Ok I have read post here for a while and I know that I need to check my codes but I was wondering if anyone has had this prob? My truck started developing the usual miss or skip as some would call it. It only did it every now and then and then here recently it has gotten really bad. The weird thing is it gets worse if the a/c is on. It mostly does it under hard aceleration and occurse abouve the 2500 mark. It gets so bad at times that the truck will stop gaining speed and I have heard it backfire a time or two. I have already bought and replaced the little filter harness you can get from Heath diesel. Before at around 3 grand with the ac off it would still start skipping real bad, now with the filter harness it doesn't do it as much. But with the ac on it still does it just as bad! What do yall think? I am going to try replacing my fuel filter this afternoon and see if that helps.

Have you checked your lift pump to see if it is still working?

it is almost brand new

OK I changed my fuel filter and cleaned my k&n filter and it still skips badly. It seems to only do it in 3rd and overdrive. When it starts doing it if I let out of it for a few min then it will stop skipping. Any ideas? How do I check the code?

www.kennedydiesel.com > Tech Tips > 6.5 > Read Codes. Got a paper clip?

Checked the codes and came back with nothing other than the normal 12 code for no rpms.... so now what? lol I called Heath diesel and they had no clue and said the best bet would be to take it to the chevrolet place and have them put their scanner on it and see if it can find any codes. What would yall suggest? It has a pretty new pmd, the guy I bought the truck from had the injection pump replaced at like 120,000 miles and it has 186,000 now. The lift pump is less than a year old.

Low fuel pressure seems likely.

Open the filter air or water bleed at idle.

what will that do or what should I be looking for when I do that? And where is those bleeds located?

The air bleed is on top of the filter, the water drain T is on the coolant crossover. The truck will pump out fuel or die from lack of pressure.

What he say's about the stalling is true, if there's no pressure, then when you open the bleed the pump will draw air and the truck will stall.

Pull the filter out and have a look at it, tell us what color it is.

Hint: Black = way past due.

Fuel cap hissing?

Check for stretched accesory belt. Bad angle on tensioner gets worse when belt is worn, problem gets worse with more load i.e. A/C.

Ok I changed the fuel filter and yes it was black. I opend the air bleed and the truck cut off. So does this mean I need to buy another lift pump? If so why would a brand new one go bad in the course of less than a year?

May not be lift pump, but the OPS instead. Check to see that you have power to the lift pump first. OPS fails because of under-rated contacts that won't handle the power requirement of the lift pump.

What is the ops and where is it located?

Ok I found out what it is but im still not sure where it is yet. So when I turn the key on to and check votage to the lift pump if it isn't getting any voltage then the switch is bad?

Coach, If I might suggest, Just hot wire the supply pump and take the OPS out of the picture completely.

All you need is one wire from the battery to a switch on the dash to the orange/white wire on the supply pump. Or, a wire from the fuse panel that's hot with the key on to the same wire on the pump.

www.kennedydiesel.com (http://www.kennedydiesel.com) > Tech Tips > 6.5 > Read Codes. Got a paper clip?

Or even closer to home our own FAQs has same info, guys/gals don't forget about them or remind others to go there also, especially new folks wanting basic info, that thread is a living one we can add to it as needed anything missing, drop bowtie, dcam, or myself a PM so we can add what ever you think is needed.

Coach, If I might suggest, Just hot wire the supply pump and take the OPS out of the picture completely.

All you need is one wire from the battery to a switch on the dash to the orange/white wire on the supply pump. Or, a wire from the fuse panel that's hot with the key on to the same wire on the pump.

Yes that will work but not safest way to go, OPS is a safety feature to shut off fuel lift pump power in event of a crash, that could result in a fire, and reduce possibility of adding "fuel to the fire". Best/safest way is to still use OPS, but have it control a relay which is low power draw coil vs heavy draw of the lift pump, then have the power side of the relay feed the lift pump, fed from the batt or another HD source.

OK all great suggestions but still no answer to my questions. Where is the ops located. My local parts store has one in stock so I am going to replace it anyway and hope for the best! And turbine I thought of the faqs page right after I made that post and that is where I went to find the answer to my own question. Great job on that stiky!

On a '94 the OPS is behind the fuel filter toward the back of the driverside head. You might want to purchase an ops wrench (~$10) to remove and replace it.

a lasting fix is to also purchase a 30 amp relay and have the OPS switch the relay and let the relay power the LP.

OK I just went outside and cranked the truck up and disconnected the lift pump and I have absolutely no voltage to the lift pump. So does this mean the ops switch is bad? And if so where the heck is it located. I looked through my haynes manual and couldn't find it listed anywhere.

Thanks Quantum. I will do it. So do you think that is my prob?

Jump the fuel pump relay under that plastic sheild (orange wire to grey) lift pump should come to life. No power to LP during operation would be the ops, yes.

Hey guys I can't thank you enough, I am on the way to get one right this min. Looks like the dragraces are back on tonight at Rockingham Dragway!!!!! Once again thanks a ton!!

Check the fuse on the firewall panel, pass side too.