95 6.5 hard starting

[dajohnson]

I'm a new user and jumping in on this discussion about i.p timing. I have a 95 Gmc suburban with a 6.5 turbo diesel. One day when my son was driving it, the ceck engine light came on and it starting being hard to start. It would only start after 7-10 seconds of cranking with the foot pedal fully depressed. I later checked trouble codes and found it had a couple related to the pedal position sensor circuits.The pedal assy. was replaced with a new one from Rock Auto.com. After the installation I erased the codes, but the light came back on. The code now says "pedal position circuit 2 in range fault". My understanding is that the pedal will still operate normally, as long as 2 of the 3 circuits are in range.Anyway, my vehicle is hard to start, hot or cold, block heater plugged in or not. I have put in a fresh fuel filter, replaced rusty fuel all the way including the sender in the tank. I checked fuel at the injector during a starting attempt, and there seemed to be no fuel, until it started , then there was fuel. I have done nothing with the i.p. timing. when the truck does run, it runs well. but the pistons sound louder than before. any ideas would be appreciated

[Robyn]

Check the ground wires at the RH rear of the intake manifold near the tranny dipstick.

Be sure battery and chassis grounds are good as well.

Check the IP ground on the top of the IP

Another possible could be a faulty ign switch.

Any other codes ???

Grounds and power on these can be a real issue.

Low voltage or bad grounds can drive the ECM nuts.

Be sure you have good voltage to the circuit breaker panel in the LH side of the engine bay at the 12v feed lug (rear of box)

Missy

[dajohnson]

Thanks for the reply!
I did check and installed new grounds at the rear of the manifold, my chassis ground might be poor. I recently replaced the heater fan and found that it had lost its ground.I will check the voltage to the circuit breaker stud. Other codes present was dtc44 e.g.r pulse width fail and DTC 45. When the truck does start it runs great.
Thanks

[dajohnson]

Robyn,
I Installed grounds to the frame, and the cab,checked voltage at the main stud on the left side fuse block, and I have battery voltage. What would a faulty ign. switch do during starting?, If I have good ground at the ALDL would that translate to a good ground the E.C.M.? The truck did start today, (35 degrees outside today), but the excessive cranking is still necessary. I didn't mention that I often get a small amount of air out of the fuel filter bleeder. and I had the intake manifold off, just to check out the fuel lines, and noticed that a sensor in the rear of the valley( I assume it is the knock sensor) is not plugged in to any wires or pigtail, and i cannot find any connector hanging anywhere. Any ideas are appreciated as the snow will soon start here and I need the truck to push snow with .
Thanks,
Dave

[phantom309]

I,m guessing you may have a problem with the lift pump on the frame,.??

with the engine running,. you should be able to open the "T" drain fitting on the thermostat housing and fuel should drain out and the motor stay running,.
If the motor just shuts off,. its a good indication the lift pump isn't doing its job,.
These 6.5 motors will run with just the injection pump pulling fuel from the tank,.but can be harder to start,.
From what you describe you have a fuel delivery problem if you are getting air in,.
A pump making noise is no guarantee its putting out pressure either,.

[dajohnson]

Thanks,
I will try that at the petcock, I have replaced the lift pump once, I'm tempted to put the old one back on, because I later found I had a rusted out fuel line in the back, by the tank. Should the lift pump be energized during cranking and therafter when the oil pressure switch has pressure?
Thanks,
Dave

[DmaxMaverick]

Thanks,
I will try that at the petcock, I have replaced the lift pump once, I'm tempted to put the old one back on, because I later found I had a rusted out fuel line in the back, by the tank. Should the lift pump be energized during cranking and therafter when the oil pressure switch has pressure?
Thanks,
Dave

For 1995 models, the LP should be running any time the key is turned to "start", then after the oil pressure comes up. Because of that, you can test the LP for flow and pressure w/o running the engine:

Set the E-Brake and/or chock the wheels; turn the key to "run"; shift to any range other than P or N (prevents starter engagement); turn the key to "start". The pump should run, but the starter should not engage.

If this works, but it stalls once the engine starts, the OPS is a likely suspect (as well as a fuel line leak).