Cranks but won't start

Shenanigans

New Member
Joined
Jun 7, 2023
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12
Location
Tahoe/Carson Nevada side
So I'm not sure if I just had an aha moment or not ...about 2 years ago I was doing some work on my Jeep it's an O2 Wrangler X 4.0; I was putting headers on it and I drained all the air conditioning "coolent" it was always cold as hell there so I didn't bother putting it onto a vacuum and then putting new coolant back in it.
THINKING CAPS:
So last year I had a crank no start and I was working a lot so I haven't really gotten around to it I've changed just about everything couldn't figure it out, had others come by and look at it they couldn't figure it out I was just looking at the maintenance manual for my model and it started talking about the PCM communicating with the AC system...
Wouldn't it be possible for me not getting any fuel? Would it trigger an ASD situation keep in mind I checked everything fuel pump does not kick on it's brand new I pulled it out and tested it I tested everything!! I mean everything! would it be possible that I wouldn't be getting a no startup because of the AC system I don't know if anybody's ever heard of anything like that I never have anyway thanks in advance for your response...
And just to look back on what I said it's pretty obvious that I didn't test everything because if I had tested everything I would have found the something but I've tested everything that I could think of and everything that you guys could think of and everything that the mechanic I had come out and look at it could think of hell I even replaced the computer.
So that being said Thank you guys very much in advance
 
Having no refrigerant in the AC system would have nothing to do with a Crank/No Start situation.

I would check for power and grounds. Make sure none of your power and ground cables have green crusties. Check all fuses and also try swapping relays in the under hood fuse block especially the fuel pump relay.

Before your crank no start situation how long had it been BEFORE that when the jeep started and ran?
 
Having no refrigerant in the AC system would have nothing to do with a Crank/No Start situation.

I would check for power and grounds. Make sure none of your power and ground cables have green crusties. Check all fuses and also try swapping relays in the under hood fuse block especially the fuel pump relay.

Before your crank no start situation how long had it been BEFORE that when the jeep started and ran?

Bout a year
 
Maybe you have a similar situation to this? Main culprit was only getting 11.65 volts on the power wire to the fuel pump (tested with meter at the fuel pump connector while turning the key) The wire only gets voltage for 1.8 seconds with key on in the accessory position. The fuel pump will not turn on at that voltage. We finally supplied 12.5 (same as battery was showing) to the pump and she fired up. Here is what I posted this morning about it:

Just thought I would add my recent experience with fuel pump woes for anyone who may be searching for a solution.

This is on my Son's 2005 TJ 4.0. He had a cylinder misfire code (can't remember the code), a warm up catalyst code P0431, Evap small leak code P0456, and Evap lose fuel cap code P0457. We replaced the spark plugs, ignition coil, and fuel cap. Jeep started and drove great for 2 days then suddenly had trouble starting to the point where he called me to bring the trailer. He was able to get it started running roughly for the first few minutes to get it home. The jeep over the next few days ran great.
We needed to drop the fuel tank to address the evap leak on one of the lines on top of the tank as well as the hard to fuel situation (the hard to fuel situation from the plunger inside the tank connected to the filler neck). The plunger was sticking and we took it out to sand it slightly to make it move and not stick. We removed the tank and cleaned it up. In the process of putting the fuel pump back in trying to get the clamp to seat, the punch slipped and broke the plastic nipple that connects to the fuel line (crap). We installed a new fuel pump and the jeep started right up after cycling the pump a few times. We let it run for about 5 minutes then shut it off. When we restarted the jeep cranked and died. Upon further start attempts the jeep would struggle to stay on more than a few seconds - obviously to us a fuel starvation issue. We could no longer hear the pump come on with the key. We pulled the plug off the pump and put it on the meter with the key on I was getting 11.65 volts. Battery showed 12.5 volts. We looked at the pinouts in the factory service manual and found the orange wire with red stripe OR/RD providing power came from the relay box. We swapped relays with the fuel pump relay and no dice. We tested continuity on the OR/RD at different points and found it was testing ok. That OR/RD wire runs through the C102 gray connector at the fire wall, we disconnected C102 and checked continuity there and had it. We then tested voltage across that wire at the C102 connector and were getting 11.65-7 volts. So we cut the OR/RD wire as close to the relay box as we could in the harness that runs on the side of the battery. Stripped the wire and tested voltage there and we got 12.5 volts. We then ran a new wire from that point all the way to the fuel pump connecter about 2 ft from the connecter and spliced into it there. That gave us 12.5 volts and made the fuel pump come on with the key! Hell yes! We then routed that wire through the harness and inside of the wire loom as best as we could.
Jeep cranked right up without stumbling or mumbling. We think we found the source of several woes this jeep was having. The cylinder misfire code we were getting (still can't remember the code) claimed as one of its causes a faulty fuel pump and in our case it was the wiring.
 
We then tested voltage across that wire at the C102 connector and were getting 11.65-7 volts. So we cut the OR/RD wire as close to the relay box as we could in the harness that runs on the side of the battery. Stripped the wire and tested voltage there and we got 12.5 volts. We then ran a new wire from that point all the way to the fuel pump connecter about 2 ft from the connecter and spliced into it there. That gave us 12.5 volts and made the fuel pump come on with the key! Hell yes! We then routed that wire through the harness and inside of the wire loom as best as we could.

Can you explain in more detail what you did here? "tested voltage across that wire at the C102 connector". I'm guessing you mean you checked voltage against ground on both sides of the connector and found that after the connector you had your 11.6V.

It sounds like you're saying the issue was at the connector, but your solution was to bypass the entire run, from fusebox to to fuel pump. So I'm a little confused.
 
Sorry this took so long to reply. Yes, that is what we did because I had already cut the wire just after the PDC, so we just ran it from there.
 
It's interesting that your Jeep Wrangler X 4.0 cranks but doesn't start, and you're asking if taking out the AC system could be causing it. Typically, the air conditioning system shouldn't directly impact whether or not the engine starts.