After doing the headgasket my truck does not run well. My first thought was the cam gear must be off a tooth and when I pulled the valve cover, I discovered that when the #1 cylinder is at top dead center the mark on the gear is at the top (12 o clock) but the mark on my chain is off 90 degrees. This should not affect anything as long as the crank pully is at 0 degrees and the cam gear is at 12 o clock right? I know it's on the compresion stroke because the #1 valve springs are not compressed. When I start the truck, it only runs on two cyinders (I can pull #1 & 2 plugs wires and the truck continues the run exactly the same). I hope this isn't too confusing and any insight would be very appreciated thanks!

 

Chain mark will only line up at install, once run, it can be anywhere.
Check the fuel injectors for power and ground. There are splices in the wiring harness that connect the various wires together. Those splices are known to fail over time.

 

alright so I checked the splices and they are both intact. When I put a test light to the injector harness both pins are positive (test light grounded out). with the truck off the test light is on solid and with the truck on it dims just a bit rapidly (I'm assuming injector pulses) I'm fairly sure that both pins on the harness should not light up right? I put a volt meter across the injector and got 3.5 ohms which is .5 over spec but I have a cheap volt meter which I don't trust and even so .5 shouldn't make a difference right? would a noid light tell me anything a test light couldn't? I had all the injectors cleaned and balanced and when I picked them up I was told they were all good so I don't think it could be the injectors.
ANY thoughts/comments/experiances would be greatly appreciated! thanks

 

You can also check the injector ground wires. The ECU grounds the injectors to make them turn on. Power comes from the ballast resistor on the fender. The ground wires are likewise spliced together and run back to the No10 and No20 pins on the ECU.

 

alright so I put a noid light to the injector harness and it seems to say it's fine (rapid dimming of the bulb). Is there any way to test the resistor ballast? I still have a hard time beliving that the extra .5 ohms I'm reading would keep my injector from firing at all (I know this because the plugs are dry).

For any one who might bring this thread up in a search here a couple pictures of where to look for the splices in the harness. You don't need to strip the harness all the way back to the fire wall. All the splices are within a 6 inch section right where the main harness splits into two (but they are in the thick part of the harness).

 

Per the FSM, it lists 2-3 ohms measured between the B+ and either No10 or No20 terminal for the resistor (two resistors inside the heat sink, one feeds 2 injectors and the other feeds the other 2.

 

This is killing me! using a better voltmeter, the ballast resistor reads 3.3 ohms through each pin and the fuel injector reads 2.5 ohms. Seeing as my #3 and #4 cylinders are firing, I think it is safe to rule out the wiring, ballast resistor and ecu (#3 and #4 should be completely independent from each other). Has any one dealt with an injector that tested fine using a voltmeter but didn't actually fire? Can I probe the injectors driectly from the battery and listen to see if it fires? And if I can it shouldn't matter which pin get positive and which gets negative right?

4Crawler I really appreciate your patience in trying to help me out with this!

 

SUCCESS!!!

After some more research on yotatech I pulled my valve cover to re-check my valves. I must have not torqued the lock nuts properly because two valves were wayyyy too loose (#4 intake, #3 exhaust). I resest the valves and buttoned up the valve cover only to find it made no difference, still running on two cylinders. In a move of total frustration I started whacking the injectors with a socket extension and what do you know, the idle smoothed right out!!! go figure it's some thing stupid like that. So even if your injectors are professionally rebuilt, I guess they can still stick.