T-100 starts fine when cold, won't when hot until about a half-hour has passed to cool....
What is your question?
Starts when cold, will restart if shut off while hot but immediately re-started. But if it sits for about 10 mins while hot, it won't restart. It coughts and kinduv backfires with a weird smell . . I have to let it sit for a half hour or more, then it starts just fine. I have cleaned/tested the IAC valve, put new gaskets and hoses in, cleaned the MAF and throttle body, but no good. Funny, it started in the winter but only did it then for a few minutes, but now that it's hot out it just won't restart..gonna try changing out the ECT sensor next....Any ideas?? Thanks!!
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*Why not* have the temperature sensor reading tested before replacing it .. Some relatively inexpensive code readers will have live sensor data so the sensor reading can be compared to the actual ambient temperature! .. Test readings while engine is COLD (before starting, after sitting overnight) then when engine is at normal operating temperature .. Purchase a descent code reader or scan tool and learn how to use it .. it'll pay for itself very quickly ... Test , don't guess ... That's the key to ANY successful repair!
I came to this forum to ask for a clue from someone who may have experienced the same problem I am having with my truck. I thought that's what forums were for...instead I got a lesson from Captain Obvious on how to waste time diagnosing a temperature sensor that is easier (and worth the $16 ) to replace, especially after 325K. I guess I need to upgrade my tools also, (my OBD doesn't do live) rather than ask for a hint, and just troll these forums reminding folks to test, don't guess, and chock your wheels and disconnect the battery, and don't hit your head on the hood and other pertinent stuff.... Thanks for your time, tho, I am running out to the shop to try your suggestion!!! :)
I'd rather spend a little time diagnosing a problem than spend money on parts that are NOT needed, that's the only thing that's wasted, not to mention my time trying to help a Yankee for FREE!!!
Do a fuel pressure test and see if it holds residual pressure after its shut off. Usually the concern is extended crank. But after a hot soak it's extended crank,hard start and sputter. If it does not hold pressure could be fuel pump ck valve,pressure reg,external fuel leak or leaking injectors. Leaking injectors could be hard start after shut off due to flooding.
Thanks for your reply! I liked your suggestion about the injectors, it seemed to fit the problem! 325k is a lot to ask of the originals! I had to replace the valve cover gaskets anyway, so while I was in there I replaced the injectors (heck, worth it at 325k) and the fuel pressure regulator and engine temp sensor since I was there. I tested and cleaned the vsv's, replaced the a/c vsv cuz I broke it lol... replaced every vacuum and fuel line (again, I was there)... Maybe some others won't agree, but I plan on keeping this truck (It still looks good too!) as I will eventually figure out the problem, so throwing parts is not a waste.... It is not my main vehicle, only a work truck now, so not a huge priority. But anyway, no luck after the parts swap, still same issue.. Only I swear it runs even better now, and bonus, doesn't leak oil!! I even swapped out the main computer, ( I had a spare) and no luck there, either...Remember, no codes have been thrown, MAF has been cleaned and tested, only have crank and cam sensors to go :) Heck, I'd take the thing cross country as long as I didn't have to stop! smh Thanks again tho for your suggestions, I will check the pressures, might as well....Cya!
my OBDII tester showed a bunch of defective sensors
however when replaced there was NO change
so
I replaced the fuel filter
and
instantly the truck ran better, and the hot start problem [appears] to be gone
Hey klaskinera*****, same thing! Bought a live OBDII, only it showed all sensors normal, but decided the only thing I hadn't done was replace the filter and check the pump. Didn't consider it at first as I had change both a little over two years ago....I already checked the fuel pressure and it was steady at about 20. Changed the fuel filter and the pressure went up to about 30 but then it fluctuated, so I thought I should look at the pump...turns out the Ebay pump I installed had a short rubber hose connecting the pump to the fitting, and that had damn near disintegrated with pieces just falling off into the tank...dump the tank, new pump and another filter, and she now runs...40+ psi fuel pressure. Of course, then a month late she quit completely, and I was about to call the junk yard, but a check of the last thing left to swap was a crumbling crank sensor....She's back to her old self now!
Thanks so much to you and others for their suggestions, glad I didn't give up!!!
If you are still fighting this problem I would suggest it sounds eerily similar to the old days on the rare occasions a condenser would go bad on a coil or weight advances stick under the distributor, (same results).
You still have all those parts built into solid state ignition modules. High voltage step up coils have to have buffer condensers as they are switched on and off and pickup coils can go grumpy with age and heat.
OK I did a lot of sensor replacing [even though they all tested correctly] with an ohm meter
because
the OBDII tester said they were faulty.
however
nothing made any difference.
SO..... I replaced the fuel filter and INSTANTLY the truck ran better, and the HOT START problem went away.... so far anyway!
TOYOTA SENSORS are NOTORIOUSLY RELIABLE
and as such they can give misleading readings because of REAL PHYSICAL PROBLEMS that they were not designed to sense....
below is my original post
I have a 1998 T100 six cylinder V6 which has started doing the
"will not start when hot" thing.
We found that dumping snow onto the two sensors (one located at the rear of the engine on the manifold)
and
[the other on the outlet side of the airbox]
expedites the recovery process....
goes from waiting 30 minutes to waiting five minutes or less.....
however I have replaced the rear sensor and it has not stopped the problem.
both of these test as if they are working (check them on an ohmmeter and they should be several thousand ohms) so I suspect there is more to this than meets the eye....
truck runs fine when hot or cold, just will not start [sometimes] when hot.
I also have a 1996 T 100. Same no start issue when hot. I discovered that it means that you are low on oil. Top off the oil and it will start immediately. I realize that this sounds too simple to be true, but it actually is a heat sensor that gets too warm when the oil is below a certain level. It does not mean that your oil is dangerously low. Just low enough to have an effect on the one sensor.
I came to this forum to ask for a clue from someone who may have experienced the same problem I am having with my truck. I thought that's what forums were for...instead I got a lesson from Captain Obvious on how to waste time diagnosing a temperature sensor that is easier (and worth the $16 ) to replace, especially after 325K. I guess I need to upgrade my tools also, (my OBD doesn't do live) rather than ask for a hint, and just troll these forums reminding folks to test, don't guess, and chock your wheels and disconnect the battery, and don't hit your head on the hood and other pertinent stuff.... Thanks for your time, tho, I am running out to the shop to try your suggestion!!! :)
I'd rather spend a little time diagnosing a problem than spend money on parts that are NOT needed, that's the only thing that's wasted, not to mention my time trying to help a Yankee for FREE!!!