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renix starts then dies

The starter relay supplies current to the fuel pump circuit (downstream of the ballast resistor) while cranking. The fuel pump relay supplies current (upstream of the ballast resistor) after the engine is running (and during cranking).

The fuel pump relay also supplies power to the injector drivers in the ECU.

I doubt replacing the relay is going to solve your problem, unless I misunderstood your issue.

IMO either the fuel pump relay is opening for whatever reason when you have to key in the run position, but is working in the start position. Or you have a wiring, splice (or connector) problem between the fuel pump relay and the fuel pump circuit.

It's possible the relay or a connection someplace is so bad, it doesn't pass enough current for the injectors, the fuel pump and a few other functions all at one time, unlikely but possible.

My best guess would be an open circuit between the fuel pump relay and the fuel pump circuit. Which is usually the ballast resistor, but can be any number of splices, connectors or a broken wire someplace.

Maybe I'm just not getting it?
 
Well I put on the new starter relay and I'm having the same problem I'm going to check the ignition switch next
 
A piece of advice, don't assume it is a component and not the wiring or a connector.

Use a volt meter or even a test lamp. Go to the *larger* yellow wire at the ignition module. It should have juice with the key in run and start, if it does your ignition switch is likely OK.

Then go to one of the orange wires at the ballast resistor. It should have juice run and start, this will tell you the fuel pump relay is likely OK. The ballast resistor will have lower voltage on one end than the other, that is what it is designed to do.

Half hour max and then you have reduced the likely trouble area by 3/4 and can zero in on the problem. I've used this method maybe thousands of times, it works.
 
I had the same issue on my 89 and found out that the asd (auto shut down) relay was not getting power, I used a jumper to test and the jeep started right up. I then attached the power wire going to the relay to a switched ignition source and it has been fine since
 
thanks 8mud for that trouble shooting tip. I have power at the ignition module but not at the ballast resistor so I moved on to check out the relay and it is not getting a signal to close that relay I can put a jumper in the place of that relay and it will run. so where does the signal come from to close that relay
 
Two parts to a relay, the activator (coil) and the contacts. You can turn the relay over and see the numbers embossed near the pins. 30 is usually main power in through the contacts and 87 is main power out. 85 and 86 are the activator coil which pulls the contacts together.

The fuel pump relay has the same yellow wire that goes to the ignition, going to the 86 pin. The 86 pin should have voltage any time the key is in the run position. The 85 pin completes the circuit and runs to ECU through a orange wire with a stripe and to the ECU, then switched to ground.

Check the 86 pin for power with the key on (sometimes the 85/86 pins are reversed during assembly of the harness).

You really have to remove the relay block and turn it over and look at the bottom. Wash all the trash out of there with brake cleaner or contact spray. Check the female plugs on the relay block for good contact.

Unlikely the ECU is neglecting to supply the ground for the fuel pump relay actuator, more likely to be a bad connector or a bad wire.
 
The yellow wire is the only one with power. If I jumper the yellow to orange it will run just fine but it still won't run with a relay in there
 
The red wire running to the 30 pin on the fuel pump relay should have constant power (anytime the battery is hooked up) and comes from a fusible link near the starter relay.

Either the fusible link is blown, the wire is open or a connector is causing issues. Possible the connections for the relay are way loose.

Next question is, if it is the fusible link what caused it to blow? Most times it is a dead short someplace, either you did it by accident or there is some kind of damage to the wire. Possible it is something to do with the transmission controls, I believe the TCU shares this fusible link with the fuel pump.
 
When I put that jumper in I drove it to my garage and it was shifting really weird almost like it did not want to hold a gear
 
Well I found a red wire that was broke I put my meter on it and the red wire at the fuel pump relay and boom there is my lost wire I hooked that up and she runs. Thanks everyone
 
Well that was not the end. I had 2 wires short out (red and orange) and so I have been running new wires and I finally got it to start today. I still need to put a relay back in it and then ill see how far I can make it
 
Well I have it running yes I drove it around today and everthing seams fine. I still have not figured out how it was wired before the wires were shorted out. I have the ignition wire running the fuel pump at this time I'm not sure it that is a good idea or not I'm thinking about having the yellow wire control a relay and give the fuel pump its own circuit. Is there any reason not to do that
 
Note from DJ
The Yellow wire which goes to the Fuel Pump Relay terminal 86 (one side of the relay coil) becomes hot when the ignition switch is in the run position.

Terminal 30 of the Fuel Pump Relay (Red wire) is the common contact for the switch part of the relay and is hot at all times from one of the orange fuse link (G).

Terminal 85 (Black wire) is the negative connector for the Fuel Pump Relay for the coil.

When the ECU is convinced that the Jeep was started OK it completed the ground circuit to terminal 85 (in other words the relay is activated by a switched ground by the ECU) plus batter voltage through the Yellow wire from the ignition switch.

When the coil is energized it switches into the normal open position from the normal closed position which completes the circuit from terminal 30 to terminal 87 (Orange wire) which then powers up your Fuel Pump.

Normal closed position for relays is the position relays are in when they are not activated (30 to 87A). 87A is not used in the Fuel Pump circuit.
 
Note from DJ
Edit to post #38

QUOTE: “Terminal #85 (Black wire) is the negative connector for the Fuel Pump Relay for the coil”.

Correction: Terminal #85 (Orange with Black tracer wire) is the negative connector for the Fuel Pump Relay for the coil. Additional information on this circuit this switch grounding circuit leaves the ECU at terminal A-5 of the ECU 24 pin connector #202.

Here is the test I developed when my 88 was having internment dying after startup which became more frequent with each startup.

I found about a 2 foot piece of scrap small STRANDED wire (22-gage) or smaller is fine. Cut a 3 inch piece off of the 2 foot piece. Now strip about a 1/4 inch of insulation of each of the 4 ends of your 2 wires; next twist together one end the exposed stranded wire on each of your 2 wires then fan-out the strands of wire on the opposite end of your 2 wires.

Now comes the technical part. Open the hood of your Jeep; next turn your ignition switch to the ON position the walk back to the passenger side of the engine compartment and lean over the fender and remove your Fuel Pump relay.

Now comes the very technical part. You must first verify that you have battery voltage to terminal #30 of the Fuel Pump relay socket (this will be the socket farthest from you next to the engine) if battery voltage is present at terminal #30 next verify you have battery voltage to terminal #86 (which will be the terminal on your left in the relay socket) if you have battery voltage to both of these terminal we are ready to proceed with the test.

If batter voltage is present at both of the above terminals we are ready to proceed with the test. Pick up the 3 inch piece of wire that you have created and bend the fanned-out end of the wire at the striped point at a 90 degree angle and take something small like a small thin screwdriver and poke the fanned-out strands of wire into terminal #87 (which is the terminal next to the fender) now repeat this process with your long piece of wire except insert it into terminal #85 which will be on your right. Now here is a very important part of the test make sure the twisted end of both of your created wires CANNOT come in contact with any ground point. Once this is done reinstall your Fuel Pump relay.

OK now that all of your pretest procedure is completed it’s on to the test itself. First take one more look at your free end of your short wire to see that it is not in or will contact with any ground point. When this is verified then take the free end of your long wire and touch it to a good ground point (negative battery is ideal). You should now hear or feel the Fuel Pump relay click in and your Fuel Pump run. Repeat this test several times if first test is OK because this is where my relay failed the test; sometimes my pump would run and sometimes it would not. I had a bad relay even though it was pulling in it wasn’t always completing the circuit to terminal #87. If you don’t hear or feel the relay pull in or your Fuel Pump run make sure you left the ignition in the on position. If relay pulls in but Fuel Pump doesn’t run take something and check to see if you have battery voltage between the free end of your short wire and a good ground point while you maintain the relay in the closed position by keeping it grounded. If no voltage is present then grab on of the other relays from an adjoining socket and try exchange the relays and repeat the test.

If the relay is not pulling in try the exchange relay procedure and retest.

I know you swapped your relays but try my test anyway. Post back what you find out before we go any farther.

 
Hey dj I emailed you the other day.. I don't have a fuel pump relay any more it melted down when the red and the orange wire shorted out. The orange wire that shorted out goes to a injector but I'm not sure where it comes from
 
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