Hi,

Here's my deal.... About 4 years ago I replaced the fuel pump, with a new delco pump. Till yesterday everything was fine, on the way home from work the truck died on the freeway. Once home I checked the fuel pressure and it reads zero. I can't hear the pump with the key on and I did a voltage test at the pump connector and have power. Sounds to me the pump is bad, but I have a few questions for you experts.

First is there an Ohm reading I can use to check the pump at the connector?

The connector is intact but shows some corrosion, could this be an issue leading to pump failure?

Last, when I did a volt reading on the connector it reads roughly 9 volts, is this right for the key on?

I should mention, I did jump the pump with 12v from the battery and still nothing.

 

I'm guessing you should have 12v to the pump, not 9.
Also you could try hitting the gas tank with a big rubber mallet while someone cranks the engine for you. If it jars the pump on, replace it....if not, technically you could bench test your pump...but it's a pain.

 

There isnt a resistance/ohm check i know of other than continuity to see if its just an open circuit/no connection, if there is no continuity you need to drop the tank and investigate further, or did you already? Could be a wire inside the tank?
You should have 12 volts or actually, whatever battery voltage is. If the battery only has 9 volts then did the alternator possibly die? Or do you have a bad ground, need to check all major electrical connections and verify 12 volts in the fuse panel and other places. Also check the fuel pump relay, corrosion and carbon on those contacts can cause low voltage too.

The connector should be replaced or cleaned very well if there is corrosion, once it has started its nearly impossible to stop, it will only get worse. I suppose it could cause failure, usually high resistance causes heat and you would see melting or charring in the connector if that was the problem, resistance means that it would not be allowing enough current to flow through the pump which wouldn't overload it but sometimes, undercurrent situations are bad too, if there isnt enough current to initially kick the motor to start the spinning it will sit on one set of contacts on the commutator and possibly overheat and fry the brushes or some windings in the motor, this would be less likely with your situation though because you were driving so it was already spinning and stopped abruptly, but that could have been the moment when the corrosion was just too much and all current stopped too.

Anyway, First you need to get 12 volts to the pump

Corrosion is bad, fuel pumps demand more current than most things on the vehicle and corrosion stops current flow.

Hope this helps
Good luck!

 

Update:

After a few more electrical tests my conclusion is the 9 volt condition is a result of low cracking amps from the battery. Most likely I need a new battery to fix this problem, but the condition of a dead fuel pump is still present. Just to make sure I did check of the fuel pump relay, here are my results. (See image one)



Orange wire to the relay should show 12v with the key in the on position. The grey wire to the pump connector is going to show 12v when the ECM toggles the relay. One way to check continuity to the pump connector is jumper the orange and grey wire, which I have. From the diagram you can see the oil pressure switch is in-line with the grey wire. I am sure this is a fail-safe to shutdown the fuel pump if there is a catastrophic drop in oil pressure. So that would lead to the ECM only applying voltage to the relay long enough for the oil pressure switch to take command of the fuel pump. I have to admit, the oil pressure switch is the last check I need to make, but I know for a fact there is line voltage to the pump during cracking and the dipstick is showing full oil so this would most likely mean the oil pressure switch is still operational.

Now on to my rant....

About four years ago I bought a supposed Ac/delco pump off of Ebay, which at the time was roughly sixty bucks. It came with filter, o-ring, wire connecter and clamps to replace the existing pump. Not knowing any better I assumed this was the real deal, which it might be but after buying a pump from a local parts dealer, Autozone, I wonder if this pump from Ebay isn’t a spin-off. The pump from Autozone ran me about eighty bucks and the filter was another ten bucks. Sure I know Ebay sales don’t have the over-head like a brick store but I noticed a few differences in the pumps.

I am going to digress a bit....

I went to my local pick and pull to get the drop assembly, buying it new seemed outrageous since Pick and pull charges roughly thirty four bucks for the assembly with pump. So, now I have the pump from Ebay, the pump from Pick and pull (which I am sure is the stock pump), and the new pump from Autozone. (See images 2 and 3) As you can see there are some differences in the stock pump and the Ebay pump. (Image 2) You can see the three pumps, (left to right) pump #1 is the Ebay pump, pump #2 the stock pump pulled from Pick and pull, pump #3 is the Ac/delco pump from Autozone. If you look closely you can see the Ebay pump has a slightly different housing than the other two.



(Image 3) If you look at the pick-up orifice you can see there are some differences. The pump in the eleven o’clock is the Autozone, the pump in the four o’clock is Ebay and the last is the assumed stock pump.



What really got my goat was I found metal shavings in the tank and in the pick-up sock. Still for the life of me I can’t figure out why there are shavings in the tank, even if the pump was spitting out metal you would think the fuel filter would have trapped them on the return to the tank.

This is for any 92 owners out there:

The connecting hose between the hard fill and tank is a different size from next year models. When I was at the Pick and pull I grabbed the rubber hose from the hard fill to tank, mine was leaking. Got back home to find out there is a size difference. (see image 4) The shorter (top) is from a 93 blazer, the middle is from my 92 and the last is new from Napa. I spent seven bucks on that hose at Pick and pull to find out it didn’t fit. Napa charges twenty one bucks for one foot of two inch hose.



Final thoughts:

FYI - at the rear connector, grey is pump and purple is gauge. Check these respective to using frame as ground.
As most know dropping the tank is a pain, always make sure you are using the best part money can buy~

 

Closing the Garage door:

The truck is back on the road, three days later.... This included one day of parts pricing. one day of Pick and pull with parts cleaning and painting. Last day installing parts. Without doubt the fuel pump failed but I am left with lingering questions. I have to assume the pump I bought from Ebay was either a spin-off or a pump authorized by Ac/Delco for resale. Never the less, the real issue now is why I found metal shavings in the fuel tank. The shaving sized ranged from a milometer to fine powdery dust. I have to assume the fuel filter would have caught these partials before they would have returned to the tank. So now I am faced with the thought of vandalism, there is someone who would fit the profile. I don’t want to go down this road so I am willing to take advisement from this community on reasons why there would be metal shavings in the tank. One thought I have is the rushed gas attended jamming the gas nozzle into the hard fill?

 

Glad you got it fixed. As for the previous pump, ac delco would not authorize a spinoff pump to be sold under their name.
Getting parts like that on ebay is risky, a lot of people put aftermarket crap in delco boxes ect.