No start or hard to start

[450marlin]

I have a 02 f250 7.3 with 136,000 on it. The batteries are new with a new starter also. Glow plugs and relay have been replaced. I will only start when cold below 40 if its plugged in. The glow plugs relay has been double checked to make sure it is engaging. Once it does start from being plugged in it takes a while 10-15 min warming up before runs right. Hooked up to a scanner and did a buzz test on injectors with 1 and 3 showing open low to high and 8 showing 7% on perdel. Have also changed the oil in the high pressure oil pump to make sure that was not the problem. Once it is warmed up it seems to run just fine. Thanks for any help.

[dray8165]

Did you do the replacement of the glow plugs yourself? Did you check the resistance or put power to them to check them before you installed them? A few people have gotten bad batches straight out of the box. Also, you may need to check the harness. Bad connections / burnt pins could cause the GP's not to engage even if the relay is really working.

Read through this for help:

Hard/No Start? Check here first. - Diesel Forum - TheDieselStop.com