here that could have gone wrong during the swap. Here's what I would troubleshoot, sensors that can cause a no-start condition that I can think of:

• Crank sensor - you covered this one
• Cam sensor - you covered this one
• MAF sensor

There's a host of CELs that can point you in the right direction. If you have an Android phone, get yourself a cheap bluetooth code reader and the $5 Torque app. If you have an iPhone, look up whatever else might work. The Torque app gives a host of information that an average OBD-II reader will not show you. Turn the engine to ON and verify that your dash is lit up like a Christmas tree with all sorts of lights on. Then turn over the engine a few times. With the key still at "ON" run the code reader and look for both triggered codes and "Pending" codes. You may not have any codes that are triggered but you should see at least one Pending code. This will give you a clue as to what signal the ECU is not seeing and pulling the spark or fuel. It won't just randomly pull spark or fuel and not tell you why, that will be set by a voltage signal that was outside of the desired range. If you turn the key off and turn it back on, the code may not still be there so be sure to do it all in one go.

It's also possible that your old brittle wiring harness cracked upon removal and reinstallation. If a critical wire is now split you may have a heck of a time finding it. Do a visual inspection of the entire harness and look for any splices, t-taps or hack jobs done over the years and look for discoloration, damage, or looseness. If needed repair the wire with either a butt connector or better yet solder it yourself.

Lastly, re-check the vacuum hose routing using the sticker under your hood as reference. A swapped hose that's not seeing vacuum or is routed to the wrong spot can cause a massive vacuum leak that will prevent the engine from starting. It'll dump fuel but never start.

I know you checked valve timing on the pulley aka harmonic balancer. One thing maybe you didn't check was against the sprocket and if the sprocket is engaged correctly on the Woodruff key. If the harmonic balancer is badly installed or if the key is sheared due to bad installation or under torqueing, then the harmonic balancer may falsely indicate good timing. Because if you have spark, fuel and compression, valve timing becomes a major suspect. Also, a missing tooth on the sprocket can fubar your ignition timing. I know it's a pain go in there, but it's about all you have left to check.

Thanks for the reply! I'll get that app and see what else I can find out. for the MAF sensor I believe its working because if I remember correctly when i was cranking over the engine the OBD2 code reader I have was telling me the amount of air coming through the MAF sensor. For the wiring harness would it be easier to check continuity for everything? or do I still need to take things apart? Vacuum hose ill double check again. Ill add some pictures soon. thanks again

thanks for the help. I was thinking this too I put on a new Crank shaft pully bolt but the new timing belt was already one so i left the gear for that. My question is could they but the timing gear for the belt on wrong? I thought that gear had a key as well as the gear that sends a signal to the crank shaft sensor. But I understand what you mean it could be damaged sending a wrong signal. I also wonder if the cam shafts could be off by 180 degrees is that possible?

If you aligned all 3 timing marks. The timing should be correct. There is only one key and slot on the crankshaft.

Now can the key be missing or the little piece that slides into the crankshaft gear Not aligned up. Possible. As unless I read it wrong. You didn't pull that gear off the saft.

So the timing may be off from that.

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It's possible that the the MAF can still give a reading but another circuit is not working but I would not replace it unless you have reason it.

For the wiring harness just do a visual inspection, meaning just follow the harness along the engine looking for damage. I would not remove it again, that would be a lot of work. You're looking for obvious visual damage. Same goes with the vacuum hoses and routing.

Ok so, I checked the timing belt sprocket at the bottom of the engine did not see any issues there all the teeth for the crankshaft sensor are there, nothing seemed wrong with the crank shaft key. The MAF seems to be good as well put some cleaning spray through it and checked the ohms. I also checked the wiring harness (that sucked) and did see any issues. I than check continuity between the igniter and the ECM had no issues there. than check continuity between the igniter and the coils them selves and had no issues there. Tomorrow I'll be checking continuity between the ECM and the cam and crank sensor. As well I'm going to pull off the valve covers and check for the correct relationship between the exhaust and intake cams. I have not gotten a different code reader yet still trying to figure out what code reader can give me a graph on the signal coming from the Cam and Crank sensor. Anything else I can check? Some people were saying when they were looking at the spark it did not seem great as it not a consistent as when they were use to seeing on other vehicles. any ideas there? that's why I checked the wiring between the ECM and Igniter and the Coils but had no issues. oh and I checked the Vacuum hoses and only say one with a little crack not even all the way through but I replaced it anyway

Wouldnt hurt to check that all the wiring harnes sconnectors are nice and tight Including the ones in the cab by the interior fuse box.

I have run out of ideas without seeing the vehicle firsthand. There has to be something wrong and that was a very detailed search and diagnosis. I'm still surprised it isn't throwing any codes at you as they usually do.

You mentioned that you had some mechanics look at it and could not find the issue either. It may be time to have it towed to a Toyota specific shop and let them have a look.

My 97 will not start if the MAF is unplugged.

You never mentioned if you verified the cam timing.

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