Fuel in crankcase
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Junior User
Joined: Jan 2008
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Fuel in crankcase
Hi guys, I have 1986 f250 4x4. Just installed 1969 460 with 73 heads. New Edelbrock carb. Truck runs well and have put a couple of hundred miles on it. I had it sit for 12 days. (checked oil after 10 days and all good)When I went to start it it acted like battery was dead. When I went under the hood noticed a puddle of what looked and smelled like gassy oil. Checked oil and it was up to top of dipstick. Puddled gas on valleys of intake. Drained oil to find abbout a gallon of fuel in the crankcase. Pulled plugs, disabled coil and hand cranked to empty cylinilders of gas. No wonder it wouldn't crank. Hydraulic lock. Checked carbfloats and they shut off when lifted manually. So where did fuel come from? I have had 2 ideas presented to me. With tanks 1/2 full vapors have built up and pushed fuel up through carb and forced past needle and seat. (Edelbrock states 6 1/2 pounds max fuel pressure). Truck has no emmissions gear (vapor canister line plugged) Other thought is that involuntary power to fuel pump (22 year old ignition switch). I have put in fuel regulator. Any ideas? Sorry about long post. Need to find root cause. Replace ignition switch. Put switch on fuel pump relay to disable when truck sits? Thanks.
Elder User
Joined: Jun 2004
Posts: 883
Likes: 2
From: La Crosse, Kansas
The canister line being plugged up needs to be vented to allow pressure to be released. Cut the hose back closer to fuel tank and let it vent there. Isn't "ecologically correct" but will more than likely be your answer. It shouldn't be building up enough pressure to make the engine fill up with fuel with the tanks vented. Also, the excessive fuel is going to wash the oil off your bearings and wash down the cylinder walls so even when you refill the case with new oil you might get scoring in the cylinder walls when you fire it up. spray some wd-40 down each plug hole to help lube the rings until your oil pressure catches up.
Post Fiend
Joined: Jul 2004
Posts: 8,786
Likes: 28
From: Northern California
I'd put a charcoal canister and system back on the truck myself. It won't effect the engine performance, and will keep the tanks vented, as well as the fuel vapors in check. I'd hate to be around that truck, if it's venting that much fuel to put a gallon of gas into the engine, when someone walks by and lights a match. I think you are on the right track though. Check the fuel pump, etc...
Elder User
Joined: Jun 2004
Posts: 883
Likes: 2
From: La Crosse, Kansas
The fuel tanks don't release that much vapor all the time. Since the truck was sitting for so long is what caused the excessive build up. And the tanks being half full added room of the vapor build-up.
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