I have a 92 Toyota pickup. Sometimes when I try starting the truck it chokes and throw black smoke when I finally start it and sometimes when I'm driving it. I changes the Maf sensor I did a tune up and I still can't find the problem.. if anyone knows please let me know

change the vacuum lines with silicone ones~

As tennisshoes has asserted the Fuel pressure regulator is overlooked because it will not throw a OBD-II trouble code out there...no use...Hardcore take it up to the next level find the cracked hoses and change 'em out~ seems so simple but can play hell with your performance~

I've witnessed the diaphragm getting sucked into the vacuum hose, and of course no longer controlling the fuel flow which is going to be the default pressure~ depends on your model but will leave you starved of gas and suffering from performance issues...put a vacuum tester on the FPR to see if the diaphragm moves...most likely you've got the defective fuel pressure regulator....vacuum hose not withstanding~

...as tennisshoes has stated~

Thank u I'm going to try it out. What are the chAnges thats the problem... I've tried for so long to fix it but I jist cant get it. ... I'll let you know the result... thanks

...well what will happen will be increased idle speed...and gutless performance~(as there will be insufficient fuel pressure)~

here's a few examples~

IS THERE a way to check if my fpr works.. or is it only w the testers.

No, with suction connect a hose and suck...see if this affects the flow..see if it is leaking vacuum~ see if there is vacuum at the source..you don't need nuthin' for that~

I checked the vacuums n it has no leaks and increased the timing and it has more strength when I put it where it has to be it loses strength. when the truck turns on fine and I start driving it starts choking and throws black smoke..

retarded spark...IAT (intake air temp) Chassis power solid at the 1/0 connection...buggered up EGR valve....all these would issue the puff- black condition....with NOT good power to the chassis ground (cable near alternator) you may have crank angle sensor problems....get good ground by wirebrushing the connection from the 1/0 cable to the chassis ground to establish 300 CCA power~

....with a battery not yet five years old~

I ran the code test and it comes up with code 43

Grounding is the key here---the starter ground (which bakes three hundred Amps or so) is sharing the same chassis ground as delicate components as the ECU and ignition system...and the fuel pump...if the base of the 12Volt current is polluted from the 1/0 battery connection to the chassis ground, which can get unreliable with just one start~ (will "weld" itself with the big AMPS)----bighuge demand put together in the same wheelhouse as teeny-tiny demand (what controls everything) seems like a thoughtless way...but is the way of the beast~

I checked and cleaned all the ground and I don't see anything out of the ordinary. Is there a way to know

Hello, I tried everything u suggested but it didn't work... I moved the TPS and it passed the smog check..but what going on now it's that sometimes it turns off n it won't start.... when the truck starts failing. The relays start clicking the ones on the fuse box... when it stops clicking the truck works perfectly... can u give me advise to solve the problem ill really appreciate

300 amps ground (about a quarter size) has different properties than the ECU ground which only takes about an amp or so~ The massive amperage is for your starter motor~....but the "brain" of the system still needs "clean" ground to function properly~

Whats your advice to fix it...