Fuel Pump Not Priming

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boy&hisdogs

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After my injectors getting worse and worse until they finally gave out, then the truck sitting for months waiting on backordered parts and a million little issues while installing, I finally got the new injectors in and the engine buttoned up. Now the fuel pump won't come on.

After the truck was involuntarily parked, I was still able to run the fuel pump to prime the lines while I tested the injectors, so I know it was working fine then. Then a couple weeks later (truck sitting, battery getting low) I went to try it just to see if the truck had changed it's mind. I remember thinking out loud to my wife and saying "I can't hear the fuel pump..." and then left it at that since we had somewhere to go at the time. Fast foreword to now, I got a plug-in battery tender/charger and replaced the spider. The battery tender only charged it to about 10v (according to the dash gauge) and said it was "full". I'm going to try it again today, see if I can get it to top off the rest of the way but when I went to prime it, the pump never came on even though there was plenty of power to crank the starter.

I replaced the relay and nothing changed. Is there some kind of safety cutoff that I need to override since it was sitting with little to no fuel in the lines for a while? Where should I start sticking my multimeter?
 

Keeper

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CEL on? I would check for codes first before getting on top of that tank.

Someone will correct me if this is wrong, but I seem to recall the fuel pump not priming when my crankshaft sensor was going out. Engine would randomly die while out driving... it would crank, but not restart and I heard no fuel pump. Then later I could hear pump and it would start, then it wouldn't... you get the idea. This was also after a long sit. I clearly remember it because I was mentally prepared to do the whole fuel pump/harness replacement again, but it ended up just being a sensor... and an easy one at that.
 

boy&hisdogs

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CEL on? I would check for codes first before getting on top of that tank.

Someone will correct me if this is wrong, but I seem to recall the fuel pump not priming when my crankshaft sensor was going out. Engine would randomly die while out driving... it would crank, but not restart and I heard no fuel pump. Then later I could hear pump and it would start, then it wouldn't... you get the idea. This was also after a long sit. I clearly remember it because I was mentally prepared to do the whole fuel pump/harness replacement again, but it ended up just being a sensor... and an easy one at that.
In addition to my injector problems I was also having these same problems as you, and lots of weird misfires. I tested the injectors individually and one was completely dead and a couple weren't spraying consistently, so that was definitely a problem, but there's no guarantee it was the only problem. I went and tried to scan the truck but I think it had been dead too long because there were no stored codes, but for $50 from Amazon it's worth just swapping it anyway.

Did you have to drain the oil before you changed the sensor?
 

east302

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There should be a connector between the master cylinder and hood hinge that will let you run the pump. It’s a single wire with a connector on the end, put 12V to it and see if it runs.

By the way, is the oil pressure sensor plugged in and not damaged? ECM-B fuse is good?

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SUBURBAN5

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There should be a connector between the master cylinder and hood hinge that will let you run the pump. It’s a single wire with a connector on the end, put 12V to it and see if it runs.

By the way, is the oil pressure sensor plugged in and not damaged? ECM-B fuse is good?

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If memory serves right the connector is a white female flat plug. What is the best way to run power? Wire from battery to a single male flat prong?
 

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1. There is no "safety" switch to be reset.

2. The pump should prime for two seconds when the key is turned from "Off" to "Run". Some TBI applications run the pump longer--20 seconds or so. But all applications prime the pump for at least two seconds.

3. Sometimes the fuel pump test connector is integrated into the ALDL connector. Varies with model year and vehicle. But SOMEWHERE there's a fuel pump test connector. If you apply battery power, the pump should run.

4. EXCEPT FOR PRIMING, the pump won't run if the ECM doesn't receive an "engine cranking/running" signal from the sensors. With TBI, the signal comes from the pickup coil, via the ignition module. With Vortec, it comes from the crankshaft sensor. In either case, if the wire harness is damaged, the sensor can be good but still not supply a signal to the ECM.
 

boy&hisdogs

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Got the new sensor but may have dun goofed. It was sticking so I gave it a little wiggle and it came out... at least half of it did. The head is still stuck in the hole. o_O

Any ideas? Put a screw in it and slide hammer it out? Could I reach it if I drop the oil pan?
 

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Crank sensor?

You might be able to pull it out with a screw and slide-hammer. Access to the sensor for the slide-hammer is going to suck.

Might wind up pulling the timing cover off.
 

boy&hisdogs

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Enough of a lip was left that I was able to pry it out. Still no fuel pump and no start though with the new one installed. I'm going to look for that fuel pump test connector you guys have been talking about.

Edit: I have power TO the relay, but jumping the relay gives me nothing, not even with the test light.
 
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boy&hisdogs

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There should be a connector between the master cylinder and hood hinge that will let you run the pump. It’s a single wire with a connector on the end, put 12V to it and see if it runs.

By the way, is the oil pressure sensor plugged in and not damaged? ECM-B fuse is good?

The ecm B fuse and oil pressure sensor both look good, and I think I found the connector you are talking about. Is it this? If so, I tried to jump it and got nothing, didn't run the fuel pump and didn't light my test light.

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