Dads 94 steppie rough running

[Curtis Woodhams]

So I went to get dads steppie yesterday and it will idle great go to give any gas it spits and sputters and falls on its face. Dad had a stroke in November so it has been sitting since. Just before that I rebuilt the tbi. He put a good used fuel pump in it and new fuel filter. New plugs, wires, cap and rotor. Any suggestions on what could be going on. It has 375,*** miles on it also.

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[RawbDidIt]

So I went to get dads steppie yesterday and it will idle great go to give any gas it spits and sputters and falls on its face. Dad had a stroke in November so it has been sitting since. Just before that I rebuilt the tbi. He put a good used fuel pump in it and new fuel filter. New plugs, wires, cap and rotor. Any suggestions on what could be going on. It has 375,*** miles on it also.

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Sorry to hear about your father.

As for the truck it could be any number of things. Start with checking the vacuum and fuel pressure. If it's not misfiring, the timing and spark *should* be good. If you don't have a fuel pressure and vacuum gage, try starting the truck and go to manually opening the throttle body. If you smell unburned fuel, it's running rich which would point to the fuel system, possibly the fuel pressure regulator. If not, it's probably running lean, listen for a vacuum leak. Confirm results with a test gage before buying parts.

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[Schurkey]

Connect a scan tool, look at the data stream. Coolant temperature, O2 sensor voltage and cross-counts, MAP sensor reading, knock sensor will all be important.

How long has it been since this vehicle had a proper tune-up? Plugs, wires, cap 'n' rotor, verify timing, verify fuel pressure, verify cranking compression, check for "codes", etc?

The last time I saw a TBI engine act like that, it had burned the carbon button completely off the inside of the distributor cap, and the coil wire was cooked.

 

[turboedge]

I recently purchased a TBI that acted like this and it was the fuel pump. Other issues too, but at least primarily. It's not the easiest to check the pressure on these, but with a good scan tool you can see the fuel trim. If the number is much over 128 it has been trying to add more fuel and a good sign that the fuel pump is not up to *****. At least if you have a good working o2 sensor which can be checked with the cross-counts and whether the ECU has enabled closed-loop. If it stays in open-loop mode the ECU does not think the sensor is working. Good luck!