[Somehow I sent the draft to myself, but not the list...sorry for the double post, if
so.][
Yes. Just getting over it.
I can't comment on the specific cause, because I don't know for sure. My GMC has had an electric pump for the 21 years I've owned it, and who knows how long before that. Has always worked as intended and with no worries.
Never had a problem until just a few months ago. I should have known better, but I cheaped out when I saw a fuel leak from the mechanical pump. The leak was from a hole on the side of the pump, at what appeared to the the pivot point of the pump arm. Instead of replacing the pump (the "cheap out" part of the story), I removed the pump, tapped out the hole and plugged it with a short piece (@ 1/4" long) of threaded stock JB-welded into place. That took care of the leak.
All was well when I ran the engine -- UNTIL -- I started noticing a "miss" and rougher-than-usual idling. Fearing it might be time for a new timing chain/gear-ectomy, I sort of let it go until I figured I could get to that project. On subsequent startings, I noticed more idling deterioration and almost no acceleration, but a LOT of white/gray smoke out the exhaust with a really bad smell.
In an effort to verify my "timing problem", I lined up the timing mark and the distributor #1. Following the t-shooting chart, I determined that timing was spot on -- no chain looseness, no tooth skip -- exactly on spec.
I'll skip over the "yada, yada, yada" part, but suffice it to say that I pulled the oil pan plug and drained out 2-1/2 gallons of liquid from the pan. Terrible color, worse smell. That was my clue. The electric pump was filling the oil pan with gas. No wonder my carburetor seemed to never get primed.
After doing two complete oil and filter changes (with a few minutes of idling to circulate between changes), and installation of a new mechanical fuel pump, I now have my smooth 455 back. It's taken a few runnings to get rid of the smoke, but it has now subsided, and things are back to normal for an engine with 113,000 miles. All the "clacking" is gone, and I get good revving. I haven't taken it out on the road yet, but I'm confident that all will be well.
If you notice a change in the way your electric pump sounds, that's a sign.
If you check your oil, and the indication on the stick is above the FULL mark, that's a sign. (My dipstick tube is broken off behind the manifold.)
If your engine all of a sudden starts to "miss" and belch out foul smoke, that's a sign.
If you don't do anything about it, (as Bill Engvall would say) "Here's your sign!"
Hope this helps.
Toby Maki
73 Glacier 230
Riverside, CA
-----Original Message-----
>From: Thom High via Gmclist
>Sent: Sep 9, 2020 10:42 AM
>To: gmclist
>Cc: Thom High
>Subject: [GMCnet] Remove or not remove
>
>A friend of mine, pretty good mechanic, cautioned me on adding an electric fuel pump and not removing the mechanical fuel pump. Said that if the
>diaphragm in the mechanical should rupture, could fill up the engine with fuel. Makes sense, has anyone experienced this?
>Thanx
>Thom High
>Vancouver Washington
>
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