1997 Riv Dies on the Highway!

[Jolly_John]

My friend has a supercharged 1997 Riviera, with around 90,000 miles. He will be driving at highway speed, and all of sudden his engine kills. This happens periodically, not on every highway trip. He will coast to the side of the road, and try to restart the engine. It cranks and cranks, but does not start. Then, after a couple of minutes of periodic cranking (and NO other action, like wiggling the gear shift or tugging on wiring), the engine will suddenly start and run fine...and off he goes. No codes have been set as a result of this problem.

Do any of you have suggestions of what to check, given the fact that no codes are being set? Thanks, John in Wisconsin

[page2171]

I would check the fuel pump. Sounds like what I went through with a 94 Sable when I was moving out to California back in 2000. Finally got to the point on the trip where I had to take it in somewhere when I we got stuck in Utah in 100 degree weather and had to push the car about a half mile. Called the first AAA approved place I could find and told the guy what the car was doing, he immediately knew it was the fuel pump. Next day he replaced the fuel pump and we were on our way.

[NTX5467]

If the ignition is working solidly all of the time, the most probable cause is a loss of fuel pressure. It takes a minimum pressure for the injectors to file--if that min press requirement is not met, the engine just cranks over until the pressure might rise enough for things to start happening again.

First thing to do is change the fuel filter. If it has become clogged/restricted internally, it'll make the fuel pump work harder to build the necessary pressure. With time, the pump works too hard and pulls too much juice through fuel pump sending unit wiring such that the insulation can melt, plus becoming more noisy over period of time.

In the case of an "extended crank time", when you put a fuel pressure gauge onto the fuel rail fitting, then crank the engine, the fuel pressure will come up slowly until the min pressure (something like 55psi or more) is reached and then, just like the transmission upshifting at a minimum rpm, the engine starts and runs. It'll run, but not with totally full power available.

There have been similar problems discussed in the BCA Forums in the past year. A new fuel pump unit assembly usually takes care of the problem . . . plus a new fuel filter to ensure everything in working fine.

For good measure, you might get the charging system checked too. If there is something flaky going on in the electrical supply system, sporadically and intermittently, letting the car run on battery power only, that can cause the car to die unexpectedly. But it would not allow the car to immediately crank over as the battery would be "dead". GM's engine management systems, by observation, will allow the engine to run and operate as the battery voltage decreases to about 5 volts, then things stop.

When the battery voltage gets that low, right before "stoppage", by observation, the various icons on the instrument cluster will flash in a certain sequence. This might not be noticed, but before it gets to that point, things like the a/c electrical controls will become unresponsive to input to change modes or functions--again, by observation.

I mention these electrical things for reference. Although they might not apply in this particular situation, I've had a car whose negative battery cable had an internal problem which caused a sporadic hot-restart problem. Everything looked fine on the outside, and it was the orig cable with many years of use on it, but when I changed it, everything worked fine ever since.

Just some thoughts,

NTX5467