Eratic behavior from an 85' 6.2 (more below) requesting help please (Two vids in one)

[WarWagon]

so I suppose i can rule that out.

No. You have a PROBLEM. Start troubleshooting over and NOTHING gets a free pass. It's a year old and "used" at this time.

Do you have a fuel heater anywhere is this aftermarket filter setup? Or is it an OEM setup with a fuel heater at the filter?

I don’t remember the year it went away but remember my 88 they were gone.

Our 1988 6.2L NA 1/2 Ton Suburban had a mechanical lift pump.

if anyone could point me to a tutorial on how to replace it

Assure us you did the air test as noted several times here with the clear return line before you WASTE YOUR TIME DOING THIS!!! It's step #1 in the GM shop manual for a good reason! Bluntly your symptoms indicate air/lack of fuel to the IP. Been there done that got the T-Shirt.

Pull the intake and PLUG THE PORTS with paper towels. Keeps say the return line worm clamp etc. from falling into the engine.
Remove the oil fill tube.
Remove the ip lines from the IP - you don't need to remove them from the injectors. (Easier if you do but a time thing.)
Remove the two fuel lines supply/return. Good time to replace the rubber lines.
The e-clip on the throttle cable is easy to loose. I put a paper towel under the pump to try and catch it.
Rotate the engine backwards with a ratchet on an alternator pulley and remove the three ip gear bolts one at a time through the oil fill tube hole. Use a paper towel in the socket to make it tight on the bolt or magnetized socket.
Remove the three bolts holding the IP in.
Note the position of the locator pin on the IP going into the drive gear as the IP will likely turn as it's being wiggled out around the IP lines.

Reinstall new/rebuilt/patched up IP making sure the locator pin goes in the correct hole. If it goes in the wrong hole there are two (or one of the bolt holes) you can't get all three bolts in the drive gear.

Reinstall things...

Remove the easy to get to glow plugs. Spin the engine in 30 second bursts till you get a flammable mist out the glow plug holes. This has primed the fuel system. Reinstall the glow plugs and the engine should start.

 

[WarWagon]

And some fool has drilled a bunch of holes in the air cleaner housing to CHOKE the turbo and engine on hot underhood air (and raise NOx emissions). Compressing HOT air with a turbo robs power...

Get a used housing without the holes.

 

[nycxjeremyy]

Got the clear tubing finally, will keep you updated with how it goes

 

[nycxjeremyy]

No. You have a PROBLEM. Start troubleshooting over and NOTHING gets a free pass. It's a year old and "used" at this time.

Do you have a fuel heater anywhere is this aftermarket filter setup? Or is it an OEM setup with a fuel heater at the filter?



Our 1988 6.2L NA 1/2 Ton Suburban had a mechanical lift pump.



Assure us you did the air test as noted several times here with the clear return line before you WASTE YOUR TIME DOING THIS!!! It's step #1 in the GM shop manual for a good reason! Bluntly your symptoms indicate air/lack of fuel to the IP. Been there done that got the T-Shirt.

Pull the intake and PLUG THE PORTS with paper towels. Keeps say the return line worm clamp etc. from falling into the engine.
Remove the oil fill tube.
Remove the ip lines from the IP - you don't need to remove them from the injectors. (Easier if you do but a time thing.)
Remove the two fuel lines supply/return. Good time to replace the rubber lines.
The e-clip on the throttle cable is easy to loose. I put a paper towel under the pump to try and catch it.
Rotate the engine backwards with a ratchet on an alternator pulley and remove the three ip gear bolts one at a time through the oil fill tube hole. Use a paper towel in the socket to make it tight on the bolt or magnetized socket.
Remove the three bolts holding the IP in.
Note the position of the locator pin on the IP going into the drive gear as the IP will likely turn as it's being wiggled out around the IP lines.

Reinstall new/rebuilt/patched up IP making sure the locator pin goes in the correct hole. If it goes in the wrong hole there are two (or one of the bolt holes) you can't get all three bolts in the drive gear.

Reinstall things...

Remove the easy to get to glow plugs. Spin the engine in 30 second bursts till you get a flammable mist out the glow plug holes. This has primed the fuel system. Reinstall the glow plugs and the engine should start.

Video of the air test is up! Please let me know whay you all think

https://www.reddit.com/r/Diesel/s/rZMjyYOR5y

Got the clear tubing finally, will keep you updated with how it goesView attachment 92490

 

[MrMarty51]

You have terrible amounts of air intrusion.

 

[nycxjeremyy]

You have terrible amounts of air intrusion.

I can't even begin to imagine where it's coming in from

 

[Will L.]

Start with your fuel filter. If his is a common point . Remove, wet the seals and reinstall.

If you have not replaced your old rubber lines yet- this is a good place to start.
From the tank all the way foreward AND the 5/16” return line back to the tank.
Replace it all with SAE30r9. Use new high quality hose clamps with it.

Examine the metal lines as you do that for rust.

This is a seriously annoying fix, we know. But we all know from experience because it is simply a must.

 

[nycxjeremyy]

Start with your fuel filter. If his is a common point . Remove, wet the seals and reinstall.

If you have not replaced your old rubber lines yet- this is a good place to start.
From the tank all the way foreward AND the 5/16” return line back to the tank.
Replace it all with SAE30r9. Use new high quality hose clamps with it.

Examine the metal lines as you do that for rust.

This is a seriously annoying fix, we know. But we all know from experience because it is simply a must.

Yup, never once did the lines or anything, both rubber and metal

Would oriellys or autozone have a whole set? RockAuto perhaps??

If i must do this, may as well knock it all out in one go

 

[ak diesel driver]

Personally I'd start by replacing the short pieces of rubber hose with clear to identify where the leak is coming from

 

[dbrannon79]

There is no "kit" for these trucks. simply get you a roll of rated fuel line and some clamps and have fun!

having said above, when running, air will only enter the system behind the lift pump due to the lift pump "sucking" from the tank. everything in front of the lift pump will be under a low amount of pressure and will leak fuel. Now having said this, if your lift pump is not building pressure your IP will still suck fuel and cause the all of the fuel lines to go into a vacuum which will also be suspect of sucking air into the lines. this is why we also need to attach a pressure gauge at the IP inlet to verify the LP is indeed working.

Now that you have the clear hose installed and on your video at the end it seems most of the air has stopped. I assume that was your first startup after installing the clear tubing. let it sit overnight and before starting, look at that clear tube to see if fuel has drained out and is empty. this is a good indication of a leak on the return side. most common is the tiny hoses going between each injector. there is a kit for this sold at the auto parts stores. but if this isn't the issue, then the lift pump could also be the issue too. there should be an internal check valve within the lift pump to prevent backflow. these valves will fail long before the pump fails. you can't service the valve as it's part of the lift pump. cheap fix is to install a one way check valve right in front of the lift pump.


Next steps:
get a pressure gauge installed on the supply hose going into the IP. check for clear line draining out, check fuel pressure when running.

Best solution= replace everything including fuel tank sending unit/pickup tube, all fuel supply and return lines rubber and steel. verify working lift pump, if in question, replace.

Note: intake will have to be removed to replace rubber supply hose to the IP so order a set of intake gaskets while your at it.

 

[nycxjeremyy]

There is no "kit" for these trucks. simply get you a roll of rated fuel line and some clamps and have fun!

having said above, when running, air will only enter the system behind the lift pump due to the lift pump "sucking" from the tank. everything in front of the lift pump will be under a low amount of pressure and will leak fuel. Now having said this, if your lift pump is not building pressure your IP will still suck fuel and cause the all of the fuel lines to go into a vacuum which will also be suspect of sucking air into the lines. this is why we also need to attach a pressure gauge at the IP inlet to verify the LP is indeed working.

Now that you have the clear hose installed and on your video at the end it seems most of the air has stopped. I assume that was your first startup after installing the clear tubing. let it sit overnight and before starting, look at that clear tube to see if fuel has drained out and is empty. this is a good indication of a leak on the return side. most common is the tiny hoses going between each injector. there is a kit for this sold at the auto parts stores. but if this isn't the issue, then the lift pump could also be the issue too. there should be an internal check valve within the lift pump to prevent backflow. these valves will fail long before the pump fails. you can't service the valve as it's part of the lift pump. cheap fix is to install a one way check valve right in front of the lift pump.


Next steps:
get a pressure gauge installed on the supply hose going into the IP. check for clear line draining out, check fuel pressure when running.

Best solution= replace everything including fuel tank sending unit/pickup tube, all fuel supply and return lines rubber and steel. verify working lift pump, if in question, replace.

Note: intake will have to be removed to replace rubber supply hose to the IP so order a set of intake gaskets while your at it.

Alright sir, will let it sit overnight and see what happens, will let you know of this the next day, thank you so much for your assistance in all this, im hoping to have this back and we'll running for the coming spring

 

[Will L.]

Most situations, I would diagnose exactly where the leak is and repair it.

But these rubber lines are now 40 years old. And the diesel fuel we have now has ethanol in it- which the rubber is not rated for.
Fix one line now, another in a few months, the next a year later, so on and so on.

No, sometimes you don’t patch the tires- you simply buy a new set.
Oh , 41 years- it was built the calendar year before 85…
So yup- time to correct it.

I do suggest a fuel pressure gauge tapped at the inlet of the ip. Use a metal T between the king nipple and the inlet cone. This way the reading is always at the ip even if something should happen to the new fuel line. The reason is: low incoming fuel pressure wears out the ip much quicker. And the LP (lift pump) will flow fuel on failure so that the ip sucks fuel past it.

Yours is old enough that you might still have a mechanical LP. I suggest learning that gm ditched these do to engine failures when the bladder fails in a specific way. When it occurs, fuel will continue to the ip, and also flow slowly into the crank case washing out the bearings and seizing the engine.
Roll of the dice. The alternative is an electric lift pump which cheap ones fail often and expensive ones that are reliable and close to a grand when done-

If this truck sees 1,000 miles a year and is just a play thing- no biggie. If it is a daily driver and critical use… well that becomes a different matter.

 

[nycxjeremyy]

Most situations, I would diagnose exactly where the leak is and repair it.

But these rubber lines are now 40 years old. And the diesel fuel we have now has ethanol in it- which the rubber is not rated for.
Fix one line now, another in a few months, the next a year later, so on and so on.

No, sometimes you don’t patch the tires- you simply buy a new set.
Oh , 41 years- it was built the calendar year before 85…
So yup- time to correct it.

I do suggest a fuel pressure gauge tapped at the inlet of the ip. Use a metal T between the king nipple and the inlet cone. This way the reading is always at the ip even if something should happen to the new fuel line. The reason is: low incoming fuel pressure wears out the ip much quicker. And the LP (lift pump) will flow fuel on failure so that the ip sucks fuel past it.

Yours is old enough that you might still have a mechanical LP. I suggest learning that gm ditched these do to engine failures when the bladder fails in a specific way. When it occurs, fuel will continue to the ip, and also flow slowly into the crank case washing out the bearings and seizing the engine.
Roll of the dice. The alternative is an electric lift pump which cheap ones fail often and expensive ones that are reliable and close to a grand when done-

If this truck sees 1,000 miles a year and is just a play thing- no biggie. If it is a daily driver and critical use… well that becomes a different matter.

That's what I'm saying, i rather just replace all the fuel lines, given that they're over 40 years old and it's just better to knock that out of the to do list.

I actually do have a mechanical lift pump in it, I replaced it last year, this is it

For 1987 Chevrolet V20 6.2L V8 DIESEL Fuel Lift Pump Delphi | eBay

1987 Chevrolet V20 Engine: 6.2L V8 DIESEL; EngineVIN: C; FuelSystem: FI ; Engine Mounted;. 1987 Chevrolet V20 Engine: 6.2L V8 DIESEL; EngineVIN: J; FuelSystem: FI ; Engine Mounted;. Fuel Lift Pump. Year Make Model Application Notes.

www.ebay.com

I'm hoping oriellys or autozone have these hoses, id be so much better than chasing hoses online.

Also, my motor is an 85, but the vehicle itself is a 90 K5, the previous owner swapped it out from another truck, so the motor itself has 75K miles on it. If that matters

 

[MrMarty51]

I believe that none of the parts houses will have that SAE30R9 hose. IIRC, Oriellys and NAPA over here had only 30R4.
I tried John Deere and even they did not have diesel rated hose. Only the 30R4.
If You have a regular diesel shop that repairs a lot og fuel systems then it MIGHT be possible that they coukd have some diesel rated hose.
I had to order the stuff I have from online sources.
I dont remember the brand name but I did manage to score some made in the USA hose. I also got some with a brand name of evil, IIRC was the name and it was made in china. I used some but then shopped and got some made in USA, removed that chinese and replaced it with American made.

 

[nycxjeremyy]

I believe that none of the parts houses will have that SAE30R9 hose. IIRC, Oriellys and NAPA over here had only 30R4.
I tried John Deere and even they did not have diesel rated hose. Only the 30R4.
If You have a regular diesel shop that repairs a lot og fuel systems then it MIGHT be possible that they coukd have some diesel rated hose.
I had to order the stuff I have from online sources.
I dont remember the brand name but I did manage to score some made in the USA hose. I also got some with a brand name of evil, IIRC was the name and it was made in china. I used some but then shopped and got some made in USA, removed that chinese and replaced it with American made.

I think i unknowingly discovered im leaking (rear) diff fluid aswell https://photos.app.goo.gl/61uZBQh7JHHRLtm76

 

[nycxjeremyy]

I think i unknowingly discovered im leaking (rear) diff fluid aswell https://photos.app.goo.gl/61uZBQh7JHHRLtm76

This is clear line today, left it overnight untouched

 

[nycxjeremyy]

I think i unknowingly discovered im leaking (rear) diff fluid aswell https://photos.app.goo.gl/61uZBQh7JHHRLtm76

I'm not sure how to tackle this one either, im somewhat new to all this

 

[Will L.]

Holy cow…
That differential is probably really low on oil.
The input seal is what is leaking- you have to have the rear end fully set up for replacing that.

Degreaser- clean it all off to start. Remove fill plug & top it off - keep checking it VERY OFTEN until you can learn it all & buy the tools to diy or take it to a shop.

Some people learn it easy and do fine- for others it seems to be rocket surgery.

Imo- again age of truck- you might open it up and find way more than just seal needs replacing. My thought it when doing input seal to do the axle seals at same time. Replace any questionable bearings. Get it all new condition again then you can ignore it for the next couple hundred thousand miles.

YouTube videos get you a decent understanding of the task.

 

[nycxjeremyy]

There is no "kit" for these trucks. simply get you a roll of rated fuel line and some clamps and have fun!

having said above, when running, air will only enter the system behind the lift pump due to the lift pump "sucking" from the tank. everything in front of the lift pump will be under a low amount of pressure and will leak fuel. Now having said this, if your lift pump is not building pressure your IP will still suck fuel and cause the all of the fuel lines to go into a vacuum which will also be suspect of sucking air into the lines. this is why we also need to attach a pressure gauge at the IP inlet to verify the LP is indeed working.

Now that you have the clear hose installed and on your video at the end it seems most of the air has stopped. I assume that was your first startup after installing the clear tubing. let it sit overnight and before starting, look at that clear tube to see if fuel has drained out and is empty. this is a good indication of a leak on the return side. most common is the tiny hoses going between each injector. there is a kit for this sold at the auto parts stores. but if this isn't the issue, then the lift pump could also be the issue too. there should be an internal check valve within the lift pump to prevent backflow. these valves will fail long before the pump fails. you can't service the valve as it's part of the lift pump. cheap fix is to install a one way check valve right in front of the lift pump.


Next steps:
get a pressure gauge installed on the supply hose going into the IP. check for clear line draining out, check fuel pressure when running.

Best solution= replace everything including fuel tank sending unit/pickup tube, all fuel supply and return lines rubber and steel. verify working lift pump, if in question, replace.

Note: intake will have to be removed to replace rubber supply hose to the IP so order a set of intake gaskets while your at it.

End result of letting it sit overnight with the clear tube on

 

[nycxjeremyy]

There is no "kit" for these trucks. simply get you a roll of rated fuel line and some clamps and have fun!

having said above, when running, air will only enter the system behind the lift pump due to the lift pump "sucking" from the tank. everything in front of the lift pump will be under a low amount of pressure and will leak fuel. Now having said this, if your lift pump is not building pressure your IP will still suck fuel and cause the all of the fuel lines to go into a vacuum which will also be suspect of sucking air into the lines. this is why we also need to attach a pressure gauge at the IP inlet to verify the LP is indeed working.

Now that you have the clear hose installed and on your video at the end it seems most of the air has stopped. I assume that was your first startup after installing the clear tubing. let it sit overnight and before starting, look at that clear tube to see if fuel has drained out and is empty. this is a good indication of a leak on the return side. most common is the tiny hoses going between each injector. there is a kit for this sold at the auto parts stores. but if this isn't the issue, then the lift pump could also be the issue too. there should be an internal check valve within the lift pump to prevent backflow. these valves will fail long before the pump fails. you can't service the valve as it's part of the lift pump. cheap fix is to install a one way check valve right in front of the lift pump.


Next steps:
get a pressure gauge installed on the supply hose going into the IP. check for clear line draining out, check fuel pressure when running.

Best solution= replace everything including fuel tank sending unit/pickup tube, all fuel supply and return lines rubber and steel. verify working lift pump, if in question, replace.

Note: intake will have to be removed to replace rubber supply hose to the IP so order a set of intake gaskets while your at it.

End result of letting it sit overnight with the clear tube on