Is that the same relay from other pump that failed? If so get a new relay
CK5
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Black Betty - Formerly Blaze the Monster Machine
- Thread starter centexk5
- Start date
1984 K5 Project for Dad and kids
Nope. Replaced that with this one when I did the new pump. 40a instead of 30a.
Well not a heat soaked relay. It pulled the same problem on me just now after driving it around and I jumped the pins again and no pump.
I’m really perplexed here. The tank is cool to the touch even right next to the exhaust pipes. Could it be my ground? It’s bolted to the body and I sanded it down to bare metal. Wouldn’t make sense about the heat though. I’m at a total loss.
I made an 8 mile round trip and it ran great. Idled good. Ran right up to red line no issues. Computer was pulling fuel and AFR’s were in the 13’s. It wasn’t lacking or starving for fuel like I’ve seen it do in the past when the pump was losing pressure.
I made an 8 mile round trip and it ran great. Idled good. Ran right up to red line no issues. Computer was pulling fuel and AFR’s were in the 13’s. It wasn’t lacking or starving for fuel like I’ve seen it do in the past when the pump was losing pressure.
The ground should be bolted to the frame, not the body.
It sounds to me like a bad connection somewhere.
It sounds to me like a bad connection somewhere.
Just went and tried it. Been sitting for an hour. Nada.
I’ll try that next cause I’m scraping for ideas.
Intermittent open
At least it’s home again.
Outside of moving the ground, any other thoughts? Should I upgrade the gauge of wire? The wires coming from the pump hanger are probably 18-20ga. Wire from the relay to the pump is 12ga.
Test the pump at the sending unit plug, and test the pump itself if needed.
If the pump is good, there is a bad, intermittent connection somewhere. 12 awg wire is plenty for that pump.
If the pump is good, there is a bad, intermittent connection somewhere. 12 awg wire is plenty for that pump.
Went outside this morning to try it. Pump kicked right on and truck fired right off.
Intermittent connections are the hardest to solve because they seem to work fine when you are actually ready to test them.
It's often not until you fix and duplicate the problem that you have found it.
I had a relay go bad once, because the relay terminals were not tight they lost there springy contact. This poor connection increases resistance there, where they contacted the relay, and that caused the relay to overheat, and then that made it worse, so the terminals themselves became loose and intermittent. I had to squeeze the terminal tighter with the pliers, then put everything back together with some dielectric grease. This was before I used weatherproof terminals for anything that isn't in the cab.
It's often not until you fix and duplicate the problem that you have found it.
I had a relay go bad once, because the relay terminals were not tight they lost there springy contact. This poor connection increases resistance there, where they contacted the relay, and that caused the relay to overheat, and then that made it worse, so the terminals themselves became loose and intermittent. I had to squeeze the terminal tighter with the pliers, then put everything back together with some dielectric grease. This was before I used weatherproof terminals for anything that isn't in the cab.
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So that was my original thinking was the relay was overheating and causing the scenario you described. I’m going to move the relay to inside the cab, swap the ground to the body, and then go for a drive and see what happens.
Fired it up for the first time since November today. Cranked and idled nicely. Forgot how good it sounded. After 2-3mins of idling I shut it off. Went to crank again and no fuel pump. I've eliminated the weather pack connector and soldered that connection and I've moved the ground to the frame. I've got 12v going all the way back to the fuel sending unit. I'm at a complete loss as to wtf is going on and at this point I think I'm going to just buy a new sending unit and see if maybe something is stupid inside of this one. I don't know what else it could possibly be.
Reason I'm leaning towards the sending unit as a potential culprit is I can't get the fuel level gauge to work. It's got power, is the correct ohms, it powers up, but no matter how I move the float arm, it never changes. I'm wondering if there's something wrong with the ground or the connection that once the fuel pump warms up, it can't overcome some level of resistance to make a complete connection.
I think the grounds for the sending unit are all exposed. You can see one of them at the top of your picture you took below.
Also, did you remember to hook up the external ground to the frame after you cut your access hole?
Also, did you remember to hook up the external ground to the frame after you cut your access hole?
Could the exposed grounds may be getting affected by sitting in the gas or are you thinking of something else?
If by external ground you mean the loose ground wire coming from the top of the sending unit then yes, that's the one I moved to the frame.
If by external ground you mean the loose ground wire coming from the top of the sending unit then yes, that's the one I moved to the frame.
I just meant you should be able to see them and ohm them out before replacing it.
Duh Tyler.
