6.9 idi no start

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Dec 16, 2025 | 09:22 PM

Bump1904

Thread Starter

2nd Gear

Joined: Dec 2025

Posts: 2

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6.9 idi no start

Hey. Im working on a 6.9 idi for a buddy. Not to familiar with the idi motors as I am with powerstrokes. The issue im having is he put a motor in that a guy swore up and down ran when parked. He has it in the truck, but the truck side harness is a nightmare. And he switched the engine harness because the "new" one was in way better condition. Im just wondering what do these idis need to run? I have a 5 pin relay on the inner fender on the passenger side that has no ground. And I just fixed the signal wire for the glow plugs and fss. Have the glow plug light on now when key is on. Didn't before. And the fss is clicking now, I know these dont like to start unless its sunny and 75. I just need some guidance and any is appreciated, TIA!

Dec 17, 2025 | 12:28 AM

BigBlue2

Lead Driver

Joined: Apr 2002

Posts: 5,317

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Definitely need glow plugs operational to start in cold weather. Some say the block heater can get you there. Did you wire in the original glow plug controller system or modified for a manual controlled momentary switch?

Here's the link to the EVTM for the 86 which includes the diesel.

https://www.garysgaragemahal.com/1986-evtm.html

Dec 17, 2025 | 06:19 AM

Olds64

Logistics Pro

Joined: Jun 2017

Posts: 3,963

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From: Edmond, OK

If you leave the block heater plugged in for an hour or two you should be able to get her started. Make sure you drain the Schraeder valve on the fuel filter. You should get a solid stream of fuel out of it while cranking.