Hello everyone! I'm a bit stumped with an issue that I am having and am reaching out for some possible expert advice. Here is what I have done so far and where I am at. I have a 98 4runner 3.4L 2WD 310,000 miles that I recently swapped heads due to a burnt valve as well as replaced the timing belt. After removing and reinstalling everything, I went to crank the 4runner and it would just crank but no start. At this point I removed the top timing belt cover, checked the timing, thought I was 180 degrees off due to the crank to cam turn ratio. I removed the belt lined the cam pulleys up with the timing marks, manually turned the crank, clockwise 5 full rotations to assure all marks stayed in line. At this point my crank is lined up with the 0 and confirmed TDC by removing plug #1 and manually checking with a long screw driver, the cam pulley marks are at 12 o clock, aligned with the given marks. After putting everything together, I try cranking again and it sounds as if the timing is off. It cranks but no start and if I give it a couple tries I get blow back out of the throttle body. This led me to believe that the intake and exhaust valves are not working together in time. I then thought that maybe I aligned the cams wrong by getting the cam marks mixed up, since we have 2 dots on the RH to align and 1 dot on the LH cam. I removed my valve covers to find that on the RH cam, the 2 dots align, rotated the engine 180 degrees to check the LH cam and the single dots align. Now I am looking at RH and LH cam pulley, aligned with their timing marks, both cam gears are positioned to where they both have the single dots aligned and my crank pulley is at 0 degrees TDC. I am scratching my head on this on. Does anyone have any suggestions on where to look next?
The only things that I've done outside of FSM instructions was replacing the knock sensors, knock sensor harness and soaking both ends of the fuel injectors in lucas injector cleaner, overnight. I had them standing up in a container half the night right side up and the other have upside down. I understand that soaking the injectors may have been ineffective for the most part but I thought why not... I have also used a multimeter to check the given FSM specs on the crankshaft sensor,cam shaft sensor, fuel injectors and coil packs.
I appreciate that there is a community out here to reach out to and would like to thank anyone in advance for their input.

I took a ride back to the house to get some pictures for you guys and I noticed something that I'm not understanding. I have everything aligned as pictured but when I rotate the engine 720 degrees, my cam pulley marks line up, the came sprocket marks line up but the crankshaft pulley mark is off this much. What is the explanation for this?

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You have the belt and cams right. I would suspect there's a sensor not communicating or unplugged. Double check the big ones like the camshaft position sensor and crankshaft position sensor, along with the MAF. Those three will cause a non-start issue. I would suggest getting a cheapo bluetooth code reader and the Torque app if you have a compatible phone. $40 and you can pull codes and it will tell you which sensor is preventing the engine from starting.

This might seem silly, but if you fuel pump is old it will take a while to pump fuel into the lines and build pressure. It only operates when the engine is turning over so you have to crank and crank and crank.

Thanks for your reply. I have checked over the sensors thoroughly, many times. I've also thought about replacing the cam and crankshaft sensors just to see but I also don't want to be foolishly chasing the wrong rabbit.

I have a Scan Gauge II but have no codes. If a bluetooth reader is able to give any more information than the scan gauge, I have no problem purchasing one. I would even be willing to buy one of the $500-$800 handheld scanners if I knew that it would output the information that I need to get this straight but I wouldn't know which one to consider. I do all of my own automotive work so it could also be useful in the future


I have cranked it quite a bit. It seems obvious that there is combustion going on but doesn't seem to be at the right time and if I continue to crank I get a "PFFFT" from the throttle body that smells like combusted gas exhaust. I will crank more if that seems normal in this scenario.

No codes? Then we have to assume it is not a sensor. I would not replace any. The only other logical steps are to ensure you have good spark and fuel. If you are smelling fuel, you've got it. If not sure, crank it a little then pull one of the spark plugs (whichever is easiest to get to). If it's wet with fuel that's not the issue. You can check spark with a spark plug wire light. It'll blink when the wire is energized when a spark passes through.

The other thing than can cause a non-start issue with no codes is a mismatched vacuum hose. You may have your hose routing wrong causing a massive vacuum leak. That will cause the engine not to start, or start for a second then die. I have no tips here, it's just a matter of double checking everything. See the diagram on the underside of the hood. You're obviously handy with engines if you've swapped the heads so hopefully this isn't coming across as patronizing. Sometimes it's the simple things we forget.

Okay. I've used a light to check for spark and everything checks out.

I will check the fuel. After I soaked my injectors, I thought that it might have been foolish and useless thing to do. Someone with more knowledge on injectors may be able to say if leaving the injectors in undiluted lucas fuel injector cleaner could have caused any internal damage to the injectors. I was intentional not to soak the electrical plug but filled the top port of the injector while soaking the lower.

I will look at a vacuum diagram as well. Any time that I remove vacuum lines, I use electricians wire marker stickers so I'm pretty confident there.

It doesn't come off patronizing at all. I want to be humble in taking suggestions and will check the same thing 100 times if that's where people with more knowledge are pointing me to. I appreciate all the input that I can get.

The fact that the timing marks are good at one point but when turned 720 degrees it is off that much at the crank pulley shouldn't be any concern?

I've soaked injectors before with no issue, I doubt that was it.

If you are comparing the belt, the timing marks may not match up again. As far as the crank to cam ratio, I can't remember how many times each one spins. But as long as it lined up when you put the belt on, it's still perfect timing. Not like the a new belt can start jumping teeth.

Okay.. I've already turned the engine over multiple times so I am not comparing the marks on the belt at this point. I am using the stamped marks and notches on the engine and pulleys. The turn ratio would be 720 degrees on the crank rotates the cam 360 degrees. If I look at my engine now, all of the marks on the cams and crank pulleys are TDC. If I rotate the engine 720 degrees my CAM pulleys line up correctly but if you look in the 2nd picture of the crank pulley it's almost 1/4" off of 0. If I rotate 720 degrees again, everything will line up.

I'm going to break it down and start over. I'm thinking the crankshaft sprocket timing marks and the crankshaft pulley timing marks are not true with each other causing it to be those few degrees off,every other rotation, that is shown in the picture.

Make sure you have the plug wires on correctly as well, they can trick you...

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I guess I can rule that out. It's on point every rotation

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If you have a friend that knows the 5VZ maybe have them look it over? It's hard to to diagnose without seeing the engine. There has to be something that was overlooked. Even if there was something mechanically off, it would at least sputter and start for a few seconds.

Is the engine still backfiring through the throttle body?
If the firing order is correct and the both cam timing marks and crank timing marks are on, it should fire.

The wiring harness makes it impossible to mix up the coil electrical plug going to the wrong coil...so you should be good there.

When you got the burnt valve replace, did the shop work on your actual head that you turned in? And that's what you got back?

That is understandable. I know I can't expect a diagnosis but your suggestions have still been helpful in giving me some things to look into. We have bad weather coming so it may be a few days but I'm going to button everything back up and move forward with some of you guys suggestions.

I really appreciate you taking your time to give input. I'm open to any suggestions.

This company rebuilds and sells heads, taking the old heads as a core.