Truck Repair: 95 ford 7.3 powerstroke diesel turbo, path of least resistance, crank sensor

Question
QUESTION: Hi MATT I STARTED MY TRUCK AND LEFT I DID NOT SET AND LET IT WARM UP LIKE I ALWAYS DO . I DROVE 1/2 MILE IT SHUT DOWN.I PUT A THERM0STAT IN LAST WEEK.IT HAS BEEN HARD TO START FOR A MONTH ,IF I PLUG THE HEATER IN FOR 1 HOUR BEFORE IT WOULD START WRITE UP.I READ ABOUT CAM SEN.I PUT ONE IN TODAY STILL NO RUN.IT WILL START WITH STARTING FLUID,IF I PUMP THE GAS I CAN KEEP IT RUNNING FOR A LITTLE BIT NO POWER JUST LITTLE FIRE.THANKS GEORGE

ANSWER: Hi George,
NEVER EVER use starting fluid on an engine equiped with glow plugs!!!! detonation can occur and cause severe damage internally!! here are some pretty common problems that powerstrokes have in the range of years that your truck is. #1 the vavle cover gaskets have a wiring harness built into them and they tend to cook thmeselves and short out or open the curcuits wich can cause similar symptoms #2 the crank sensor not operating correctly will cause simillar issues #3 the glow plugs and glow plug solenoid could be open or out of spec causing it to have hard starting issues. #4 when was the last time you changed your fuel filter? if it is getting plugged it will cause starting and operational issues #5 low batteries will cause it to not start even though it sounds like it is turning over fine it may not be getting enough juice to the fuel control module. (path of least resistance - the starter), have your batteries load tested properly or have someone crank the engine over while you read the voltage at the battery with a multimeter. you need to buy a manual for this engine and follow the troubleshooting procedures to the letter, don't try to solve this issue by changing parts...parts manufacturers have enough money they don't need donations too, however, some items only require a visual inspection (valve cover gaskets,...)

good luck,

Matt

---------- FOLLOW-UP ----------

QUESTION: HI MATT I CHECKED THE FUEL RELAY IT DOESN'T WORK.PUT NEW ONE ON IT IS NOT WORKING HAVE 12 V ON ONE SIDE O ON OTHER WITH SOMEONE HOLDING KEY ON. MY WAIT TO START LIGHT IS NOT COMMING ON.THANKS GEORGE

Answer
Hey,
do you have 12v at both the primary and secondary pins? also do you have a good ground to the relay? you may need to find a wiring schematic to figure out what controls this relay and where the wiring for it goes. it may not be the relay...it may not be getting it's signal voltage to close. check for power at pins 30 and either 86 or 85, if you have 12v at both these pins check for ground at either one of pins 85 and 86 that is not positive. pins 85 and 86 are the primary (control)curcuit and pins 30 and 87 are the secondary curcuit. relays are used so a small current can control a larger current without needing larger capacity switches. when 12v is supplied to the primary curcuit it operated a small solenoid that connects pins 30 and 87. a switch such as your ignition switch, neutral switch...etc will switch the primary curcuit on and off...so if there is no primary power the problem lies else where. test these items and let's go from there.

Matt