Surging issues with my '97 OBS… any ideas?

I’ve got a 1997 OBS with 253k miles. When I start it up, it surges a bit. Someone suggested replacing the ICP sensor, so I did, but it’s still acting up. The guy who sold it to me mentioned the second fuel tank has trash in it, so he switched it over to the front tank and replaced the fuel filter. Still no luck.

With that mileage, the injectors might be nearing the end of their life. I had a 2000 with a similar surging issue at around 250k. I sent the injectors to two different shops and they both said they were fine, but replacing them fixed the surge for good. Sometimes, it’s a real pain to diagnose.

@Micah
What’s a decent brand of injectors to go with?

The CPS and IPR can cause surging too. On every 7.3 I’ve owned, I make sure to replace the CPS, ICP, and IPR sensors as a baseline.

Hale said:
The CPS and IPR can cause surging too. On every 7.3 I’ve owned, I make sure to replace the CPS, ICP, and IPR sensors as a baseline.

I saw two recalls on this truck, but it looks like neither of those sensors was replaced, including the CPS.

I’m driving a 2005 6.0, but I had a similar issue where the fuel pickup tube in the tank started breaking down. It would cause surging when I got down to about a quarter tank, like it wasn’t getting enough fuel.

If it were the injectors, wouldn’t it surge all the time and blow more black smoke? Mine only does it at startup.

Perrin said:
If it were the injectors, wouldn’t it surge all the time and blow more black smoke? Mine only does it at startup.

In my case, it was one injector that needed more oil than the others. It ran perfectly at anything above idle, and I didn’t notice any extra smoke. Mine were custom injectors since I’d built my engine for towing.

@Micah
I think I’ll start with an oil change since I’m not sure when the last owner did it. I’ve heard good oil quality is crucial for these engines. Had a 6.0 before this 7.3, so kind of familiar.

Perrin said:
@Micah
I think I’ll start with an oil change since I’m not sure when the last owner did it. I’ve heard good oil quality is crucial for these engines. Had a 6.0 before this 7.3, so kind of familiar.

Good call. I’ve been running Delo 400 15/40 in mine for years and haven’t had issues.

@Micah
Turned out it was the selector switch on the transmission.

Perrin said:
@Micah
Turned out it was the selector switch on the transmission.

That’s interesting, thanks for letting us know!

Micah said:

Perrin said:
@Micah
Turned out it was the selector switch on the transmission.

That’s interesting, thanks for letting us know!

No problem!

Micah said:

Perrin said:
@Micah
Turned out it was the selector switch on the transmission.

That’s interesting, thanks for letting us know!

Apparently, it was stuck between first and second gear, which caused the surging.

You’ll never be able to replace the ICP! Whoop whoop! (For the juggalos out there)

I had the same issue until I swapped out the IPR. Problem went away after that.