two vaccuum lines blew off when I started my truck

[zebrex]

Last night after work I get in my truck and bump the starter like normal, truck makes a loud noise the whole truck shakes and then dies. I restart it and it acts like it is in learn mode with the rpms surging up and down. I drive it home and find that two vaccuum lines have been blown off. one for the cruise and one on the vacuum tree that the cruise and the break booster connect to.

What would cause pressure in the vaccuum lines to blow them off? its fixed now but I have been a do it yourself wrench for 16 years and have never seen anything like that before.

 

[Burns]

my has done that once and i was told that it just was probly on a missfire and just kinda backfired

 

[metstalker]

happened to me many times happens when i dont give the fuel pump time to prep the engine i dont think it is too serous

 

[V8BoatBuilder]

Your truck backfired, and pressurized the upper manifold.

 

[85Dave]

Your vacuum modulator valve on the transmission is bad. When the diaphram in the modulator goes, transmission fluid is sucked up into the intake. The fluid then causes all the vacuum lines to soften and swell. The fluid also made the engine backfire, which pressurized the upper manifold, and blew the soft and swollen lines off.

Replace the modulator valve and the lines will eventually return to normal. Also check the transmission fluild level. I bet its down.

 

[Positive Vibes]

Your vacuum modulator valve on the transmission is bad. When the diaphram in the modulator goes, transmission fluid is sucked up into the intake. The fluid then causes all the vacuum lines to soften and swell. The fluid also made the engine backfire, which pressurized the upper manifold, and blew the soft and swollen lines off.

Replace the modulator valve and the lines will eventually return to normal. Also check the transmission fluild level. I bet its down.

This has happened three times to me. But I never new there was a solution.
Where is the modulator valve (I don't have my Chiltons with me). And how much do you think it would cost and was it an easy fix? Thanks.

 

[zebrex]

ok im sold, my lines were soft and swolen (and replaced last night). I am also interested in knowing where the valve is and how hard it is to change. so from what you are saying I am actually burning a little atf through the engine that would explain where the atf is going since I dont have any leaks.

 

[85Dave]

The modulator valve is on top of the transmission. You can't see it from below. Ford recommends removing the passenger seat, the center console, pulling up the carpet, and unbolting the access hatch. If you attempt this, make sure the little plunger rod doesn't get lost. If it does, you're screwed.

I always do all my own mechanic work. Except for this. I paid a transmission shop about $75 (I think) to do it. That included the part. Money well spent in my opinion.

 

[Positive Vibes]

The modulator valve is on top of the transmission. You can't see it from below. Ford recommends removing the passenger seat, the center console, pulling up the carpet, and unbolting the access hatch. If you attempt this, make sure the little plunger rod doesn't get lost. If it does, you're screwed.

I always do all my own mechanic work. Except for this. I paid a transmission shop about $75 (I think) to do it. That included the part. Money well spent in my opinion.

Thanks Dave. Thats good info!!!

 

[Glacier991]

The modulator is on the side of the transmission under the rear most part of the heatshield. Do a search, there are pics of it here.

 

[Brandons]

and that heat shield can come off, ive done it a few times, just examine how it connects and youl see what to do. I never knew about that part on the tranny acting up. When i pulled the vacume lines off to the tranny when i dropped it, luckly no fluid had been leaking up into it.

 

[rocco123]

As I recall there are (2) 10MM nuts to remove to get at the modulator. Not a hard job after you squeese yer hands into place to remove the heat shield.

 

[85Dave]

Glacier's right. Here's a link to a picture.
http://www.explorerforum.com/forums/showthread.php?t=128033&highlight=modulator+valve

Here's a link on how to replace it.
http://www.explorerforum.com/forums/showthread.php?t=62684&highlight=vacuum+modulator