HELP!!!!!!!!!!!!!!!!!!!!
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More Turbo
Joined: Jan 2001
Posts: 574
Likes: 0
From: New England
HELP!!!!!!!!!!!!!!!!!!!!
I HAVE A VACCUM LEAK SOMEWHERE , I HAVE BEEN THROUGH ALMOST EVERY HOSE, CONNECTION, VACUUM TEE, ETC. I HAVE CHECKED TRANS MODULATOR. WHEN I CAP OFF THE VACUUM TEE AT MANIFOLD SO THAT NO EQUIPMENT IS RECEIVING A VACCUM, IT STILL HAS A LEAK SOMEWHERE. MAYBE INTAKE? I HAVE CHECKED WITH CARB CLEANER ALL OVER. NOTHING NOTICED.CAN A HEAD GASKET LEAK SLIGHTLY AS TO LOSE VACCUM?? IT DOES NOT RUN HOT BUT RUNS LEAN BECAUSE OF THE LEAK. I NEED POINTERS. SORRY ABOUT THE CAPS, IM NOT YELLING, MY KEYBOARD IS CRAPPED.
THANKS!!!!!!!!!!!!!!!!!!!!!!
THANKS!!!!!!!!!!!!!!!!!!!!!!
Moderator
Joined: Jan 2001
Posts: 56,992
Likes: 2,741
From: Virginia
HELP!!!!!!!!!!!!!!!!!!!!
I know you have already diagnosed it as a vacuum leak, but obviously it's not or you would have found it. What's going on with your truck? Why do you think it's running lean? A vacuum leak will only mess it up at idle, won't have much effect running down the road unless it's a big leak, and if it was that big you would have found it already.
New User
Joined: Jan 2008
Posts: 0
Likes: 24
HELP!!!!!!!!!!!!!!!!!!!!
Why are you Yelling ?
Please shut the CAPS off, besides the letters are really Hard to read when posting in ALL Caps.
Thank you.
Like Franklin said ,Vacuum leaks are most noticable idle.
Dennis
It's Almost Time Everyone.
https://www.ford-trucks.com/user_gallery/sizeimage.php?&photoid=314&.jpg
78 F-150 429CJ C6 ,Silver w/Explorer Pkge
641/2 Mustang,Pre-World's Fair Car #8092
64 Fairlane S/C waiting for a 390-4spd.
68-Mustang.Sunlit Gold 80,000 miles
Please shut the CAPS off, besides the letters are really Hard to read when posting in ALL Caps.
Thank you.
Like Franklin said ,Vacuum leaks are most noticable idle.
Dennis
It's Almost Time Everyone.
https://www.ford-trucks.com/user_gallery/sizeimage.php?&photoid=314&.jpg
78 F-150 429CJ C6 ,Silver w/Explorer Pkge
641/2 Mustang,Pre-World's Fair Car #8092
64 Fairlane S/C waiting for a 390-4spd.
68-Mustang.Sunlit Gold 80,000 miles
New User
Joined: Dec 2001
Posts: 8
Likes: 0
From: Littleton U.S.A.
HELP!!!!!!!!!!!!!!!!!!!!
I had the same problem with my 71 ford 390ci. I couldnt find the vacuum leak anywhere until I started to remove everything in preperation to replace the engine. The leak was under the the plate that is in between the carb. and the manifold. The leak was under the plate, between it and the manifold at the rear, (carb. cleaner did not detect this). This find saved me ALOT of money!
Hope this helps a little.
Ron
Hope this helps a little.
Ron
Senior User
Joined: Feb 2001
Posts: 180
Likes: 0
From: Powell RIver Canada
HELP!!!!!!!!!!!!!!!!!!!!
An easy way to find a vacuum leak is with a portable propane torch. If you have access to one, what you do is turn on the truck, take the propane torch, NOT LIT, and run it around your intake manifold, carb gaskets, anywhere you might think you have a leak. If there is a leak, the engine will drop down in RPM and the outlet of the propane torch will freeze over. I found this works in most cases, it's pretty simple and easy.
Posting Guru
Joined: Jul 2001
Posts: 1,613
Likes: 2
From: Gainesville, FL
HELP!!!!!!!!!!!!!!!!!!!!
Foz,
I'm not convinced of a vacuum leak. Does your idle modulate? That is, does it go up and down consistently? If a vehicle is running lean that does not automatically mean "vacuum leak." How old is your carb? Have you had it off recently? Did you try the "Tiaquana Tune up?" While your vehicle is running, pinch off the fuel line and pick up RPMs to a high idle. Run the vehicle out of fuel. Unpinch the fuel line and restart it. If dirt is caught in the carb this can sometimes clear it of crap in the bowls.
Yeah, it's a bit shade tree, but it's worked for me in the past. Another way is to take the carb off, hold it upside down, drain it, and throw it back on. It's a quick fix, sometimes.
Good Luck, Have Fun,
KingFisher
I'm not convinced of a vacuum leak. Does your idle modulate? That is, does it go up and down consistently? If a vehicle is running lean that does not automatically mean "vacuum leak." How old is your carb? Have you had it off recently? Did you try the "Tiaquana Tune up?" While your vehicle is running, pinch off the fuel line and pick up RPMs to a high idle. Run the vehicle out of fuel. Unpinch the fuel line and restart it. If dirt is caught in the carb this can sometimes clear it of crap in the bowls.
Yeah, it's a bit shade tree, but it's worked for me in the past. Another way is to take the carb off, hold it upside down, drain it, and throw it back on. It's a quick fix, sometimes.
Good Luck, Have Fun,
KingFisher
Lead Driver
Joined: Nov 2000
Posts: 6,635
Likes: 349
From: Albuquerque
HELP!!!!!!!!!!!!!!!!!!!!
Don't know your vehicle type but if you have a V-8 with the aluminum EGR plate under the carb......They get eaten up internally by the hot exhaust gases. Causes bad idle and surging and doesn't show any external leak.
Bear
Bear
Trending Topics
Junior User
Joined: May 2001
Posts: 97
Likes: 0
From: Modesto USA!
HELP!!!!!!!!!!!!!!!!!!!!
The best way I've found to diagnose a vac leak is to choke off the air at the carb by removing the air filter and placing your GLOVED hands ofer the venturies. You know you have no leaks of the RPMs decline smoothly until it dies. You have a leak if the RPMs jump just before the engine dies as the fule mixture gets right. KEEP YOUR FACE BACK, a backfire haircut looks like crap!
I've had trouble with aluminum 2bbl carb spacers on California '68 - '69 FE's not matching the manifold on the each of the 4 trucks I've owned. There was a thread about that a month or so ago where I posted a sketch of my spacer. This is a hard leak to find since you have to get carb cleaner Under the back (or sometimes) front of the spacer.
I've hsd some success using JB Weld to fill in the area that doesn't match up then grinding to match the rest of the spacer.
MB
I've had trouble with aluminum 2bbl carb spacers on California '68 - '69 FE's not matching the manifold on the each of the 4 trucks I've owned. There was a thread about that a month or so ago where I posted a sketch of my spacer. This is a hard leak to find since you have to get carb cleaner Under the back (or sometimes) front of the spacer.
I've hsd some success using JB Weld to fill in the area that doesn't match up then grinding to match the rest of the spacer.
MB
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New User
Joined: Dec 2001
Posts: 8
Likes: 0
From: Littleton U.S.A.
HELP!!!!!!!!!!!!!!!!!!!!
I think beartrack is right on the head, this is what happened to me, and no propane, carb. cleaner ect. could detect it. mine idled ok, the problem was when I was cruising about 30-35 mph, it would surge and drive me crazy!,
