07 ASET "Gray Motor" No Start

[c-mac]

I have a 2007 Pinnicle with the gray Mack motor that turns over great but no start. I have tech tool but its not much help on the older stuff plus I have no shop manual either. When I first checked it out it had many dtc's but engine position sensor stood out.  I cleared all the codes out and none came back. Anyway I swapped the cam sensor and crank sensors out with a running truck and nothing. I swapped the ECM also and nothing. Id kind like to check the circuit but I don't know where it goes in to the ecm. I check for voltage at the sensor but i've ohm'ed and tested so many things on this truck I can't remember what I had there but it wasn't 5v. I saw a pic online somewhere that showed the circuit to be five volts but I not even sure it was for the same engine.I guess tomorrow I'll start tearing into the harness unless you guys can help.

[fjh]

Check the eecu plug for coolant wicking also don't rule out the relays tucked in behind the dash rh side of the former glove box location. Seen them fail try swapping one or two.

[c-mac]

Thanks, I've already swapped the four relay around and checked them individually. The eecu has no coolant in it but someone before me added some dielectric grease to the connectors. I've tried to get that out just to be sure I was making a good connection.

[staxx]

Fuel psi ? Lift pumps fail often 👍🏁

[Mackpro]

Here's a "VMAC III Engine Cranks But No Start" guide that I found buried in my stash. Bad news its in Microsoft Office format, I hope you can open it. Its for the 1999-2002  ETECH's but yur ASET AI is almost the same.  I have had a shorted EUP keep one from not starting and not set a code and check the same OHM's  as the good ones. That one was a hard one to figure out. 

engine_cranks_no_start.doc

[c-mac]

Thanks for the link. Engine has a brand new pump. I was trying to find a way to test fuel pressure so I pulled the check valve out and was going to tap it there but the hole in the block is some weird size, I can't find a fitting to screw into it. The outlet of the lift pump is in a real bad spot but I guess I'll have to try to tap it there

[Mackpro]

Check the fuel pressure at this port. Port is on passenger side front of engine block  at top of timing gear cover.  It's 1/4" pipe thread so its easy to plumb up.  All CCRS and ASET's should be 58 psi at idle and go up when you throttle it up. If fuel pressure goes down when you throttle it up or your way below 58 psi , you got fuel problems. 

[turckster]

Something I've seen many times is the ground relay pop open while cranking preventing the engine from starting. Usually its caused by a bad starter internally shorting out causing the ground relay to open while cranking. You could try a heavy gauge jumper wire and connect the terminals and try to start the engine or try a DVOM to see if the relay is open or opens while cranking. 

[c-mac]

Thanks a bunch! I read somewhere the pressure should be 90psi. Anyway you say it should be 58psi. Will it make that much pressure just cranking? Where is this ground relay?

[Mackpro]

Older ETECH engines in the 1998-2001 range had 2 different possible fuel pressure regualtor part numbers.  One was a 100 psi valve  which we always installed if there was a issue . The other was a 75-80 psi valve. These pressure regualtors had the small barb nipple on them for the plastic fuel return line that came from the cylinder head.  Starting in around 2002 the CCRS engine came out and Mack came out with the "Leak less" injectors and did away with the fuel return line from the injectors/head. CCRS engines and up including the ASET AC/AI  have a fuel pressure regulator without the barb nipple on them and fuel pressure was 58 psi.  This is a quick easy way to tell if you have a ETECH ( has the plastic fuel return line coming from head to regulator) or the CCRS engine ( no plastic line) . The pressure regulator screws into the side of the block above the air compressor.

Edited September 29, 2016 by Mackpro

[c-mac]

This one has the regulator in the right side of the block. I removed the return line and I get a drip from regulator, but I dont think its enough to cause a pressure problem. I just noticed that the engine oil is an inch over full and appears thin, like contaminated with fuel. I hooked up the pressure gauge as pictured. I had to turn the engine over for a long time to get 20psi. 

[turckster]

13 hours ago, c-mac said:

Thanks a bunch! I read somewhere the pressure should be 90psi. Anyway you say it should be 58psi. Will it make that much pressure just cranking? Where is this ground relay?

The ground relay is usually mounted right next to the wiper motor. 

[c-mac]

Well I guess I'm in the clear. The boss called the Mack field tech to com look at it. 10 hours later he had nothing either. we just pushed it outside and will tackle it another day.