Fuel pump replacement

gmbwrenchn · #1 02-19-2007, 09:45 PM

97 Blazer LT 4x4. 135k miles. 4.3 Ltr. Just went outside {temp is 40*} to start her up. Nothing. She turned over with plenty of power. Have had no prior problems. I cannot hear the fuel pump like I usually can when I turn on the key. Checked fuses. All good. Anything else to check? Can the fuel pump relay switch go bad? How can I test that? Any words of wisdom on dropping the tank and replacing the pump? Also could someone tell me which one is the correct one to order on RockAuto.com? That's where I want to get it. Thanks much. GB

mike2004tct · #2 02-20-2007, 07:50 AM

Quote:

Originally Posted by gmbwrenchn

97 Blazer LT 4x4. 135k miles. 4.3 Ltr. Just went outside {temp is 40*} to start her up. Nothing. She turned over with plenty of power. Have had no prior problems. I cannot hear the fuel pump like I usually can when I turn on the key. Checked fuses. All good. Anything else to check? Can the fuel pump relay switch go bad? How can I test that? Any words of wisdom on dropping the tank and replacing the pump? Also could someone tell me which one is the correct one to order on RockAuto.com? That's where I want to get it. Thanks much. GB

First thing to check is to make sure it's not the ignition switch gone bad (a common problem on 97s).
Next, on the driver side fender/firewall area, you should find a RED wire with a fast-on terminal sticking out of a wire harness. This is the 12V HOT wire for the fuel pump. Putting 12V from the battery positive should run the pump ( This didn't work on mine, but it's worth a try).
The fuel pump relay is inside the glove box behind a plastic panel. There are 3 relays in there. swap them to see if it's a relay problem.

You can search for both "Ignition switch" and "fuel pump replacement" in this forum group and find many posts related to these problems.

If you do buy a new pump, the only difference in pump styles depends on whether the truck is a 2 door or four door. Whatever you do, DO NOT get a pump for an S10 pick-up. The tanks are different on all 3 models, so the pump assembly height and sending unit arm lengths are different.

lynndiwagon · #3 02-20-2007, 09:54 AM

Just got through replacing the fuel pump on my Son in Laws 2000 Jimmy, four door. The job is not to bad, just time consuming, took about 4 1/2 hours. I did it in 40 degree weather out in the dirt driveway because he doesn't have a garage. It is a two person job IMO. One piece of advice would be to take the spare tire off. This gives you good access to the fuel lines and wiring plugs going to the pump. Be sure and use jack stands under the vehicle, and have a good floor jack handy.
Good Luck

Lynn Wagoner
Yukon, OK

gmbwrenchn · #4 02-20-2007, 06:16 PM

Ok check this out. Went out to the Blazer today. Did the 12v red wire jump {ignition off} to the battery. Nothing. Then I went inside to turn the key to the on position and I could hear the fuel pump working. What the hell?

mike2004tct · #5 02-20-2007, 09:48 PM

Quote:

Originally Posted by gmbwrenchn

Ok check this out. Went out to the Blazer today. Did the 12v red wire jump {ignition off} to the battery. Nothing. Then I went inside to turn the key to the on position and I could hear the fuel pump working. What the hell?

I had a Carter pump fail after 13 months in my '97.
That's exactly what happened. It stopped running. The next day it would prime and start the truck. Turn the truck off, try to restart, no pump priming.

Could be your pump is on the way out. The 12V shock my have adjusted it's attitude.

gmbwrenchn · #6 02-20-2007, 10:15 PM

You don't think it may be an ignition problem? What would you do in this situation? Thanks for your opinion on this.

DelCoch · #7 02-21-2007, 02:33 AM

First order of business is to check the battery with a load type tester. AutoZone does it free. If the battery is just a little weak or a little down, it will still run the starter just fine, but the starter draws all the current away from the fuel pump and the pump can't reach the max pressure of 61+ for a cold start.

Do a search on this board and you can find several posts on trouble shooting fuel pumps.

Let us know what you find out.

mike2004tct · #8 02-21-2007, 07:29 AM

Quote:

Originally Posted by gmbwrenchn

You don't think it may be an ignition problem? What would you do in this situation? Thanks for your opinion on this.

Hard to say without seeing it. One thing I would try doing next time your pump doesn't prime or the truck won't start; Under the steering column, you should see a wire harness coming down to a junction block from the ignition switch. In that harnesss is a pinkish-red wire. Jiggle that wire vigorously with the ignition to "on", and if the pump starts to prime, you have a bad ignition switch.

I had the triple wammy,all at different times; Pump failed, Ignition switch failed, and EEM failed.
All three items had the same symptoms.

With the ignition switch, there's a lot of possible things that can go wrong.
With mine, the engine would turn over but not fire. I had no cluster lights and the gauges didn't work, fuel pump didn't prime, with the ignition switch to "on", I couldn't shift the truck out of the "park" position.

Regardless if this is your problem or not, I would suggest you change the switch/harness if it hasn't been replaced. Just a good insurance policy.

gmbwrenchn · #9 03-03-2007, 04:08 PM

Damn thing just did it again, week later. Now it's stuck ten miles away!!!!!!!! Could this still possibly be a relay problem? I'm towing it home and putting in the fuel pump. I've had it. I jiggled the pinkish red red that goes to the ignition......nothing happened. Tried to jump the red wire in the firewall.........nothing. First I'll do the relay thing though. Jumping that red wire on the firewall bypasses the ignition switch right? Then if that was the case it wouldn't be the ignition..?? Should I go with a Carter or a GM pump if I go with the pump.

mike2004tct · #10 03-03-2007, 04:48 PM

Quote:

Originally Posted by gmbwrenchn

Damn thing just did it again, week later. Now it's stuck ten miles away!!!!!!!! Could this still possibly be a relay problem? I'm towing it home and putting in the fuel pump. I've had it. I jiggled the pinkish red red that goes to the ignition......nothing happened. Tried to jump the red wire in the firewall.........nothing. First I'll do the relay thing though. Jumping that red wire on the firewall bypasses the ignition switch right? Then if that was the case it wouldn't be the ignition..?? Should I go with a Carter or a GM pump if I go with the pump.

See post #5.

Go with the Delphi part (ACDelco)

gmbwrenchn · #11 03-05-2007, 10:40 PM

Ordered up the AC Delco pump. Special order item so I'll have to wait a few days. Anything I should be aware of or watch before I drop the tank? There is about a half a tank of gas in there. Thanks.

n2dsky · #12 03-06-2007, 08:41 PM

Don't break the vent at the front - top of the tank. $16.00 from the my dealer! Just went thru this process. Try to reach over the front of the tank from the front to get to it. It will be about a 4 inch rubber tube bent in a "U". Drop the spare tire for head room and plan on it being a real pain! Other posts in this section have full description and some pix to look at. Good Luck!

mike2004tct · #13 03-07-2007, 07:50 AM

Quote:

Originally Posted by n2dsky

Don't break the vent at the front - top of the tank. $16.00 from the my dealer! Just went thru this process. Try to reach over the front of the tank from the front to get to it. It will be about a 4 inch rubber tube bent in a "U". Drop the spare tire for head room and plan on it being a real pain! Other posts in this section have full description and some pix to look at. Good Luck!

No such thing on a '97.

There's 3 lines on the top of the tank where it enters the pump assembly.
1 is a pry off vent line with a circular ring type retainer, the other 2 are pinch connectors that have 2 plastic arms protruding from the inlet of the hose. You pinch those arms towards/against the hose and pull the unit from the pump housing at the same time. 1 is 3/8" (return hose), the other is 5/16" (feed line). When you install the new pump, make sure you use new pinch connectors as they're plastic, and the old units will be stretched. I got mine at Napa for $2.50 for a box of 5 each.

Before removing the tank, you might try to get some of the gas out of it. Just remember, it's rather hard to get a siphon tube down the filler pipe as there's a ball valve in the tube that prevents gas from coming back up the tube, thus obstructing the siphon tube from entering the tank. I cut the rubber hose on mine that connects the filler tube to the tank so I could siphon off the tank (the rubber hose is only 6" long by 3-4" in diameter, and I couldn't get it off, so I cut it off)

I have a 2 door, so my spare tire wasn't mounted under the tank. If you have a 4 door, remove your spare tire, then remove the skid plate, then you'll be able to remove the two straps that hold the tank. Before removing the straps, disconnect the filler tube from the quarter panel such that it will slide out when you lower the tank. There should also be a ground strap that's connected from the filler tube to the frame, remove that also. Jack the truck rearend up as high as possible (I removed the left rear tire so I could access everthing easier), and support it on stands (if you don't have a lift). I put my hydraulic jack under the tank with a board on the lift cup to support the tank while I removed the straps. I dropped the tank enough to enable my arm to reach up to the top of the tank to disconnect the 3 above mentioned hoses, plus the two electrical connectors that are on the pump housing. Be careful at this point, as the 3 hoses and 2 connector cables are not very long, and if you drop the tank too low, you might break something (like a gas line)
Once the hoses are disconnected, you can then lower the tank all the way. Once lowered, I then rotated the tank 90 to 180 degrees so that I could slide the tank and filler tube out from over the frame rail.
Good luck.

gmbwrenchn · #14 03-09-2007, 08:43 PM

Thanks for that info. Right now I am in the process of getting the 3 top hoses off of the fuel pump. Got the two hoses with the pinch connectors but I'm having a hell of a time with the center one. How do I go about removing that one?? The pry off one. Thanks.

mike2004tct · #15 03-09-2007, 09:41 PM

Quote:

Originally Posted by gmbwrenchn

Thanks for that info. Right now I am in the process of getting the 3 top hoses off of the fuel pump. Got the two hoses with the pinch connectors but I'm having a hell of a time with the center one. How do I go about removing that one?? The pry off one. Thanks.

If you can get your hand on it, try and twist it at an angle.

I used a flat bladed screw driver on mine. Inserted it inside the opening and twisted the connector off (it's semi-rigid plastic, so be careful not to break it.)

POST REPLY TO THIS THREAD