daughter's 88 245 DL; 238K miles; always has had good maintenance... trying to diagnose her troubles today over the phone while she's located at other end of the state (CA).

Symptom: Loses power at higher speeds (40-60). Has gradually worsened. Problem seems to set in after car has accelerated and is at sustained speed. Now, she's afraid to take it anywhere, fearing Murphy will set in at worst moment, e.g. nowhere to pull over if/when it stalls on freeway or a bridge.

- Starts/idles fine, warm or cold
- runs OK around the neighborhood
- Exhaust seems to be flowing freely out the tail pipe (at idle)
- No shakes, missing, screeching, squeals or buzzing sounds, "it just loses power and won't go".
- Fluids, wiring and hoses look fine (me over the phone, prompting her visual inspection at engine bay check points)

My thoughts on what it may be (almost as if it's running out of gas):

- Failing fuel pump relay
- Fuel filter
- plugged cat (original)

Any other thoughts, like failing AMM or stuck airbox thermostat?

The 88 has the infamous 25 amp blade fuse... mounted on the fender... could it contribute or is that fuse a go/no go situation? (I havent asked her to check that, yet)

Thanks for any troubleshooting ideas.

Robert

Following up,

Removed air preheat hose, no change to the condition.

Next, son on gas pedal, daughter at exhaust pipe: idle rpm, good exhaust flow; 2000 rpm, much less flow.

So, am surmising its a plugged cat that needs to be replaced.

Thanks, Robert

Let us know when the problem is fixed. My thoughts were exactly the same as yours, I'd like to hear the outcome for future reference.
--
'75 Jeep CJ5 345Hp ChevyPwr and two motorcycles: it wasn't Volvos safety , it was Longevity that sold me

Will do;

will have to pay a shop to do the work since I'm not there for DIY.

I'll let you know

Robert

Robert --

I'd agree with your second and third suggestions: A plugging fuel filter or a plugging cat. Usually, a bad fuel pump relay either works or it doesn't, and sometimes it's intermittent.

Bad AMM? Maybe, but again, the usual symptom is inability to run at all.

You can test the airbox t-stat by simply disconnecting the metal hose. Then, if the t-stat's stuck, it'll simply inhale cool air instead of preheated air..

It's easy enough to check the 25-amp fuse by simply cleaning and reinstalling it. A little vaseline or synthetic grease goes a long way in preventing future corrosion on the fuse tabs.

--
Don Foster (near Cape Cod, MA)

Don,

Appreciate the quick feedback! Daughter's calling back in an hour; we'll do telephone procedure together for checking/disconnecting the pre-heat hose and 25 amp fuse.

Will focus on fuel filter and cat, next, if needed.

Thanks again; nice to get expert's validation.

Robert