Another 7.3 idi won't start thread... I'm sorry...

[Ryan Nunez]

Replaced the glow plugs and still no start. Jumped the started solenoid to crank from the engine compartment and checked fuel at shrader valve and had a good constant stream. My batteries have 12.3v so now I’m thinking my starter isn’t spinning fast enough due to @The_Josh_Bear ’s video he posted in his comment earlier. I can’t see any fuel or bubbles at any of the connections on the injectors so I’m assuming my prime held but like @ISPKI said I don’t have clear lines so I really can’t be sure.

 

[MtnHaul]

Perhaps you've already done this but make sure your battery terminals and cables are clean and shiny before dropping in a new starter. I had an intermittent no-start issue with batteries off-gassing and causing buildup, but a quick brushing and the ol' girl would fire right up Also, resting voltage for a 12 volt battery should be more like 12.7--probably not a big deal but I thought worth noting. .

 

[ISPKI]

Replaced the glow plugs and still no start. Jumped the started solenoid to crank from the engine compartment and checked fuel at shrader valve and had a good constant stream. My batteries have 12.3v so now I’m thinking my starter isn’t spinning fast enough due to @The_Josh_Bear ’s video he posted in his comment earlier. I can’t see any fuel or bubbles at any of the connections on the injectors so I’m assuming my prime held but like @ISPKI said I don’t have clear lines so I really can’t be sure.

Thing about batteries is, the voltage doesnt really measure a battery's capacity to energize the starter. You can have a battery read 12.7 volts but only have 200 CCA capacity. Think about how a small car battery can be at 12.7v but only has 350CCA. Same thing can happen to our larger batteries and it happens often - ive replaced my truck batteries every other year since I bought it, fortunately under warranty. Alternatively, the battery can read 12.3v but still have 800CCA in it. As long as the battery is reading over 12v it will work to engage the starter and thats realistically all you can determine without a load cell to properly test it. Our starters will pull upwards of 500amps in the cold so if your batteries are low on their capacity by even a little bit, they wont spin the starter fast enough.

 

[Ryan Nunez]

@ISPKI you are 100% correct, I do know that the batteries are good though because I just dropped $350 on them two days ago lol.

@MtnHaul I checked the terminals when i put the new batteries in and the crimps were all clean and tight and the terminal ends are nice and tight on the terminals. I didn't notice anything out of the ordinary with the connections at the starter either. The insulation on my positive cables are starting to show signs of wear but they are not cracked down to the copper or anything like that

 

[ISPKI]

@ISPKI you are 100% correct, I do know that the batteries are good though because I just dropped $350 on them two days ago lol.

@MtnHaul I checked the terminals when i put the new batteries in and the crimps were all clean and tight and the terminal ends are nice and tight on the terminals. I didn't notice anything out of the ordinary with the connections at the starter either. The insulation on my positive cables are starting to show signs of wear but they are not cracked down to the copper or anything like that

Got it, yeah they should be solid then. Do you have a multimeter? probably worth measuring resistance from + terminal to the starter lug. The cables on my truck appeared fine, jacketing was all in good shape. I ended up cutting the jacketing off both + cables. One had clean copper, the other was packed with copper corrosion. Ended up cutting a good 6 inches down before I found good clean copper. Many of the strands were broken from corrosion as well. Ended up building new cables along with installing a new starter motor. DB electrical gear reduction starters are pretty cheap and supposed to be good. Fact of the matter is, if your starter has 100k miles on it, especially on a vehicle like ours that takes massive amounts of power to crank, it could probably stand to be replaced.

Think of it this way, our trucks probably put the most strain on the starter compared to ANY vehicle on the road, aside from big rigs most likely. We have one of the largest diesel motors with the heaviest rotating assembly with the highest compression you are going to find in a vehicle, and our starters really arent that much larger than your average big block truck starter.

 

[Ryan Nunez]

@ISPKI Thats not a bad idea, I hadn't thought about doing that. Side note to anyone reading this thread, please disconnect the cables before testing resistance on the positive wire or else you'll blow the internal fuse on your meter. Sorry just had to put my 2 cents on that as an electrician lol.

I actually have a DB starter coming tomorrow so fingers crossed the ole boy is gonna fire right up but if not I'll definitely look into troubleshooting the cables. If anyone is curious the DB starter for our trucks is available on amazon with 2 day shipping if you have prime. They also have great reviews on both this forum and on amazon.

 

[Stu Bailey]

Whenever you do find the problem post an update with a summary. I know plenty of people like me will appreciate it and I’ll probably come back to it one day when my truck won’t fire. It sounds like you’ve done a lot already so I’m hoping you’re up and on the road for the New Year!

 

[Ryan Nunez]

@Stu Bailey I definitely will post a full update when I have it consistently starting. I have done a lot already but having just bought the truck a week ago, they are all things that I am happy I did so that I know when they were done and that they were done correctly.

Id love to be able to drive it jan 1 but once I need to get it starting correctly so that I can change the oil and flush the coolant. Then I need to rewire the rear lights after I trace and test the wiring since the guy that changed the bed just hacked up all the connectors. Not a lot of expensive fixes just a lot of fixes in general that will take some time to complete! Couple other little things that will need done to pass PA inspection but at least I don't have to worry about emissions with it being a diesel!

 

[Stu Bailey]

Yes, one of the many perks of a classic diesel! I do remember now you mentioning the wiring and what the PO had done. I’ll be looking forward to the post when you’ve got it all done!

 

[The_Josh_Bear]

That tells me it has something to do with the glow plug system. You mentioned that the GP relay was replaced recently. Just because it's new doesn't mean it's good. The GP relay has to pass a lot of current. I've had GP relays work intermittently too. The new ones just don't seem to be as good as the old ones. Some members here have gone to the White Rodgers/Stancor relay:

https://www.amazon.com/stancor-586-902/s?k=stancor+586-902

Kinda spendy, but you get what you pay for...
Perhaps the guys that got the W-R relay will chime in.

Before you throw money at the problem, pull an easy to get to glow plug and ground the body of the GP. Connect a booster cable to the negative post of one of the batteries, and the other end to the body of the GP, for example. Connect the GP to the GP wiring harness. Make sure the GP is not touching/near anything that can burn/melt. Turn the key on, and see if the GP gets red hot. It should take about 10 seconds.

If it doesn't, check the GP relay feed wires at the connector on the passenger side of the engine. There are 2 yellow wires that go into a connector. This is a weak point on these trucks. This can be a high resistance connection and can melt the connector in some instances!

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I got rid of the entire automatic GP system and went manual with individual relays:

https://www.oilburners.net/threads/manual-glow-plug-update.73571/

Did you check these two yellow wires out? They are a common source of resistance to the relay and you can have a working system without getting full amperage to the glow plugs.

Sounds like you're getting a lot done on the rig, at least the nice part is that once air intrusion and the glow plug and starting systems are done, you don't have much else to fix under the hood for many many miles of dependable service. The problem is we mostly tend to get neglected rigs then feel like it's so much effort and a bad design...but really it's the PO not taking care of business since 1989!

 

[MtnHaul]

Not a lot of expensive fixes just a lot of fixes in general that will take some time to complete!

Yeah, that^^^^ describes my truck perfectly, even though it came with an inch thick folder of receipts

 

[Farmer Rock]

Yeah, that^^^^ describes my truck perfectly, even though it came with an inch thick folder of receipts

The only receipts I got,was a McDonald's receipt for a hamburger that was under the seat of my 250.Lol...not having maintenance records annoys me something awful,but what can I do?Just a lot of little things to fix.




Rock

 

[IDIBRONCO]

The only receipts I got,was a McDonald's receipt for a hamburger that was under the seat of my 250.

Now that's just funny.

 

[ISPKI]

... The problem is we mostly tend to get neglected rigs then feel like it's so much effort and a bad design...but really it's the PO not taking care of business since 1989!...

This is so painfully accurate. Its surprising how neglected these trucks usually are considering how valuable they are as work vehicles.

 

[Dski1991]

I just had this problem with my truck. I couldn't narrow it down but I replaced the injectors and put a electric pump on and it starts right up now.