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Violent Idle When PCV Connected
https://slantsix.org/forum/viewtopic.php?t=68306		 Page 4 of 6
Author:  morsim [ Sat Aug 23, 2025 11:07 pm ]
Post subject:  Re: Violent Idle When PCV Connected
Quote:
Also, what does the engine oil smell like? Pull the dipstick and smell it. Does it smell like gasoline?
Oh yeah, big time...
I'm getting ahead of myself as I wait for a response here, but as per this post, it could be a ruptured fuel pump diaphragm. Could I have accidentally done that while blowing compressed air from the inlet side to clean it out earlier? That wouldn't explain the burning of the oil though, would it...
Author:  Rick Covalt [ Sun Aug 24, 2025 4:55 am ]
Post subject:  Re: Violent Idle When PCV Connected
Was the oil level over full?
Quote:
That wouldn't explain the burning of the oil though, would it...
Yes it could. The gas would thin down the oil and allow it past the rings much more.
Author:  SlantSixDan [ Sun Aug 24, 2025 11:43 am ]
Post subject:  Re: Violent Idle When PCV Connected
Drain the oil, pronto. It will also be a good idea to service the oil pressure relief valve to make sure it's doing its job, as described in these two threads: thread 1, thread 2.

You likely didn't ruin the fuel pump with compressed air; it probably just failed on its own; that's a thing.

Put in a new fuel pump. Pick carefully; parts-store items currently available are garbage. Get an AC 6972; one of the ones you see here.

And show us those spark plugs.
Author:  morsim [ Sun Aug 24, 2025 12:33 pm ]
Post subject:  Re: Violent Idle When PCV Connected
Quote:
Was the oil level over full?
Yes!

I've been too pressed for time, and I'll be away from the vehicle for a bit... Couldn't get those pics yet since waiting on a friend for the socket after mine disappeared.
I won't let it run with that fuel oil invasion, but not much I can do right now other than let it sit for the time being while I'm away. :(
Quote:
You likely didn't ruin the fuel pump with compressed air; it probably just failed on its own; that's a thing.
Quite the coincidence, same time as the carb rebuild.

Will order a new pump for when I get back. Rebuilt is okay in this instance? (e.g.)
Author:  SlantSixDan [ Sun Aug 24, 2025 3:39 pm ]
Post subject:  Re: Violent Idle When PCV Connected
I know the as-built AC pumps do okeh with curent fuel formulations. No way to know if the rebuilts will, until you try. Odds are pretty good.

Also, to be clear: new oil filter along with new oil.
Author:  morsim [ Wed Apr 15, 2026 6:53 pm ]
Post subject:  Re: Violent Idle When PCV Connected
Right on, back with the vehicle! :D
Quote:
I know the as-built AC pumps do okeh with curent fuel formulations. No way to know if the rebuilts will, until you try. Odds are pretty good.
I've replaced the fuel pump with this guy (as mentioned above). Can't reconnect the outlet hose since the hole on the new one is too small for the fuel line... Adapter?
Unsure of the exact thread specs
Author:  SlantSixDan [ Wed Apr 15, 2026 7:13 pm ]
Post subject:  Re: Violent Idle When PCV Connected
Outlet should take a 5/16" inverted-flare fitting. Do the Fuel line mod.
Author:  morsim [ Wed Apr 15, 2026 8:23 pm ]
Post subject:  Re: Violent Idle When PCV Connected
Quote:
Outlet should take a 5/16" inverted-flare fitting. Do the Fuel line mod.
Got it.
Looks like the 90° angled fitting won't come in time. I've got the Holley 1920; can I just go with 2x 180° fittings instead, and angle the pump outlet hose upward? Those are available locally (Dorman 785-402D)
Also, can't quite tell precisely, but that angled Holley fitting looks like it's long that it'll hit the ignition coil before turning upward, not the case?
Author:  SlantSixDan [ Thu Apr 16, 2026 9:39 am ]
Post subject:  Re: Violent Idle When PCV Connected
180° straight fitting is actually preferable for the carb end with the 1920. You could use a straight fitting on the fuel pump end, but 90° is preferable. I haven't run into interference with that Holley elbow, but this 90° piece is more compact if it looks like your install would encounter that difficulty.

Be sure and use hose marked SAE J30R9, and appropriate clamps for it.
Author:  Rick Covalt [ Thu Apr 16, 2026 9:51 am ]
Post subject:  Re: Violent Idle When PCV Connected
The fuel pump I got and installed on my car did not have an inverted flare on the outlet. It was a taper thread and luckily I had a brass fitting that fit it in my junk drawer. Never seen one like that and it was the same number you installed.
Author:  morsim [ Thu Apr 16, 2026 11:51 am ]
Post subject:  Re: Violent Idle When PCV Connected
Quote:
The fuel pump I got and installed on my car did not have an inverted flare on the outlet. It was a taper thread and luckily I had a brass fitting that fit it in my junk drawer. Never seen one like that and it was the same number you installed.
Yeah... Just noticed as well. I was able to fit a 3/8" straight fitting in there but not all the way.
You had a tapered fitting? Cannot find that part
Author:  Rick Covalt [ Thu Apr 16, 2026 12:43 pm ]
Post subject:  Re: Violent Idle When PCV Connected
Quote:
You had a tapered fitting?
Well, I thought it was, but maybe not. I just put teflon tape on it and snugged it up and no leaks. If it was a straight thread it would normally have a gasket. I don't think my fitting had one. I will see if I can put eyes on my later for you.
Author:  morsim [ Thu Apr 16, 2026 12:56 pm ]
Post subject:  Re: Violent Idle When PCV Connected
Quote:
Quote:
You had a tapered fitting?
Well, I thought it was, but maybe not. I just put teflon tape on it and snugged it up and no leaks. If it was a straight thread it would normally have a gasket. I don't think my fitting had one. I will see if I can put eyes on my later for you.
On a double take, looks like I actually did get tapered. And it's 1/8", not 3/8" (Dorman 785-412D)
It's not supposed to go in all the way from what I understand.

As far as teflon tape, I was recommended against since it'll break down and potentially clog down the line/carb
Author:  Rick Covalt [ Thu Apr 16, 2026 1:01 pm ]
Post subject:  Re: Violent Idle When PCV Connected
If it is put on properly there is no problem. But you could use a little liquid teflon on the threads also.
Author:  morsim [ Thu Apr 16, 2026 4:06 pm ]
Post subject:  Re: Violent Idle When PCV Connected
Quote:
If it is put on properly there is no problem. But you could use a little liquid teflon on the threads also.
The inverted flare fitting connection (Dorman 785-402D) from the hose to carb is leaking fuel at the threads. What to do? :shock:
Here's where the leak is: https://i.imgur.com/2YyKJCF.jpeg
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