5.3 Woes

wgamble · Sep 19, 2015

Got a 5.3 that has set up for a year, replace the fuel pump, put fresh gas in it and got it to fire off with a little starting fluid for a couple of seconds.

Here is my question: Pulled the number 1 plug (plug closest to radiator on driver side, just in case I have the wrong one stated) and put it on alternator bracket to make sure that I am getting fire. Bumped the key and it fired right off. Put the plug back in, tried to fire it up and it just turns over.

Help Please.

grcthird · Sep 20, 2015

Do you have injector pulse and fuel pressure? If so the injectors may be stuck shut, gummed up. I have been able to tap on them (different application) and get them to break the pintles free where it would run.

d_daffron · Sep 20, 2015

Check fuel pressure. It sounds like the fuel pump may not be running. It is unlikely (but possible) that all 8 injectors have clogged up. find the fuel pressure test port. Dont know what year 5.3 you have but the test port is most likely on the passenger side on steel crossover line that connects the two fuel rails. If you dont have a fuel pressure guage, cycle the ignition a couple times to run the pump then take the little black cap off the test port and push the little stem in the center of the test fitting. Fuel should spray out under pressure BE CAREFULL!!!!!

If fuel doesnt spray out , you probably have a bad pump next step would be to check for power at the fuel pump.

wgamble · Sep 20, 2015

I HAVE ALREADY REPLACED THE FUEL PUMP

I want to know why it would run when I ground out the #1 spark plug to the alternator bracket but once i reinstalled the plug it would not start.

grcthird · Sep 20, 2015

I misread your post, I thought you were saying that it had spark, as in the plug fired, not the engine fired off and ran, my bad. That is very strange, unless somewhere in the area of that spark plug you moved a loose electrical connection that then started making contact. :dunno: