Rwillia4 Rob That is a normal injector pulse to prime the motor to start. All injectors are turn on a 2-4 times every 90 to 180 degrees of distributor, depends on system. The gauge bounce is the fuel going into the motor 8 injector pulse at once and the pump trys to keep the pressure up while the fuel pressure regulator is trying to control this at 45 psi. You have crank signal for injectors but we don't know about good spark. DON'T Keep cranking the motor with fuel pressure on There is enough pressure to start the motor without running the pump. You are washing down the cylinders.
Pull all the plugs, Are they wet or black?? Picture would be nice to see. If wet we need to go back and check out the spark end of the system. either air dry plugs or get a new set. Easy way to test, Pull coil wire at 1 end and have motor crank. Keep anything metal out of area and yourself a min of 1 foot. If you lay plug wire on side you want to see a bright spark during crank. Blue or yellow and jump about 3/4 " of an inch to contact. If not get wire little closer and retry. If spark is weak, cheapest is start with coil. If you have no spark need to check for signal to MSD box, Box could be cooked. I had a new box cook on my first startup. Internal short of a shunt. Car started after repair. After this testing, smell the
oil in the motor, if it smells like gas, change the
oil and filter. Old FAST system was batch fire on crank and then went to sequential or stayed batch. Have this in my notes from 15 years ago. Can you you tube this test of spark? I know of people that have run 6AL boxes for years and never a problem, also know poeple that have not gotten there cars to start with a new out of the box kit. Unhook fuel pump from spark testing. The motor could already be flooded. Could get nice bang out of side pipes or enternally damage motor if gas vapors go off. Pull plugs and check spark. Rick L.