Fuel pump????

97blazermadness · #1 01-13-2005, 09:18 PM

Was driving home today, everything fine until the engine shut down on me. Was going about 65, when I felt a small jerk (couldn't tell where from) the RPMs died off, no response when pressing the gas pedal, the SES light on, check gauges light on, and battery indicator light on.

Pulled over and checked stuff out. My electrical is fine, the starter will crank but the motor will not stay running. My Blazer gas gauge hasn't worked for almost 2 years now so I'm quite used to resetting the trip odometer to keep track of gas. Just to be sure, I put 2 gallons in and tried again, still the same thing -- will turn over but not start.

I then tried dumping some gas straight down the throttle body, it started and ran a few seconds then died. I need to fix this myself -- is my diagnosis right? I had my car towed to a friends house because I know the dealer will wreck me on this.

Is the fuel pump bad? $300.00 -- ouch!
Anything else I should do to make sure?
Is the job difficult?

Thanks guys!

BlazerLT · #2 01-14-2005, 02:15 AM

check fuel pressure.

Fireplug · #3 01-14-2005, 11:03 AM

If you put gas into the throttle body and it ran then your problem IS a fuel problem. Do you hear the pump run for 1.5 to 3 sec with the ign key turned to run??
If no go to the gas tank and check for power there. If good power and pump no run you found your problem

mikeleew · #4 01-15-2005, 03:15 PM

Is there supposed to be 12 volts at the connector to the pump? I show 3.5v and then it will go up to 8.5 and hold.

Quote:

Originally Posted by Fireplug

If you put gas into the throttle body and it ran then your problem IS a fuel problem. Do you hear the pump run for 1.5 to 3 sec with the ign key turned to run??
If no go to the gas tank and check for power there. If good power and pump no run you found your problem

BlazerLT · #5 01-15-2005, 04:28 PM

Check you battery voltage.

mikeleew · #6 01-15-2005, 11:44 PM

I did but forgot to mention it. 12.5v This string of posts are written as if I wrote them about my blazer. The only thing I would add is, after it was towed to the house, I removed the out line at the tank and turned the key. Gas flowed, but not at what I would call high pressure. Reconneted the line and the engine started. I shut if off and tried it again and had nothing. Now, the motor doesn't run for the 1 or 2 second time frame at all. I have a new pump and will finish replacing it in the morning. The car has 200k so it won't hurt. What should I look at next if that doesn't fix it. Again though, should there be 12v at the pump connector between the two wire? Or it the 8.5v good when the key is just on without the engine running?
'
Thanks,
Michael.

BlazerLT · #7 01-16-2005, 12:09 AM

12.5volts is a little low for any battery.

mikeleew · #8 01-16-2005, 08:22 AM

That is when it isn't running and the engine cranks great. As a matter of fact, it has been cranked without starting many times.

I did but forgot to mention it. 12.5v This string of posts are written as if I wrote them about my blazer. The only thing I would add is, after it was towed to the house, I removed the out line at the tank and turned the key. Gas flowed, but not at what I would call high pressure. Reconneted the line and the engine started. I shut if off and tried it again and had nothing. Now, the motor doesn't run for the 1 or 2 second time frame at all. I have a new pump and will finish replacing it in the morning. The car has 200k so it won't hurt. What should I look at next if that doesn't fix it. Again though, should there be 12v at the pump connector between the two wire? Or it the 8.5v good when the key is just on without the engine running?
'
Thanks,
Michael.[/quote]

mikeleew · #9 01-16-2005, 02:10 PM

The 8.5 holding voltage must be okay. It starts and runs fine with the new pump and still shows the same voltages.

Quote:

Originally Posted by BlazerLT

12.5volts is a little low for any battery.

BlazerLT · #10 01-16-2005, 03:26 PM

Quote:

Originally Posted by mikeleew

The 8.5 holding voltage must be okay. It starts and runs fine with the new pump and still shows the same voltages.

Sorry guys, 12.5volts is low for ANY battery.

I don't care if it cranks, a properly charged battery should be 12.8-13.6volts.

mikeleew · #11 01-17-2005, 10:02 AM

Now that I have driven the Blazer for a day, I'll recheck the voltage and if it is still low I'll have the battery checked. The .3 difference on the low end of the battery shouldn't have the resulting effect of the 8.5 on the fuel pump which was the original problem.

Quote:

Originally Posted by BlazerLT

Sorry guys, 12.5volts is low for ANY battery.

I don't care if it cranks, a properly charged battery should be 12.8-13.6volts.

97blazermadness · #12 01-17-2005, 11:40 AM

Hey guys,

After some additional troubleshooting, it was found that indeed my fuel pump crashed. Electrical was all ok, good signal to the pump but it would not kick on.

Removed and cleaned gas tank, tested new pump, installed pump in gas tank, put everything back together and replaced the fuel filter.

I turn the key to "on" the pump fires for 2 seconds and shuts off -- sweet sound -- go to start the car and it fires right up!!!!

And as an added bonus, the gas gauge appears to be working correctly!

Thanks for all of your helpful replies everyone!

chevycruizer · #13 01-17-2005, 03:41 PM

i want to read the string "12.5v" i did a search here in Blazer and i did not find it. can you post a link or possibly be more specific on its location? i also have a 97 that has the gas guage problem along with other electrical problems. I have found if i jiggle the ignition key i can make most of them disappear. here is one - while driving the ABS light comes on and the fan blower motor cuts out. just a little jiggle and everything is fine. odviously i have the ignition swith problem. i just need some time to fix it. my main problem is hard starting. sometimes i really need to crank over the engine before it will start. it seems to take longer when it is warm. when it finally starts it pumps out some black smoke. overly rich condition i know. then it clears up and the thing runs like it is new. i ocassionally get a p0300 "random cylinder misfire" i did a tune up and i still get the same results. plug numbers 3 and 6 were fouled (really black) i am hooking up a fuel pressure guage today and i will drive around with it taped to the windshield. but i suspect the fuel injector poppets are sticking.

BlazerLT · #14 01-17-2005, 04:24 PM

Sounds like the sending unit and fuel pump has gone bad.

chevycruizer · #15 02-27-2005, 01:04 AM

well it took me two months, but it was my fuel pressure regulator. it has a pin hole leak in it and it was bumping fuel down the back of the engine. I has a typo earlier it was numbers 5 and 6. The regulaor sits right on top of them. Ans yes my ignition switch was bad. i replaced it a month ago and have not had one electrical gremlin since then. i still need to do the fuel pump - sending unit. the gas guage is all over the place although the pressure is right where it should be.

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