96 Sub stalling and cutouts

**ssbums** · 03-15-2007, 10:34 PM

I have a 96 sub (gas) that has an intermittent problem. Intermittent means that it will not have the problem for a week but does it multiple times in the same day (both morning and evening on my 7 mile drive to/from work).

The truck will act like the ignition drops out or it is momentarily starved for fuel while driving down the road...usually around 45 MPH and after it has warmed up a little (so presumably it is in closed loop). The other thing is that it will just stall at a stop light. Not every time, but once out of 10 stops. It stalls and then cranks right up. I've even had it in park before after driving it and had it stall in the driveway.

The only code it threw was a P0102 (Mass or Volume Air Flow Circuit Low Input) when it stalled at a light, but the stored data was bogus since it was at 0 RPM. So I think that P0102 code was probably just the effect of the stall and not the cause.

The only things I have done are checked the distributor cap (cleaned the electrodes that had some residue on them) and hosed down the MAF sensor. Plugs and fuel filter have less than 10K on them.

Sooooo, I have a couple of questions...

1.) Anyone have any suggestions? I'm pretty clueless on how to proceed.

2.) As much as I hate to take the thing to the dealer, I'll do it if I think they can diagnose the problem for me. What are the odds of their diagnostic equipment finding something when the problem is not occurring? I just have visions of them throwing parts at the problem. I can do that myself...and at a much cheaper price!

I HATE INTERMITTENTS!!! Especially when I need to drive this truck 2,000 mies in a couple of weeks!

thx for the help

**unplugged** · 03-15-2007, 11:56 PM

I would be checking the fuel pressure. When was the last fuel filter change?

**ssbums** · 03-16-2007, 12:29 AM

Fuel filter has about 10K miles on it. What do you think about the fuel pump? Is that a possibility? I'll check fuel pressure this weekend.

**ssbums** · 03-17-2007, 01:59 PM

I checked fuel pressure...

pump on-->62 psi
pump off--> 53 psi
running/idle-->54 psi
running, pop throttle to over 1000 RPM-->quicly rises to 62 psi

According to the FSM, all of that appears OK expect the "pump off" and "running/idle conditions might be a little low (the spec is 55). That could be within the error of my gage.

I think I will change the filter for good measure.

Also, is there any reason to suspect the 02 sensors??? They have never been changed and when I am idling, two of them (I think the front ones) read about .700-.800 V and then every few scans will drop to around .100 volt.