Srr7172

Hmm, well the rebuild fixed the gas leak, good job Assuming the stock Mikuni is on your truck, my totally unprofessional advice is to remove the electric fuel pump and use a good original type fuel pump, thanks O'Reilly's & NAPA... My truck ran better (less starving for fuel) when a new stock fuel pump was installed... Assuming your ignition system is OK (look at the spark plugs ON A COLD ENGINE) use dielectric grease SPARINGLY it causes misfires... I must clean out the dirt & dielectric grease on the main electrical harness connector on my carburetor (possible goof on my part)... All my vacuum lines are tight & correctly connected but I have not cleaned or tested EGR or Thermo Valve yet... No start Grrrrrr... My spark plugs as black and as coated as can be, never seen any worse... Running a lilttle rich perhaps..? Well not running he he he...

Maybe try these checks: (all gaskets are good & fasteners snug BUT not over tightened, lithium grease is friendly for actual torque read)...

There is a round metal vacuum diaphragm at the rear of the carb (FSM names it Depression Chamber) which opens the secondary butterfly throttle valve, does it open the throttle? There is a short approx 3" long piece of vacuum hose (white stripe coded) from that diaphragm to a nipple at the bottom rear of the carb... Maybe you could use a brake bleeder hand vacuum pump to see if it opens the secondary throttle blade (the primary throttle needs to be opened for the secondary to open/there is a metal to metal interference of throttle pieces otherwise) The depression diaphragm should be able to hold vacuum without having to keep pumping the vacuum pump... I used a DMM innova 3320 to test resistance of the carb's selenoids FSM reading requires 49.7 ohms (more ohms = more electrical resistance = less work being done by the selenoids) Open the carb's main harness connector and test on the male ends attached to the carb side of the harness... You can also DMM test resitance of the TPS (yes the Mikuni has one, shocked me) test at it's harness connector which is a round black connector abt the size of a little finger... FSM shows how to adjust the ohm readings of the TPS if out of spec -- throttle open 4.9 kilohm & closed throttle 1.2 kilohm... Check that the choke plate is open when the engine is warm (a choked engine will lack power as bad as a weak fuel pump)... Might be the float level is out of adjustment but that requires carb disassembly (I have not done that yet) OFC you changed the fuel filter & removed the gas cap for a spin up the hill too, right..?

Do yourself a favor (if not too late) DO NOT adjust any screws on the carb EXCEPT one named (SAS1) idle speed adjusting screw... Too late for me, I already made that mistake... I have just started down the road of trying to rebuild my Mikuni carb (my truck won't start/flooding?) possible dirt in the needle seat..?

If you read this far & did the above BUT still have problems; people say a Weber carb conversion is an option (not for me)... If you decide to convert to a Weber, please be advised, I am wanting the phenolic plastic fuel bowl/throttle body center section of a 1985 or 1986 Mikuni; mine is cracked... My truck a California emissions & assuming a Federal carb of those years is same enough... Your engine "U" 2.0L & mine "W" 2.6L might be same enough there too..?

Well, if you did, thanks for reading this far & best of skill 'n luck to you... If anyone can fix it, YOU CAN..!
Aloha --
George