trl97blazer

I'm kind of new to this so please forgive me. I just had my fuel pump changed in my 97 blazer LT. It was driving fine for about 2 hours then it started acting like it was starving for gas. A code did come up about the O2 sensor but i didn't change it yet. Now since I parked it won't start just sounds like it wants to. Oh! before I turned it off I put it in park and gave it some gas and it hesitated quite a bit. Need help guys.. puzzled . Could a bad o2 sensor do be the problem?

JoulesWinfield

Turn the key to the on position and listen for the pump. You should hear a buzzing sound in the left rear of the vehicle.

Also change your fuel filter. I dont know how an 02 sensor could stop it from starting or running.

trl97blazer

Thanks I have been doing some reading on various threads and I think it may be the ignition switch as well. What do you think? Everyone feel free to chime in for input.

mike2004tct

A well known prob for '97s. Turn your key to on. Are the guages workings/idiot lights on? (If no, it's the switch). If you have gauges/lights,Is the pump priming as stated above? If no whining from the pump, could be either the relay (in the glove box, switch them around), or the pump itself (connector came off), or the dreaded ECM unit took a crap (on the right fender well, check the connections at the ECM, and also on the fire wall by the 3 relays close to the wiper motor.

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trl97blazer

I will re-check the connections. All the gauges/lights are working and the pump priming. I can hear it. Stays on for about 2 seconds. As stated I just put the pump in on Sunday. Could it still be the switch because of all the phantom problems it causes because i did get a sensor code but no Check engine light? So I'm lost?????

someguy000001

How much gas did you put in after changing the pump? I know I used a full 5 gallon gas can and the thing was bucking by the time I got it to the gas station down the street. It needs a fair amount of gas to run. Check the fuel pressure with a tester from the local parts store. Only $40 bucks or so, and you can use it on plenty of other types of cars.

As far as the O2 sensor goes, it needs to be at a proper operating temperature to work, so it isn't used at all at startup. I mean, it won't cause a no-start if it fails.

If it's a '97, replace the ignition switch. I'm not a fan of throwing parts at a possible problem, but they all seem to go bad, with differing symptoms. My dying ignition switch gave several transmission codes/problems.

trl97blazer

Ok. I got very low fuel pressure about 35-45 psi but the pump is running. Could it be the fuel regulator and is so can someone tell me where it is and how do I get to it? The ignition switch is new by the way and fuel filter is new. Help!

DelCoch

What brand of fuel pump was the replacement? The consensus on this board is to use a Bosch, AC Delco or Delphi replacement pumps. The rest are junk.

Remember when turning the key on the fuel pump will only run for 2-seconds and then the key must be off for 10-seconds before the pump will run for another 2-sec. During the 2-seconds the pump runs you need at least 60-61 psi at the schrader valve. When the pump turns off the pressure will leak down some, but it needs to hold around 50 psi. A quick leak down to 35-45 usually indicates a leaky regulator or the pump failing to hold pressure. If you have a quick leak down, clamp off the return line to the fuel tank and if you still have a quick leak down then the problem is probably in the upper intake, i.e., regulator, nut kit or injector lines.

Check this thread for info on fuel regulator And, this one

trl97blazer

Wow! Great thread! Thank you! I used a GM dealer pump. I will check the intake for that leaky regulator and report back. I hope that is it.

trl97blazer

Okay. I got to the FPR and man was it shot! I wonder was the replacement of the new fuel pump just enough push to force the old FPR to the point of going or was it already on it's way out. Just curious

DelCoch

I imagine it was already on the way out. It seems as though GM engineered everything to die of old age on these things.

trl97blazer

I have now replaced the Fuel Pressure regulator, ignition switch, fuel pump and fuel filter and last night I did the fuel pump test by putting a 12v supply to the red fuel pump test wire and making the fuel pump run. I heard it primming but the psi only reached to about 45. So now I am lost,confused and I don't get it! It was running fine when the fuel pump was first put on then after about 70 miles started to stall and then when I cut it off it developed the no start problem. What is up???

BlazerLT

I bet you your battery is pretty dead after constant starting attempts.

First, test the battery voltage, it should be over 13.4volts.

Unconnect it and charge it with an automatic battery charger.

Also, what kind of pump did you install? Carter or Delphi?

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DelCoch

How much fuel do you have in the tank? In case the gauge is different than before the fuel pump replacement, make sure you have 1/2 tank of gas reading on the fuel gauge.

At this point, the only thing that would make for low PSI at the schrader valve would be a plugged fuel filter, a bad pump or low voltage going to the pump. Is your battery fully charged? Try putting a jumper start on the battery and see it the fuel pressure comes up.

Check the battery with a load type tester. AutoZone will do it for you. I had a similar problem when my battery was going bad. Cranked over great, but the starter was taking all the juice and nothing was left for the fuel pump.

Did you put the pump in yourself or have the dealer do it. It's possible the fuel filter could be on backwards which might clog it up. (The filter has little arrows on it to indicate the direction of fuel flow) The pump should be under warranty, but that doesn’t cover labor cost.

If jumping the battery doesn’t help, I would replace the fuel filter, as they are not a high dollar item and not that hard to replace. If that doesn’t help then no doubt it’s the fuel pump.

However, before replacing the pump, disconnect the fuel pump wire connector at the gas tank, apply a 12v supply to the red fuel pump test wire and leave it there while checking for current on the 12v feed wire in the wire connector at the gas tank. (On my 95 the 12v feed wire going to the tank is gray) Test the current with a voltmeter, while using the ground wire in the connector for a ground. It should read 12.5v or something a little more than 12v.

If you don’t have at least 12v on the Gray wire try using a different ground. If you have 12v, make sure the wire connector at the gas tank is making a good connection to the fuel pump wire connector.

If you have 12v+ and the pump still doesn't put out 60+ PSI, the pump is toast and needs replaced. (Make sure the battery has 12V+ when doing this test)

If you need to replace the pump, get a Bosch, Delco or Delphi – in that order. The rest are junk, which is probably what you got from the dealer, as they often use after market replacement parts. Here’s a link for a good price on a Delphi fuel pump, but also check out the on-line prices at AutoZone and O’Reilly’s.

http://store.getgmparts.com/index.html

Good luck and let us know what you find, as it will help others.

Oh yeah, Welcome to the world of used S-10’s and S-15’s. Once they get 10 years old they become very high maintenance pieces of crap.

BlazerLT

Amen brother....amen.

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1995 Factory Blazer Service Manual for sale, PM if interested.