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Discussion Starter #1
Found this little bugger inside the screen on the inlet on the injection pump in my 98 6.5, Aussie Suburban. Have been having this issue with an intermittent miss at around 2000rpm.
strange thing is it does not do it under
load such as when towing.
I have cleaned from the fuel tank through to the IP and today just finished on the injectors. Have done the earths, trolled the forums( not in a bad way) trying everything, yes new pmd, remote mount etc. IP is about 15k miles old.
it has me stuffed and this little blighted is the only thing that is strange.
Can anyone tell me what it is, I will appreciate it.
Cheers
John
 

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Welcome to DieselPlace
Not sure what that object is. Could be some junk material left behind from the IP rebuilder

For your issue, perform a lift pump test: Reference Material: Lift Pump/OPS
If your lift pump fails the test then replace with Ac/Delco: EP158
Open your fuel cap. Do you hear a large "Whoosh" sound? If so then you have a restriction and need to modify your fuel cap for better venting
 

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Discussion Starter #3
Hi there. Thanks for the response. Have tested the lift pump / pressure tested up at IP. Have tried the fuel cap trick as well but no change. Really has me stumped.
what really puzzles me is why it stops stumbling / cutting out when the vehicle is
under heavy load. By this I mean towing a heavy trailer or driving it at 70mph.
In my mind if it was fuel then I would have thought that it would get worse not better.
I am beginning to think it is electrical. For the record I have three PMDs and when I change between them it stays the same. I have cleaned all of the earths, check the ignition switch etc. only thing I haven’t done is pull the wiring loom apart. That is something I would dread.
do they have an O2 sensor or similar?
Have put on a new OPS as well for the record.
Seems to be worse when the vehicle has warmed up, say about twenty minutes into the journey. Just like a
PMD issue.
haven’t posted before because I feel bad because this is like dragging up the same subjects and I don’t want to waste your time.
appreciate any help though.
cheers
 

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Are you using any fuel additive with each tank of fuel? If not, then try using some TC W3, two-stroke oil ( 1 ounce of oil per every 2 gallons of fuel ).
Run a few tanks and see if it improves.

There are no O2 sensors on a 6.5L Diesel but there can be a Catalytic Converter or Soot Trap as we sometimes call it. They can become restrictive and cause performance issues.
It would be located just after the Turbo downpipe and look like this:
trap.JPG


If you do have this then remove it unless your region requires emissions equipment on the vehicle
 

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1995 GMC Suburban
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Did you replace the hoses that goes into the IP?
 

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How are your batteries? My 95 suburban had random stalling and hiccups that I couldn’t figure out for 2 years and this winter the batteries gave up(they were at least 5 years. I put 2 new batteries in and haven’t had a stall or hiccup in 5 months.
 

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Also make sure that there is no "kink" on those hoses.
 

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Discussion Starter #8
Are you using any fuel additive with each tank of fuel? If not, then try using some TC W3, two-stroke oil ( 1 ounce of oil per every 2 gallons of fuel ).
Run a few tanks and see if it improves.

There are no O2 sensors on a 6.5L Diesel but there can be a Catalytic Converter or Soot Trap as we sometimes call it. They can become restrictive and cause performance issues.
It would be located just after the Turbo downpipe and look like this:
View attachment 634930

If you do have this then remove it unless your region requires emissions equipment on the vehicle
Hi, Thanks for the response, have tried the additives a while back in the fuel, two stroke oil as well but only one tank full. Will try that again.
Have removed the CAT as well but don’t tell anyone. Did notice an improvement on turbo spool up so was happy with that side of things.
 

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Discussion Starter #9
Batteries are 12 months old but will get them tested. Have not had any starting issues as such so they are in good condition I would think.
I did replace all of the lines leading up to the IP with the exception of the metal ones. No kinks as such. One was a bit restricted so I lengthened that to make sure it had a gradual curve to improve flow. Appreciate the responses guys.
Cheers
 

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Batteries are 12 months old but will get them tested. Have not had any starting issues as such so they are in good condition I would think.
I did replace all of the lines leading up to the IP with the exception of the metal ones. No kinks as such. One was a bit restricted so I lengthened that to make sure it had a gradual curve to improve flow. Appreciate the responses guys.
Cheers
Install a piece of clear fuel line on the return side of the Injection pump, as shown here: Question: - 1999 GMC Bluebird 6.5L TD - PMD &amp...
If you notice any air bubbles within the line then you still have some air intrusions to hunt down
 

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Discussion Starter #11
So, I thought I would close this one out for you guys.
Unfortunately I am not able to identify the mystery object but I am able to resolve the issue with the intermittent missing.
Finally got around to checking for air in the system fuel system on the outflow if the injector pump. Put the clear hose on and when to start the engine but it would not fire. Strange for this car as it always starts. Went back and wiggled some of the wires on the harness near the outlet where I had been messing around then went back and it fired up.
I then went back to lol for air bubbles and as I touched the wiring loom it cut out.
Turns out when I did the joint on the extension cable for the PMD (had a bad connector so had to modify it) one of the soldered wires (that I swore I did perfectly) had come apart. My guess is the heat shrink had been holding it together but as it-heated up it started to seperate and caused the missing. Still not sure why it never missed under load but very happy as this has gone in for months.
Up side is I have gone over the whole vehicle from electrics (earths etc) to fuel (dropping the tank, filters, pumps, injectors) so it is in good shape.
Arrogance is the only thing I can really put all of this down to. I was adamant that I had done that particular job right, would have put my life on it. Lucky I didn’t.
Hopefully there is a lesson in all of this for someone other than me. Check your work. Other upside is I know the fuel and electrical system on a 6.5 inside out now.
Just want to say thanks to those of you who took the time to respond with some potential causes, I really do appreciate it. I have seen a lot of posts where guys do t bother to come back and close out the cause of their trouble and I think that is poor form.
Hope you guys in the states are staying safe. Don’t want to get into the politics but as an ex cop I know what goes on in the job. Our two countries are very similar in some of the issues we face in society.
God bless
Cheers
John
 

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So, I thought I would close this one out for you guys.
Unfortunately I am not able to identify the mystery object but I am able to resolve the issue with the intermittent missing.
Finally got around to checking for air in the system fuel system on the outflow if the injector pump. Put the clear hose on and when to start the engine but it would not fire. Strange for this car as it always starts. Went back and wiggled some of the wires on the harness near the outlet where I had been messing around then went back and it fired up.
I then went back to lol for air bubbles and as I touched the wiring loom it cut out.
Turns out when I did the joint on the extension cable for the PMD (had a bad connector so had to modify it) one of the soldered wires (that I swore I did perfectly) had come apart. My guess is the heat shrink had been holding it together but as it-heated up it started to seperate and caused the missing. Still not sure why it never missed under load but very happy as this has gone in for months.
Up side is I have gone over the whole vehicle from electrics (earths etc) to fuel (dropping the tank, filters, pumps, injectors) so it is in good shape.
Arrogance is the only thing I can really put all of this down to. I was adamant that I had done that particular job right, would have put my life on it. Lucky I didn’t.
Hopefully there is a lesson in all of this for someone other than me. Check your work. Other upside is I know the fuel and electrical system on a 6.5 inside out now.
Just want to say thanks to those of you who took the time to respond with some potential causes, I really do appreciate it. I have seen a lot of posts where guys do t bother to come back and close out the cause of their trouble and I think that is poor form.
Hope you guys in the states are staying safe. Don’t want to get into the politics but as an ex cop I know what goes on in the job. Our two countries are very similar in some of the issues we face in society.
God bless
Cheers
John
Glad your issue is resolved.
Thanks for giving us an update!

(y)
 
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