Can't get it to start

[04mystic]

So I bought a 91 SHO as a project car. The motor was bad. I got a used motor off of craigslist to replace it. It came out of a 92. I changed the fuel injectors out with the ones that came with the car. Bought a new clutch and some new hoses. We put the motor back in and hook all the wire up. The car will turn over and it has spark. So the first place I think is the fuel. The fuel rails have pressure. But when you hook the battery up the fuel pump turns on and does not turn off even with out the key on. Which I have never had happen. Does that mean my RCM is bad? The car would start and drive before all this and I used the same rcm that was in it so I'm confused. Does any one have any advice for me? I have done multiple searches and found some info but not on exactly what I'm dealing with. I would appriciate any help you can provide.

Thanks Tim

 

[Northwestvoodoo]

Could be your ccrm. I had a similar problem, mine would start and die if I tried to move it.

Have you pulled the codes on it? Could also be a simple ground issue or CPS, DIS?
Pull the codes and that should shorten the list of possible issues.

 

[04mystic]

Anyone else have any ideas? I got a scanner hook up. But everytime I hook the rcm up it starts tweaking out then smokes. I'm pretty sure there toast but I would like to know if anyone has seen this before if so what they did to fix it. I only see one connection on the back passenger Side of the motor that's not plugged in. Can someone take a look under there hood and tell me if it supposed to be hook up? It's black, round, and has only one prong??? Thank u

 

[rubydist]

the symptom you describe will happen if the connection to the pcm is bad, or if the ccrm is not connected. re-check all those connections.

the connector you describe sounds like one of the ground connections, which you definitely need to have connected.

 

[04mystic]

Well I'm thinking the RCM burnt up because I have the 92 engine harness on the motor still. It's the only thing that changed electrically. Does that make sense to any one. Are they different from 91 to 92??

 

[Eric VerValin]

95% sure they are the same... do you have a decent multimeter to test your grounds? Resistance from say the bottom bolt of your dis to the - on the battery... things like that... you can also check some sensors resistance values ....

Run a wire from where that single wire bolts to the firewall, for the ECU, and run it to the battery. I had my 92 not want to start when I put it all together... just ended up being something simple.. not really sure what I did.. just wiggled stuff, added a few extra ground wires.. and it just worked..

Your car might just be stubborn...


PS... I had a 96 mystic years ago.... how is that leather holding up in yours? Still changing color? Tint? Garaged? I have been wanting another... I can already feel the itch when I read your name... lol

 

[04mystic]

95% sure they are the same... do you have a decent multimeter to test your grounds? Resistance from say the bottom bolt of your dis to the - on the battery... things like that... you can also check some sensors resistance values ....

Run a wire from where that single wire bolts to the firewall, for the ECU, and run it to the battery. I had my 92 not want to start when I put it all together... just ended up being something simple.. not really sure what I did.. just wiggled stuff, added a few extra ground wires.. and it just worked..

Your car might just be stubborn...


PS... I had a 96 mystic years ago.... how is that leather holding up in yours? Still changing color? Tint? Garaged? I have been wanting another... I can already feel the itch when I read your name... lol

Well I'm almost positive that the dis is not the problem becuase I have spark when trying to turn the car over. But the fuel rail is now not getting any pressure because that dame rcm burnt up. But even before the fuel injectors were not spraying which is telling me that the cpu can not communicate with them.

I tried the wiggle technique and almost moved on to the smash technique. haha jk But I read on a post on here that you can not use a ATX engine harness with a MTX car other wise you have to change the RCM out. Does that seem possible?

You had a 96 mystic! I loved them too, those had alot darker color to them and I was really into that body style. But when I came acoss a Mystic Termi I couldn't pass it up. The seats are still in great shape as the car sits in the garage for a large portion of the year. I only have 32k on it which is no where near as low as I would like it but I didn't buy it to store it all the time. lol You should look around at the 03-04 cobras now, they are going for killer prices with low miles.

 

[St Louis SHO]

ATX/MTX harness is completely different...

 

[04mystic]

ATX/MTX harness is completely different...

For future knowledge, what exactly is different about them?. I'm not sure the new harness is from a ATX but I do know that all the same connections are on both. I thought maybe some wires went to different prongs on certain connections but I thought I would ask.

 

[St Louis SHO]

I'm not 100% sure. So you have a 91, and used a 92 harness?

91 has a 2 speed fuel pump. I'd swap harnesses if I were you, then go from there.

 

[rubydist]

For future knowledge, what exactly is different about them?. I'm not sure the new harness is from a ATX but I do know that all the same connections are on both. I thought maybe some wires went to different prongs on certain connections but I thought I would ask.

there are significant differences, enough to make your life painful if you try to use the wrong one. there are circuits that exist on one and not the other, and vice versa. the pcm pinouts are different, etc. etc.

 

[04mystic]

I'm still having problems with this car. Now the fuel pump will only pressure the lines when the battery is first hooked up or when the key turns off after trying to start the car. I'm not sure what direction to go now. I changed the harness bad to the orignal and got another rcm off of a different car that would run. Put it all together and still problems. Does anyone else have any suggestoins because as of right now I'm stuck. Thanks

 

[kevinspann]

What car did the CCRM come out of?

 

[04mystic]

What car did the CCRM come out of?

It came out of a 89 SHO.

 

[220ksho]

'92 would be MTX.
Did you try connecting the fuel pump lead to ground in the diagnostic connector?

 

[04mystic]

'92 would be MTX.
Did you try connecting the fuel pump lead to ground in the diagnostic connector?

No I'm not much of a electrical guy so I'm not sure of what to do. So just take a wire and plug the fuel pump lead to a ground? What will this determine?

 

[220ksho]

Yep, with the key set to "on". Jumping this lead to ground will turn the fuel pump on. If it does not, you either have a pump problem or a faulty inertia switch.

 

[04mystic]

Yep, with the key set to "on". Jumping this lead to ground will turn the fuel pump on. If it does not, you either have a pump problem or a faulty inertia switch.

I'll try this tonight when I get home. Now if the pump comes on what would be the problem? Because it seems like things are completly backwards so.

 

[04mystic]

So when I connect the wire to ground then the fuel pump the pump does not come on but the rcm clicks. What does this mean??

 

[rubydist]

see post #17

then try to reset the inertia switch. if that doesn't help, confirm all wiring to the pump is good. if it is, then change the pump.