4.0L swap starting problem

[Bucks86Renegade]

Hello, I've been trying to get my Jeep started for a while now and was hoping someone who has done the 4.0L swap can help me diagnose why it isn't starting. Here's what I've got:

'93 Cherokee 4.0L engine, ECM and AW4 auto tranny with '93 engine harness and under-dash harness, E2000 fuel pump using the fuel lines (main and return) from a '93 Cherokee- all installed in a '86 CJ7 .

The engine turns over and will sometimes start and run for 1-2 seconds.
Fuel pressure at rail is at 40 psi, timing verified with a timing light.
I've checked my grounds with a tester light.

Here's my compression readings from cyls 1-6:
89, 155, 142, 170, 125, 123
I don't think that they're too low for it not to start, but tell me if I'm wrong.

Any ideas why it might not be starting would be appreciated. I'm out of ideas.

 

[mtnwhlr]

My only thought would be the crank trigger. Where did you mount it?

 

[Bucks86Renegade]

Thanks, but I'm using the crank position sensor that came with the engine and AW4 tranny so I didn't have to reposition it. I've already replaced it with a new one, but as I understand it, a bad CPS would not give me a spark. No?

Here's another question, if the gear set was installed incorrectly, or not at TDC, would I still get the timing light to flash when the #1 cyl was firing?

Currently, the timing light flashes for the cyl #1 when the harmonic balancer hits 0. I was wondering if the gear set could have been installed when the timing was 180 degrees out. I bought the engine and tranny from a Jeep being parted out. It looks to have been rebuilt before I bought it.

 

[AussieCJ7]

Runs for a few seconds then dies is sometimes the PCM missing security input. If it is you will need to get the skim code removed or a non skim model PCM

 

[mtnwhlr]

Runs for a few seconds then dies is sometimes the PCM missing security input. If it is you will need to get the skim code removed or a non skim model PCM

This is very possable. If it runs for a few seconds your timming is fine.

 

[Bucks86Renegade]

Thanks for the suggestions fellas, but the cherokee ECM doesn't have the alarm/security feature like the grand cherokee ECMs. I've tried three different cherokee computers (years 95, 93, 92).

By the way, the engine doesn't always start. I just tried to start it and it combusted for what seemed like one cycle. Repeated attempts at starting douses the plugs with gas and they won't fire until they dry out.

I think I have a weak spark or not enough spark to detonate the fuel.

My buddy helping me thinks it fuel related- such as too much fuel. However, I'm using a recommended fuel pump for this swap (E2000), using the cherokee fuel lines and have a new fuel regulator at the rail. Fuel pressure is good at the rail. My return line feeds into the tank and I have a vent line open to the atmosphere for now.

 

[AussieCJ7]

Thanks for the suggestions fellas, but the cherokee ECM doesn't have the alarm/security feature like the grand cherokee ECMs. I've tried three different cherokee computers (years 95, 93, 92).

By the way, the engine doesn't always start. I just tried to start it and it combusted for what seemed like one cycle. Repeated attempts at starting douses the plugs with gas and they won't fire until they dry out.

I think I have a weak spark or not enough spark to detonate the fuel.

My buddy helping me thinks it fuel related- such as too much fuel. However, I'm using a recommended fuel pump for this swap (E2000), using the cherokee fuel lines and have a new fuel regulator at the rail. Fuel pressure is good at the rail. My return line feeds into the tank and I have a vent line open to the atmosphere for now.

What is the ASD (auto shut down relay) doing ? if it is getting a signal to shut down before it dies you can work back to electrical/sensor issues if it is not then look at spark fuel air

Do you have a factory service manual there is a good description of sensor and inputs to follow through

 

[doublec]

I would check the ballast resistor, it kicks in to reduce the noise and heat generated when the fuel pump is running. Most likely it's missing or not hooked up.

 

[Bucks86Renegade]

Ok, I believe I've read about the ballast resistor. Where should it be located? Thanks.

 

[doublec]

I bought my harnes and doner head from separate people, never saw the doner vehicle. I have a CJ7 and the parts came from a 91 XJ. Someone else maybe able to chime in here on the physical location. I think it's located on the passanger side on the fender well on the XJ.

However, on the setup I have the resistor connected between the fuel pump relay pin 87 and the balast relay pin 87A. These are located on the power distribution box.

First time doing this but I created the attached drawing to help me. This should be good for a 4.0 1991-1996

 

[CJ]

FYI - the ballast resistors purpose is to reduce the voltage to the coil during normal running operation (not during a start) from 12v to about 7v to enable longer life and less heat in th coil.