I don't know what to do and I'm hoping you guys could help. I have a 94 jimmy. I installed a brand new delphi fuel pump just 3 months ago. I did it myself with my dad and my boyfriend. My dad is a mechanic. The truck ran fantastically until yesterday when it just gave out on me without any warning while I was driving down the road. It stalled very quickly and quietly, no sputtering or anything and so my boyfriend and I pulled over and called AAA. We have had distributor problems before in our other blazer, once for the cap and rotor, and once the distributor itself went. Both times felt exactly like what my truck had just done and so we thought this was what had happened, or at least something else electrical.

I live in Ct and my boyfriend lives in Mass. We were just leaving his town to go to ct and I live too far away to have it towed home for my dad so we got it towed to the shop that my boyfriend used to work at. The owner said to my complete surprise that he checked everything and that it's the fuel pump. There is zero fuel pressure and the relay is fine. Something seems wrong to me. Has anyone had a brand new pump just die like this? I read articles on here warning against using anything but delco or delphi, which is why I bought the delphi in the first place. Could it be the fuel pump fuse or the spider? The spider is also new but I figured I'd ask.
My confusion is because of the fact that when I realized I needed a fuel pump the first time it would be very difficult to start the truck but once it was started it would get you where you wanted to go and never stall. This just completely disabled the truck with no warning whatsoever. I wonder if there are any other possibilities? I'd like to think of any other thing it could possibly be before I let the guy tear into and replace my brand new fuel pump. This whole experience is really discouraging...
Also does anyone know what delphi's warranty is? I'm hoping they'll send me a new one if the pump really did go.
Thanks,
Melissa

 

Did you lose anything electrical when it died, like gauges or interior lights or did the truck just die?

 

The truck is an electrical mess, which is why I automatically assumed it was something electrical. It just quietly stalled out and died. I don't have any interior lights to begin with which is a whole other story so I don't know, but it stalled out so I lost everything as soon as it happened, (power steering, brakes, etc.) I don't know if this helps but almost none of my gauges work. The gas gauge always reads 3/4 after filling it. I figured when I put the new pump in it would be fixed, but this was not the case. I decided that it was probably a ground problem rather than the brand new sending unit...I am not good with electrical problems so I have no idea.

 

Just a thought, since a guy on the Astro forum just had this same issue; it could be the plugin on the firewall (behind the battery on an Astro, but I can't remember where on a Blazer/Bravada). Ended up being loose and causing an intermittent no start/stall issue.

 

check if you got power going to the sending unit wires with a test light

 

Thanks for the ideas. I will ask about power to the sending unit in the morning. I really suspect that something electrical has something to do with this. Also Leeann, I don't have any idea where that plug is on blazers either. I wish I did. Do you know what the plug in does?

 

Might not help, but I will tell about it, a few years back the 1st fuel pump that went out on me had been replaced just a short time. My mileage was plus 100,000.

The wife and I was out riding around in the backwoods, miles from everyone, in the middle of a game & fish wildlife reserve, late afternoon, night time approaching very fast. Easing along a dirt road, Blazer went dead.

I stated to wife, "Blazer just died," we were still coasting, she replies, "No, we are still going," I replied quickly, "No we are coasting," she quickly looked at the dash and said, "The engine's dead!"

Of course I said, "Isn't that what I just said?" She did appreciated that the least bit.

Like many others I had just filled up my gas tank about 30 miles back, when going into the back woods I always life a full tank of gas.

No cell phone coverage, finally we walked to a top of a hill and barley had cell phone coverage. My son-in-law happened to be fairly close to us and came and pulled my blazer to my house about 80 miles away.

Bad ground, behind the gas tank. the ground wire to the frame was just a tad lose, tightens it, all was well. But I did take the bolt out, cleaned off the ground wire and frame were it bolted to be sure it was a good ground.

 

When you turn the key to the "ON" position the fuel pump should cycle for about 2 seconds to pressurize the system. Depending on several things like amount of fuel in the tank and stuff in the truck you should be able to hear the pump cycle but you could always have someone put an ear next to the tank as you turn the key. If you get nothing from the start up cycle there is a bypass jumper for the fuel pump.

On this post you'll see that pin "G" on the OBD1 port is used to bypass the relay and direct connect the fuel pump to 12v.
https://blazerforum.com/forum/1st-ge...-blazer-58972/

Of course this all assumes you do have a working electrical system. If you find a jumper from the battery to pin G starts the fuel pump it doesn't mean the relay is the cause. It might also mean there is no power getting to the relay, but if using a jumper get's the truck running I suggest driving it home as soon as possible and then start to troubleshoot the problem. On a side note, you might want to have an inline fuse with your jumper wire. You should be able to find out with a search what amp fuse to use.

I really don't know what could be causing your problem, but with that said there is one possible condition that could cause the fuel pump relay to stop operating. If oil pressure reaches a low threshold the relay will shutoff the fuel pump. This is a safety feature built into the relay that assumes if the oil pressure becomes low you have crashed the truck and really don't want fuel dumping on the highway. There might be a problem with that circuit.

 

Thanks for the info guys. I'm definitely going to check the ground and check for possible issues there. I am very used to hearing the pump cycle before I turn the truck on and it definitely is not doing it when you turn the key. I had heard about the low oil pressure causing the pump to shut off. What could cause this? I just changed my oil a week or 2 ago so I know the oil level isn't low. Thanks for your help. I'll also look into trying to jump the pump.

 

The first thing I would do is jump the pump to test it. If it runs while jumped then the pump should be OK. If the pump checks out then test the relay next. If that checks out then proceed to checking the oil pressure switch. If both the relay and oil pressure switch are working properly then check the pump ground on the frame rail behind the gas tank.

I will add this caveat: I recently replaced the fuel pump in my '94 Blazer with the Airtex pump from my wrecked '94 Jimmy. The Blazer pump would randomly and intermittently not come on for periods of up to a half hour. Since I put the Airtex pump in it hasn't failed to start for over a month. I may be the only person with a working Airtex pump. I hope it stays that way. While I was testing the stock pump in the Blazer I would frequently get perfect readings when I jumped it. It took a full six hours of testing the pump to finally get a no-run condition to occur. When that happened I was able to verify that the pump was not working even when jumped. I made up a special jumper wire for testing purposes that included an alligator clip for the battery terminal, a switch, a 10A fuse and a blade terminal for the pump test lead end. You don't have to be as fancy but I found it very useful.