7.3 IDI start issues

Reply Subscribe

Thread Tools

Search this Thread

Apr 18, 2017 | 01:53 PM

drs1023

Thread Starter

Junior User

Joined: Nov 2011

Posts: 80

Likes: 2

7.3 IDI start issues

My 7.3 IDI in a 91 F350 has just developed a start issue. I turn on the key. The Wait To Start light comes on then turns off when it appears to be ready to start, but the engine will not start. Fuel feed is OK as is evident by the smoke. It will start only after I spray chain saw gas lightly into the breather box. I have never used starting fluid. Since it had been 10 or more years since new glow plugs, I replaced all (Bosch). No help at all although 1 of the old plugs was blown. No start! How about the glow plug relay/controller? I had to put on a new one 7 or 8 years because of a broken wire at the base of the solid state portion.
All replies appreciated.

Apr 18, 2017 | 02:32 PM

jrodimus

Senior User

Joined: Jan 2010

Posts: 181

Likes: 0

Did you replace your Ford glowplugs that lasted 25 years with some not Ford bosch plugs. Get you some real ford glowplugs, check your relay. Replace it with a Ford relay. I sell 1 a week here to the guys that have bought one from the bluebox outfit...

Apr 18, 2017 | 03:48 PM

drs1023

Thread Starter

Junior User

Joined: Nov 2011

Posts: 80

Likes: 2

Yes, Bosch plugs. I put Bosch in 10 years ago and 1 was blown the other day. Is there a site which explains the full test procedures for the relay? Thx for the help.

Apr 18, 2017 | 03:52 PM

tjc transport

i ain't rite

Joined: Mar 2005

Posts: 65,422

Likes: 5,507

From: Marlboro Mental Hospital.

how long does the WTS light stay on? it should be around 15 seconds.
i ONLY USE motorcraft ZD-9 glow plugs in my 7.3 IDI. i am on my third set with 495,000 miles on it

Apr 18, 2017 | 07:19 PM

drs1023

Thread Starter

Junior User

Joined: Nov 2011

Posts: 80

Likes: 2

WTS stays on about 10 seconds. I just remembered that the voltmeter used to drop when the light came on, then rose just a little when it went off. Not doing that now

Apr 19, 2017 | 03:57 AM

tjc transport

i ain't rite

Joined: Mar 2005

Posts: 65,422

Likes: 5,507

From: Marlboro Mental Hospital.

i have a led or small 12 volt light hooked to the output of the glow plug relay on all my diesels so i can tell whether the glow plugs are getting power or not. i do not trust the wait to start light. way too many times the WTS light comes on but the led does not, telling me the controller is telling the WTS light the glows are working, but the led is telling me they actually are not.

Apr 19, 2017 | 12:47 PM

madpogue

Lead Driver

Joined: Oct 2003

Posts: 8,476

Likes: 37

From: Madison, WI

^^^^^ Good idea; the GLOW PLUG light in the earlier trucks with the old-style, often-maligned controller works exactly this way. Much more useful IMHO, as it also tells you when it after-glows.