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New and random stalling issue

I’m watching this thread, and I will check for pinched wires, a few years years ago I changed the transmission, and intermittent running, but long cycles of running. I drove to Toronto and it hasn’t run since. My truck is set up similar to AK. There’s pressure to new ip, fuel exits the transition from hardline to hose at back of engine, How much return flow should come from the return line. I need to check by the sender next. Can a bad starter relay crank, but not start engine? Sorry to hijack, but same issue, all sensors function as they should. No mist from gp holes. I did cooka battery coming home from Canada. Side post developed leak and boiled off. Replaced those and took a new alternator off shelf to eliminate voltage regulator, till I get old one tested. Today I will check pinched wires and see if flow returns to tank. OP , again sorry for hijack. Can a bad starter relay allow crank, but no start? I haven’t visited in a long time, it’s good to see everyone still here
 
It's a device you install under the hood that allows you to use a mechanical gauge but won't allow raw fuel to run into the cab. iirc the line going into the cab is filled with mineral oil up to the isolator and the line from the isolator to the fuel line will have fuel in it. there is a diaphragm in the isolator that separates the two liquids so fuel cannot pass that point but still allow the gauge to function. These isolators can be used on more than just fuel, like oil pressure too.
 
They are safe to use.

It used to be buying one, the fill/bleeder valve to fill the top of the line with its oil (baby oil often) and buy the mechanical gauge was far cheaper and more reliable than the electric gauge and a sensor. Times have changed- I ent from recommending them to not because electric ones are better priced, reliable and faster install.
 
dbrannon79 said:
if it's fuel starvation, both the clear hose and reading pressure will reveal it. do you have anything to read the PCM for codes? you can do the paper clip and count the flashes but for these trucks with the diesel, there are really only two trusted scanners that can read codes and live data along with checking and setting timing. GMTDscan for the laptop or a GM Tech 2
Click to expand...
I put in a clear fuel line where and as suggested. I haven't had any stalling issues since I posted, but today, I hit the acceleration hard, and the truck stumbled a bit. When I stopped, I checked the fuel line, and sure enough, there was a big air bubble in it. So it appears that air is getting into my fuel system somehow.
This is all new to me, so where do I start? As far as I can see, there are no leaks.
 
when you shut off the engine you will see a single air bubble form in the clear line, what you don't want to see is with it running and any air bubbles flowing through the line. you might need to get a helper watch it or run the truck for you in the driveway. crank it up while watching, if there is no bubbles at idle or free revving the engine, drop it into gear while holding the brake, put the engine under a load while watching.

also get a gauge on the fuel pressure feed and see what you are at at idle and under load. both items here will help diagnose this.
 
dbrannon79 said:
when you shut off the engine you will see a single air bubble form in the clear line, what you don't want to see is with it running and any air bubbles flowing through the line. you might need to get a helper watch it or run the truck for you in the driveway. crank it up while watching, if there is no bubbles at idle or free revving the engine, drop it into gear while holding the brake, put the engine under a load while watching.

also get a gauge on the fuel pressure feed and see what you are at at idle and under load. both items here will help diagnose this.
Click to expand...
Thanks. I'm still looking for a fuel pressure gauge that won't break the bank.
 
dbrannon79 said:
This is the exact same tester Harbor Freight sells, but looks to be higher is price. honestly all you need to temporary it is a pressure gauge that reads up to 15 psi, some hose and a tee fitting to connect it at the IP inlet. get enough hose to run it up to the windshield so you can place it under the wiper blade while you drive.

Click to expand...
Honestly for that price I ‘should’ be able to find something permanent for not much more. In theory😀
 
One thing about air bubbles flowing through the clear line.
It may not appear as A bubble followed by another.
Most likely it will be more like a whitish foamy flowing through.
If there is air intrusion, it will be between the lift pump and the inlet/suction pipe in the fuel tank.
I have read where the suction tube inside the fuel tanks has rusted through and when fuel drops below that level, in the tank, then there will ne air intrusion.
 
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