Hello everyone, Its been a while since I've been on the tech. Mainly a good thing as I have not had any issues with my Toyotas! Im having a major issue with my new Tacoma. Ill give a bit of backstory first, Ive been searching for a Tacoma for at least 2 years and have not been able to find a reasonably priced truck. Looking for a first gen Tacoma 4x4 with the 5VZ-FE. Finally a 1996 popped up for $3500 and I jumped on it. I saw it almost immediately after it was posted and by the time I got to the guys house, he had 6 other people waiting to come after me. I live in WNC and these trucks are demanding outrageous prices, and people are paying it. Anyways, I liked the truck but it had some issues. Overall it was a good running truck and I made a deal for $3300... woohoo! Owner did mention he had replaced the coils and cam sensor because sometimes it was "hard to start". After driving my trusty 85' for years, I was very excited to have "earned" the upgrade to a 5VZ-FE Tacoma The truck was showing a mere 192k and drove nicely aside from the loud roaring haha The frame was rotten and "fixed" so I knew I was going to deal with that also. First thing I did was start in on years of missed maintenance.. The things I replaced are:

timing belt - OEM
water pump - OEM
timing belt tensioner - OEM
cam seals - OEM
front crank seal - OEM
Harmonic balancer pulley (came apart when being removed) - Doorman Brand
upper and lower radiator hoses - Trail Gear Silicone Hose Kit
pulley belts - OEM
valve cover gaskets - Mahle (Japan)
intake manifold gaskets - OEM
ECT sensor - OEM
radiator cap - OEM
throttle body gasket - LCEngineering Teflon
cleaned throttle body thoroughly
cleaned MAF sensor
air filter - K&N
fuel filter - I forget
fuel pump - Bosch
Toyota RED Coolant used
camshaft position sensor - used OEM
ignition coils - used OEM
spark plugs - NGK dual electrode stock
plug wires - NGK
pcv - OEM
changed trans fluid - Valvoline 85-90
changed transfer case fluid - Valvoline 85-90
changed rear diff fluid - Valvoline 85-90
rear axle bearings and seals - OEM and used proper donald-the-bonald tool
rear shocks - KYB
front brake calipers - NAPA Eclipse
front brake rotors - Napa Premium
rear drums - turned and still within spec.
all brake fluid bled
clutch bled
frame completely fixed at local professional welding shop using Auto Rust Specialist frame replacement parts

and I still have front struts to install and a few other parts! NOW TO THE PROBLEM, p.o. was a really nice guy and told me about all the issues up front. Told me he replaced the cam sensor and coils, he didn't know what brand and when I looked at them they were some no name junk. I called my local Toyota salvage and dude grabbed the cam sensor and coils off of a "running truck" he seems honest enough and has never done me wrong in the past. Anyways, the issue at hand is that when the truck is very cold like below 40 degrees and has been sitting, it will crank for a while but make a loud POP and try to backfire or something. Almost sounds like the engine is trying to jump backward? I know that sounds crazy but its a sound that seems like the starter is getting pushed back against its will. It will just keep doing that and won't start unless you just keep trying. Eventually it will fire and run like garbage but then clear up and run fine. The colder it is, the worse it is. Sometimes it will only do it once and then crank but if its really cold, it will just keep making terrible sounds and not start. I have a smell of heavy fuel when this no-start occurs, definitely getting fuel. The really strange thing is that this will eventually throw a P0340 CAM sensor malfunction code but only when stating! If you get the truck to start before the code throws, it never comes up. But if you try to crank it too many times, and it won't start, it will throw that P0340 code. and when it does crank after that, the code will stay. While trying to diagnose and fix this issue, I knew I was doing a timing belt so I started there. I replaced the entire timing set and seals etc. replaced the cam sensor with a used OEM Denso brand. Did my valve covers and plugs and wires/coils etc. and went from there. Truck fires up perfectly (warm day) and passes the test drive. Put 100 miles or so on the truck, cranking fine, running fantastic. Cold morning, Same issue still happening. hmm... It was time for me to drop the truck off at the welding shop, so I removed the bed and decided to go ahead and replace the fuel pump while I have the bed removed. Easy enough, only $100 for a new Bosch unit and the truck has almost 200k so why not. I did see that the pump was an OEM unit so I didn't feel too bad about spending the money. Truck gets frame fixed, runs great. Cold morning, same issue. I try to search and read about as many issues as I can and nothing sounds the same as my problem. I understand that the ECT sensor is part of the fuel injection system and I decide, well its a fair chance that this could be sending a false signal and causing the computer to dump fuel. I get and OEM sensor from the dealer and replace it. Truck runs great and I drove it all day. but this morning, really cold and won't start. I would like some help in the right direction, I won't give up on this truck as I am fully invested at this point. This cranking issue will OCCASIONALLY happen also if you turn the truck off and then immediately try to start it back (like if you wanted to move just a bit further) but not as consistent as the cold morning start. The amount of time seems to have no change on the starting of the truck, it seems contingent on the actual temperature of the engine and outside air. Im stumped though! I do own an original OEM service manual for this year model truck.
Throw me a bone dudes!!!

 

Wow....a bunch to unpack here. I cant stress enough a time to walk away from a vehicle that needs too much work.
Thinking you found a gem because you found a taco is a fools errand because those trucks have an unreasonable
resale voodoo. Its just a little pick up. Thats it but the resale market commands ridiculous prices.....or you have to replace 1/2 the vehicle after the purchase along with a rotted frame etc. The 4runner is a far better bang for your buck choice and they command a more reasonable price.
My guess is that you'll be taking apart the front belts, covers and fan to check the sensors that were messed with. Maybe a bad cheapo sensor or a sensor not seated correctly. My guess is that under a warm condition.....no issues so get in there and see what people before you messed with.
Try my hair dryer / heat gun test. From a personal experience: try heating up possible bad parts with a heat gun or hair dryer prior to starting up. I had a dodge van with a bad ecu circuit board. Would not start on cold mornings unless i heated the ecu with a heat gun.
maybe you are having a similar issue

 

Thanks for your help. Obviously you didn't read my post. All of the replaced parts were replaced by myself. Im a very experienced mechanic and i'm looking for helpful information not insults.

 

Re read my post ....i was not insulting you. Just stating facts in regards to taco's and their unreasonable mystical value and costs. Then i gave you a perfectly valid temperature related way to diagnose a problem.
These days, replacing parts never puts you in the clear. Many are junk and can be defective out of the box. Re-check any parts the previous owner changed that you may be thinking are good.

 

Slow to start is “usually” a sign of a fuel issue. In Toyota’s case, it’s almost always a fuel pump that is losing pressure.

it could also be the regulator that is allowing fuel pressure to bleed off too quickly.

Have you tried power cycling the key a few times before starting. Just key on to run, but not start, wait 5 seconds, key off, key on to run, wait 5 seconds, key off, and then attempt a start.

This basically forces the pump to prime.

 

Good thinking cause that was my next thought, possibly a fuel pressure regulator. I have tried allowing the key to be in the run position for a bit and cycling it. From what I understand though, the fuel pump on the 1996 Tacoma does not prime with 12v. The pump only runs when the engine is turning.

 

Cycling the key will not prime the fuel system in Toyotas, it needs to see the signal from the crank sensor before the pump turns on, the 5vz-Fe commonly takes 4-6 rotations to fire up. Have you inspected the crank rotor for missing teeth, it should have a flat section but no missing teeth between that. Also which temp sensor was changed, there is 2, one for the temp gauge and the other for the ecu to help determine fuel trims, even a bad TPS can cause issues if it has a signal dropout through its range but sounds like a spark, fuel or timing ralated problem.

 

Okay that's what I thought about the fuel pump. I can say when I did the timing service I was looking specifically at that crank rotor and cam pulley to insure there was no damage or anything that may give a false signal. The pulleys and rotor looked normal and did not have any obvious damage. I thoroughly cleaned the crankshaft position sensor, and really everything while I had it apart. The wiring and harness looked normal with no splices or electrical tape. I did look at the terminals to make sure there was no major corrosion or a bent pin on the harness. I applied a small amount of die-electric grease to the connectors when re-installing. I was not aware they had 2 types of ECT on this motor, but I replaced the sensor on the front of the engine underneath the connecting fuel rail.