Hot Start Problem

[ayebaal]

Pertains to 79 930

Where does one start to work on a hot start problem? Example, today about 90 degrees, freeway speed 60-70, for about 80 miles. Shut down for about 20 minutes, no start. After about 6 hours it I was able to start it.

Any ideas anyone?

[dap930]

Most likely the fuel pressure is bleeding off too quickly after engine shut down. This causes the fuel in the injector lines to vaporize. You would have to crank it forever to purge the fuel lines. The most likely problem is either the accumulator or the fuel pump check valve is bad. If the diaphragm in the accumulator is torn, the pressure will dump immediately after engine shut down. If the fuel pump(s) are not holding pressure, it is usually a slower loss of pressure. The fuel system should maintain some pressure for 20 minutes. You should invest in a set of CIS fuel system test gauges, which is needed to troubleshoot these types of problems.

[mark houghton]

Following Dennis's diagnosis, here's a diagnostic thing you might want to try to narrow things down next time she won't start when hot. Turn on the ignition and push down on the fuel mixture adjustment screw/post until you can feel it making contact with the air flow metering arm, then push down hard enough to deflect the arm and thereby open up the fuel delivery ports inside the fuel head....to flow fuel to the injectors. Sooner or later you'll hear the injectors squeal. One of two things will happen: You'll fill the fuel lines and injectors and be able to start right up, our you'll flood the crap out of the engine.