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6.9/7.3 IDI Diesel tech info

 
  #76  
Old 10-08-2018, 06:44 AM
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first thing to do is make sure you have fuel in the tank,.
these trucks are known for cracking the pickup tube in the tank at around the 1/4 tank mark and then sucking air . so if your gauge is showing around 1/4 tank, try adding 5-10 gallons of fuel and then try priming it.
an inline electric fuel pump is a good investment, but do not use a cheap gas pump.they do not last when pumping diesel and will die within a few months.
you are going to need a facet duralift pump, part # 40222. best price i have found is from these guys: https://www.aircraftspruce.com/catal...iABEgJghPD_BwE
 
  #77  
Old 11-14-2018, 04:11 AM
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New to the forum, question about maintenance.

i have an 84 7.3 IDI, what is the best fuel additive. I have heard mixed opinions on the two stroke oil mixed in gas, but Iím not really so sure i like the idea enough myself to do it. I have heard good stuff about diesel kleen, standyne and regular Lucas. What is Your allís thoughts? Feel free to move this if itís in the wrong page!
 
  #78  
Old 11-14-2018, 04:50 AM
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no additives needed. but if you want to and some diesel kleen or whatever to ease your mind, it will not hurt anything.
i have seen these engines run on filtered used motor oil, vegetable oil, home heating oil, kerosene, jet fuel, and all three different versions of diesel fuel. my 88 has almost 500,000 miles on it and never any problems. also never added anything to the fuel except for once a year i fill the fuel filter with ATF to clean out the pump and injectors.
 
  #79  
Old 03-25-2019, 02:31 PM
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Howdy, been looking for a while and so far not found an explanation of the factory water separator use. We pulled up on the ring and nothing happened. No fluid dripped out below the truck. Could we just have introduced air into the fuel system by pulling up on the ring?
 
  #80  
Old 03-25-2019, 05:21 PM
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it may be bypassed. the water separator on the 6.9 trucks was a pain in the asterisk and as such, it was usually the first thing eliminated to prevent air intrusion.
 
  #81  
Old 03-25-2019, 09:33 PM
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Originally Posted by tjc transport View Post
it may be bypassed. the water separator on the 6.9 trucks was a pain in the asterisk and as such, it was usually the first thing eliminated to prevent air intrusion.
I retapped the top for a 3/8 npt plug and added a ball valve at the bottom to drain it. Currently it has no way to suck air that I know of, I can keep my cheap 6.9 filter, and the capacity for water is pretty cool.

I need to get some 3/8's diesel rated hose and hook it up to test, when I do I'll add a post with pics for others
 
  #82  
Old 04-26-2019, 09:04 PM
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Vacuum pump, first point of failure?

I searched this thread for "vacuum pump" but got (Sorry - no matches. Please try some different terms.) Seems like it might be a good addition.

If an IDI in otherwise good shape suddenly loses brake boost, where would you suspect the fault lies? My vacuum pump looks old. The truck is an 89, with only 104k miles on it, and the pump looks as old as Moses.

Would you start with replacing the vacuum pump? I'll check the plastic check valve on the booster first, of course, and that there is vacuum there. If none, it's gotta be the pump at fault.

Thanks guys!
 
  #83  
Old 04-27-2019, 06:14 AM
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Originally Posted by RenoHuskerDu View Post
I searched this thread for "vacuum pump" but got (Sorry - no matches. Please try some different terms.) Seems like it might be a good addition.

If an IDI in otherwise good shape suddenly loses brake boost, where would you suspect the fault lies? My vacuum pump looks old. The truck is an 89, with only 104k miles on it, and the pump looks as old as Moses.

Would you start with replacing the vacuum pump? I'll check the plastic check valve on the booster first, of course, and that there is vacuum there. If none, it's gotta be the pump at fault.

Thanks guys!
I would hook a gauge up to the output of it to verify you have no vacuum they are like $350
 
  #84  
Old 04-27-2019, 07:23 AM
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Originally Posted by 81Bronk36 View Post
I would hook a gauge up to the output of it to verify you have no vacuum they are like $350
first thing i do.
if it has at east 19 inches vacuum, i then step on the brake pedal twice to see how long it takes the pump to recover.
if recovery is almost instant, than the booster is bad.
if it takes a while the pump is bad.
if no vacuum, i backtrack towards the pump looking for vacuum to see if i have a leak.

no where near $360.
bronco graveyard has them for $82 :
https://shop.broncograveyard.com/Vac...yABEgJ87fD_BwE

rock auto has them priced between $76 for cheap, and $149 for motorcraft:
https://www.rockauto.com/en/catalog/...cuum+pump,5172
 
  #85  
Old 04-27-2019, 03:34 PM
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We have vacuum at the check valve. 19 inches is about 9 psi vacuum, and that feels about like what we have. But there's no brake boost at all.
I'm thinking it's the booster that quit.
 
  #86  
Old 04-27-2019, 06:29 PM
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sounds like it.
 
  #87  
Old 04-30-2019, 02:10 AM
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Originally Posted by RenoHuskerDu View Post
We have vacuum at the check valve. 19 inches is about 9 psi vacuum, and that feels about like what we have. But there's no brake boost at all.
I'm thinking it's the booster that quit.
I would invest in a vacuum gauge, mine dropped to 16 and the brakes didn't have but one cycle and they were harder than a rock, swapped the pump with a spare and all was well.
 
  #88  
Old 04-30-2019, 08:18 AM
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Originally Posted by DarkOverCast View Post
I would invest in a vacuum gauge, mine dropped to 16 and the brakes didn't have but one cycle and they were harder than a rock, swapped the pump with a spare and all was well.
Good advice, thanks. We put a reman booster in today, and the brakes are better but still not good enough for my wife. So we put a vacuum gauge on it and there are only 3 inches of vacuum. DOH. Well, on the bright side, that old booster was 30 years old so it's good money spent.

The vacuum pump is not real expensive, but you need a good puller to remove and replace that crappy sheet metal pulley without bending it. I'm going to let my local tire/brake/alignment guy do the job. He has a Gen I Bronco body on a rotisserie right now so it's fun to hang out and watch. The frame and powertrain are restored, now it's body time.
 
 
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