2wdiesel2021

Oh yes sir it was fine as best i could tell, I also vice gripped that line off to see if that helped and it didn’t change anything. So it has to be a suction issue somewhere.

Where is this fuel regulator? I put vice grips on the return side and pumped the primer and got maybe 6psi fuel pressure. It will stay running, sounds terrible but won’t die unless I rev it and hold it until it dies. Just idling it will run all day but rough like it’s lacking fuel. Suction has to be the problem.

Yes sir that’s all there. We even pulled it apart and checked it again. I have two other Mack’s here and i checked all the hose routing with those trucks and it’s the same. I take the fuel pressure sensor out and no fuel comes out even when I get it running. I can get it to rev if one guys primes it and one guy pushes the petal then it just dies off.

I have a 2010 Mack CHU613 with an MP8 and we put a new filter head on it and new pump because it idled terrible and wouldn’t rev. New pump abs filter head and exactly the same. Showing zero fuel pressure and will only stay running if we pump the primer the entire time. I am lost here with all these new parts it still won’t make pressure

no sir 10 speed

new starter yes sir, we pulled one relay that says pwr PT and then we get the on off over and over. when that really is put back then nothing works. The pwr ems relay is the one clicking on and off. the starter will not crank unless we jump it.

well then it’s good, so I am at a loss here. The ignition constant on the key switch has 12v until I turn it to the on position and all the wires for to 3ish volts like everything loses power. Turn the key back to off and the main feed to the ignition gets 12v back.

I saw it there and I bypassed it. I got the truck with no batteries in it. It looked like the fuseable link was on the ground side of things. Does that seem correct?

I am working on a 2010 CHU613 with an MP8. I got the truck and the dash would come on with the key but it wouldn’t crank with the key but I could jump the starter and it would crank but still not start. I have fuel pressure. I started looking into electrical and now the dash only comes on when ai turn the key all the way forward then turns off when I go back to the Run position. New batteries. when I pull the relay in the dash cab PWR i believe it says the dash comes on and then 5 seconds it resets and keeps doing it. The pre ems relay is the one clicking on and off. Where do I need to go to resolve this? what usually causes something like this?

Well i would think it was the wire strictly for the number 2. Reason being is that it only affected EUP number 2. Only had a code for that one and it only missed on one cylinder. I would assume if it was power for more than one it would have affected those three cylinders.

What’s crazy is you couldn’t actually see an issue at all. The wiring looked very good, it’s where it was twisted to go to the EPU. It was dark in the shop and under the heat shield and i literally saw sparks and that was a good thing.

Ok, got the fuel gauge plumbed in and had a fairly consistent 70psi. Took the EPU harness off and inspected and couldn’t find a problem anywhere. Reinstalled new split loom and put back in the truck. Started the truck and had a very obvious miss at idle. Getting a code for 2 cylinder voltage high. Go move wires around and saw spark right where the wiring touches. No bare wires at all but it was arcing through the insulation. Repaired the wire and now everything is good. And the sewing needle on the pins on the harness worked great. Thanks guys for all the help.

Got it, thanks. That front ones easy access. Any idea if it’s NPT thread or what?

Well crap, have to redo my whole set up.

I have it after the regulator, which i was told previously that’s correct.