bulldogfan

I finally replaced the fuel lines that run from primary filter to ecm then to the mechanical lift pump. Problem solved. If you have the quick connect fuel fittings, it will be the issue with truck losing prime...Go, with regular hydraulic style fittings.

I replaced the APADS unit with a new one. Problem solved.

Have an 07 mack with the APADS controller. A/c works perfectly, until you come to a stop. Then the problem starts. The engine fan is not coming on. Therefore the high side pressure skyrockets, until the drier pressure relief valve opens. Wow, what a racket that makes! So, I replaced the high side pressure switch and the relay mounted to the apads box. No, difference. So, my question is do these boxes fail? Also, the orange wire coming out of controller is the fan wire. I am not getting any voltage on this wire, even when high side pressure is over 400 psi? What tells the fan to come on? I can get fan to engage if I disconnect the relay, of some of the other connectors nearby. So...............

I have an 07. With the grey mack motor. Almost to a million miles. Runs great (most of the time)! Mine has the 6 speed. and am getting 7.5mpg. Its all in what the maintenance schedule has been.

As the title says, as soon as I replaced the starter, code 9-2 appeared? Truck starts and runs perfectly. The one exception is that I am having problems with my eld communicating with ecm. It is also intermittent. Of course! Any pointers will be appreciated!

Thanks for that! I'll keep it in mind incase the problem comes back. Still curious about the fuel line between primary filter and ecm. Makes sense that I first noticed a hard start and rough idle immediately after service, including changing the centrifuge oil filter. Which you have to move fuel line out of way, to change. Ever heard of the swivel fittings going bad on fuel lines?

For future reference... something that I have replaced seems to have fixed issue. Fingers crossed.

I am now wondering about the fuel line that runs from primary filter to the back of computer? It has swivel fittings, and they have slop in them. Not leaking fuel, but maybe letting air in?

Dealer sold me a checkvalve. It looks like a hydraulic coupling? Can't seem to locate it. I am sure it's not attached to filter housing. Going to get my bore scope and look behind the egr cooler. And hope it's not back there! Lol.

I replaced the transfer pump. Also installed factory fuel filters. Took a while to get all the air to purge. But truck finally fired "rough at first" than smoothed out. Actually seems to idle a lot smoother now too. I bought a new check valve, but don't see where it goes? Is it behind the egr cooler? Thanks.

Just left mack with$1000 in parts. I will keep updating this post...

Thanks. Drain back valve? Is it also called check valve?

Hello, It is a gray engine. And I am thinking fuel supply pump also, but do you think the pump would fail intermittently? And if so, would that cause the hand primer to be pretty spongy? Thanks.

I have a real head scratcher! I replaced the two fuel filters a week ago. Truck fired up, did the usual stumble than seemed to run okay. Idle seemed a little rough though the next day. Then, I parked truck with driver side leaning down a bit to unload. Would not fire. Cranked great, but no fire? This is where I get confused, we dragged truck backwards to other side of road so that now passenger side was leaning downwards a bit. sat for a minute, cranked truck and fired right up! Been running truck all week, seems fine, except first thing in morning spins over well, but takes just a bit longer to fire. Then today, truck starts good, drove for 3 hours, perfectly, had to park with driver side leaning slightly again, get in to move and will not fire. Spins over great, but doesn't even attempt to start? So far, I have opened hood and pumped hand primer. It feels to have little to no resistance. So I replaced hand primer. Still has little to no resistance. Truck is almost full of fuel (single tank). If truck runs fine, shut off for five mins, get back in and then cranks great, but no fire? Seems electrical? But then why no firmness in hand primer? Help!!

I'll give it a try! Thanks.