Hey yall,
i own a 1998 blazer that i love but is the biggest peice of junk. baught it almost two years ago and ran great till cold weather. btw its a Lt, with the 4.3L vortec, 4door, 4-wheel drive. My problem started out slow in cold weather. seemed like transmistion was sliping. Acts like it wants to take off idles way up but dosent want to go. took it to the local transmition place, who rebuilt my 700r4 in my camaro. said it wasent a transmition problem. was told 1 of 3 things. fuel pressure "had it checked 57psi" while idle told that wuz normal. 2nd Check fuel filter "changedfuel filter soon after" No result. 3Rd exhaust is pluged. Took it to a local muffler place and had Dual cat back exhaust (http://www.blazerforum.com/m_66020/tm.htm#) put on with a magnaflow glass pack and stainless tips "3 in". ....Sounds Great.... no Result. problem persisted till warm weather and then it ran great. This past winter the problem wuz basiclly the same but much worse. no power at all taking off. push down on exelerator and it wants to die and sputter. let off a bit and it goes slowly, hard to go over 40 on a bad day. some days it still runs great no matter what the weathers like. had a rattle in the exhaust by this time knew it wuz catalitice converter. had a new cat put on. no result, solved the rattle though "Big White Rock". By This point My new father inlaw wuz trying to help me find the sorce of the problem, but wouldnt ever do it with him in the vehicle nore any mechanics. he told me to check distributer cap and roter wich i had already done on my own. replaced distributer, distributer cap, rotor, plug wires, and new plugs. No result once agian. He is pointing fingers at fuel pressure agian. got thinking about it it dosent do it while ideling it does it when ur giving it gas. Please let me know if im on the right path now or if anyone else has had this problem and let me know i would greatly appreciate it.
Brett

Are you getting any codes?

You might check the egr valve or maybe the evaporative emissions system. Also check the MAF sensor if it is really dirty it might not be sending the correct air flow information to the computer. Could even check O2 sensors....

would be best if you get the truck's computer scanned for trouble codes to get an idea what system might be causing the problem, Autozone does a basic scan at there stores for free. And to get a more in depth scan you might have to pay up to $50 dollars, but check with local mechanics to find out the true cost for your area.....

no it isent throwing any codes. iv done replaced all 3 oxygen sensors. replaced mass airflow sensor with a junkyard replacment, still no results

I would have a pressure tester hooked up when the problem is acting up, and watch the fuel pressure. I have seen these fuel pumps lose pressure like this before. Korey.

From what you are stating, what has been found is a fuel system issue.
Even if your PSI for fuel is at the right point, there could be a leak or connection issue. Seeing as its cold related (due to metal shrinks when its cold), I would be checking all the connections for your fuel system. I also would have an OMS check of the electrical parts (too bad this can only be found when its acting up).
Like with my 95 it works fine, but when the tank gets 1/4 or less it will die when it warms up and it can take anywhere from 5 min to 1/2 a day before it will run again. (Known fuel pump issue)

father inlaw told me a month ago he had a fuel pressure guage he could hook up and run it to the cab where i could watch it... any one know where i could get my own, since ill problly never see his. and how much do they usshually run in price

I would go further back through the ingnition, to the coil. Also make sure to check the grounds especially that which comes off the fuel pump in the the rear. Although a fuel pressure test could prove to be usefull.
P.S. MNHawk, I have that exact problem with my 95' right now, is there any way to fix it?

welp bad news, got my fatherinlaws fuel pressure guage last night couldnt sleep so 4 am this morning i hooked it up and drove around the block a few times, constant 60 psi never droped 1nc. now im absolutly baffeled............... no idea what to do next anyone have any suggestions. sorry iv replaced coil also when i did ignition system stuff.

ORIGINAL: Gonzo7

I would go further back through the ingnition, to the coil. Also make sure to check the grounds especially that which comes off the fuel pump in the the rear. Although a fuel pressure test could prove to be usefull.
P.S. MNHawk, I have that exact problem with my 95' right now, is there any way to fix it?


Does your's happen when you get to 1/4 tank or less?
If you want you can pm me the information and we can go over this to help fix it.
Later

ORIGINAL: llxll_69_69_llxll

welp bad news, got my fatherinlaws fuel pressure guage last night couldnt sleep so 4 am this morning i hooked it up and drove around the block a few times, constant 60 psi never droped 1nc. now im absolutly baffeled............... no idea what to do next anyone have any suggestions. sorry iv replaced coil also when i did ignition system stuff.

While you were driving around, did it start to act up? If not then you might not had hit the issue point yet.

Seeing as these internal pumps are cooled by the gas, once the gas gets below the pump it can take anywhere from a few min to a few hours before it can start to impeed the impeller. The Pump works the same as a Fish Tank filter. An electronic flow spins the impeller to create the flow. Just about anything can impeed this flow (dirty tank, bad filter from pickup tube, water, ice, deposits). And its not like you can take it apart and clean it out. If we could, there would be less of a need to replace them. Atleast until the magnito inside crapped out, but then again that only happens when the wires come disconnected, which could be fixed also if you could take it apart.

Auto Meter makes a nice Electronic sending unit FPR gage. They retail for around $289 at your local parts store. And are really easy to hook up and run the wires.

If it only does it when cold... Try putting in some gas line anti-freeze...

Yeah it wuz acting up while i had fuel presure guage hooked up. I say cold but not really below freezing, pretty much does it anytime the weathers below 50 degrees. dosent matter 1 way are another how much gas is in it eitherfull tank, 3/4 tank, 1/2 tank or less does it all the time. My id is the same as my yahoo mess if u want to tey and help

Just to throw in another idea...maybe a coolant temp sensor. If the sensor is out of range (reading warmer than the engine is) the injectors will not deliver enough fuel even if you have 60psi fuel pump pressure.

What about the Intake Air Temperature sensor it is located directly behind the MAF, check its wiring and should have two wires running to it....in the corrugated section behind the MAF....

ORIGINAL: llxll_69_69_llxll

Yeah it wuz acting up while i had fuel presure guage hooked up.

How did the fuel pressure read when it was acting up?

sorry yall net wuz down for a few days, but back on topic. yes i have replaced air flow sensor, havent thought about coolent temp sensor need more info on that maybe ill try that idea. And yes it wuz acting up really bad when i had fuel pressure guage on it and wuz at a constant 60 psi even shut it off down the road let out pressure and started agian to make sure it wuzent a fluke

did everyone give up on me??????????????????

Did you replace the MAF sensor before, and then now the problem has surfaced? Or it could be that you have gotten a bad one. Disconnect the MAF and drive it, if the problem does not resurface with the MAF disconnected, then that is your problem. Also could be a fuel volume problem, you may have enough pressure, but not enough volume. If the truck has close to or over 100k then it could also be the pump yet. HTH.