Community Forums

JerryLook · 03-01-2021, 04:45 PM

With a suction type system is it possible to get fuel if I cracked a line by the filters? Or should I go straight to one of the injectors and crack a line while cranking the engine?

Does the ISC have a fuel shutoff solenoid ike the older mechanical 8.3?

Also, while I don’t have a dash light for low coolant (or a code), is it possible that’s the issue? I could always run a jumper from ground to the wire on the sensor to test it.

Also I guess I should check and see if I have some kind of obstruction in the air intake system. We don’t have snow here like Fffrank got in his filter, but maybe something got sucked up there like a plastic bag

Mile Marker 42 · 03-01-2021, 10:38 PM

I would start with the fuel. I would crack or disconnect a line coming out of the lift pump, or the hose going into the Caps pump, whichever is easier and verify you have fuel pumping out.

JerryLook · 03-02-2021, 05:57 AM

That sounds like a good plan. I’m also going to see if the lift pump bolts are loose while I’m in there. I do have a new gasket for it if it needs it, but since it hasn’t been leaking I haven’t replaced it yet.

Plus the low pressure fuel on the lift pump side I can check by myself. Later on I’ll have to ask the DW to crank the engine while I crack an injector line.

paul65k · 03-02-2021, 06:17 AM

I hate to be the bearer of bad news but it sounds EXACTLY like what happened to us when we lost our CAPS pump..... and sounds like what others have said on similar failures.

If you are getting pressure from the lift pump you will want to check the pressure at the injectors and see if you are getting fuel there or have someone plug with a Cummins scan tool run diags..... in our case the diagnostics narrowed it down to the fuel pump (CAPS)..... I hope this is not your issue as this was a $6K repair but this is likely the worst-case scenario and you'll probably want to eliminate this as a potential failure.

Good luck and I hope I'm wrong

JerryLook · 03-02-2021, 06:35 AM

Yes the caps pump is something always in the back of my mind. I’ve read the threads about caps failure, including fffranks ordeal with his break down. I’m really hoping that’s not the problem, but if it is it’s getting changed right here in my driveway

We have a trip planned in two weeks and I’m just glad the coach broke down a 1/2 mile from my house instead of 400 miles from my house.

jacwjames · 03-02-2021, 07:15 AM

With a dead stop on the engine the fuel must have either choked off quickly or your CAPS pump is gone.

One thing to check is the hoses supplying fuel to both the filters. There has been at least on post where the internal hose broke down and chunks of rubber plugged the hose just before the filter.

JerryLook · 03-02-2021, 07:29 AM

My lift pump has some weird screws in it. Nothing I have fits it. Maybe this is the later style that isn’t meant to be taken apart?

Also can I check for low pressure fuel at this fitting on the caps pump? Looks like it comes straight from the lift pump

oakcreekeric · 03-02-2021, 07:41 AM

Quote:

Originally Posted by JerryLook

My lift pump has some weird screws in it.

Those look to be Torx Plus heads - See below link

https://www.lislecorp.com/specialty-...lus-socket-set

JerryLook · 03-02-2021, 07:44 AM

Ok thanks on the torx plus

So I loosened the banjo fitting on the caps pump. When I turn the key to run fuel doesn’t come out for about 30 sec. You can hear the tone of the lift pump change and then there’s pressure. If I turn the key back off and on again it does the same thing. About 30 sec to get the prime back. So it would seem like I have something sucking air into the system big time.

JerryLook · 03-02-2021, 07:57 AM

I took off the line coming from the fuel tank at the primary filter and I have no fuel running out. I have half a tank of fuel, I would think it would be right there at the line.
Maybe I can pressurize the tank with compressed air and see if I can force the blockage out? If it’s a collapsed line I’ll need to run a new one of course

I have one of those little Harbor Freight drill pumps. I hooked it up to the hose coming from the tank. It took a good 2 min of running it before fuel started coming out.

JerryLook · 03-02-2021, 09:07 AM

I can bleed the system from the top of the caps pump until fuel shoots out, then as soon as the lift pump turns off it loses the prime. I have to run it another 30 sec until fuel shoots out again.
I’m tempted to run a hose from in front of the primary filter into a diesel can so I can see what side of the system I have a air leak on. Nothing I’ve looked at in the engine side and around the primary filter show signs of a fuel leak.

RS505 · 03-02-2021, 09:58 AM

I have a Mityvac that I use to prime pumps and filters, but it can also be used to leak check fuel hoses. Cap off one end of the suspect hose, put a gage on a tee on the other end and pump all of the air out (15" 0f vacuum should do it). If the vacuum leaks down, then the hose might be leaking.

Of course, you can do the same thing with compressed air, just don't go too crazy with the pressure.

JerryLook · 03-02-2021, 10:37 AM

Compressed air.... yeah funny story about that. So I decided to pressurize the system with compressed air. I ran a line from my air compressor to the tank vent. I have one of the little air nozzles and I zip tied the handle on. I taped around the nozzle so it wouldn’t leak. I slowly opened the air valve on my compressor. It turns out at a around 10 psi the fuel tank goes boom when the top part pops up. Haha. So 10 psi is too much. It made me jump a little when the tank expanded.

So I reduced pressure to around 5psi and checked around for leaks. I didn’t see or hear anything in the engine compartment or over by the primary filter.

clifford j · 03-02-2021, 11:04 AM

JerryLook, early on you said you had black junk in the fuel, you also said you keep loosing prime, I'm guessing the fuel check valve is stuck open and fuel run's back to the tank.

CLIFFORD