4.2l engine knocking

Dropped the gas tank down a little to take a peak. Think I found my return line issue. If I’m not mistaken, that pinched soft line is the return line.
IMG_0228.jpeg


My theory on why this became an issue all of a sudden?

Rusty bondo’d skid plate that was flaked apart plus no hold down straps to hold the tank to the skid plate plus driving around hitting bumps eventually lead to layers of rust and debris build up under the tank that pressed the tank up into the crossmember/tub and pinched the line. Any returned fuel couldn’t return and increased pressure.

That’s my story and I’m sticking to it. At least until I get my new skid plate and new soft lines installed and the problem persists.
 
Caver Dave said:
Isn't that "Mr.Gasket" device post-filter a regulator?
Click to expand...
yes sir it is. It seems to be helping with the running issue. However, the upstream lines seem to be under greater pressure than they should be because of the regulator.

Waiting on the new skidplate and hold down straps to reinstall the tank. Hopefully have all that by 2:30 tomorrow.
 
Last edited:
Little update.

Couldn’t for the life of me get the fuel pump outlet compression fitting to seal up and not leak. Tried two different hardlines fitting, one being new. Nothing. Pulled he pump, exchange it on warranty (I’m still suspect of that pump being a major culprit), cleaned up all my softlines, routed new softlines on the tank, went to install the new skid plate… my dumb ass ordered a 15 gallon skid plate and I apparently have a 20 gallon tank. So I used some fencing wire and wired the tank up in place while I wait for the new skid.

So now, I fired it up with the new MC2100, filter, pump, softlines, pressure regulator, and…. All is GREAT.

I did find the supply and return lines pinched above the tank. I’m halfway thinking someone installed an aftermarket 20 gallon tank, and used the OE 15 gallon skid, compressing the whole assembly up tight to tub. If that’s even possible.

Now to wait for the new skid plate and it’s back to the knocking issue. That should prove fun I’m sure. But hey, it’s running smoother and easier than it has since I bought it.
 
Last edited:
Back
Top