95 Tahoe hesitation and backfire (Help!!!)

[Trevor238]

Howdy! I'm new to the forum and thought id be able to bounce some info off you guys in the hope for a little advice.

I own a 95 Two Door (5.7 L) and lately it has been giving me some issues that has me scratching my head. Start up and initial driving are fine for the first 20 minutes or so with no issues with the truck whatsoever. After that time period or so my truck will lose power and backfire out of the exhaust under medium to hard acceleration and will not run properly until i proceed with moderate to light acceleration. It almost seems like its getting choked when i press ******* the pedal but comes back to life and idles perfectly when i take my foot off the pedal and just chug along.

So far i have replaced the fuel pump (which i tested), cleared the fuel lines, checked and tested wire connections, checked fuel filter, and replaced the O2 sensor. I'm not in a position to keep throwing money at it currently being a poor college student and all aha.

Anyways.... Any help would be greatly appreciated!


p.s. More fun.... Now the truck wont even start. When i turn the ignition, it cranks but no fuel is coming to the injectors. Anyone out there willing to throw some advice??? School is coming up and i need a means of transportation.

 

[SunlitComet]

Well verify again the fuel pressure and if good see if you have possibly clogged injectors. To help verify that borrow some injector noid lights to test for power to the injectors when they pulse. They are positive voltage powered and negatively triggered. So with the key on check each pink wire on the injectors for system or lack thereof. It runs thru the ECM-1 fuse.

 

[retorq]

Checking fuel pressure is a good idea but it's not easy on a 95, you have to cut the fuel lines and put a pressure gauge inline or get one of those $$$ adapters. Check for vacuum leaks too while you are under there ... since you aren't sure if the initial issue was spark or fuel related you might wanna check that module while you are there...

 

[Trevor238]

Thanks for the info guys.... I'll check that stuff out. I have a little more info if this helps out. When I had the initial backfire issue, I suspected the fuel pump. So I dropped the tank and installed the new pump. After I put everything back together I took my truck out for a drive to make sure everything was working properly. I drove through an industrial park and hit a bump which instantly caused my truck to shut down and I would fire back up. The truck would crank but nothing happened. After I towed it back home, checked the injectors for power, cleared the fuel lines with air, tested the new fuel pump, cleaned my ground connection and cleared/checked the fuel filter. After all this it was put back together and it started right up and ran but still had the backfire and hesitation issue. Anyways, I tried to start it up the other day after checking the MAP sensor and it would turn over. It will crank but once again my truck is in the same condition as when I had to tow it.

Hopefully this info is useful!

 

[retorq]

It is backfiring thru the intake or is it popping thru the exhaust??

 

[Trevor238]

Exhaust