Vacuum leak?
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New User
Joined: Oct 2011
Posts: 24
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From: Dothan, Alabama
Vacuum leak?
My wife's '59 F100 223, 3 on the tree loses power when under load. Starts good and idles ok. Has power in 1st and 2nd gear but when she shifts to 3rd it starts losing power. Especially climbing a small incline. We did a complete tune-up. We found what seemed to be a small vacuum leak and repaired it. and it did run somewhat better. We were wondering how to test for other vacuum leaks. Anybody else had this problem? New fuel filter? Carb. rebuild? New fuel pump?
Elder User
Joined: Feb 2012
Posts: 948
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From: Central Oregon
You can try spraying WD40 around the carb base and intake to block junctions. If the engine speeds up upon application, that would indicate a vacuum leak. Be careful around any source of high heat or flame.
Hotshot
Joined: Oct 2009
Posts: 16,155
Likes: 4,754
From: Burbank, WA
A more likely culprit is your distributor not advancing correctly. If the advance is not working up to spec, it can create all kinds of drivability issues. You might even have a ruptured vacuum advance diaphram, if equipped, which would cause both a vacuum leak and a non-op advance. A vacuum gauge would be a good investment for checking that.
Logistics Pro
Joined: Nov 2011
Posts: 4,685
Likes: 80
From: Northville, MI
A more likely culprit is your distributor not advancing correctly. If the advance is not working up to spec, it can create all kinds of drivability issues. You might even have a ruptured vacuum advance diaphram, if equipped, which would cause both a vacuum leak and a non-op advance. A vacuum gauge would be a good investment for checking that.
Here is a handy chart to use with a vacuum gauge attached to the intake with the engine running. Kinda old school but very effective.
Fleet Mechanic
Joined: Aug 2010
Posts: 1,994
Likes: 3
From: Morgan Hill, CA
My son has a 66 Mustang with a 200 6cyl. The vacuum diaphram had become broken for the distributor advance. It ran OK, but I popped the hood to check it one night & we could see the exhaust manifold glowing red hot from the late ignition. The vacuum gauge will tell you about the condition of the engine, but you need to attach a piece of hose to the distributor vacuum diaphram and either put a vacuum pump on it and watch the plate inside the distributor (pop the cap), or suck on the hose and watch the plate....it should move. If you suck on it and air flows without any resistance, the diaphram has failed.
Also...check your fuel filter. Those symptoms could be a lot of things.
Dan
Also...check your fuel filter. Those symptoms could be a lot of things.
Dan
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