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Newbie Trying For Engine Start

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Newbie Trying For Engine Start
H

Hog Head

Jeeper
Posts
127
Thanks
0
Location
Rockwall, TX
Vehicle(s)
'83 CJ7, FI 4.0L, Jeep T18 Short Tail, Dana 300, Dana 30 Front, AMC20 Rear w/one piece axles
'51 Willys M38 Original
Hey friends, can you help me out here? I'm ready to start the engine on my project 83 CJ7 with 93 4.0L engine. I purchased a combined harness from thisguyuknow. So all electrical items should work, given I have installed it correctly. The engine turns over good, but so far have not been able to get any fuel to the rail. Currently have the hose off the rail and in a bucket so I can see when fuel arrives. Any ideas would be greatly appreciated on the fuel issue and anything else I might need to do. Thanks in advance.



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When you turn the ign switch to 'run'. Can you hear the fuel pump run?
LG
 
Lumpy grits, no I can't hear it. I am a little hard of hearing and my wife says I'm a lot hard of hearing. But you know how that goes, I call it selective hearing.
I've had the hose off the fuel rail thinking if it started to prime I'd be able to see the fuel running into the bucket. But nothing yet. Today I installed the mil light with switched 12v and the ground labeled check engine that thisguyuknow labeled on my harness. The light comes on with the key on and stays on indicating there are some codes. But I've not figured out yet how to retrieve them.


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Run a jumper wire from the POS(+)of the battery to the POS(+)lead of the pump if it ain't inside the tank.
Does it make noise now.
Also-you may need to bleed the fuel rail of air.
I'm pretty 'dum' with FI. Many folks here have forgotten more about FI, than I'll ever know.:notworthy:
LG
 
Thanks, the pump is in the tank, but I've got plenty of wire. I'll run one back there.


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As LG said with the key in the run position the pump should be running if you aren't getting gas coming out of that line it isn't running. You need to see if it's getting power or if the pump is no good.
 
Hi there,
I have a very similar setup in my CJ. The first thing to check is like the others said, as soon as you turn the key from accessory to on before pushing it over to start, the fuel pump should kick on and run for about 2 seconds to prime the system. You need to confirm this first. There are a lot of posts on here and other forums about the 5 wires that you need to connect to get a 4L to run in a CJ. The ASD relay and the Fuel Pump relay need to be wired properly for the fuel pump to have power.

I think i have more information from my build but didnt want to overwhelm you.
 
Thanks mz8z
This morning I checked voltage on the wire that runs from engine compartment to pump and got 0 volts in the on position and not cranking and 0 volts while cranking. I purchased the combined harness from thisguyuknow who actually took it off his CJ7 with a 4.0L. So I'm assuming it's wired correctly unless I've connected something wrong. All the leads weren't labeled.
Yesterday I installed a mil light to switched 12v and the wire he had labeled negative check engine light. And the light comes on when cranking and stays on, I'm assuming with some malfunction codes. I've tried the on, off, on, off and on to check the codes but the light just stays illuminated. I also replaced pump relay and asd relay. Still no joy.


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Hi Hog,

So, i just pulled up my wiring diagram for a YJ. They are all pretty similar, and years vary for wire colors but the idea is the same. The control side of the relays is controlled via Fuse 5 which is a 10A fuse. That wire is the control side of both the Fuel Pump and ASD Relay. The ground side goes to pin 51 of the PCM. The hot side of both of those relays comes from Fuse F1 which is 30A. The output of the fuel pump relay goes directly to the fuel sending unit in the tank. The output of the automatic shutdown (ASD) relay goes to power the injectors and power the O2 sensor. So, I would start by checking the fuses to make sure you have power going to both the high power and control sides of the relays. Then you can check continuity between the PCM connector and the relays to make sure you have a good wire connection there. Try these troubleshooting guides, noting that the wire colors may not be correct:
1993-1995 Auto Shut Down (ASD) Wiring Diagram (Jeep 4.0L)
1993-1995 Fuel Pump Wiring Diagram (Jeep 4.0L)
 
mz8z said:
Hi Hog,



So, i just pulled up my wiring diagram for a YJ. They are all pretty similar, and years vary for wire colors but the idea is the same. The control side of the relays is controlled via Fuse 5 which is a 10A fuse. That wire is the control side of both the Fuel Pump and ASD Relay. The ground side goes to pin 51 of the PCM. The hot side of both of those relays comes from Fuse F1 which is 30A. The output of the fuel pump relay goes directly to the fuel sending unit in the tank. The output of the automatic shutdown (ASD) relay goes to power the injectors and power the O2 sensor. So, I would start by checking the fuses to make sure you have power going to both the high power and control sides of the relays. Then you can check continuity between the PCM connector and the relays to make sure you have a good wire connection there. Try these troubleshooting guides, noting that the wire colors may not be correct:

1993-1995 Auto Shut Down (ASD) Wiring Diagram (Jeep 4.0L)

1993-1995 Fuel Pump Wiring Diagram (Jeep 4.0L)
Click to expand...



Thanks so much for the in depth troubleshooting steps. I really appreciate that. I just got back in my office from the shop and logged on. What I found (with the help of thisguyuknow), was I had no switched 12v to pin 9 on pcm. Which also runs directly to the fuel pump relay. The problem was the connection at the back of the CJ7 fuse panel. Instead of tracking it down, I just bypassed it and tapped into switched12v at another location in the engine compartment. And presto, relay kicked in and the pump ran fuel out into the bucket. So I reconnected the hose to the fuel rail and tried for engine start. No joy. First thing I checked was spark from coil to distr, no spark. Pulled the mal codes off my newly installed mil. 12, 33, 35 and 41. Any ideas on this one?



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To start, since you have other power problems. Have you checked that you have power at the coil, the output is shared with the ASD output?


Here is the info from the FSM on the DTCs you provided:
12* . . . . . . . . . . Battery Disconnect: Direct battery input to PCM was disconnected within the last 50 Key-on cycles.
33* . . . . . . . . . . A/C Clutch Relay Circuit: An open or shorted condition detected in the A/C clutch relay circuit.
35* (XJ Only) . . . . Rad Fan Control Relay Circuits: An open or shorted condition detected in the radiator fan relay circuit.
41** . . . . . . . . . . Generator Field Not Switching Properly: An open or shorted condition detected in the generator field control circuit.

These are the footnotes to the above codes:
* Check Engine Lamp will not illuminate at all times if this Diagnostic Trouble Code was recorded. Cycle Ignition key as described in manual and observe code flashed by Check Engine lamp.
** Check Engine Lamp will illuminate during engine operation if this Diagnostic Trouble Code was recorded.



After pasting all that, Im not sure that any of those would stop spark from occurring. I would expect a speed signal to be an issue with spark typically on these engines and you should get one of the following DTCs for that:
11* . . . . . . . . . . No Crank Reference Signal at PCM: No crank reference signal detected during engine cranking.
54* . . . . . . . . . . No Cam Sync Signal at PCM: No fuel sync (camshaft signal) detected during engine cranking.

Ive also heard that you need a functioning speed/distance sensor plugged into the back of the Transfer Case to get the engine to work properly, but I have not done much research on that as I added a Dakota speed sensor to mine.
 
I do have a speed sensor plugged in but I don't have the 5/8 to 7/8 adapter for the speedometer cable to attach to it yet.
No I didn't get codes 11 or 54.
Can I check voltage on the small wire going into the coil?


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Thank you sir. That's a great site. I did all those things and hit 0 on every test. It's really pointing to the crank position sensor. And I'm in denial, not wanting to change that bad boy. I installed it when the jeep was down to the frame and motor. So looking at it now put back together looks like a really bad task to change it. Am curious if it is the cps, why didn't it throw out a code indicating cps failure?
Again, thanks for all your help.

I'm trying to get this rig ready for the aug ouray, co trail ride. And I surely need to drive it some or a lot before we go. I know I'm close here, just a little spark, that's all I need[emoji22][emoji848]


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I was wondering that too when you sent me the flashout of the fault codes. I am pretty surprised you didn't get it. I did when i first hooked mine up and had to swap to a new sensor. Its been working well ever since.

Assuming you are using a modified bellhousing or a YJ Transmission , the sensor is on top of the bellhousing and i agree its not easy. I used a couple of extensions and a swivel to get it out and I dont remember if i went from the Transmission cover or from underhood. Either way, its not the most comfortable part to change.
 
Ok I think I'll give up on all other leads, because it appears everything else is working properly. So today's the day, I'm gonna pick up a new cps. My son in law (everyotherusernameistaken), is in town for a few days. Maybe I can get some assistance in changing it out. He to has been busily readying his fig for the ouray trip. I think we're gonna make it. Thanks for all your help here.



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Fig is really "rig"


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Latest update.
Installed a new crank pos sensor. Fuel pressure but no spark. Put in a new coil, now have spark to plugs. Still no start. So I put my fuel pressure gauge in line on pump side of regulator, got 20psi with key on no crank, and 70psi while cranking. Put the hoses back together and moved the gauge to the fuel rail, 0 psi in on position and 0 while cranking. Must be the regulator. Had an old rail that came with the project, so changed it out. Still 0 psi at the rail. Any suggestions free, friends? Got spark just need some fuel pressure.


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Free should say "here", darn spell checker is dumber than me.


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One other thing, here's the codes I get outa the mil light 12, 36, 33, 33


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