Dreaded Air in fuel line....

can you pressure test the fuel system and do the bubble test with soapy water. there are so many gd fuel lines going every which way to know which one is cracked without systemically replacing stuff

 

A) - Do not under-estimate the Dawn soapy water trick.
B) - I also got a niece that was 11 or 12 to listen, and she heard leaks I couldn't hear.
C) - If you have it narrowed down to a specific area,
a mechanics stethoscope may be helpful.

 

I know this is a old Thread having same issue hard starts in the morning and if I turn it off for a little while hard start trying to start back up I have bubbles in my passenger side Tank return. Line . 2014 Mack with the mp8 . Anybody know what to look for don’t want to just jump into cups .

 

See previous posts - first look at check valve going into engine.
This keeps the head of fuel up to where it can easily be drawn into lift pump.
I changed a filter and even with pre-filling with diesel, it wouldn't start.
That time ended up taking the suction side of a small pancake compressor
and putting together different dia. hoses to fit, then sucking on the line to fill it.
It worked, and started.
Then changed out the bad check valve, and - good to go.
You can also try air hose with a clean rag around it to pressurize tank,
but that does not work as good.

 

check valve is the thing in the fuel filter with the little ball in it right? if the ball is still there how do you know it's gone bad? a leak down test?

 

You will know because your truck won't start. (he, he.)
In my Cat 3126 engine it is a hex shaped brass fitting behind head, and by firewall.
A 50 buck part.
I can only tell you what worked for me.

Don't know if there's one inside filter housings; I thought it was just flow-thru.
Is a fuel filter housing expensive?
Hate to be a "just change it and see" mechanic, not my style.

In your case, maybe a trip to the Dealer-Stealer to view the fuel diagram?
Or Google search?
This is an old thread; maybe use the search bar here @ TTR for more current solutions?

 

So if I'm understanding this thread correctly. My issue with what seems like low low power, engine rev to shift gears sometimes on its own (ishift), bouncing and shaking going up as well as down hills, and absolutely dismal fuel mileage (low as 4.92 MPG by pen and paper math) could all be caused by a little crack in a fuel line? I've got a 2013 780 volvo D13 ishift transmission.

Bouncing and shaking I guess would be better explained as some serious jerking going on. I thought I had bad tires or shocks. But noticed the engine feels like it misses, especially if I try to hold the accelerator steady in just about any gear in manual mode.

 

Cylinder needs fuel, oxygen, and compression to avoid misfiring. Use the process of elimination to determine what it's missing. I'd start with the cheapest and easiest and go from there. Sometimes the symptoms will help point where to start first. If you're losing prime and have hard starts, begin with the fuel system. You can attach a clear line to the overflow valve on the head so you can if the bubbles stop when bypassing a section of fuel lines. If you're still getting bubbles, it might be time for new injectors.

For oxygen, I'd start with a clean air filter. Then check for intake/boost/exhaust leaks. Test EGR valve and turbo.

For compression, I think there's a test you can run with PTT. If you've ruled out air and fuel issues, then the next step I'd take is to check the engine. Since I don't have the confidence or an enclosed shop area, I don't really mess with anything under the valve cover. It might be that you just need a valve adjustment, or could be a new head or an overhaul.

Find a shop you can trust and hope for the best.

 

Above post by loudtom about sums it all up nicely; especially last line, good job.

To clarify a point,The previous comments made on spraying soapy water on lines was for finding leaks in air lines,
not for fuel lines. Fuel lines sucking air thru a crack in plastic line, or bad rubber hose, would induce bubbles into fuel flow. Get to a place on fuel system where you can see the fuel flow, and look for bubbles. If you have a rats nest of hoses like in posted pix, replace all the dealer type spring clamps with the special wrap-around hose clamps for injector hoses.

I like the "monkey doing brain surgery" idea.
My comment always was - "It's hard to do brain surgery over the phone with a dull fork."

 

You could be right. I did some investigating with paperwork from guy I bought truck from. They claimed to have replaced the injector cups. I hear this tick tick tick in my driver seat if I hold my head the right way sounds like it's near the doghouse, changes tune a little. They state on the invoice they adjusted the valves. I know when I hit 3 on the VEB, the truck shakes like the wheels will fall off and come to think of it, that's how it kind of acts when it goes into its jerky episodes. I'm willing to bet they either didn't adjust them right or not at all. The accelerator pedal feels weak. Like I'm pushing it about 20% to get it to move, and to the floor feels like I'm barely pushing more than that 20% of pedal travel space. You may be on to something there with the valve thing. My brother looked it up and says the engine brake and exhaust valve are "on the same circuit". He thinks it's trying to jake when I'm still on the pedal.

Before people bust my chops I say what I have about the people done the valve adjustment cause same folks that replaced exhaust manifold gaskets. I had to pay a real mechanic to go behind that and tighten every bolt they left loosened.