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View Full Version : 93 3500 - First Diesel/Truck, Warm Start Problem



6.5l_Roofer
06-24-2020, 22:48
Howdy, I just picked up a 93 3500, with a auto. 118k miles, just had the injectors, radiator, oil pan seals, glow plugs, oil lines, and some other minor stuff done at the Dealer before i picked it up. The only problem is that after driving and warming up, if i park it for more then 30 minutes, it cranks for over 20+30 seconds before sputtering to life with a cloud of white smoke. In the morning it starts on 3rd crank, white cloud of smoke, and sometimes a rough hesitating idle until you give throttle a tap, then it evens right out and runs smooth. Starts good when cold, or after stopping for 20 minutes or less. Now I have concluded it could be anything from the lift pump to batteries, after a night of searching online, I plan on testing the "cold water trick" on the injection pump.
I have ordered so far

A fuel filter
PMD kit from Leroy Diesel.
A lift pump oem ac delco
thinking about in the near future
Thinking about wiring myself a harness for the ops bypass
exhaust

I know these things are beasts, i drove one for work with 230k, 150 miles a day and asked my boss if he had checked the oil (it leaked from every gasket) he hadnt in months. Drained 1 qt, fillled her up with fresh oil and it kept on running. Moral of the story, i want this to be a realible work truck, i dont want to leave a jobsite cranking for 1 minute. Any advice is appreciated, I'm a little overwhelmed atm, but plan on learning and reading a lot more. Over all the truck is great, nice interior, have new speakers on the way. Thanks any suggestions would be kindly appreciated.
heres it compared to one of my other vehicles https://photos.app.goo.gl/kCCWgJVuREqmL1fF9 https://photos.app.goo.gl/kCCWgJVuREqmL1fF9

56pan
06-25-2020, 06:11
Mine's a '93 and I had that exact problem quite a while back. It's likely either the lift pump or burnt oil pressure switch contacts. There's a GM service bulletin about it: 93-286-6A that gives the part no. of the updated oil press. switch: 10243574. The SB has a very good check for the voltage to the pump and you can do that at the ALDL connector under the dash with a voltmeter. I had 7 volts going to my pump due to the burnt contacts in the oil press. switch. Changed the pump and the switch about 11 yrs. ago and has been fine since. There's also a very good mod. you can do by putting a relay in line with the pump to prevent the oil pressure switch handling the excessive current of the pump. I'm sure someone here can steer you in that direction. The updated switch worked good for me.

Yukon6.2
06-25-2020, 09:43
Are you sure it's a 93?
93's didn't have a electronic injection pump.No PMD or OPS

6.5l_Roofer
06-26-2020, 18:11
Oh im sure, I just checked, your right i feel like an idiot, but i should be able to return it. I bought an acdelco lift pump, and the wiring harness from kennedy, i will buy the updated switch to. thanks for your guys help, saving me alot of headache!

56pan
06-26-2020, 19:30
Are you sure it's a 93?
93's didn't have a electronic injection pump.No PMD or OPS

No PMD on a '93, but they do have an oil press. switch for the lift pump and oil press. indicator.

trbankii
06-27-2020, 07:41
You don't mention glow plugs other than that they were replaced before you bought it. Do they cycle when you go to start the truck? The glow plug relay may be bad.

Yukon6.2
06-27-2020, 09:52
No PMD on a '93, but they do have an oil press. switch for the lift pump and oil press. indicator.
Yah sorry i meant the optical sensor

6.5l_Roofer
06-27-2020, 20:23
Pretty sure it's the lift pump and ops combo. Glow plugs cycle

6.5l_Roofer
06-27-2020, 22:42
Okay oil sender got updated at dealer talked po. Hoping a new lift pump from AC fixes my problems, I'll buy the Kennedy kit with the relay soon..