So I'm helpin a friend get his car running, which hasn't happened apperently in the last 4 months. I'm a 2gnt w/turbo guy, so the 4g's are a little new to me, wiring and everything. Issue was it'd crank, but no start. I've got no spark, no fuel. Okay, did some searching, came up with the MFI relay. Hunted the bastard down behind the radio and did some probing, found out there's no ground signal comming from the ECM to switch the relay for all the power to the sensors (Crank/cam, MAF, etc). The fuel pump half seemed okay. I tried jumping the relay, and now I have spark, but no start still. I can't seem to find a pressure port to check fuel pressure, as I can't tell if the fuel pump is engaging or not. Possible the fuel pump AND the ECM is bad? Are there any other parameters that tells the ECM to ground out that relay other that just turning the key on? Any help would be appreciated, I'd just Megasquirt the damn thing if it was mine!

Disconnect the fuel line. Turn the key to ON. If the pump is working, you'll get some Old Faithful action from that fuel line. Trust me on this one.

As for the spark the only time I've had a similar situation involved my not even having the ECU in the car. (I had set it on the 1G shell when I got home and just never put it back in.) Might be worth double checking the connection at the ECU, pins and all that.

Have the caps been replaced in the ECU? If you don't know, open it up and look for anything burninated in there. Be sure you do this somewhere the ECU case will not get a static discharge (ie: rubber shoes on carpet, socks on tile, etc.)

Caps? Capacitors? Is there a common problem poppin them? As far as I know (at least that I can tell) this thing has never been touched, as far as an ECU R&R. I'll try the fuel test; I wasn't sure if it did a prime pulse or only when you cranked it. BTW, I forgot to mention (if it matters) it's a '92 Talon. I may go junk-yard shopping and try another ECU if I can find one...

Caps? Capacitors? Is there a common problem poppin them? As far as I know (at least that I can tell) this thing has never been touched, as far as an ECU R&R. I'll try the fuel test; I wasn't sure if it did a prime pulse or only when you cranked it. BTW, I forgot to mention (if it matters) it's a '92 Talon. I may go junk-yard shopping and try another ECU if I can find one...

woah, deja vu.

yes, Brian means capacitors, it's a known issue with the capacitors in the 1g ecu's cracking open and leaking.

Sorry about the double-post! happened when the server was acting up apparently. Admin can delete...

I'll hafta crack open the ECU when I can get time and check it out... Thanks

IIRC there's a pretty big writeup on how to fix the ECU with radio shack caps on DSM.org

well good news is the capacitors aren't melted, but theres like 4 other components around them that are fried. I might try to get a pic up, but I'm more leaning that I'll need a new ECU (hint hint to anyone that has an extra for a 1g turbo!!)

BTW, the 1g cap r&r page is missin on DSM.org...

Originally posted by justins71
well good news is the capacitors aren't melted, but theres like 4 other components around them that are fried. I might try to get a pic up, but I'm more leaning that I'll need a new ECU (hint hint to anyone that has an extra for a 1g turbo!!) BTW, the 1g cap r&r page is missin on DSM.org...

That's interesting. From what I've heard, when the caps go, the shit they leak or smoke out wreaks havoc on neighboring components. You should be able to scoop up a non-EPROM ECU out there for less than $100. Expect to pay more than $150 on average for the EPROM unit if you want one that badly. They have their benefits, but you have to consider your down time.

Okay, on further research/inspection maybe the caps are bad. I've had some on other boards fry, and they literally melt, but these *appeared* ok. Read up on it a bit, and looks like they don't melt, just leak acid onto the board. That looks a bit more like what I have goin on (took some pics, will upload a bit later tonight). And it's not the EPROM version, and the guy isn't a tuner at all so I don't think anything fancy will be up his alley.

put an order in with DigiKey today for the new caps, since RadioShack doesn't carry them... We'll see how it goes when they come it, I'll practice on an old stereo board or something on r&r the components

They're pretty easy to swap out. I did mine in about 1/2 hour.
When I did mine on my 1G. Everything "looked" fine but you could smell them (think rotten fish). Then when I pulled the old ones out, you could see that they were in fact leaking.
Started right up and no troubles again after the fix.

learned how to solder on printed boards and replaced 'em, car fired right up. Only thing is i think i overheated the 100uF one, (had a hell of a time getting solder to soak all the way through the board) and sure enought about half-hour into test-driving it, it died again, no check engine light with key on engine off. guess I'll try it again! There really isn't another chain store that carries those type of parts? Fry's maybe? or is just a location-specific thing and ya might luck out with a distributor? just sux payin $10 for a $.20 part after shipping

Originally posted by justins71
just sux payin $10 for a $.20 part after shipping

Cost me $11 and change IIRC. But I also got like a 5 pack or something. God knows what happened to the extras... :(

I can get an ecu if you need one I have a 1g gst parts car (its a 90)

pm me.

So here's a pic of that board, I think this one's fried as it looks like there's too much that the bad capacitor leaked on.


It ran like 5-10 minutes with the new caps, then died again.