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Re: Fuel Pump Diagnosis '93 Dakota....... [Re: IMGTX] #2941390
07/08/21 10:23 PM
07/08/21 10:23 PM
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Between Houston & Galveston TX
Satilite73 Offline OP
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Security system? It's a '93 Dakota, it's its own security system... laugh2 (I know what you meant, the thought of a security system on a '93 Dak made me chuckle). Back when I worked at a used car lot, I had to deal with no-start issues due to added on alarms. I appreciate the comment. Oh, I'm grounding to the chassis.

Can someone tell me how to properly hot wire the pump? It has five pins, the middle one is where I found 8 volts. How do I ground it?

I appreciate the comments and am taking notes. I won't be able to get back over to it until this weekend.


That is a simple truck to diagnose and repair. Sorry, unless its a system pretty basic like my wagon, electrical kicks my butt. I'm not scared of it, I just don't know how to correctly trouble shoot something with a computer. frowwn

[Linked Image]


John

Imagine a '73 Satellite Wagon picture here. 😁
Re: Fuel Pump Diagnosis '93 Dakota....... [Re: Satilite73] #2941396
07/08/21 10:54 PM
07/08/21 10:54 PM
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Dcuda69 Offline
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2 second Google search. Looks like the dark green/black wire should see 12 volts key on(2 second prime)/engine cranking.

https://easyautodiagnostics.com/chrysler/5.2L-5.9L/fuel-pump-circuit-diagram-1

Re: Fuel Pump Diagnosis '93 Dakota....... [Re: Dcuda69] #2941409
07/09/21 12:02 AM
07/09/21 12:02 AM
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Satilite73 Offline OP
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2 second Google search.

I must've used the wrong combination or something, because I did look before starting this thread, and didn't come across that.

beer

WAIT A MINUTE!!! According to the page you posted, the relay gets power from the fuse box from fuse 16. That is the same fuse that powers the OD switch, which I've been having problems with.

Coincidence? What does this tell you?


John

Imagine a '73 Satellite Wagon picture here. 😁
Re: Fuel Pump Diagnosis '93 Dakota....... [Re: Satilite73] #2941528
07/09/21 02:11 PM
07/09/21 02:11 PM
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moparx Offline
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"everything is connected to everything else"...........coincidence ? hmmm...... work
or as my old man liked to say : "what a co-inky-dink".......... laugh2

you may have stumbled on to a solution to two problems. now to find out where the issue is presenting itself in the harness.
beer

Re: Fuel Pump Diagnosis '93 Dakota....... [Re: moparx] #2941680
07/09/21 10:14 PM
07/09/21 10:14 PM
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rhad Offline
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when i was having trouble with my 92 dakota i spliced in a long wire to the hot wire at the fuelpump,then ran it up to the battery,touch the wire to the battery and you can hear the pump run


my ladder of success is missing some rungs
Re: Fuel Pump Diagnosis '93 Dakota....... [Re: rhad] #2941737
07/10/21 09:55 AM
07/10/21 09:55 AM
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WAIT A MINUTE!!! According to the page you posted, the relay gets power from the fuse box from fuse 16. That is the same fuse that powers the OD switch, which I've been having problems with.

Make sure you have constant power there before testing(after the fuse).
This is only to power the coil for the relay, After "jumping" it you need to make sure you have power at terminal "D" of the relay. This is what gives the pump power.

Re: Fuel Pump Diagnosis '93 Dakota....... [Re: Moparite] #2941949
07/11/21 01:17 AM
07/11/21 01:17 AM
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When I field tested mine, I hooked 12 volts from the battery to the female terminal at the relay that feeds the fuel pump. It will either run, or it won't, it doesn't need power very long to determine if the problem is with the pump or not. Doing this eliminates everything between the battery and the pump except the immediate wire to the pump, the pump itself, and the pump ground wire. Once you determine which wire powers the pump, you can also power the pump right at the pump if need be, but you would also probably have to provide a ground for the pump as well.
If the pump runs when 12 volts is applied in place of the relay, then the issue is before the relay, probably the wire splice discussed before. Gene

Re: Fuel Pump Diagnosis '93 Dakota....... [Re: poorboy] #2942165
07/11/21 09:43 PM
07/11/21 09:43 PM
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Satilite73 Offline OP
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Finally got over there this afternoon. eyes

Was able to confirm a few things, but she's still not a runner.

Using starting fluid, she DOES run, albeit briefly.

I was able to figure out how to hotwire the pump and found BOTH pumps work. (Meh, not upset, I don't know when it was last replaced)

Where I had a voltage reading at the tank, was actually voltage for the fuel gauge.

Looking at the diagram Dcuda69 provided, I'm getting voltage everywhere I should be EXCEPT at the pump. At the pump I've got nothing. confused

And that's where I ran out of time. mad

I need to look more closely for the wires Gene is referring to. I don't have any wires that pass directly under the battery. I have a harness that passes in front of the battery that I thought was for the lights, horn, etc.


John

Imagine a '73 Satellite Wagon picture here. 😁
Re: Fuel Pump Diagnosis '93 Dakota....... [Re: Satilite73] #2944637
07/18/21 07:43 PM
07/18/21 07:43 PM
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Satilite73 Offline OP
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Question:

If I jump the fuel pump at the relay (with the relay in) to make the pump run, should it start while hot wired like this?


John

Imagine a '73 Satellite Wagon picture here. 😁
Re: Fuel Pump Diagnosis '93 Dakota....... [Re: Satilite73] #2944691
07/18/21 09:56 PM
07/18/21 09:56 PM
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Originally Posted by Satilite73


Question:

If I jump the fuel pump at the relay (with the relay in) to make the pump run, should it start while hot wired like this?


Just a long shot, all the relays in the under the hood box use the same relays. Did you try swapping the fuel pump relay for a different one (like the one for the wipers for instance, one you know works)? Maybe you just have a bad relay?

An answer to your question: Yes, as long as the relay has 12 volts to it, and the wire that feeds the pump is good. Usually, its the wire that supplies the 12 volts to the relay that fails, but I've also seen the feed wire to the pump fail.

If you have 12 volts coming into the relay: Remove the relay, run a jumper wire (make one about 3" long with two male spade terminals on it). Put one end of the jumper wire into the slot for the 12 volt power supply on the relay, and put the other end into the [censored] that the wire goes back to the pump. You should be able to hear the pump run. If the pump runs, the truck should start. You can drive the truck that way, but you will need to disconnect the jumper wire to turn off the fuel pump. If the pump does not run (since we know its good), the wire is broken somewhere between the terminal and the fuel pump. If you are really fed up with the whole deal, you can get under the under hood fuse box, and find that wire that goes to the pump from the relay, and run a whole new wire back to the fuel pump.

If you do not have 12 volts to the relay: Your truck has the under hood fuse & relay panel, there is a bundle of wires that go into that box. Follow them down to where the bundle splits. From memory (we know how that works right?), the bad wire splice is in the bundle of wires that turns back towards the firewall, about 6" or so from the bundle split, towards the firewall. Some of the wire bundles are warped in the non-sticky friction tape, and some are in the black plastic wire loom stuff. You are going to have to undo what ever is covering the wires to find the splice. A sharp razer knife will cut through the tape, but be careful not to damage the wires in the process of cutting the tape. Usually unwrapping the friction tape is a royal pain. I usually just cut the tape with a slot running along the length of the wires and peal it off like a banana skin. Your local auto parts store should have a roll of Friction tape, the last roll I bought was under $5 and it goes a long ways. Once the wire repair is complete, you just wrap the wire bundle back up with the new friction tape.

Your issue has to be one of these two things, provided the wire connection at the pump is good.

Last edited by poorboy; 07/18/21 10:04 PM.
Re: Fuel Pump Diagnosis '93 Dakota....... [Re: poorboy] #2944694
07/18/21 10:13 PM
07/18/21 10:13 PM
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Satilite73 Offline OP
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Thanks Gene for the input, greatly appreciated.

Now, the reason for my question.

With the pump jumped as I stated above, the pump is running, but the truck will not start. Just cranks. (yes fuel is getting to the rails)

BUT, whether the jump wire is hooked up or not, spray starting fluid down the TB, and it tries to start just on the starting fluid.

I unwrapped the harness from the relays back to under the washer bottle, all factory splices look good, no corrosion or loose wires. I don't want to redo all the factory splices at this point just for a slim maybe.

*sigh*


John

Imagine a '73 Satellite Wagon picture here. 😁
Re: Fuel Pump Diagnosis '93 Dakota....... [Re: Satilite73] #2944695
07/18/21 10:15 PM
07/18/21 10:15 PM
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Sniper Online content
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Originally Posted by Satilite73

Thanks Gene for the input, greatly appreciated.

Now, the reason for my question.

With the pump jumped as I stated above, the pump is running, but the truck will not start. Just cranks. (yes fuel is getting to the rails)

BUT, whether the jump wire is hooked up or not, spray starting fluid down the TB, and it tries to start just on the starting fluid.

I unwrapped the harness from the relays back to under the washer bottle, all factory splices look good, no corrosion or loose wires. I don't want to redo all the factory splices at this point just for a slim maybe.

*sigh*


the injectors are fed a switched 12v, switched by a relay turned on when the key is in run. The computer will pulse the ground to fire the injectors. Back probe your injectors with the key in run and see if they are getting 12v. I am thinking the 12v that feeds the fuel pump relay is also the same 12v that feeds the injector relay.

Re: Fuel Pump Diagnosis '93 Dakota....... [Re: Sniper] #2944698
07/18/21 10:37 PM
07/18/21 10:37 PM
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Satilite73 Offline OP
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I am thinking the 12v that feeds the fuel pump relay is also the same 12v that feeds the injector relay.

You are correct. Fuel Injector Circuit

I will check that next trip over.


John

Imagine a '73 Satellite Wagon picture here. 😁
Re: Fuel Pump Diagnosis '93 Dakota....... [Re: Satilite73] #2944701
07/18/21 10:55 PM
07/18/21 10:55 PM
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Dude I feel sorry for you but it is a easy problem. Mouth shut so I do not hurt the sensitive.

Re: Fuel Pump Diagnosis '93 Dakota....... [Re: NITROUSN] #2944709
07/18/21 11:08 PM
07/18/21 11:08 PM
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Satilite73 Offline OP
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Originally Posted by NITROUSN
Dude I feel sorry for you but it is a easy problem. Mouth shut so I do not hurt the sensitive.


Send me a PM then. I'm trying to learn. You won't hurt my feelings.


John

Imagine a '73 Satellite Wagon picture here. 😁
Re: Fuel Pump Diagnosis '93 Dakota.......next question [Re: Satilite73] #2944775
07/19/21 10:01 AM
07/19/21 10:01 AM
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Re: Fuel Pump Diagnosis '93 Dakota.......next question [Re: NITROUSN] #2945839
07/21/21 10:14 PM
07/21/21 10:14 PM
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garnett kansas
rhad Offline
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just use a noid light on the injectors,it will tell you if they are getting the juice and ground they need!!,auto parts store might have a set cheap,only need i noid for a test!!


my ladder of success is missing some rungs
Re: Fuel Pump Diagnosis '93 Dakota.......next question [Re: rhad] #2945864
07/21/21 11:35 PM
07/21/21 11:35 PM
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Satilite73 Offline OP
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Truck is 11 miles away not here with me, so I can't just run out and try suggestions.

Next trip over I'm going to look more closely at the harness. In my frustration, I'm probably overlooking something right in front of my face.

As usual, I'll report my findings.

beer


John

Imagine a '73 Satellite Wagon picture here. 😁
Re: Fuel Pump Diagnosis '93 Dakota.......next question [Re: Satilite73] #2946838
07/25/21 12:20 AM
07/25/21 12:20 AM
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Satilite73 Offline OP
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Well, I got it running, but I don't have it fixed. realmad

Unwrapped the harness the full length of the fender. Every factory splice I came across was free of corrosion and not broken.

I figured out that if I ground the blue with yellow tracer wire the pump comes on and the truck will start/turn off with the key (pump remains on though). If I disconnect this ground while its running, truck shuts off immediately. Looking at the diagram provided earlier, the blue with yellow goes back to the ASD relay then on to the ECM. I tried a different relay, with no difference.



(On a side note, this thing hasn't run since May, and it fired up immediately tonite. Kinda surprised me how quick it fired up)

Am I possibly looking at a bad ECM?

confused


John

Imagine a '73 Satellite Wagon picture here. 😁
Re: Fuel Pump Diagnosis '93 Dakota.......next question [Re: Satilite73] #2946875
07/25/21 09:32 AM
07/25/21 09:32 AM
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I have never work on gas motor trucks but the diesels fail the wire between the asd and the pcm...
It will test good with a light but cannot carry any load. I would load test from ecm pin 51 and C on the asd, and also load test at terminal A of the asd. You can make a load tester out of an old headlight and socket, one filament is about 4 amps, both filaments is about 9. Make sure it will light both coming from the ignition switch, jumper the control side of the asd, and test it at pin 51. To not spread misinformation, diesels almost never fail the blue/yellow, they fail the green/black, pin2 to the asd, and get that wonderful no start, no buss message. You need to load test, as I know a lot of diesel guys that now own 2 good pcm/ecm because they will not listen. I will add I had a friend that had a 93 Dakota brand new that would strand him all the time, no pump, dealer installed 2 fuel pumps, the fix was a new loom back to the pump, but I do not know all the exact details, maybe a hero tech cut it.

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