7.3 gurus

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7.3 gurus

Post  bbf-falcon on November 18th 2014, 10:57 am

My 99 F350 7.3 won't start unless its plugged in on these cold mornings.I have a new set of a
MOTORCRAFT glowplugs on order.My Question is , with the wait to start light (wts).does the glow plugs stop their heat cycle WHEN the light goes out, or does it keep heating longer? And is there a way to know whether it's the plugs or the relay.
Thx

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Re: 7.3 gurus

Post  whitefield on November 18th 2014, 11:44 am

bbf-falcon wrote:My 99 F350 7.3 won't start unless its plugged in on these cold mornings.I have a new set of a
MOTORCRAFT glowplugs on order.My Question  is , with the wait to start light (wts).does the glow plugs  stop their heat cycle WHEN the light goes out, or does it keep heating longer? And is there a way to know whether it's the plugs or the relay.
Thx

I was taught heat or voltage stops a few seconds after the light goes out. With high mileage vehicle I change glow plug relay and glow plugs and sometimes valve cover gasket and wiring harness. use IH or factory Ford parts . This is just another after thought and may not be anything to it , but Also oil may make a difference in the way a 7.3 starts in the winter .
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Re: 7.3 gurus

Post  Curt on November 18th 2014, 12:24 pm

I think the power to the glow plugs will remain active for maybe up to 60 seconds after the light goes out.  Are the glow plugs bad? I changed mine and it still wouldn't start without being plugged in when cold.

Is the relay working? You can test it with a test light to make sure it is supplying power. Is the harness connection at the valve cover okay? Is there sufficient oil pressure when cranking?  How old is the starter? Sometimes all it needs is a little faster spin.  I replaced my old one with a new gear reduction off of a 6.0 and it made a huge difference in cranking speed.  How are the batteries, connections and cables?
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Re: 7.3 gurus

Post  Curt on November 18th 2014, 12:31 pm

Mine ended up being a $55k repair.

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Re: 7.3 gurus

Post  David Willingham on November 18th 2014, 12:40 pm

Everything Curt said. The glow plugs stay on a good bit after the light goes out. I wait about 30 seconds after the light goes out to start it. Then I go down my 500ft driveway and out onto the road and in about a few hundred feet, the lights brighten up meaning the glow plugs have just shut off. The colder it is, the longer they stay on. Mine is getting a little hard to start. I have 283,000 on mine.
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Re: 7.3 gurus

Post  David Willingham on November 18th 2014, 12:43 pm

Also, if there is white smoke coming out while trying to start it, it's the glow plug system. If not, it's supposed to be the injectors. This is what I've read for years and it's the case on my Dad's truck.
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Re: 7.3 gurus

Post  cool40 on November 18th 2014, 1:19 pm

My wrecker is a 96 and I replaced all the parts mentioned and it still dont start good. I noticed the amp gauge dont come up for 30 seconds after starting.
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Re: 7.3 gurus

Post  69F100 on November 18th 2014, 1:29 pm

[quote="cool40"]My wrecker is a 96 and I replaced all the parts mentioned and it still dont start good. I noticed the amp gauge dont come up for 30 seconds after starting. [/quote


Lee they do that to keep from putting a big load on the alt from the glow plugs they drow like 80 amps after they glow plugs shuts off the alt kicks.in then.from what I have read.
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Re: 7.3 gurus

Post  res0rli9 on November 18th 2014, 1:42 pm

One sure fix is to move to FL... Smile

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Re: 7.3 gurus

Post  bbf-falcon on November 18th 2014, 6:37 pm

The batteries are new, the truck only has 113k mi. It has been hard too start in cold weather since I've owned it.And yes, the smoke is white from the exhaust until after it starts.

FLORIDA CAN'T COME SOON ENOUGH FOR ME Rolling Eyes

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Re: 7.3 gurus

Post  72puller on November 18th 2014, 7:08 pm

Mine starts A LOT better if I cycle the glow plugs twice. I've owed mine since 02 and the only thing I have had to replace starting wise other than batteries was the glow plug solenoid.
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Re: 7.3 gurus

Post  bbf-falcon on November 18th 2014, 7:18 pm

72puller wrote:Mine starts A LOT better if I cycle the glow plugs twice. I've owed mine since 02 and the only thing I have had to replace starting wise other than batteries was the glow plug solenoid.
What made you choose the solenoid over the glow plugs? Just curious Idea

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Re: 7.3 gurus

Post  Larry T on November 18th 2014, 8:12 pm

over the last 4 years I had starting problems as others I replaced injectors,glow plugs,solenoid,batterys,fuel filters,put a helper pump on and did the fuel tank mod.when I put the helper pump on the motor started just fine in all weather until last thanksgiving day.i found the oem pump not working so I looked around and found a heavy duty hi psi on ebay about 70 bucks.the motor started just fine this morning @17* not saying that is everyones problem but I would put a fuel pressure gauge on it and watch it like a hawk.
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Re: 7.3 gurus

Post  whitefield on November 18th 2014, 8:16 pm

bbf-falcon wrote:
72puller wrote:Mine starts A LOT better if I cycle the glow plugs twice. I've owed mine since 02 and the only thing I have had to replace starting wise other than batteries was the glow plug solenoid.
What made you choose the solenoid over the glow plugs? Just curious Idea

One other thing I forgot to mention is the fuel heater can also can cause a hard start cold.
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Re: 7.3 gurus

Post  Lem Evans on November 18th 2014, 10:06 pm

Curt wrote:Mine ended up being a $55k repair.


Ruby Red be pretty Exclamation

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Re: 7.3 gurus

Post  514Fox87 on November 18th 2014, 10:18 pm

Hey Rick mine is getting hard to start also but have found if I cycle the key 2-3 times waiting till light goes out it starts right up. Just haven't had time to get the plugs changed.
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Re: 7.3 gurus

Post  Lem Evans on November 18th 2014, 10:37 pm

7.3 guys please do not go psycho on me.

Most of the time when the 7.3 do not start well or at all in the winter is because the ring seal has went to hell.

Don't ask me how I know....just trade a worn out 7.3 POS to a dumb ass Ford dealer before the weather gets cold.

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Re: 7.3 gurus

Post  res0rli9 on November 18th 2014, 10:41 pm

Lem Evans wrote:7.3 guys please do not go psycho on me.

Most of the time when the 7.3 do not start well or at all in the winter is because the ring seal has went to hell.

Don't ask me how I know....just trade a worn out 7.3 POS to a dumb ass Ford dealer before the weather gets cold.

Dam I don't want to know what you call Cold Rolling Eyes

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Re: 7.3 gurus

Post  72puller on November 19th 2014, 12:07 am

bbf-falcon wrote:
72puller wrote:Mine starts A LOT better if I cycle the glow plugs twice. I've owed mine since 02 and the only thing I have had to replace starting wise other than batteries was the glow plug solenoid.
What made you choose the solenoid over the glow plugs? Just curious Idea

I tested it and it wasn't working. They have a metal piece in them that gets a piece burnt out of it and they won't make contact.

http://www.ebay.com/gds/Ford-diesel-glow-plug-relay-trouble-shooting-/10000000009400380/g.html
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Re: 7.3 gurus

Post  69F100 on November 19th 2014, 1:21 am

Rick I just replaced my IDM on my 95 the guy where I bought it from ask me what it was doing told him I had to replace the ECM and when it would fire up it was skipping and popping. I had the ECM and IDM off of a guy's truck at work and as long as I had his hooked up it ran fine. He told me a few things to watch and what usually gets the IDM on the 7.3 was bad batteries, a dragging starter and corroded battery post terminals. He said if the truck get hard to start cold and have checked glow plugs, solenoid, and valve cover connections it could be the IDM is getting weak and not sending the correct voltage to the injectors to fire them. When the oil is cold and fuel is cold it take the 115 DC voltage to fire them to open them cold where when the engine is hot they will fire off at 105 DC volts and run fine but the fuel mileage will be down some. If this is true I don't know but that is the info he was telling me and I do know mine was started with bad batteries a few times before I put the new batteries in it and it would not run with it. Now I have a new ECM and IDM and 2 bad glow plugs it started up today at 45* but tonight with it down to 31* it didn't fire right off so it time for glow plugs. They are calling for mid 20s tonight so I plugged it in tonight and will see in the morning how it fires off.
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Re: 7.3 gurus

Post  bbf-falcon on November 19th 2014, 8:15 am

My truck runs great once it starts, it was 9* here yesterday morn and 3* right now.I'm going to check relay solenoid afterbit.Thx for help guy's. Wink

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Re: 7.3 gurus

Post  Curt on November 19th 2014, 11:08 am

Lem Evans wrote:

Ruby Red be pretty Exclamation

Thanks! I was afraid I would regret selling my 7.3L Excursion, but so far I am in love with this new unit.

I can't believe how easy this thing pulls without any mods.

My biggest complaint is the unbelievably small fuel tank! What were they thinking??????? No
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Re: 7.3 gurus

Post  Lem Evans on November 19th 2014, 11:20 am

Curt wrote:
Lem Evans wrote:

Ruby Red be pretty Exclamation

Thanks!  I was afraid I would regret selling my 7.3L Excursion, but so far I am in love with this new unit.  

I can't believe how easy this thing pulls without any mods.

My biggest complaint is the unbelievably small fuel tank! What were they thinking??????? No

Maybe 'they' were not thinking Laughing

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Re: 7.3 gurus

Post  Curt on November 19th 2014, 12:29 pm

Lem Evans wrote:

Maybe 'they' were not thinking Laughing

For sure! rabbit
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Re: 7.3 gurus

Post  aquartlow on November 19th 2014, 5:38 pm

The glow plug relay stays energized after the WTS light goes out, mine stays on for at least 45sec to 1 minute(cold starts) even in 80 degree Florida weather, in colder weather the glow plugs stay energized longer depending on how cold it is. You may want to install a new glow plug relay, by now yours is probably fubar'd. I just ordered one for my '00 with 278K. If you do replace the GPR, wire in an in-dash LED to the "load" side of the relay when the key is on, that way it will show if the relay is turning on and for how long. I have to replace mine because it was making a clicking/humming noise, basically it was telling me the internal contacts are burned/pitted. I have heard/read that the glow plugs can use quite a bit of current, as much as 175+ amps or 20-25 amps each in extremely cold situations. Try International part # 1831646C1 can be found on Ebay for $25, here:
http://www.ebay.com/itm/NEW-Glow-Plug-Relay-International-T444E-7-3L-1995-2003-/230568175171

Good luck. Todd
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