C4 transmission not shifting

[Sal]

Can an engine backfire blow out a modulator so the transmission doesn't shift properly on a '68 Ford C4 transmission?

 

[paul2748]

Check your vacuum connections - the C4 will not shift without vacuum

I doubt that an engine backfire will knock out a modulator, but replace it if its got a lot of miles and years on it.

 

[ponymare]

Easy way to tell if the modulator is blown, pull the vacuum hose off of it, if oil drips out its blown.

 

[Sal]

Thank You for your replies.

 

[wbedwards]

Could have blown the hose off =]

 

[cohammer60]

Just replaced my modulator and hose . Started shifting better but still a slight slip from 1 to 2 . Added Lucas oil and Been shifting good since . A cheap way for trial and error .

 

[Alaska Jim]

you might try adjusting the bands, it may help things a bit.

 

[Sal]

Thank You for your replies, I appreciate your help.

 

[Sal]

I was finally able to get under the car yesterday, I found the hose going to the modulator dry rotted and cracked. I replaced it and the transmission shifts well. Thanks to all who offered help.

 

[dmsfrr]

If any of the rubber fuel lines are even close to the same age, replace them too.