2G 98 Eclipse Spyder GS AWD Conversion Stalling/Dying

[n7k1]

I've got a 1998 Eclipse Spyder GS and I've done an AWD conversion on it. This has been on my bucket list to do since I first saw a 2G Eclipse Spyder over 20 years ago in Cali. They never sold the Eclipse or the Spyder up here in Canada in the 90s.

I've kept the 4G64 non-turboed for now. I'll be tackling the turbo in the fall. I had originally kept the 4G64's first catalytic converter under the oil pan and bolted it to the AWD's stock exhaust which had it's own catalytic converter. The AWD O2 sensor is after the cat and not before it like with the 4g64. The engine ran fine until it got warm. After that, the original 4g64 cat under the oil pan started popping, sizzling and smoking. I took it out and clamped on a straight elbow as that's what my AWD donor car had. I'm running the single cat converter now.

The car starts ok and runs ok for awhile. After I filled the tank and the engine was warm, it started stalling/dying on me around 3000rpm while driving and giving it some gas. The car starts back up and I keep going but it will die again a few minutes later. The exhaust sounds like it's congested. I've cut the cat out to inspect it. I can "barely" see through it with a light. I'm going to straight pipe it and test it out this weekend.

Some other notes: I've kept the stock harness. As part of the AWD conversion, I did this fuel pump re-wiring: https://www.dsmtuners.com/threads/gs-t-to-gsx-fuel-pump-splice.403857/. I also kept and put FWD fuel vapour purge valve behind the side panel. I also took out the cruise control.

I'm wondering if anyone out there has done a AWD conversion on a Spyder GS and can tell me if I've missed anything. I'm wondering if its the fuel pump relay module. I'm thinking of doing this mod: https://www.dsmtuners.com/threads/4g64-spyder-gs-fuel-pump-relay-module-bypass.497574/

This forum has been awesome getting me this far. Thank you in advance.

 

[DogWhistle]

It could be that GS fuel pump relay module, if the PO left it installed. Your fuel pump rewire would still require voltage on the fuel pump circuit to trigger the new fuel pump relay.

Normally, the GS fuel pump relay fails a little sooner, as the cold engine goes from open loop, to closed loop. And it does not run when the GS fuel pump relay module is hot (not functioning), so if it did restart, it doesn't run for very long.

You could well have some other contributing factor, but why not remove the old relay and eliminate the problem, or potential problem? Remember, if you are still using the 4G64 black box ecu, the fuel pump will now run anytime the key is in the "On" position, because the ground is not through the ecu, like it is on the 4G63 ecu.

 

[n7k1]

Thanks for the responses. I've got a straight pipe to replace the cat and see if that's part of the issue.

Regarding the fuel pump module, should I have replaced the fuel pump relay when I put in the AWD fuel pump? I'm still running the stock fuel pump and relay from the Spyder GS 4G64 with the AWD fuel pump.

Also, if I do the fuel pump relay module bypass, are there any downsides to the fuel pump running when the key is in the On position?

Sorry for the questions, I don't quite understand this side of my AWD conversion.

 

[n7k1]

My cat is off, and I bypassed the fuel pump module. The problem still exists. I think it's the fuel tank pressure. I removed the cap and there was some pressure relief. After that, the car seems to run fine. I'm going to look at how I plumbed the fuel tank line coming out of the safety valve at the top of the gsx tank.

 

[n7k1]

In case this helps someone else in the future, my problem was that I connected the line circled in red back to the engine bay/intake. It's supposed to go to a charcoal canister. Most AWD conversions leave it disconnected/vented.

 

[n7k1]

Rather than just vent the line, I took the old evap hoses from my fwd tank and modified the evap hose bracket to accommodate a different charcoal canister I picked up off Amazon. I extended the hoses and the solenoid to the right rear corner and mounted it to the frame.