when I set my cruise control at 55 it will speed up to 60 then let off until it drops to 50 then speed back up to 60 repeating this process the entire time cruise is on.
Sometimes the cruise control works perfect about 5% of the time.
Someone told me to check the vacuum lines they look in good shape. one is bundled with wires, wrapped in tape and goes through the firewall, I didn't take it apart to check it.
the only other part is a cable that goes from cruise control module to the top of the intake manifold it doesn't seem to be in a bind.
Any help would be appreciated I'm stumped.

 

Can't help someone who doesn't list their year and chassis, engine selection too.

 

1986 ford e-150 5.0L EFI
Thanks

 

Okay so since no one with experience on that year of E-Series I'll take a stab at it for you.

The speed control servo is "hunting" for its selected speed because its not receiving the correct input, either electrical or vacuum. First thing is to make sure the vacuum lines are intact---if they're original to the vehicle I'd be shocked if they weren't shot. You're dealing with a 30 year old van, things don't last forever.

If those lines are intact and known to be good and this problem still persist my guess would be the vacuum servo itself---those too don't last forever. I don't know they're still available in the aftermarket---Ford probably stopped supporting that vehicle 20+ years ago. Buying used might not yield any better results than what you have now---lots of work, time and money for a slim chance it'll be a reliable fix.

Apart from that not sure what to offer---I've had those type CC systems on GM cars and they work fine for a while but after 15 years its a miracle.

HTH

 

This will help you out allot
<table class="vi-centerclass"> <tbody><tr> <td style="text-align:centervertical-align:top;" width=""> Have one to sell? Sell now
</td> </tr> </tbody></table>
Details about FORD 1986 Bronco, Econoline E150-E350 & F150-F350 Pick Up Truck Shop Manual CD

Ford 1986 Bronco Econoline E150 E350 F150 F350 Pick Up Truck Shop Manual CD | eBay






I bought my 85 and 88 manual from the guys listed above but here is one from Amazon a little cheaper.. I dont know if it includes the same

http://www.amazon.com/gp/offer-listi...&condition=new


Heres a good book to have EVTM
1986 FORD E 150 250 350 ECONOLINE VAN NOS ELECTRICAL VACUUM EVTM SERVICE MANUAL

1986 Ford E 150 250 350 Econoline Van Electrical Vacuum Evtm Service Manual | eBay


If you plan on keeping your van,, you will need these as they are specific to your van.. They have helped me out greatly with repairing mine

 

Hi Phillime, the first thing I would do is get a vacuum tester, $20+/-, and pull a vacuum on the servo. Check that the vacuum does not leak down, that would indicate a bad diaphragm in the servo. Next to vacuum lines leaking, that is probably the most common failure on very old systems. jim

 

Another thing that you should check, if your setup is anything like my '88, is your throttle/cruise control cable. Make sure they are well lubricated and moving freely.

 

I would bet money on a pinhole leak in the vacuum servo OR the plumbing OR the vacuum reservoir..

Had to cover all the bases