Won't stay running after AX 15 swap

[JZLAJeep]

My sons and I (mostly my 18 and 16 year-old sons lately) have been working on our field find since May. We even had it driving for a little while.

 

Most recently we've swapped the Peugeot for an AX 15 transmission. After installing the AX 15 twice (my son learned you have to use the flywheel and crankshaft position sensor from the Peugeot? which we didn't do on the first try) we've got it mostly back together. Looks like the main drive shaft is too long now and is not installed, need to hook up 4wd linkage, a section of exhaust pipe needs to be reconnected, and a few other odds and ends, but it's in! (again)

 

We think we have it back to the point where the Comanche should at least start and run and we are having trouble. The engine starts, but stops after letting go of the key. The engine will sometimes keep running if we hold the key in the start position, but will stop as soon as we let go. We thought it might be the ignition switch and swapped that last night in the Idaho cold, but same result. Engine starts and stops as soon as we let go of the key.

 

What are we missing? Is it ignition related? Is there something we missed with the AX 15 swap? Is it related to something that we haven't reconnected yet? Any ideas will be appreciated. I skimmed through the write-ups and nothing immediately jumped out at me.

[cruiser54]

Likely not related to the swap at all. 

Look here:

 

 

[JZLAJeep]

I cleaned up the terminals on the ballast resistor with no change. The fuel pump is getting power and seems to prime up well. I really don't think it's a fuel issue because of the way it dies. It doesn't sputter out like it's losing fuel, it really just sounds like you turned off the key. Is there any reason it would have spark when it's started but not immediately after?

[cruiser54]

bad ignition switch? 

Fuel primes, but does the pump stay running when the key is released to the ON position? 

[Strokermjcomanche]

Bad fusible link near the Ignition relay? 

[JZLAJeep]

2 hours ago, cruiser54 said:

bad ignition switch? 

Fuel primes, but does the pump stay running when the key is released to the ON position? 

We replaced the ignition switch earlier in the week. Unlikely that two are bad. More likely that both are good. We'll try the other suggestions.

[JZLAJeep]

On 11/19/2022 at 7:04 PM, Strokermjcomanche said:

Bad fusible link near the Ignition relay? 

Getting back on this. Replacing the starter relay (same as ignition relay?). I'll check wires for fusible links.

[cruiser54]

Rereading this. The ballast resistor could be bad. Jumper it and see what happens. 

[JZLAJeep]

Working on the Comanche more tonight. We've confirmed that the fuel pump gets 9 volts while cranking(is that about right?) but no power when key is turned to on. Definitely does not prime the pump when first turned on. We thought that was the problem, so we tried hotwiring the fuel pump with constant 12v. This made no change, so it must not be a fuel problem, or at least that's not the only problem.

 

Is there anything that could cause the jeep to lose spark after about a second of rolling the key back to the on position? We've also noticed a clicking noise from the drivers side dash that wasn't there before. Could that be a relay related to our problem? Are there any relevant relays in that fuse panel in the drivers footwell?

[gogmorgo]

Take the two wires off the ballast resistor and connect them together. See what happens. 
The ballast resistor is bypassed while the engine is cranking, and back in the system with the key in the run position. Only getting 9v to the fuel pump while cranking is probably due to the load on the battery from the starter and it being somewhat discharged due to lots of cranking and not much charging. But having zero volts with the key on could very easily be due to a failed ballast resistor. Without the engine running it’ll only run the fuel pump for a few seconds just to prime the system, so you’ll need to be watching for power right away when the key is turned on. 
 

A bad ballast resistor, or one that’s suddenly unplugged, doesn’t really make the engine splutter. It takes a few seconds for the pressure to evenly bleed down then it quits. Very much as if you just shut the key off, other than everything other than the engine still being on.

[JeepSchmidt O'Guinness]

I've had new ignition switch failure after a week or so of operation. I think I didnt have the origional lock cylinder seated properly. If your ign' switch is still under warranty I'd try exchanging and see if that fixes the no volts during key on.

[JZLAJeep]

That is probably our issue for why it won't prime up. But even when we bypassed all that and gave the pump straight constant 12v, it still wouldn't stay running. So doesn't that mean its a spark issue?

 

What we did is unplugged the fuel pump from the comanche and just stuck wires in the connector. One straight from the battery, and one straight from the transmission housing for ground. It was very audibly running before the engine started and after it died. We did double check that it was building pressure at the rail.

[jpnjake]

7 hours ago, JZLAJeep said:

That is probably our issue for why it won't prime up. But even when we bypassed all that and gave the pump straight constant 12v, it still wouldn't stay running. So doesn't that mean its a spark issue?

 

What we did is unplugged the fuel pump from the comanche and just stuck wires in the connector. One straight from the battery, and one straight from the transmission housing for ground. It was very audibly running before the engine started and after it died. We did double check that it was building pressure at the rail.

It has to be spark if there is constant fuel at the fuel rail. Try this, put 12 volts to the connector underneath the coil, that should fire up the ignition system and get the fuel pump running, then try to start the truck, if it starts and runs that means the wires going into the coil aren’t doing what they are supposed to

[Ωhm]

Using a voltmeter or 12vdc testlight (preferred) check for Battery_Voltage_(B+) on the following pins (use battery_negative terminal for ground):
D1_5:  B+ (Hot at all times)
D1_6:  At KEY ON only (B+ (Hot for 2-3 seconds)).
D2_4:  B+ (Hot during KEY ON and Hot during CRANK).
 

 

[JeepSchmidt O'Guinness]

Misread the second ignition switch install, apologies. 

 

 

[JZLAJeep]

On 12/8/2022 at 8:03 AM, Ωhm said:

Using a voltmeter or 12vdc testlight (preferred) check for Battery_Voltage_(B+) on the following pins (use battery_negative terminal for ground):
D1_5:  B+ (Hot at all times)
D1_6:  At KEY ON only (B+ (Hot for 2-3 seconds)).
D2_4:  B+ (Hot during KEY ON and Hot during CRANK).
 

 

We just tried these tests. It did not have power at D1_5 or D1_6, but did have power at D2_4 during both key on and crank. What does this mean?

[Ωhm]

Find C103 on the Engine Harness Side. Don't confuse with C105. Both are 6pins. C103 will have a RED wire in C103_B. Disconnect C103 and measure for (B+) on pin C103_B (Engine Harness Side). If you have NO VOLTAGE, then you have open circuit between C103_B and fusible links (starter relay).

 

 

[JZLAJeep]

1 hour ago, Ωhm said:

Find C103 on the Engine Harness Side. Don't confuse with C105. Both are 6pins. C103 will have a RED wire in C103_B. Disconnect C103 and measure for (B+) on pin C103_B (Engine Harness Side). If you have NO VOLTAGE, then you have open circuit between C103_B and fusible links (starter relay).

 

 

Thanks! There is power at that pin.

[Ωhm]

Connect C103. On the Engine Control Harness Side look for Splice_E (circle with E in it). Make sure Splice_E has all good connections (RED wires). Backtrack wire from D1_5 to Splice_E for location of this splice. Measure for (B+) on Splice_E. Looking for Splice_E to be HOT at all times. If repair is needed at splice, disconnect Battery_Negative_Terminal before beginning repair.

 

 

[JZLAJeep]

I just pulled out this relay because it was clicking almost constantly. It was way to the left in the drivers footwell. Now the jeep primes the fuel pump, starts, and stays running. Hallelughah! I have no idea what this relay does, other than keep my jeep from running.

 

The numbers on the relay are 8343  and 25523703.

[cruiser54]

Horn relay? 

[JZLAJeep]

Still running into issues. After removing the relay the Jeep would run, but would still shut off after a few minutes. Based on the tips, bypassed the fuel pump ballast resister with a piece of wire between the clips and it seemed to work if the connection was just right, but would still shut off. Tried again today clipping off the clips and no better performance. So it seems there is still something else that keeps it from starting reliably and stay running. Encouraged by the progress. Discouraged by not solving the issue yet.

[JZLAJeep]

Going back to the original title of this thread, could this be associated with the crankshaft position sensor? We used the crankshaft position sensor and flywheel from the Peugeot transmission in the AX-15 as we understand we needed to do, but it's got me wondering if that is part of what is causing the issue. Seems cheap enough to replace it just to rule that out, but what else are we missing?

[Manche757]

Where is the committee? Someone help this guy out.

[cruiser54]

CPS can be tested.  

 

CRUISER'S MOSTLY RENIX TIPS

RENIX CPS TESTING AND ADJUSTING

OCTOBER 30, 2015 SALAD 131 COMMENTS

Renix CPSs have to put out a strong enough signal to the ECU so that it will provide spark.

Most tests for the CPS suggest checking it for an ohms value. This is unreliable and can cause some wasted time and aggravation in your diagnosis of a no-start issue as the CPS will test good when in fact it is bad.

The problem with the ohms test is you can have the correct amount of resistance through the CPS but it isn’t generating enough voltage to trigger the ECU to provide spark.

Unplug the harness connector from the CPS. Using your voltmeter set on AC volts and probing both wires in the connector going to the CPS itself as shown in Figure 2 as Connector A, crank the engine over. It won’t start with the CPS disconnected.

You should get a reading of .5 AC volts.

If you are down in the .35 AC volts range or lower on your meter reading, you can have intermittent crank/no-start conditions from your Renix Jeep. Some NEW CPSs (from the big box parts stores) have registered only .2 AC volts while reading the proper resistance!! That’s a definite no-start condition. Best to buy your CPS from NAPA or the dealer.

Sometimes on a manual transmission equipped Renix Jeep there is an accumulation of debris on the tip of the CPS. It’s worn off clutch material and since the CPS is a magnet, the metal sticks to the tip of the CPS causing a reduced voltage signal. You MAY get by with cleaning the tip of the CPS off.

A little trick for increasing the output of your CPS is to drill out the upper mounting hole to 3/8″ from the stock 5/16″, or slot it so the CPS bracket rests on the bell housing when pushed down. Then, when mounting it, hold the CPS down as close to the flywheel as you can while tightening the bolts.

Another little tip to save tons of aggravation is to stick a bit of electrical tape to your 11mm socket and then shove the bolt in after it. This reduces the chances of dropping that special bolt into the bell housing.