Some might remember my Bad Fuel question from last month. Here's an update:

96 LT1 Auto- symtoms are hard starting when warm, aceleration cuts out approaching higher rpms, cruising in the mountains on 95 degree day results in no power at any speed, engine stalls, backfire, however it can be restarted and limps home, some codes set on that run, think it was "lean cond, O2 sensor"...

All the while it starts and drives normally if I don't push it (cept slow warm starts) with no more codes.

Anyway, someone suggested change fuel filter and another said try octane boost and gas dryer...thanks but still have problems with no power condition at higher rpms and weird warm starts.

Got a Helms Manual and followed different diagnostics which has lead me now to this area:

Bad fuel pulse dampener and/or strainer and/or pump.

Turns out the fuel pressure goes to about 40psi in the first two seconds when the pump is running as you turn on the ignition, then rapidly falls to zero. You then start testing for a fuel leak by closing off the fuel system at various points.

With the "feed line pinched" at the tank, it holds pressure, per the manual, this indicates problems with either fuel strainer, fuel pulse dampener or the pump check valve (in the pump). All of these items are within the "fuel sending assemby" inside the fuel tank which is easy (and smelly) to get at.

Note* the manual suggests installing a bunch of special parts to do these tests, I believe they are little cut-off switches you install in the fuel lines, I almost did this until I saw Andy Bogus' suggestions for pinching the lines at the tank, at this poit they are rubber hoses easy to pinch with vise-grips or the like.

Here's what I found:

1) no strainer at all, not in the tank nor attached to the pump...? tank fairly clean and nifty looking.

2) the recommended replacement seal for the assembly to tank interface is nowhere to be found, none at parts stores, none at dealer, dealer can't even verify that there is such a "seal" or gasket. I finally found the ACDelco Part number and photo at(RockAuto.com). It is ACDelco part#25091503, RockAuto calls it ACDelco Part #G1. On order...

3) replaced pulse dampener and added a new strainer, inexpensive and easy to find at several parts stores, however still have leak indicated.

More later after I replace the fuel pump tonight(w/check valve inside) which is the next step, also easy to find at several local stores...

 

Put in new fuel pump rock steady pressure at 40-43. Runs like scalded cat. Thanks Forum Folks and the Helmses.