Fuel filter: its mostly clogged and when it sucks itself fully clogged, the motor starves and dies. Sitting lets some of the particles reverse back into the tank so the motor runs again.
Had this happen when i had a shop replace my fuel pump in a S-10 blazer and they forgot the strainer "sock". This same thing happened -- it would run for 30-40 minutes, then die completely until the filter reverse flowed the clog back into the tank, only to reclog when restarted and run another 30-40 mins.

 

Dies at low load, no problem at higher load at highway?

 

Yep or completely plugged exhaust system

 

My wife had a 81 Camaro that did just this and it ended up being the catalytic converter. Time and cheap gas finally takes its toll on the older style converters. If you handy you can make up a pipe to temporarily eliminate the converter and see what happens.

 

Sorry if I am about to offend someone. At least its not my intention.
It just seems as a lot of advices are guess work, or once this happens to me etc.
This is not trouble shooting, but shooting in the dark!

Javiramone wrote: It starts ok and run very well but after some miles - especially when i drive through the city (low speed -run, stop, run, stop) - the car loses power and the engine finally stops. I start the car again and only run for some meters to loses power and stops again. If i leave the car stopped for a while - 30 to 60 minutes, it runs ok but after 3 or 4 miles back the same problem.

Hi....thank you for your help. Until this moment, the car didn't stop when it was running through the highway. Just only in the city, driving slowly or the last day driving up the small hill.
Basically the engine dies at low speed (low load, low fuel consumption), but not at highway speed (Higher load, higher fuel consumption)
My question is: How can this point to a plugged exhaust, catalytic converter, fuel filter, strainer sock and under pressurized gas tank?

This is a great please posting these sorts of problems and I have found answers to many questions in here due to a lot of great inputs?
However, basic trouble shooting should prevail.

Point 1: If the car starts OK and run very well, particular on highway, one can assume that the ignition is OK.
Point 2: Dies at low speed, but run well at highway speed. Most probably the fuel system!

It either die running too lean or too rich!

If its caused by lean mixture you should check your low speed metering jets (Check the colour of your spark plugs, white if you suffer from lean mixture)

If its due to rich mixture its most probably your fuel bowl level that’s too high or overflows. (look down through your venturies while the engine is idling to see fuel droplets. If, your fuel valve is most likely stuck, and your spark plug is also fouled)


On the contrary to my comments above, the enquirer posting for help should feed the forum with as much information and symptoms about the affected equipments as possible.

Good luck with your trouble shooting
Lars

 

With you new info I would look at the fuel pump. They offen lose pressure at low rpm when they start to go but when its revved up or cruising down the highway it can maintain pressure because of the higher rpm.

 

I agree you with assessment mrvette. I had an 82 Monte Carlo SS that did the exact same thing. It seems once the engine compartment built up enough heat the ignition would shut down, cool down period and it would refire and run till the engine compartment heated up again. Changed the ignition module problem fixed.

 

He said it looses power slowly until it dies....

 

I have had clogged fuel filters display these same exact symptoms.

 

Niether have I but I've had a mech. fuel pump act up just like he described