I have an 89 volvo that after driving for a long period of time (50 miles yesterday in town driving) during the heat of the day (we hit 100 yesterday) will begin to lag when I press on the accelorater and then the car will finally die. I waited about 20 minutes before I started the car and drove for about 2 miles before the car died again. We then waited 2 hours and made it home.
At first I thought the car had overheated, but the Thermostat never went past middle. I've since watched the thermostat and it does seem to function correctly.

When the car first starts to fail it feels like the car is starving for gas. It reminds me of a a jeep I once that got a little silicon in carb jet and when I stepped on the gas the car would 'pause' for lack of fuel.

About 25k ago I had all the fluids changed. I also had the fuel filter changed and fuel injectors cleaned.

In short, I don't the car is overheating, but the heat is somehow affecting something?

Any thoughts??

IMO, It's as good a system as the Bosch, but the Fuel pump seems to be shorter lived.

If your '89 is one of the first Regina 740's, the pump may be on its last legs. The failure indicators are a low/fluctuating fuel pressure test, or by measuring the pump's current draw at a connector in the left rear wheel housing (or by inserting "meter jumpers" in place of fuse 11).

Bruce, Have you ever seen an 89 Regina? I believe that would be one rare bird. But I've been wrong before (as you know).

No, but "the documents" say that '89 was the first year for the Rex/Regina combo.

What surprises me is a current/recent post by someone who has 3 non-turbo Bosch FI 700/900 cars from the early '90s.

Our 1990 is a Regina, but it was "manufactured" in Sept '89. Possibly that's where the "1989 with Regina" info comes from.

I believe the California NA's (with EGR valves) never did go to the Regina system.

The Crankshaft Position Sensor, Fuel Pump Relay, and Radio Suppression Relay (which supplies power to the injectors) can all three temporarily fail as an effect of heat soak. A crankshaft sensor failure "should" record a fault code in the OBD syatem, but the other two won't - at least not directly.

The majority of 740 stalling and no-start problems can probably be traced to one of those three components.

I have an 89 -740 regina,its either/or the knock sensor,,,replace it w/a recycled upullit one,,,or the screen on the fuel pump,,pulled mine to do the fuel pump&holding it up to the noon day sun,,,it was black,,,thats prob.why the pump dies.
they should have the fuel go through the filter first thing&the pumps would last for a million miles.

It the problem was the initial fuel pump in the gas tank was dead. The main fuel pump was able to do the work, but the extra load combined with the 100 degree weather caused the pump to overheat.

Thanks for the help.