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Old 6.5-T strikes again !

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M123KT-450

M123KT-450

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Coming home Easter Sunday it started bucking n studdering then the water in fuel light came on along with the check engine light!

I was at 1/8th of a tank so I stopped threw 7 gallons n dumped in a half bottle of 911 drove 3 miles home truck ran fine.

Now this morning heading into the shop it had the same simptoms but no lights !

Not sure what to do from here ?

PMD/FDS is relocated to bumper...

Mikey
 
Change fuel Filter, clean the cannister, check your lift pump for operating presure while you're at it.
 
Will do ! I was kinda thinking it was pump related as it don't appear to have been changed .

How do I go about testing it ?

Mikey
 
Make sure you pump out the filter assembly before changing filter. Open the drain valve by thermostat and power up the LP with the truck off. For powering LP with IGN OFF you'll have to jumper power to pin G (bottom left) of the OBD1 port, or jumper power to the fuse/relay center, like jumper 12V to the plug contact that LP relay spade 87 went to.

The only time Ive seen the WIF light was when I had the truck sitting for almost a year and went to crank it. Maybe you got some watery fuel.
 
Well I should have the new Lift pump and fuel filter tonight. . .

Even tho it has ran great all day today i ain't trusting it New filter new Pump. . .


Mikey
 
Do you have a vacuum/fuel pump guage to check the LP pressure at the drain valve?

I'm guessing you actually had some water causing the issue and if youve drained the filter assembly a little while youre rid of it.
 
Nope i do not have such a gauge in-stock but i am thinking i should get one rather soon. . .

But now i do have a brand new LP and a brand new FF, weather it was bad yet or not it would have gone bad at some point so i am going to just change it out. . .

The old works still so i'll keep it around yet. . .

But i am sure with 130K miles on the LP its not as good as it once was, Which may or may not have been part of its subberen starting issues from time to time and maybe a cause of the lack of get up n go power. . .

who knows all i know is its 1 more commonly failed part replaced. . .

Mikey
 
Make sure the OPS is working by checking for voltage on Pin G (bottom left) of the OBD1 port while the truck is running. There should be 14V, battery voltage. With the truck off there should be no voltage, and you can power the LP by jumpering power to this pin. If there is no voltage there with truck running the OPS is not working.
 
Aah yes the good old Oil Pressure Switch. . .I will be sure to test it for sure i do believe this was changed once in its past history IIRC from when i went threw all the work orders n invoices from the PO who bought truck new. . .

I will be sure to test tho. . .thanks much for the help i shall report back on the findings and progress of this repair. . .

Mikey
 
There should also be a crank fuse that powers the LP relay during IGN in the Start position (cranking). In my 94 I have the crank fuse that power the LP relay and an LP fuse on the line leaving the relay to the LP. If you have hard starting the fuse or relay could contribute. OPS can also contribute by not leaving the line primed when you shut it off.
 
Ok now dose the lift pump run continually?

If all is well and the O P S dose not send power to the lift pump can it be hooked to a switch for temporary use to get by ?

Mikey
 
The LP should run whenever the truck is running, via the OPS.

And it would most likely power the LP for about 5-10 seconds after you shut off the truck, especially running the heavy weight oil. The OPS does not stop sending power until oil pressure bleeds off after shutdown. I always hear mine after shutting down. I like that so I know the fuel line is primed for next startup.
 
New lift pump is in along with a new fuel filter system is bleed !

Ill post up the new pump old pump n new filter old filter photos later very tired !

Truck ran great for half hour at the shop...

Ran it down the road made it about a 10th of a mile it started acting up only lasted about a mile then it ran great!

I think it might have been water in the fuel turned O D on additive?

I filled it up so we will see how it goes...

Mikey
 
I hate to say it ! But its acting just like an over heated PMD ! ! !

Only with out the stalling out and failing to restart !

When it bucks now if let off the throttle it idles perfectly ! If I slam on it it bucks n kicks a bit harder but it speeds right up !

Mikey
 
If the OPS is functioning, I would be looking for air leaks in fuel lines.

And another member just had this issue and it turned out to be a bad fuel cap, which by loosening it resolved the problem. Obviously needs to be a Diesel fuel cap.
 
buddy said:
If the OPS is functioning, I would be looking for air leaks in fuel lines.
Click to expand...

Boy, I walked away from my computer for no more than 2 minutes. I came back to mention it sounds like air in the system and you had already posted that! Oh well - me snooze, me lose. :smile5:
 
Yea the pressure switch works as it was a bit stubborn starting this morning after it spun a few seconds I let off n the
LP continued to run another 15 or 20 seconds...

After 3 rounds of this it fired right ran great for a few miles then it did its little number of bucking n studdering then it ran great again !

So bleed the fuel system again ?

Mikey
 
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