Anonymous

So back in the summer you guys were great help with me diagnosing my E7 for low hp after overhaul. I have 1990 E7-400 that had a series of issues after the rebuild. I got most of the kinks worked out and the biggest problem I found was that someone had installed the incorrect rack plug and the pump couldn't get full fuel. Truck is running pretty good now but I can't help but wonder if someone possibly could have put the wrong fuel plate in the pump too. the numbers on mine are 2 372 on the top and 2 071 on the bottom.

Back at it!! So after some use with the new turbo I still fell like I'm short on power. For reference I hooked my lowboy to a friends freight liner with a wore out M11 in it and it ran much better than my truck. I have decided to send the pump back to the pump shop. So I pulled it off this morning and noticed the rack plug is stamped 2000. And from my younger days we used to take the "Mack rack plug" stamped 2095 and put them in our dodges so the pumps would go full rack. My question is did Mack use any other rack plugs other than the 2095 plug? I did talk to the previous owner of the truck and he had the pump rebuilt at some point and said it never ran as good as it did before they had it rebuilt. Im wondering if someone put the wrong plug back in the pump.

That was the trick!! Now if we weren't in a drought I would be able to use them lol.

Can anyone guide me on replacing the wiper pivots on my CH613? I can't really tell how to get at them.

What a difference a new turbo makes. Got 25psi boost just driving not hooked to anything. Going to tweak the pump a little and try and get a little more out of it.

I feel like an idiot for it catching it earlier. And I also thought it should be smoking more. Guess it was getting just enough air to keep smoke down. Now I have to try and get the pump set back to where it was when I started. Will give a full report all is done. Thanks for all the help.

Well curiosity got the best of me this morning. I decided to take one more look at the turbo before I send the pump off. I removed it this time and really wanted to get a better look at the exhaust side. At first glance everything looked fine. But as I was on a phone call I was fidgeting spinning the compressor side when I noticed it had a drag for a split second then it released and spun freely. Kept on messing with it and it kept doing the same thing. I put some shop air to the exhaust side and it didn’t spin as free as it should. Would come to a stop as if it had a break applied to it. Then I removed the exhaust housing and found the carnage. New turbo should be here later this week.

Had some time to tinker today. Here's what all I did. Loosened the afc all the way up. No difference. Tightened the "smoke screw" all the way in to push the afc to wide open and kinda bypass the afc was my thinking. No difference. Even pulled the pipe off the muffler elbow to make sure it wasn't plugged up somehow. No difference. Double checked the turbo for shaft play and to see if it had any oil in it only to find it clean and free of play. Guess I will make sure the timing is correct and if so I believe I need to send the pump back off and have it rechecked.

Are you talking about the star wheel or what some people call the “smoke screw” on the backside? I have the star wheel set pretty lightly but the I found the smoke screw was backed all the way out. I turned it in and started driving and adjusting until I ran out of time l. Seemed to have a little improvement.

Not much.

Got the afc rubber replaced, shimmed the fuel return spring, slid the fuel plate just a smidge (its maybe at the half way point, drained the fuel tank and found a washer in the tank, replaced fuel line from tank to filter housing and found that the air compressor intake line had a small leak and replaced it also. Now we have 30psi fuel pressure and no boost leaks. Moved my excavator this evening and the truck runs much better but still not where I believe it should be. Could only get maybe 20psi boost pulling a hill. Has no low end power. Will spool quickly if it at higher rpm tho. going to get a guy I know that is pretty good with the Bosch pumps to come look at it and make sure I'm not missing something or doing something wrong.

I pulled the housing off. It moved freely with shop air but I just felt like something was still wrong so I pulled it all the way down. There’s actually two cuts in it. I think I can find one at my dads. I’ll let y’all know how it goes once I get it sorted.

Found this today hoping it’s going to fix it

No mine doesn’t have that.

I did check the afc for by sucking and blowing into it. I’m going to pull it off and check it out and make sure that it’s working properly. And not set for too high of boost to get full rack. If all that checks out I’m going to recheck timing.

Checked return spring and the ball. They appeared fine. Replaced all fuel lines from filter housing to pump. and replaced lift pump with new pump from PAI. will now maintain 20Psi at idle and under load. Still feels really sluggish/bogged down and under powered. Hooked to my lowboy empty could only get 20psi boost giving it all it had up a slight hill. Going to shim the spring in the fuel return to try and get fuel pressure up a bit more. If that don't work Im draining the tank and checking the suction tube. Am I on the right track or am I missing something.

Just finished up another round of testing. AFC is good, applied 20psi of shop air from the turbo on out and sprayed with soapy water. Only leak I found was on the compressor inlet line. Will be replacing that as soon as I get some new hose. I also checked all my fuel lines for blockage with shop air and rechecked fuel pressure and its still bellow spec. will be looking for a lift pump. Anyone have the part number for the lift pump? and what hose is suitable for the compressor inlet tube?

I will try that this evening. Checked fuel pressure under a load this morning and it was agin 20psi at idle but under a load it was dropping down to 10 then cruising would come up to around 18psi. I think fuel pressure maybe my biggest power thief now. I'm going to check all the lines agin make sure I don't have one that's pinched or collapsed also will be checking the draw straw from the tank too. I forgot all about the air compressor inlet line too. will check that out for sure.

Checked operation of linkage tonight they are both correct. Need to double check afc. Checked the charged air cooler while waiting on parts and it was split on both sides and replaced it with one from Mack. I need to double check for boost leaks. I guess need to also check fuel pressure under load. I was just watching it at idle. I did notice the gage was bouncing at 20psi and thought that was odd for an oil filled gage. It built up to 22psi at say half throttle.

Hello everyone. Have 1990 ch613 with a 9 speed and an E7 400 all mechanical motor that is very sluggish. This is my fist Mack bought to pull equipment and haul grain. Truck was bought as a project with a blown engine. My dad and overhauled the motor and had the pump and injectors sent off and checked. Pump shop put new delivery valves in and set it to 10% over factory specs. We set the timing to 21 degrees. Pulled my first load with it last night. It was a light load and then truck is just slow to rev under load and has a shutter/serge. Checked fuel pressure at pump and have 20 psi at idle but have no clue if that’s in spec or not. Anyone know what the fuel pressure spec is? Only builds 20psi of boost. So I will be checking for boost leaks. Did find the air line to the afc was cracked and replaced it thinking I found the problem but made little to no difference in power. For reference I feel like my old ford with an L10 has the same amount of power as this truck. Any help is appreciated.