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87 Renix No Fuel at Rail + Low Fuel Pump Voltage

Pokey_87

NAXJA Forum User
Location
Calaveras County
Went for a drive in the rain, Jeep ran and started fine. Parked the jeep, and it wouldn't start.
No fuel pressure at the rail, so I replaced the fuel pump and filter. That didn't help. Long, strong crank, but no start.






'87 Cherokee Laredo, Renix, no fuel-pump ballistor in this model, 4wd and manual transmission. Followed the maestro Cruiser54's tips: 1-6,8,9,11,19,20


You can hear the pump turn on when the key is first turned (6.8v at the harness), and then when you turn to crank the voltage drops to 3 something.
I've cleaned the C101, inspected the ECU, added a 4g ground from the block to the chasis, cleaned all connections in the engine bay, replaced the 02 sensor, replaced the CPS, and am still not getting any pressure or fuel to the rail.

Jeep will start with a bit of Starter Fluid. Pump will turn on from jumping 87 to 30 on the relay, but isn't moving fuel to the rail.
There is a spot where the pink wire for the fuel pump dips down next to the starter and there is a harness connection, on the other side of the harness is a small piece of wire that just connects the pink wire to the wire next to it. What is this?

What could be causing the pump to not receive power? Could it be something with the starter relay? or some other ground that I'm missing?
 
The power for the fuel pump is supplied from the starter relay during cranking and bypasses the other relays. Believe it is an orange wire going to the pin marked BAL (most times) on the starter relay.

Starter-relay.gif


Renix-Fuel.png
 
If memory serves me correctly the schematic I gave is for an 88, the 87 has a slightly different wire color layout between some of the connectors on the drivers side harness front to rear. You have to pay attention to the wire colors as they change on you between the connectors.
 
There's a connector in the driver side kick panel that could be the culprit.

Pink wire with tracer in a gray colored 10 pin connector

My 87 had a crispy connector near where it goes over the left rear wheel well and behind the cargo side panel. But I imagine any of those connectors with a loose pin could get crispy and melt. I deleted all the connectors on that harness. spliced, soldered and heat shrink tubed all of them. I'd say 80% of all the issues I had with my 87 were ground points. harness, splice or connector related, made in Mexico.
 
I maybe mistaken, but is not the fuel pump ground point behind the rear driverside interior panel? (plastic interior panel below the driverside rear quarter window) maybe that is in need of cleaning and tightening?
 
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