93 Blazer 5.7L, rough idle after 2nd or 3rd start

Discussion in 'Chevy Blazer Forum (GMC Jimmy)' started by michaelfriesz, Sep 26, 2012.

  1. michaelfriesz

    michaelfriesz New Member

    Hi...new to this but here goes... I sometime put info out of order so please read twice if ness.

    problem have been going on for nealy a month now...i am out of work and have very little if no $$ avail, also do not have basic test tools for this problem so all is by observation.

    I can start the Blazer 1st time ea day ( morning/afternoon/evening ) there is slight missing at low rpms but upon accel that goes away...now the problem... I go to a store, come out and a) vehicle starts fine and im on my way..b) vehicle starts but runs rough as *ell and almost dies ( most times this happens, after a 1 min or up to 3 min, it surges and then comes down to a normal idle and away i go). Any starts after the problem has started will always result in the rough idle and gets worse ea time in length before it comes back to life.

    ok, first ill tell you what i have replaced. Fuel filter, plugs, Dist. cap and Rotor, Pcv valve and hose (boot fell apart as i was checking for vaccuum leaks) another part i will mention in next step.

    second is my observations and what i have done so far... removing the air cleaner assy. when it was running rough, i climbed up in carefully and noticed that the drivers side Fuel injector was not supplying fuel (the passenger side was and still always is supplying fuel ). Wiggled the injector connector and it would start supplying fuel (Sometimes this worked and i could make it all the way home other times just for a few min.) got online and went to Chevy talk ( not very fast responces there but 1 that led me to next course of action ) everyone always says your fuel pump is bad and i dont want to rule this out but everything ive read about the fuel pump symptoms, this was not leaning that way ( btw this vehicle had its Fuel pump removed 5-6 yrs ago ). One person said i might have a short in the in the wires from the connector of that injector. I could not safely at the time remove the actual wire from the connector fearing i would break it and then be totally stranded, but looking as best i could inside it looks as if it had abnormal wear on the power node side. I bought a new Connector whip and spliced it on ( yes soldered and heat shrunk). seemed to work ok but i could still wiggle it and get it to fail. tested a cple days and no change. Traced the power wire all the way back to the firewall and could not find any short. So yes i read up on injector failures and sounds as if the wiring (coil) inside the injector can go bad? also noticed that this problem occurs after engine temp (also coolant?) has reached operation norm.

    So at this point the question is: Is the injector bad and if i replace should i replace both? and or does the Coolant Temp sensor have the ability if faulty to only distrup 1 injector?. need help that cost the least $$ since i may be out of work for more months and have no un-employ left.
    Last edited: Sep 26, 2012
  2. michaelfriesz

    michaelfriesz New Member

    First off....I see many have viewed my post but no one has replied with even the slightest bit of advice...are there any actual techs that go thru these posts?


    I have found a worn thru ground strap that i could not see from above...replaced...cleaned the ground by the thermostat...no change. I have a new CTS w/whip i will install when i can.

    A freind online mentioned that i may have a faulty signal forming from the Coil as the engine temp rises. he asked me to swap the connectors at the injectors and see if the problem followed. I did this...( remember now that i replaced the connector and whip at the suspected injector). After a bit longer warm up...yes the problem followed and now the oppisite injector failed. i could still wiggle it and get it to work but by wiggling the connector or bending ( the now brand new wires) wires right at the connector i could get it to fail. The problem seems to be right at the TBI but how can bending a wire reduce the voltage signal?

    Ok...now...does this sort of say the split signal from the coil is bad and is this the coil near the Distributor or is there a coil on the Distributor itself? Am i now on the right track?

    Please...someone reply and help me out here...when/if i find work, i need a reliable vehicle which this once was and its paid off.
  3. HDFF

    HDFF New Member

    for starters let me say im new to this site and to that i might add also new when it comes to wrenching on chevys.
    i know my way around fords and have allways wrenched on and fixed my own vehicles. i also have just recently became a chevy driver buying a 93 chevy blazer 5.7L 4x4 fullsize. so i feel obligated to a bro blazer man to throw in my two cents and if you get a nickle back then so be it. i ve had tranny problems and in my search of figuring out my tranny problem i have done a couple of things that might help you out. first off i would try pulling the trouble codes if any have been logged by the vehicle. im shur theres a post somewere on here that tells how to. if not ask and i will try and guide you threw it. this is not a difficult task and is necessary in my opinion to acheaving the desired results in the daunting tasks of haven a problem and limited budget to fix it with. hopefully from there you
    will find a code that is in a direction that you already have pinpointed . plus clearing the codes will allow you to see if you have fixed the problem area or if there is another direction one might go. this is what i did for trying to figure
    out my trans problem and there was not a single code that said anything about the trans. but with trying to eliminate the problems with a limited budget i trying any and all cheap fixes i try and fix problem parts instead of replacing. for instance i had a code that said tps bad signal or ground. so i removed the air intake and filter removed the tps and noticed that it did not move freely back n forth cleaned it with brake cleaner and MAF sensor cleaner witch is like electrical cleaning fluid. this fixing and freeing the movement of the mechanical part of the tps. reinstalled it and noticed there was a lot of brown tarnished looking fuel all over the throttle body. sense i was right there with brake cleaner i just hosed it down a bit with it trying to keep it at a minimum were electronically parts were and then used the MAF sensor cleaning fluid on the electrical wire connections and so fourth. started the vehicle witch was kinda hard to start cause of the cleaning fluids i used probably flooded it out a bit. when it started it ran doggish at first till i reved the motor a few times then it leveled out an ran the soomthest it has ever ran. while it was running i took the brake fluid cleaner and sprayed again the throttle body area to clean the tarnished looking fuel off. the motor would die down when i would spray then pick rpms back up and run fine. this also will aloow you to see if you have any vacum leaks around your throttle body. all n all when done with this i took the blazer out to see if i could notice any difference in performance and you could say that again. throttle responce increased overall the sluggish running blazer turned into a pepeehy running 4x4 and the tranny shifted better and way smoother. so there you have it i cleaned instead of replaceing parts and my foucas was towards the trans not the tps. results from reading the trouble codes and eliminating or fixing them gave me disired results in a better shifting trans witch i was looking for from the begging . hope this might help if not atleast you could say you got a responce : )
  4. K15 Blazer Guy

    K15 Blazer Guy Member 2 Years 100 Posts

    you can do a fuel pressure check for free with a tool from the store.
    but if an injector is failing, then simply go the bone yard (thanks to Bob Seager millions of these trucks and engines were sold. there are 6 in my local yard right now...)
    so you can simply get a "new" throttle body or injector for pennies on the pound.
    but if its cranking and firing well... the problem is not ignition related
    and if it is doing this inconsistently..... then its not a vacuum leak
    sounds like you should pick out a throttle body from a totaled low miles tuck in the yard

Share This Page

Newest Gallery Photos