Stepper Motor - DTC 34

[BillK]

I keep throwing a DTC-34 Stepper Motor code. Replaced Crank Position Sensor (was definitely shorted out from oil decomposing the insulation).

Symptoms are:
1. Code 34
2. Code displays during idle, goes away at speed.
3. Engine runs fine during morning run to work (about 15 miles on freeway), but dies during drive home after sitting all day. Goes about 3 miles and then engine shuts off without warning. If I turn key off and wait a few seconds it will restart. Sometimes it dies several times in a row. Sometimes difficult to restart. Usually clears up then and runs fine the rest of the way home.
4. I was having no lift pump activity so I installed a direct switch to it and problems are less when lift pump is on.
5. I've checked all the grounds/connectors.
6. I did find the gasket on the upper intake manifold was missing a piece and blowing intake pressure out the front.

7. I removed the Stepper motor and it is difficult to move the plunger in and out. I don't know if this is normal though.

[ucdavis]

Stepper motor shaft is tough to move when new so that is normal. New motor @ Standyne lists @ $84 as of January. Easy R&R for DIY types.
You can get a spare off a dead ebay pump that will almost surely work, possibly for less than new; the stepper motor is quite reliable & failures are rare. Possibility fault could be ground or signal line to stepper (DTC doesn't tell a part is faulty, just indicates trouble in that circuit) so the cheapest approach is to clean up all connections & grounds & retest the original.

[sbdaigo]

do you have to pull the pump to replace the stepper motor? By the look of it I see that I would have to remove the intake, but it looks like one can get to it.

Rino

Looking to rid my DTC34

[Barry Nave]

No LP on a PMD,stock mounted driver and low fuel in tank will take out the FSD.
Start,sit,wait and then runs sounds like a class of FSD woo's.

[David Brady]

Bill,
Does the '95 use the Oil pressure switch for anything else? Like shutting down the pump in other ways maybe? I don't know but it sounds like you should replace that OPS and put in a fuel pressure guage (electronic). Do the symtoms vary with the amount of fuel in the tank or the heat of the day or any other thing?
Dave

[Kennedy]

Best way to verify is by doing Time Set with the Tech 1 or 2.

Basically, it sounds like your pump is too far advanced. You could also try to nudge the pump slightly to the passenger's side which will likely cure the problem.

Basicallym, sound like the ECM is calling for 8.x