So i picked up this 95 f250 7.3 manuel 4x4 with 165000 kms on the 8 hour ride home i noticed it ran good at cruzing speed but when i slow down for stop lights it has a very rough idle and shakes like crazy and somtimes catches itself and smooths out any help would be apprecaited. Thanks

 

Take a look at the valve cover gasket pins and harness, both the outer ones and the under cove ones, for burned pins and/or melted connectors.

 

Do i have to pull the valve covers for that?

 

Do i have to pull the valve covers for that?

 

I remember reading on here a while ago that with a factory fuel pump a slight lope at idle when warm is nothing to worry about. Mine's done it for 90K mi but as soon as I give it a little throttle, it smooths right out. It also idles smooth when cold and idle RPM is slightly above what it is when warm. The fuel pump is mechanical and the faster the RPM the faster it pumps. At idle when hot, fuel pressure at the injectors can fluctuate enough to cause a slight rough idle. Putting a BB behind the fuel pressure regulator spring helped some. You can search for that mod. It's easy. It bumped my pressure at the schrader valve from 45 up to 65psi. I'm still trying to remember details here but there are some other mods you can do to the fuel system while maintaining the stock pump that will also help but you'll need to search around or maybe someone more knowledgeable can help. If it smooths out above idle or when cruising down the road I don't think you need to worry about your valve cover connectors. But take a good look at them anyway. They can get hot and melt over the years. Also take a look in the engine valley under the pump. If the pump is going out it will leak there and leak on the ground behind the engine.

 

To see if the under cover harnesses are melted, the covers have to come off. Usually if the fuel pressure is low. it won't run better at higher rpms.

 

Alright thanks guys

 

How does it run when the engine is cold ?

 

I have the same problem, my truck has a better idle when cool (50*) starts than a warm engine. Put the BB behind the fuel pressure spring a while back and had no luck. I ohmed out the glow-plug pins on the valve cover gasket to test for burnt wires and/ bad glowplugs but all passed. I also put a code scanner (no codes) on and ran buzz tests and injector tests and all passed perfectly.

 

I'd pull the ipr and check for damaged orings.

 

Ok guys thought ud wanna know replaced the fuel filter solved the problem thansk guys forbthe info tho 👍

 

That was my first thought.