This is our old 4x4 farm beater, being pressed into service pulling a horse trailer that's a little big for it. Took it for a drive (about an hour each way) the other night. On the way there, after 40-50 minutes of driving, it was stumbling a little when I stepped on it at highway speed. The gas was low at the time, and I kind of thought it might be starting to suck some air. On the return trip (and after fueling up), again, after it had been running for close to an hour, it suddenly stalled when I slowed for a highway corner. Took a few minutes and a few tries to get it to start again.

My gut is leaning toward fuel pump, with ECU running a close second. Can anyone offer an opinion?

 

I would go for the cheapest and try a fuel filter, then fill the tank with 92 octane.

 

On the 1991, there's an inline fuel filter on the frame rail, inside, on the driver's side.

I'd swap that FIRST.

I'd also think about flushing the tank out - running out what fuel is in there and putting fresh in - to make sure it's not some old crud that got sucked into the lines.

RwP

 

Mmmm... good points all - I didn't know where the filter is. That's certainly the cheapest thing to test, and I'm so used to just pumping regular that I didn't even think of trying hi-test for some extra guts pulling the trailer. Sure would be welcome if the filter solves it - a new pump is around $200, and the ECU is a can of worms that would mean trolling the junkyard and probably doing a firmware swap.

Thanks very much; will advise.

 

I have a used pump and it works great. It is probably from a newer Dakota. AFAIK you can just get another computer of the right kind and plug it in.

 

Crawl under the truck, follow the gas line forward from the tank; it's about under the driver's seat rear IIRC, on the inside (towards the passenger side) of the frame rail (not inside the middle of the frame rail, that'd be silly.)

Here's the RockAuto listing with pictures:

http://www.rockauto.com/en/catalog/d...el+filter,6200

RwP

 

I'm the world's biggest fan of boneyard parts, but given that this is a really transient, intermittent problem, I'm strongly tempted to buy new. On the other hand, if the same pump is used in much newer trucks, maybe I can get one with low-enough miles. But I'm just bolting up a new filter right now.

The ECU swap is another can of worms altogether - I did it once with this truck and it involved a change of software because it's a TBI V8, afaIk a relatively rare combination. I'm going to post to the Interchangeable ECU thread about it.

 

Update: Fuel filter didn't help, though it sure won't hurt either. Towing trailer last night I still got the same hesistation while stepping (relatively) hard on it, and one big whompin' backfire. So I'm back to thinking about the fuel pump.

Problem: Local wrecker (pick-n-pull) has a cross reference sytem that's normally okay, but this time it's reporting that only the '91 Dakota used this pump, and I'm not buying it. Can anyone tell me where else this pump might be found?

 

Fuel filter didn't hurt, that's for sure.

The pump ASSEMBLY may be one year one model only; but the PUMP itself (separate from the top hat and fuel level sensor) is a fairly standard one.

Check on RockAuto for the crosses that they have for the repair kit.

I'd rebuild that one; new pump, new hoses, new strainer, new gasket, and disassemble / repair / reinstall the fuel level sending unit, and let'er rip.

RwP

 

Id be looking at the ign coil breaking down once hot, my son's 90 3/4 ton just had that. next Id be looking to the pickup within the distributor, that would be a good chance to check condition of cap n rotor too....