Renix Questions. Semi starts, dies after 1-3 seconds....

[magimerlin]

Look on line for the renix fuel injection manual. Best thing I have come across. And is a very valuable bit of info. There is alot of sensors that are used at start up and when running. Some can cause it to run rough and others can cause it to die/stall out.

Honestly get yourself the section of harness that you say isn't fixable at the moment say from the junk yard or someplace and fix it to be right.

Renix distributors are indexed so unless it's base was modified it can not be adjusted. The computer takes care of all that.

The switch is wired direct to the battery but shuts off with the key??? That's not possible.

There is more going on here on this jeep you may not be aware off. Sounds like it got a few "red neck" fixes in it's life time. Gods know I have a few on my rigs.... lol.

Find that manual I mentioned above and read through what you can. Just do a Yahoo or Google search, it's literally every where. Something is not communicating correctly with each other.

 

[djgrayxj]

Note from DJ
Here is my interpretation of the information provided in the 4.0 L MULTI-POINT FUEL INJECTION SYSTEM MANUEL on the Fuel Pump Relay

The fuel pump relay is located on the right inner fender panel. The feed side of the relay coil is powered by the ignition switch. The relay is energized by the ECU by grounding the other side of the coil.

The relay contacts are normal open [NO] and will close when the ECU provides a ground path for coil terminal #85 with a #16 ORN/BLK wire from the ECU 24 pin connector #202 terminal A5. Battery voltage to relay coil is supplied from the Ignition Switch I-1 terminal by a #14 YEL wire to terminal #86 of the relay. Battery voltage for the relay contact #30 originates at a power splice that is connected directly to the battery through a fusible link G 20 ORN on a #14 RED wire located at the starter relay. When the relay is in the (NO) but now closed position the injector feed signal is transmitted from terminal #87 of the relay on a #16 ORN wire to the ECU 32 pin connector #201 terminals D10 & C11

The fuel pump circuit is completed during cranking and whenever the engine is running. If the ignition switch is turned to the RUN position prior to START UP, the fuel pump will operate for one to three seconds and then shut off. If the ECU does not receive a crank or run signal, it deactivates the pump by opening the relay coil ground circuit. The one to three second time limit is used to prevent unnecessary operation of the pump once the system is pressurized. If the engine were running, the ECU would maintain the coil ground circuit which would allow the continuous operation of the fuel pump.

The fuel pump relay is an electro-mechanical switch used to connect the electric fuel pump to battery voltage. Inside, the relay contains a coil and a set of electrical contacts. Externally, the coil and contacts are connected to the battery, ignition switch, Electronic Control Unit [ECU] and the fuel pump.

When connected to the battery through the ignition switch and to ground through the ECU, the coil becomes an electro-magnet. The magnetic field generated by the coil attracts and moves the relay armature. Movement of the armature moves the contacts from the normally closed position [at rest or no power applied NC] position; to the normally open (NO) position. When the NO contacts close, the battery circuit to the fuel pump is completed and the pump operates. When the ECU opens the relay coil circuit by interrupting the ground path, the magnetic field collapses and spring pressure opens the NO relay contacts and the relay is returned to its NC position.

If I have misquoted any of the above information please correct me so that I can correct my notes.