Well im havin almost same issues besides ac is fine. If im in P and rev it quick it hesitates and backfires then gives power. Its runnin lean. I checked fuel from shredar valve in fuel rail by intake. Getin like 53psi primed and 47psi running. After i shut it off fuel drops to 45psi after 5 mins. Codes p0171 and 174. Plus in N if im drivin fuel gauge drops from 1/2 to 1/4 which is weird

 

Those fuel gauges were flaky at best. With pressures like that I will vote that the pump is failing, but There is a troubleshooting guide on here for diagnosing the fuel pump/Regulator. Its cheaper to troubleshoot a second time than replacing the wrong pump!

Good luck!

 

i used the $150 loaner fuel pressure gauge from autozone. i dont think its that flaky. my only other problem now is both my low and high beams on my driverside dont work. guna check to see if there getting power, but my blinker and parking lights all work on both sides.

ENGINE RUNNING
as you can see in the picture the gauge needle fluctuates while engine is running



PRIMMED its goes to 52psi then when the pump shuts off it drops to 47ps


AFTER 5 MINS OF IT BEING OFF

 

so everyone thinking what im thinking? new fuel pump? filter is new, also going to put a new FRP and uper and lower intake gaskets on. hopfully fixes my problem

 

Why not take it to a mechanic to diagnose it then fix it yourself? I tried going down the path myself and spent a lot of unneeded money so I'm just going to take it to a pro to tell me what it is then do the actual work myself.

 

i did take it to a mechanic and waisted $105 $65 for the diagnostic and $40 for labour, they said i did a bad job of cleaning the maf and i missed a vacuum line when i replaced them all. check engine light has been off for 4 days now but its still running the same way. if i open the hood and rev it fast it hesitates and back fies out the tb then gets up the rpms. no problem getin on the freeway but i notice i dont have as much power as my sonoma did and im waisting more gas while im at it. sometimes power is nice sometimes not, sometimes i get hesitation from moving from a stop light.

so i believe it is still running lean. in drive it has vibration and you can see the engine rattling. in neutral its idles fine.

and sorry for hijacking your thread juanfpina and tell me what your outcome is after you have it checked...

 

When I mentioned the fuel gauge being flaky, I meant the one on the dash... Not the fuel pressure gauge. You pressures are definately too low.

Were you able to find the troubleshooting guide?

 

ya but im not that technical. i went to autozone and with both codes only 3 posibilities came up, 1. fuel pump, 2.vac leak, 3. fpr. but ever since they put the new vac hose on the light hasnt come back on. but it still shows signs of hesitation. but not as bad. so ima get my check and have my buddy put in new spider new upper and lower intake gaskets and a pump. probably needs it either way being theres 226k on the odometer. probably still has the first gen spider. also thinking about running some sea foam through it. can you hurt your engine using sea foam through the brake booster vac line? ive done it acouple times on my sanoma and when i shut the truck off it sounds like a dieing car in a movie that dosnt want to turn off. stays on for about 3-4 secs pinging to life.

 

I would start with the fuel pump first. test drive it and see what it does. I have 225k on the original spider. Runs fine. I would change the spider unless it proved to be bad. Why replace a working part?

I use sea foam in my crank case on really gummed up motors. I usually dont dump it into the intake to de carbonize. Just curious what youre trying to accomplish. One concern I would have is breaking a bunch of carbon loose and getting it stuck in the catalytic converter.

I see youre doing the lower intake gasket...Coolant leak?

 

no collant leak that i am aware of but when i had my thermostat in i could smell burning / hot collant. when i took out the thermosta the smell stopped now im running with no thermostat, also i heard sea foam cleans the catalytic converter and also the top of the motor. i bought this blazer from a police auction a month ago so i dont know how it has been treated. and what kind of maintanace was done. when i put new plugs the old ones were burnt. so i put in rapid fires