So I've been trying to figure out why I'm still getting the 654 code and found that the connector wasn't fully seated in the MLPS, you really have to push pretty hard to get the lock to engage. Drove it around after and rescanned it. The 654 code is gone got a 111 on the KOEO but still have the 634 and 332 on the CM side.

I tried to test the EGR after determining there are no vacuum leaks by applying vacuum directly to the valve, it's seems to not be functioning. Tried squirting a little WD 40 into the vacuum port and tapping with a screw driver handle but no change. Would this be definitive enough to spend the money on a new valve or are there other things I should test first?

The 634 seems to be tied to the alignment marks, I'm pretty sure it's right but will check again. Like I said above tho there is a significant improvement in drivability since I changed the MLPS so I am very pleased that I seem to headed the right direction for a change Lol

 

Continuous memory codes only MEAN the fault occurred at some time but are not currently active. You clear those codes by running the test again and as the reader is giving codes turn it off and the codes should be erased. Run them again to make sure they are gone.

 

I've unplugged the battery and run the scan each time I adjust something. I'm pretty sure they are current issues, but I appreciate the advice.

 

You said the 634,332 codes were in CM. If so, they are not current and can be cleared as above. Your reader should show a small c on the screen when it goes from KOEO to CM.

 

That's right I get an "O" at top a 111 then a 10 at the end the KOEO codes then the cm codes which comes up 634 and 332. It is my understanding that the codes are cleared from the truck by disconnecting the battery and the codes are cleared from the reader by running a new scan. I will double check though, no harm in that.

 

Checked the MLPS alignment again and it was just slightly off the mark so I adjusted it with the battery unplugged went for a test ride and scanned it again and sure enough all that is left is the 332 code. Looks like I'm ordering a new EGR valve. Thanks again for the advice.

 

If it's holding vac, (as you said above) don't order a valve. You need to test the sensor & solenoid + hoses & wiring.

 

It's definitely holding vacuum, hoses seem good manifold vacuum is right at 18 inches. I will do some research on how to test the other components. Thanks for the tip.

 

So I've been playing with my Junk Yard fuel pumps, pulled them out of a '95 that I had also taken the bare dash from. Saw that it looked like it had both fuel modules and they looked original. When I pulled them out they were still holding gas in the module bodies and it smelled pretty fresh. So I took a chance and put the front unit in after just cleaning it up hoping it was still working, it wasn't. So I pulled it out and replaced the pump with the one that came on the aftermarket unit I bought that never worked right it was a perfect match. Put it back in and it pumps like a champ but the fuel level sender still wasn't working. So out again, replaced the sender and I checked it while it was out of the tank it worked fine went to empty went to full travelled smoothly between the two. But when it was put back in the tank it went straight to below empty like the original did. The only difference I can think of is when it's not touching the tank it is on the ground wire in the wire harness and when it is installed it is grounded to the frame, any ideas?

 

Post delete

 

Did you check to see the float to see if it actually "floats"? If it has been compromised it may be more of a paperweight instead of floating at the top of the fuel.


The fuel pump and sender do not ground through the tank/frame. It is only grounded through the connector to G100.

 

Good Morning, I see what you are saying about the ground. I think I may have unintentionally grounded the tank through the straps, I can see where it had some sort of material between the straps and the tank but having taken the tank out at least a dozen times in the last few months it has come off. It looks like the FDM hanger is grounded through the harness the hanger makes contact with the tank through the locking ring and the tank is grounded to the frame through the straps. Not sure if that would even make a difference but it sure acts like the fuel sender signal wire has gone to ground somewhere once it is installed back in the truck. I actually changed out the sender yesterday since I thought I might have damaged it, the signal wire became detached from the board during handling and even though I re-soldered it it still appeared to be going to ground. But it appears that neither the sender or the float is the problem.

I guess I'll drop the tank again, yesterday I checked the sender with the FDM removed from the tank and it worked beautifully. So today I will check it out of the tank, attached to the tank but tank uninstalled then lastly with the tank grounded to the frame with a jumper cable. If for some reason the stray ground is the problem I will get some sheet rubber and make sure the tank is isolated from the hanger straps. Will update this afternoon.

Thank you again for all your help I really appreciate it.

 

By design the fuel sender circuit has a dedicated ground as I previously stated. Whether the tank is sitting on the ground, hanging by a rope from a tree or bolted into the truck it has no influence on the operation of the fuel sender circuit. The caveat to that assumes the wires are not getting pinched when the tank is mounted. That is where you need to look.

 

Totally understand, ground is ground is ground. Here's what I checked.

FDM out of the tank, sender works fine.
FDM in the uninstalled tank sender works fine.
FDM hanger connected to frame with a test lead sender goes to ground.
FDM in the tank fuel lines connected, sender goes to ground.

It all added up to reversed polarity of the sender wires, problem solved except for the problem of self inflicted wounds Lol. So after all this time I have one tank that pumps correctly and only to the fuel rail and a working gage. Now back out to drop the back tank and finally put this issue to bed.