• Welcome to The Truck Stop! We see you haven't REGISTERED yet.

    Your truck knowledge is missing!
    • Registration is FREE , all we need is your birthday and email. (We don't share ANY data with ANYONE)
    • We have tons of knowledge here for your diesel truck!
    • Post your own topics and reply to existing threads to help others out!
    • NO ADS! The site is fully functional and ad free!
    CLICK HERE TO REGISTER!

    Problems registering? Click here to contact us!

    Already registered, but need a PASSWORD RESET? CLICK HERE TO RESET YOUR PASSWORD!

Opinions needed - Performed Optical Bump

Here's a good thread with info on timing, you see I've sought the same help as you although I still haven't made time to mess with the IP and am being lazy and hoping to get my hands on a built DB2 first lol

Q&A for DS4 timing thread

I'm at -1.50. I can't tell ya how i got there. Just got lucky.
www.thetruckstop.us
 
@DieselAmateur Thanks for that link, there was some good info there.

so from what I am reading, it looks like I also need to "debump" the OS and try again. I'm also hoping that once I get it set closer to the -1.43 or so the truck will start easier. it's always taken a little more cranking time that I'd like for it to bust off after sitting a few hours. Adding a little glow plug time has helped but in this Texas weather I would think the 5-6 seconds the relay provides even with new glow plugs should be enough.

after I get the clear return line on the IP, it might tell me my fuel is draining back too.
 
dbrannon79 said:
@DieselAmateur Thanks for that link, there was some good info there.

so from what I am reading, it looks like I also need to "debump" the OS and try again. I'm also hoping that once I get it set closer to the -1.43 or so the truck will start easier. it's always taken a little more cranking time that I'd like for it to bust off after sitting a few hours. Adding a little glow plug time has helped but in this Texas weather I would think the 5-6 seconds the relay provides even with new glow plugs should be enough.

after I get the clear return line on the IP, it might tell me my fuel is draining back too.
Click to expand...
Or that there is air intrusion coming in from someplace.
 
dbrannon79 said:
but in this Texas weather I would think the 5-6 seconds the relay provides even with new glow plugs should be enough.
Click to expand...

No. IMO with self limiting Glow Plugs it needs more glow time. But in Texas and AZ heat if everything is perfect you don't need glow plugs.

Yes, start with air in the system. It's the #1 step in the GM flowchart. You want to match book shop rates or spend a couple weeks working on it till you finally check for air? :banghead:

Possible lift pump dead. This should go with air...

Possible worn head and rotor in IP causing Hot Start problems.

Possible low compression - how is the blowby?

Last to overcome all but air: add more glow plug time via a tune change or override switch. All 8 plugs MUST be self limiting plugs. We can discuss the many problems I overcame with lots of glow time mainly low compression from bent and leaking valves...
 
WarWagon said:
No. IMO with self limiting Glow Plugs it needs more glow time. But in Texas and AZ heat if everything is perfect you don't need glow plugs.

Yes, start with air in the system. It's the #1 step in the GM flowchart. You want to match book shop rates or spend a couple weeks working on it till you finally check for air? :banghead:

Possible lift pump dead. This should go with air...

Possible worn head and rotor in IP causing Hot Start problems.

Possible low compression - how is the blowby?

Last to overcome all but air: add more glow plug time via a tune change or override switch. All 8 plugs MUST be self limiting plugs. We can discuss the many problems I overcame with lots of glow time mainly low compression from bent and leaking valves...
Click to expand...
the glow plugs I installed are the AC Delco 60g's. no sure if those are self limiting. a while back I did attempt the inline 10ohm resistor mod on the glow plug control signal wire. it was suppose to increase the cycle time but as I found out that only works with the OEM relay that still has the thermal circuit in the glow plug relay. apparently mine has been previously replaced, the screwdriver across the terminals for and extra 5- 10 seconds does help. I also mistakenly discovered that when I leave the key on for maybe a minute or two after the GP cycle finishes and then crank. it starts up right away but clatters like I just squirted ether in it ( which I have never done)

Blowby! yes it does have some, I don't really know how much is considered borderline bad. but it does have little puffs from the dipstick tube at idle. I have not checked the compression, need to find a cheap adapter for the glow plug port, I have a gasser compression tester with a 300psi gauge.

Hot start isn't really a problem, it's usually only the first crank after sitting a few hours.

Lift pump should be good, one of the first things I replaced when I bought the truck, but again I have neglected to check the pressure with a gauge, just cracked the bleeder and watch it spew.

I know this might sound like a dumb question, but would you mind helping me with the flow chart or steps in checking the air or where to find a copy of the chart. my first thought is checking air filter/intake and air in the fuel system. I plan to stop by the parts house this evening to get some clear hose for the return on the IP
 
Flow chart is pretty simple assuming the LP works. If it's not leaking anything externally, fittings dripping or damp, then the leak is before the LP where the fuel is under vacuum and not pressure. It is also possible that the new LP has a leaky check valve in it.
 
Ok, I got the clear line installed. started it up and didn't see any immediate air in the line, but time will tell after I watch it for a few days. Although when I shut it off a small air bubble floated up from the steel return line. I ran it twice and both times after I turned it off a small air bubble came back, not from the IP side but from the steel return tubing.

I attached a photo of the bubble that floated up after shutdown and also a couple of videos taken with my phone. sorry if the audio is bad. I was using my remote start so I could film it. the one video also shows how bad the blowby is from the dipstick tube with the engine at or close to 185-190 degrees. the other video I has taken right after I had installed the new injectors and new to me turbo. I noticed an unusual knocking noise that seems to be coming from the far back passenger side. maybe from the #8 injector. I was curious if this is normal or something I need to worry about.

Video: Knock after injector install

Video: added clear tubing and a look at blowby

Bubble from return.jpg
 
Saw the first video, couldn’t see the second with the blowby.

The way you describe the little bubbles after shut down, you’re fine. What you would be concerned about is a small trail of bubbles while the engine is running coming out of the IP. You have NO ISSUE in your fuel supply system at this point for air intrusion.


As to the lift pump- new ones can go bad in a month or two. I always suggest putting a metal T at the ip inlet, and tap a fuel pressure gauge sensor there, mount the gauge so you always see it while driving. Bad lift pump can ruin a good ip in a hurry. Especially when poor quality fuel comes into play. 8-14 psi is your desired range. Bad lift pump will put it in vacuum and that destroys injector pumps fast.

You can test it has pressure by starting engine and cracking open the water in fuel valve. It should put out fuel (I can’t remember volume per minute at the moment). If you open valve and it dies or struggles to run and little to no fuel comes out- lift

The glow plugs you have are the ones you want to always run, they are self limiting- which is what you want to protect the engine from glow plug destruction. If you are not getting along enough glow time, buy the little solenoid the Leroy Diesel cells and add a switch to the dash feeding it. The added glow time to ecm and the resistor trick dont always work well- the switch on the dash does. I suggest a momentary switch or button so you don’t accidentally leave it on.

On the knocking injector:
Start engine and crack line nut by injector like you are bleeding the air out. Do this one at a time. The engine should slow rpm as you do each one. If you find one that doesn’t alter engine rpm- or the knock goes away- suspect that injector.
Now shut off engine and swap that injector with easy to reach one from other side of engine. Retest. If the problem follows the injector- that injector is messed up. If the problem does not follow the injector- it is not a bad injector. Could be ip, injector line, compression, valve, etc.

I can’t remember your whole thread right now, as to what else to have you go through. I will reread it all in a bit and see where to to from there. But check the injectors out, verify fuel pressure/flow from lift pump.
 
that was more like 2 hours sitting when I did that video, Sorry for the poor audio on the video I should have tilted my phone to the side for full screen.
 
Oh yeah! Saw the video- at start up and at 0:49 mark- HUGE VOLUME OF AIR.
Solve this before doing anything else.

Pressurize fuel line to 15 psi from tank foreword with truck engine off. Find and fix the leak.
All fuel line should be sae30r9.

Examine metal lines for rust/ cracking.
Sometimes it is the fuel sending assembly in the tank.
 
Will L. said:
Oh yeah! Saw the video- at start up and at 0:49 mark- HUGE VOLUME OF AIR.
Solve this before doing anything else.

Pressurize fuel line to 15 psi from tank foreword with truck engine off. Find and fix the leak.
All fuel line should be sae30r9.

Examine metal lines for rust/ cracking.
Sometimes it is the fuel sending assembly in the tank.
Click to expand...
I guess I know what I'm doing this weekend!

should I pull the feed line from the IP and plug it to keep air pressure from going into the IP? then pressurize the system by connecting my air compressor regulated at 15psi at the rear of the lift pump, use some soap water sprayer and inspect all the steel lines and connections from the lift to the connection at the IP?

if this turns out to be the tank sending unit ( fuel gauge doesn't work) I have an excuse to finish plumbing in the auxiliary tank in the bed bypassing the OE tank until I have the time to pull it and replace the sender plus make sure the tank is clean.

on another note. the lift has an internal anti-drain check valve, can I, or would it ok to install a check valve inline somewhere, maybe before the remote fuel filter for good measure?
 
Set the air pressure regulator to 8 or 10 PSI and inflate the tank through the fill hole, wrap some rags around the air blow gun and cram it all into the fill opening. Squeeze the blow gun trigger and hold for a minute or so, then crawl around under the truck and look for leaks. Or have someone squeeze the trigger while You crawl around looking for leaks.
It will not harm the injection pump.
My air intrusion problems was loose hose clamps.
 
I was actually curious about pressurizing the tank. wasn't sure if that much pressure would balloon the tank or cause other damage.
 
You must log in or register to reply here.
Back
Top