So Im new to the 6.5 just got it last week. started havin problems two days ago. after driving for somewhere over an hour on the highway the truck looses all power and just idles lettin off for a second and gettin back on the pedal it will usually pick back up and go. it would die the first day but think that was from the dirty fuel filter. remedied that yesterday and drove for a couple hours without problems.

Then today it did it again twice almost back to back. this is without any codes.
truck has had a ssdiesel pmd relocation kit and pmd put on before i got it. no idea when but looks like awhile ago. before i start throwing parts at it does anybody have any ideas?
it also has to idle for a minute before throttle

 

Will work properly. ie have to put it close to the floor before it gets any fuel. if its allowed to idle for about 30 seconds the throttle works like normal.

 

Do LP test to determine if the LP is operating when th engine runs-open water in fuel drain valve with engine idling,if it stalls diagnose dead LP,if it keeps running then LP is good.

OPS powers the LP when engine runs and is a common failure item,AC Delco ONLY for OPS replacement and google OPS relay mod and install for long term durability.

Also google 6.5 diesel APP test procedure to check if throttle peddle is working properly.
APP sensor Testing
Injection Pump my AZZ - Diesel Place : Chevrolet and GMC Diesel Truck Forums

 

Thanks Ill try those tests as well. I did find out my fuel cap is bad. tons of vaccum yesterday when i stopped for fuel.

truck needs some work for sure but for the price I expected that.

 

I would start by checking and adding grounds. Do the dual lift pump relay upgrade.

I personally do not like Racers lift pump test. I've seen to many people have hard restart issues after using this method and finding out their lift pump was bad. Then they have sucked air into the IP and have a hard start issue not associated with their original issue.

On a 1994 there is a lift pump fuse holder on the passenger side/ right side fire wall. You can power the lift pump by supplying power to one side or the other.

Do the dual lift pump relay upgrade.

If ever changing a lift pump with another OEM style only use an AC Delco for a 1993. They flow more fuel for some reason

 

Interesting. ok so by dual lift pump relay im assuming you mean two relays piggyback for the original pump correct? also if i can hear the pump running when i cycle the glow plugs do i still need to test it after its running?

 

If the OPS relay mod has not yet been done-the test described is the only way to prove if the OPS circuit is working properly.

It's not enough to know if the LP operates-you need to know when it operates.

Since the OPS powers the LP while the engine runs and the factory fuel pump relay powers the LP during the starting-you can have a working Lp during engine cranking but not when the engine fires and that is when you need it most.

If you must bleed the lines after a stall from a failed test-it's the price you pay for doing things properly.

A single OPS relay is all that is required for long term reliability when a new AC Delco OPS is installed:
http://www.dieselplace.com/forum/63-...y-install.html

If you can hear the LP run while the glows are being powered it might already have the OPS relay installed or the OPS may have been bypassed-still need to prove it is working while the engine runs though.

 

Hot wire it to test and make sure it is pumping fuel.

Google dual lift pump relay up grade. A guy called buddy posted up a schematic for the dual lift pump relay up grade.

If your pump is running when you cycle the glow plugs something might already have been done to your truck. That is one of the goals of the upgrade

 

I never test when running til AFTER I make sure the lift pump is in working order. Otherwise you get the air in the IP and the hard start issue for no reason. Other than skipping a step. I rarely do the running test.

 

The point I am trying to make about checking the LP with the engine running and opening the water drain is test the entire system-if you hotwire the LP to test if it functions you are only doing 1/2 the test,besides if you have a pumping LP when the engine cranks you have already proven that the LP works-testing the OPS is more important and your way effectively bypasses that and you have learned nothing about the OPS.

Sorry just read your second response-still need to know the OPS functions properly.