Tricky SR20DET No Start Issue (puh puhhleeazee halp)

modestmouse · 03-12-2010, 11:16 AM

Hey all,

I am helping a friend try to get his 240 back on the road and we're having no luck getting it to start. I'll try to make it as unfrustrating as possible because these threads are tough for me to read too! Here's the back info to help you out...

The car is a 1991 240 that was originally auto. The car was swapped by a sketchy shop but the engine was running well up until one day my friend decided to swap the terminals on the battery (for new ones) and said that when he finished, he tried to start it and it wouldn't start. It blew the 75A fuse but it was replaced after. It will turn over but shows no signs of starting (no fuel or spark). I've checked the terminals, the fuses, and the underhood relays. I swapped relays with my car and it could crank up and run with all of them. When I turn the key on, I can't hear the fuel pump and the fuel lines don't feel like they have gas running through either. The plugs won't fire when a coil is removed and held against a ground while cranking. I'm stuck!

After checking all that stuff I decided that the wiring for the car was just the problem because it was piss poor. It had lots of splices in the harness and was wired strangely so I got a new aftermarket SR harness and wired it up for him (and I triple checked my work) and it still wont start or even trigger the fuel pump.

I'm not an SR guy and I'm obviously not hoss with diagnostic method of electronics. I just know to make sure you have air, gas, and spark. The fact that it is missing fuel and spark and ran right before he dicked with the battery has me stuck. Thanks for reading if you did and please let me know if you have any ideas. I'm dying for some help.

madmax240 · 03-12-2010, 12:13 PM

What do you mean he switched the terminals on the battery? Like he hooked the positive wire on the negative terminal? If so he probably screwed a few things up. Blew relays if he was lucky and a computer if he wasn't quite so fortunate.

modestmouse · 03-12-2010, 05:49 PM

Sorry no that was poor wording. I told him that we should get some new terminals because his were all dicked up from the people who installed them. They were just ugly so he literally switched to new ones.

madmax240 · 03-12-2010, 06:41 PM

Sounds like its time to go through all that wiring. Sounds to me as if though something was sticking,which may have overloaded a circuit which blew that fuse. Check the remainder of your fuses including the ones under the dash. Don't just check visually,double check with a voltmeter that reads ohms(or a dedicated ohmmeter ). The resistance across any fuse should be zero(not to be confused with infinite). Then unwrap the modified connections paying extra special attention to the connectors along the passenger side fender where the battery is/was. It takes a lot to blow a 75 amp fuse,so something went way wrong! I'd take that puppy back to that shop and tell them to make good or to suffer the consequences of a bad reputation and possibly a lawsuit.

Thrasher068 · 03-14-2010, 08:04 AM

How many fueses did u replace? If u blow the 75amp fues chances are that the 5,10,15,20,25 ,30 amp are blown as well..... Also check the fuel pump relay. Then go to the trunk take off the 4 bolts to the gas pump access panel and pry that off the RTV gasket Check i believe it is a Black / Pink stripe for 12V If that doesnt work make a set of lead test wires (Speaker Cable works great because u have a ground and power wire when u run it) with alligator clips and connect them to the batt and ground in the front and the 12v power wire in the back the pump should turn on if it works check the fuel pump relay. As for spark again check the fuses Check the Black w/ red stripe for main ignition power, and red w/ black stripe for the ECU relay FRsports.com harness diagram Now make sure when u turn the key to the on position and u hear relays clicking If not get a test light and pull a relay and make sure u have power at least 1 - 2 areas depending on relay

madmax240 · 03-14-2010, 11:45 AM

Must be a glitch in the matrix,cause I just experienced some dejavouz! Those circuits affected inline only with the 75amp circuit are at risk. Just because you blew a fuse in one circuit doesn't mean you had a total system overload. All your smaller fuses aren't inline with the one big one. If anything the big fuse protected your smaller fuses,but check nonetheless.

bikrman2 · 03-14-2010, 02:41 PM

I had the same problem. check the eccm relay right next to the fuel pump relay. I tested bu putting a jumper wire between the 2 terminals that are closest to eachother

modestmouse · 03-14-2010, 03:31 PM

Hey guys, thanks for the responses and suggestions. I'm going to work on his car again this coming week and I'll see what I can find. I'll start off by making a fuel pump jumper and rechecking all the fuses. I freaking HATE doing electronics work. It's so hard to diagnose something that does nothing when it's wrong. Oh and that shop wouldn't be scared about one owner talking shit about them. It's not like they have a reputation to protect. They are, without contest, the worst shop in the area and I have no idea why this guy got his swap done there.

Thrasher068 · 03-15-2010, 11:10 AM

Do u have access to a PowerProbe? Image from link U Hook up to battery and with the handhelt it will tell u if it has power or ground. U can also can put 12v or gound to a wire with a thumb switch makes jobs easyer. I have one it it was a life saver!!!

modestmouse · 03-15-2010, 08:45 PM

Cool so it's like a simplified multimeter with some additional functions? I don't have access to one but I do have a trusty $6 multimeter woot! I'm going to be working that thing hard tomorrow.

Thrasher068 · 03-15-2010, 11:36 PM

lol i have one of those too, The powerprobe is great though but i had had t buy a few airbags.... and dashboards... and steeringwheels.... Yeah powering up the wrong wire with that thing can be unforgiving....

modestmouse · 03-16-2010, 12:05 PM

Ok, I made a jumper for the fuel pump, it still works. However to recap, the pump still isn't coming on when the key is put in any position. So somewhere between those relays and the pump there is bad wiring?

I checked the voltage across the two closest terminals on the ECCM relay circuit and it had .87 volts. The Fuel pump relay next to it had 11.88 volts across the two closest terminals with the key in the on position. The relays themselves are not the problem, I have switched them out with the working ones from my own 240.

I'll update this post as I do things...

Update, I made a jumper for the fuel pump relay and with the key in the on position, the pump DOES come on. However with the relay in, it does not. Since the relay is good does that mean that the wiring that is supposed to switch it on is bad?

I also forgot to add that the diagnostic for the ECU isn't working because some joker twisted the selector around and around.

Thrasher068 · 03-16-2010, 03:24 PM

Damn that sucks about the connector... Hmm Battery to wires - Key on - ECU Power up - Signal to fuelpump from ECU to prime rail - 12V to relay for pump, 12v to fuse... Do the rest of the car have power? The fuses after the 75amp? Check to make sure that main is tight and not blown Then go to the ECU and try tightin the 10mm bolt on the center but be cairfull not to brake it

modestmouse · 03-16-2010, 05:06 PM

Yeah, it sucks because he's paying for all this time!

I'm actually worried now that the ECU is dead. I need to get a good copy of the FSM and see if I can use their diagnostic chart on the ECU...if there even is a section on that. I made sure that the ECU bolt is tight. I have double and triple checked all the fuses. The rest of the car has power. I'm stuck!

Thrasher068 · 03-16-2010, 06:11 PM

Well you can get a FSM for the 240 at any autoparts store... He has a JDM engine but everything elce is stock locations, wires, and colors for that year and model. The only thing u need is a 180sx FSM for the ECU wiring. You have power to the fuse... Does the relay click on when u turn the key? i know u said u changed the relays with ones in your car but if the relay isnt getting power.... jump the relay... 1 part of the relay should be getting power and ( CLICK HERE FOR FSM ) ... i never though of it but under dash driver side are more fuses have u looked into that too? Worst case is u just run another powerwire to the back off a new relay with the ign switch in. Most race cars have a fuel pump & fan switch so u can turn them on and off before u start the car.

bikrman2 · 03-21-2010, 12:18 PM

put the jumper in the close terminals of the eccm relay. It also controls the fuel pump relay. do it the same way you did with the fp relay. from the sound of it should fire up.

Thrasher068 · 03-21-2010, 06:02 PM

Hardwire it to a switch in the car to turn the fuel pump on race car style

modestmouse · 03-21-2010, 11:57 PM

Thanks for the FSM link but I ended up finding the 180SX FSM in english. I got it at this link for anyone who has had trouble finding it...

http://www.silviansw.com/manuals/S13...x%20Manual.pdf

To answer questions, NO the relays (egi and egi pump) are not clicking. I did check all the fuses on the drivers side footwell but none of them seem to pertain to my problem. Still, they've been checked.

I'm headed to work on the car tomorrow morning...fingers crossed. I'll try using a jumper on the EGI relay (same thing as the ECCM relay I gather) and see if I can't get the car to start. If I can get it going with jumpers, great! At least then i can rule out bad components, however it really just isn't my style to run things to switches as any long term solution. Thanks for all the help guys!

Thrasher068 · 03-22-2010, 09:05 AM

Perm switches in hidden location is a great way to keep your car! If ever broken in to they cant find the fuel pump swith, ECU power switch,,,,, u get the point they have to now rip apart your car where u left it instead of a joy ride to a chop shop and by then some1 will see them and cant get far with armfulls of crap

modestmouse · 03-22-2010, 12:56 PM

So I checked if jumping both relays would work and it does not. There still is no spark, and even though the pump runs (only with a jumped relay), there was no fuel coming out of the injectors.

When I put the key in the on position (or any position for that matter) should there be power going to the orange start signal wire? Just asking because there doesn't seem to be.

modestmouse · 03-22-2010, 02:05 PM

Ok, I finally got somewhere. It finally occured to me that what I should do is emulate what the ecu SHOULD be doing to operate the relays. So I first double checked that the relays had power where they should. Then I checked for continuity with the ecu from the respective relay to both pin 104 as well as pin 4. Both good there. So then I made a long ground cable that went from the engine bay to a pointy tip and I grounded the pins that the ecu should be grounding (doing this with the ecu disconnected) and sure enough, the relays would click!

This in short, means that the ecu isn't turning on what it should turn on even though there is perfectly good wiring. SO my friend needs an ecu and this sucka should fire right up. I'll update when that happens.

Thrasher068 · 03-23-2010, 01:27 AM

Yes prob..... Redtop or black top?

modestmouse · 03-27-2010, 12:39 AM

Its a redtop but he already picked up an ecu. I'll be hooking it up Monday and I'll let you know how it goes.

Thrasher068 · 03-30-2010, 06:59 PM

Any luck?

modestmouse · 04-03-2010, 12:35 PM

Kinda had some luck. The ECU was bad like I thought. Now both of the relays click and the pump comes on when it's supposed to. The injectors are spraying for sure but I'm getting no spark. I'm not getting voltage anywhere on the coilpacks or ignitor. At this point I'm guessing it could be an error in the wiring.