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Cruise Control Acceleration?


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Seems my demon possessed ‘93 has decided it doesn’t like the speed when I set the Cruise Control.

It will set just fine when I press the button but…it will gradually accelerate until it gets about 15 mph faster, then it will back off about 10 before again increasing another 15.

I tell you this truck is possessed!  It has a mind of its own!

 

Any suggestions as to how I can…

1.  Fix the Cruise (what yo look at that may be the cause), and

2.  Perform an exorcism on my beloved truck?

 

oh…and one more thing…

 

My 5th lift pump just started leaking so now I have that issue to speak with too.  New one (Cummins this time) is on order through Motor Trucks in Mt. Vernon.  That SHOULD be in tomorrow afternoon.  No more Delphi rebuilds for me…


But…anyone know just WHY these things go bad so often?  Is it caused by the ultra-low sulfur fuel?  I add an ounce (or 2) of 2-stroke oil at EVERY fill-up to compensate for the lack of lubricity from the sulfur.  I have since I got her broke in in October 1993.

 

 

 

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The cruise is vacuum operated. If the valve doesn't close fully it can cause your symptoms. 

 

As for the lift pumps..... I've never had to replace one. The only thing that can eat rubber that I'm aware of is poor bio diesel. 

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3 hours ago, marksmith said:

The cruise is vacuum operated. If the valve doesn't close fully it can cause your symptoms. 

 

As for the lift pumps..... I've never had to replace one. The only thing that can eat rubber that I'm aware of is poor bio diesel. 

i never have had one leak as well, and have run delphi pumps

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9 hours ago, marksmith said:

The cruise is vacuum operated. If the valve doesn't close fully it can cause your symptoms. 

 

As for the lift pumps..... I've never had to replace one. The only thing that can eat rubber that I'm aware of is poor bio diesel. 


yeah…the check valve on the brake booster is epoxied together because 2 of the 3 breasts were broken off and so far  I haven’t been able to find another one (discontinued by Dodge).  That may be the cause.

another possibility would be a bad speed sensor?  Although I did change that a few months ago (as part of my ABS light issue)  and the Cruise worked great all the way to Missouri and back.

Edited by Ternkiem
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Well…changing the check valve didn’t fix anything….

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  • 1 month later...

GOOD NEWS…I GOT IT FIXED!

Turns out I had not plugged the cable from my TPS mod back in all the way after repairing my fuel return lines a few months back.  Found it in about 30 seconds after I opened the hood this morning.

disconnected, checked for cleanliness, and reconnnected it.  Took her for a test drive and she works good as new!

Color me happy!

 

Happy Thanksgiving all!!

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