Izyk
New member
So this is going to be a long post and I am going to go over everything that I have done to try and find my vacuum leak. I have posted this many many times and have tried many many things so I am going to go everything I have tried.
So I have just finished rebuilding the 250 inline 6 engine for my 1970 Ford Maverick and the build was a success.. or so I thought. After I finished it I got it running somewhat ok.. the carb has some hesitation but it still ran. I took it on a test drive and drove it maybe a mile and it was running good until I pulled back into the driveway and it start to run terribly and then shut off.
I tried to start the car back up but it didn't want to run at all and would shut off when I gave it any gas and would only run if it was incredibly rich. Of course just my luck I had a vacuum leak. I went back and forth searching for what could be the issue and even got a new carb in the process because the old one had definitely caused me issues before.
I finally got it to run and somewhat handle throttle although still running rich so I parked it after driving it around the yard to test it out. Once parked again however the vacuum leak somehow got worse once again. So I started to go everything.
I check and replaced every line, checked every port and adapter I could find and still nothing. I took the lines that were going to the distributor and blew through them to see if the diaphragm in the distributor was fine and I couldn't blow through them so the diaphragm was fine.
I took some brake cleaner and sprayed it around the carb and flanged and it made my gauge jump from 15 to 20 and the engine started to run better so I figured thats what it was. I took off the new carb and put the old one back on and I double gasketed the spacer because I figured the spacer was probably warped but after doing this the vacuum had somehow gotten worse.
I thought it was odd and I put the new carb back on and it didn't changed anything and the car wouldn't even start at this point. So I went and I bought a weber adapter and threw on a Weber 32/36 with the new adapter (along with the needed fuel pressure regulator) and I was still having the same issue. The vacuum gauge was still reading 15 and when I gave it any gas it immediately would drop to 0 and shut off. But the car would still run although very rich. So rich that my spark plugs were coal black and it was started to pull fuel down into the oil pan... Not good (I've been trying to run the engine the least amount possible due to this issue.)
I went out a few days later and the car wouldn't even start at all. Hooked up the vacuum gauge and when cranking it barely reads ten. Nowhere near close enough for it to run. Ok so I retraced all my steps and blocked all the vacuum ports to see if it was one of those but it didn't fix my issue. I went over every gasket everywhere and they are all fine and yet I still have a massive vacuum leak somewhere.
At this point I am at a complete loss... After trying 3 different carbs, 2 different adapters, test my distributor, going over every gasket and every vacuum port I cannot find this leak and I have completely given up on this car because I FINISHED the engine rebuild 3 months ago. I have spent probably 20 hours in total searching for this vacuum leak and I cannot find it and I have given up.
I have posted this a dozen times across many forums so I am going to answer some questions most people have.
No it does not have a break booster or air conditioning. There are no vacuum lines that lead to under the dash. All the vacuum lines in this Maverick start at the engine.
I have replaced the vacuum line that leads to the transmission control valve and even when I block it off it doesn't fix it.
The intake doesn't separate from the head. It is casted as one piece. (Although since we are on a ford six forum most of you probably know this.)
The head was machined so the intake flange for the carb spacer is not warped.
I have a brand new pcv valve connected with a new line for it.
The current vacuum rating for the engine is 10 when cranking and will not start.
The current carb attached is the Weber 32/36 stock.
The original carb was a Carter RBS. The first 2 carbs I tested were Carter RBS carbs.
So I have just finished rebuilding the 250 inline 6 engine for my 1970 Ford Maverick and the build was a success.. or so I thought. After I finished it I got it running somewhat ok.. the carb has some hesitation but it still ran. I took it on a test drive and drove it maybe a mile and it was running good until I pulled back into the driveway and it start to run terribly and then shut off.
I tried to start the car back up but it didn't want to run at all and would shut off when I gave it any gas and would only run if it was incredibly rich. Of course just my luck I had a vacuum leak. I went back and forth searching for what could be the issue and even got a new carb in the process because the old one had definitely caused me issues before.
I finally got it to run and somewhat handle throttle although still running rich so I parked it after driving it around the yard to test it out. Once parked again however the vacuum leak somehow got worse once again. So I started to go everything.
I check and replaced every line, checked every port and adapter I could find and still nothing. I took the lines that were going to the distributor and blew through them to see if the diaphragm in the distributor was fine and I couldn't blow through them so the diaphragm was fine.
I took some brake cleaner and sprayed it around the carb and flanged and it made my gauge jump from 15 to 20 and the engine started to run better so I figured thats what it was. I took off the new carb and put the old one back on and I double gasketed the spacer because I figured the spacer was probably warped but after doing this the vacuum had somehow gotten worse.
I thought it was odd and I put the new carb back on and it didn't changed anything and the car wouldn't even start at this point. So I went and I bought a weber adapter and threw on a Weber 32/36 with the new adapter (along with the needed fuel pressure regulator) and I was still having the same issue. The vacuum gauge was still reading 15 and when I gave it any gas it immediately would drop to 0 and shut off. But the car would still run although very rich. So rich that my spark plugs were coal black and it was started to pull fuel down into the oil pan... Not good (I've been trying to run the engine the least amount possible due to this issue.)
I went out a few days later and the car wouldn't even start at all. Hooked up the vacuum gauge and when cranking it barely reads ten. Nowhere near close enough for it to run. Ok so I retraced all my steps and blocked all the vacuum ports to see if it was one of those but it didn't fix my issue. I went over every gasket everywhere and they are all fine and yet I still have a massive vacuum leak somewhere.
At this point I am at a complete loss... After trying 3 different carbs, 2 different adapters, test my distributor, going over every gasket and every vacuum port I cannot find this leak and I have completely given up on this car because I FINISHED the engine rebuild 3 months ago. I have spent probably 20 hours in total searching for this vacuum leak and I cannot find it and I have given up.
I have posted this a dozen times across many forums so I am going to answer some questions most people have.
No it does not have a break booster or air conditioning. There are no vacuum lines that lead to under the dash. All the vacuum lines in this Maverick start at the engine.
I have replaced the vacuum line that leads to the transmission control valve and even when I block it off it doesn't fix it.
The intake doesn't separate from the head. It is casted as one piece. (Although since we are on a ford six forum most of you probably know this.)
The head was machined so the intake flange for the carb spacer is not warped.
I have a brand new pcv valve connected with a new line for it.
The current vacuum rating for the engine is 10 when cranking and will not start.
The current carb attached is the Weber 32/36 stock.
The original carb was a Carter RBS. The first 2 carbs I tested were Carter RBS carbs.