Low fuel pump voltage?
06-28-2017, 11:55 PM
#16
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from the ground terminal to each of the other terminals, had 12.2 volts with the key off, and 11.9 volts with the key on.
I do have a ballast resistor, it measured 10.5 volts on one side, and 6.2 volts on the other
for further testing, I pulled the fuel pump relay and checked the voltages across those terminals. All zero voltage with key off. With key on 30-86, 30-87, 30-87A all measured 11.1 and 30-85 was 0.4
the battery was getting slow to crank from all the non-starts, so pulled and am charging it up.
I do have a ballast resistor, it measured 10.5 volts on one side, and 6.2 volts on the other
for further testing, I pulled the fuel pump relay and checked the voltages across those terminals. All zero voltage with key off. With key on 30-86, 30-87, 30-87A all measured 11.1 and 30-85 was 0.4
the battery was getting slow to crank from all the non-starts, so pulled and am charging it up.
06-29-2017, 11:56 AM
#17
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Could it be also the ground?... I remember one of your tips was to make a new ground but from the connector of the fuel pump.
Just curious, have your tried bypassing the ballast resistor to see if that does it?
Just curious, have your tried bypassing the ballast resistor to see if that does it?
06-29-2017, 03:34 PM
#18
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There's a connector behind the driver's side kick panel that can be the culprit.
Gray rectangular 10 pin connector. Pink wire with tracer is fuel pump wire.
06-29-2017, 05:30 PM
#19
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It should look like this... but with more wires... i found out that the pink wire pin had melted into the connector
* this is just a sort of reference
* this is just a sort of reference
06-29-2017, 06:19 PM
#20
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06-29-2017, 07:59 PM
#21
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I'll look for the pink wire, it should match the voltage coming out of the ballast resistor, right?
Also, is the 38 psi fuel pressure I got on the rail too low? What should it be?
Also, is the 38 psi fuel pressure I got on the rail too low? What should it be?
06-29-2017, 09:05 PM
#22
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39 running with fuel pressure vac hose disconnected and 31 with it connected.
06-29-2017, 09:50 PM
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It might almost work on 6.2 volts but if you are chasing a problem you don't need that boogering things up.
Might well be that same circuit with low voltage is powering other things also. Renix has no ASD (Auto shutdown) relay. The fuel pump relay sort of "pinch hits" to fill that function, powering everything that makes it go.
Last edited by DFlintstone; 06-30-2017 at 05:17 PM.
06-29-2017, 10:42 PM
#24
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https://www.cherokeeforum.com/f2/sta...solved-232507/
This sounds like my exact symptoms, so may check for loose timing chain too.
Will have some more time this weekend to troubleshoot.
Will also try bypassing the ballast resistor to see if the pressure will increase and completely rule out the fuel issue (or not)
This sounds like my exact symptoms, so may check for loose timing chain too.
Will have some more time this weekend to troubleshoot.
Will also try bypassing the ballast resistor to see if the pressure will increase and completely rule out the fuel issue (or not)
06-30-2017, 09:18 AM
#25
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No matter what, you need enough voltage at the pump.
07-04-2017, 02:00 PM
#26
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Problem solved!!
I bypassed the ballast resistor, fuel pump sounded louder, but still 38 psi at the manifold. After failed starting attempts, pulled a plug and found it wet and gassy smelling. Checked the timing using the TDC method in the link above, and that was right.
Stuck, called a mechanical friend and he said there may be too much gas in the cylinders to fire. Pull all plugs and turn over engine to blow it out.
So I did that, and replaced the plugs with new ones. It grudgingly fired and sputtered a little bit, but cleared up in 30 seconds, now is running fine!! We were even late getting it smogged and re-registered. Drove it around a little to clear it up, and passed a smog test, so all is really fine!
Thank you all for your help and advice! Every time there's a problem, we learn more about how the jeep works, really appreciate it. And thanks Cruiser54 for the webpage, did a couple of the tips already, but will be doing more in the near future!!
I bypassed the ballast resistor, fuel pump sounded louder, but still 38 psi at the manifold. After failed starting attempts, pulled a plug and found it wet and gassy smelling. Checked the timing using the TDC method in the link above, and that was right.
Stuck, called a mechanical friend and he said there may be too much gas in the cylinders to fire. Pull all plugs and turn over engine to blow it out.
So I did that, and replaced the plugs with new ones. It grudgingly fired and sputtered a little bit, but cleared up in 30 seconds, now is running fine!! We were even late getting it smogged and re-registered. Drove it around a little to clear it up, and passed a smog test, so all is really fine!
Thank you all for your help and advice! Every time there's a problem, we learn more about how the jeep works, really appreciate it. And thanks Cruiser54 for the webpage, did a couple of the tips already, but will be doing more in the near future!!
07-04-2017, 03:25 PM
#27
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Nice to hear you solved it! To Start a flooded engine you hold the petal solid on the floor. This cuts off fuel from the injectors while providing max air. 
07-04-2017, 05:54 PM
#28
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Problem solved!!
I bypassed the ballast resistor, fuel pump sounded louder, but still 38 psi at the manifold. After failed starting attempts, pulled a plug and found it wet and gassy smelling. Checked the timing using the TDC method in the link above, and that was right.
Stuck, called a mechanical friend and he said there may be too much gas in the cylinders to fire. Pull all plugs and turn over engine to blow it out.
So I did that, and replaced the plugs with new ones. It grudgingly fired and sputtered a little bit, but cleared up in 30 seconds, now is running fine!! We were even late getting it smogged and re-registered. Drove it around a little to clear it up, and passed a smog test, so all is really fine!
Thank you all for your help and advice! Every time there's a problem, we learn more about how the jeep works, really appreciate it. And thanks Cruiser54 for the webpage, did a couple of the tips already, but will be doing more in the near future!!
I bypassed the ballast resistor, fuel pump sounded louder, but still 38 psi at the manifold. After failed starting attempts, pulled a plug and found it wet and gassy smelling. Checked the timing using the TDC method in the link above, and that was right.
Stuck, called a mechanical friend and he said there may be too much gas in the cylinders to fire. Pull all plugs and turn over engine to blow it out.
So I did that, and replaced the plugs with new ones. It grudgingly fired and sputtered a little bit, but cleared up in 30 seconds, now is running fine!! We were even late getting it smogged and re-registered. Drove it around a little to clear it up, and passed a smog test, so all is really fine!
Thank you all for your help and advice! Every time there's a problem, we learn more about how the jeep works, really appreciate it. And thanks Cruiser54 for the webpage, did a couple of the tips already, but will be doing more in the near future!!
