279 replies to this topic

[Old School REX]

Either buy a noid light(very handy tool) or just put your volt meter on the plug and turn it over.

This is what I was going to try next... pulling the plug, turning the car over with the volt meter hooked up. I hope my grounds are good... but man it really seems like they are just weak, like everything electrical is not getting the proper voltage. There are just so many variables with all the work I've done. With my battery relocation all the way in the back of the car, I began to worry if this was the problem; so I switched by to my stock battery, but in the same location. It seems better, but not totally.

Here's how the main battery is grounded. I ran the negative cable all the way up to the front of the car and to the frame rail beside the tranny, this is linked to the ground strap for the main engine harness that goes to the thermostat housing and on the tranny grounding ear thing. Should I have a second ground for the main battery? Say one that is alot closer to the battery? I fear that might be my problem... Easy fix, so I hope thats it really...

[DEIVIONCRX]

For my battery relocate i ran the 2g ground up to the radiator core support, removed the paint in the shape of the cable lug, then bolted it down. I then ran my normal 8g wires from the valve cover to the core support, and from the transmission bracket to the frame rail.

Make sure you take the paint/rust off where your ground hits the body. Also make sure youve got the thermostate ground bolted tight, that is THE ground for all the ecu sensors.

You might check and see if your coil is good. Resistance between the 2 small screws + and - should be around .7-.8 ohms. Then between the + and the output should be about 15,000-20,000ohms. If its lower or higher then you should suspect the coil.

Also the 3 sensors in the distrubitor should be about 370ohm each.

[Old School REX]

Thanks ALOT Devion for that... I'll check it when I get home, as of right now I'm in Atlanta GA going to drift Atlanta!!

[Old School REX]

Still having trouble guys... I will upload some photos later, but for now I will describe what I have done. I am using the factory CRX battery for now, as it has more juice for troubleshooting. it is grounded twice. Once down to the seat belt bolt hole for now and again up into the engine bay on the passenger side frame rail. then the engine harness is grounded to the thermostat housing and the ground strap on the tranny bracket is tied into the same bolt for the battery ground on the frame rail. I have not put a strap from the valve cover to the radiator support yet, but i didn't really think that matterred just to start the car. Now that I have got it all wired up, I went to start the car yesterday (or try to again) and my main fuse next to the battery (a 100amp unit I added to the main hot wire from the battery) POPPED when I hit the starter. And I am STILL getting a weak fuel pump prime. Like the battery is dead, but its freshly charged and everything else electrical works fine. What are some other grounds I may be missing, as I can not think of anything else!!???

Are there any more grounds in the engine bay that I could have missed?

thanks guys

[Old School REX]

Here are the photos...

All I had yesterday was my camera phone so....

The battery and its two ground wires (I know... one is red... its all I had laying around... lol)


Scraped off the paint under the seat belt bolt and used that for now as the second ground.


Main ground goes up and into the engine bay on the frame rail, and also ties into the tranny ear ground.



Power wire goes into a fuse block before running to the starter. And here is my shame, the blown 100A fuse... why???





You know what I just realized however... I did NOT bolt the engine harness ground to the thermostat, I grounded it directly to the tranny ear bracket thing that ties directly to the main battery gound on the firewall.... Could that be the problem? Is that unacceptable? Must it be grounded to the thermostat housing???

[DEIVIONCRX]

It just needs to be grounded, i always ground it to the Thermostat housing, but that shouldn't have a problem at the transmission. Might move it for shits and giggles but it shouldn't be a problem. But i do know if its not properly grounded you wont start for sure.

[Old School REX]

Wonder why I popped the main fuse? It only popped when I hit the starter... and I tried starting it for hours a week ago and it was fine. The only thing I changed was the addidtional ground strap to the seat belt bolt and the jumper strap from the frame rail to the tranny ear.

[DEIVIONCRX]

IF your popping fuses you've obviously got a problem. Having said that, 100amp might not be enough, but I'm not 100% sure. I got a 150amp circuit breaker for mine.

If your blowing fuses you've got a short somewhere. With the weak fuel pump and shit you've got a parasitic draw somewhere as well, could be one in the same. Or a bad ground.

If you've got a spare starter swap em out.

But it really sounds like a bad ground, or a really weak battery. Or possibly your loosing too much current on the cables.

[Old School REX]

Alright... I got two of my problems figured out today. The fuse is no longer popping and the starter is turning strong with a good battery. Everything is working as it should! However, I am still getting a really weak fuel pump. The problem was my main battery ground. Thanks Devion!

My question is this... what are the pins on the ECU that are for the fuel pump control? I wonder if I have them grounded properly or something... On all the tables I have, there is no mention of fuel pump power or ground specifically, so I'm assuming its routed in with something else.

[Old School REX]

Also thought it would be helpful to note this as well... I do NOT have any kind of O2 sensor hooked up at this time. Just haven't bought an OBD1 O2 yet; but Ive seen plenty of cars run fine with bad O2's... however one not even connected?? I dunno...

Then there is this. I have the two plugs (big long and little square 4-pin) that go to the factory "black box" disconnected. I did try just plugging it in real quick to see if there was any change in the fuel pump primming or the car starting, but there wasn't. For the future reference for a code free car, will I need to remove and use anything in the "black box"? Isn't there a purge cut-off sol. valve in there or something?

[DEIVIONCRX]

OBD1 nothing in the black box matters.

The fuel pump on OBD1 has one wire that needs to ground to run the fuel pump, Its A7, the other wires run through the main relay. So check both.

[Old School REX]

Okay, but I didn't actually touch the main relay in all my working... so I doubt there is a problem there. However I will check it when I get the chance. Its up behind the fuse pannel drivers side under dash right?

[strudel]

The Main Relay starts the fuel pump but if you don't have the ECU grounded at the thermostat housing that may be a cause. The ECU takes over after the prime starts. I know of a complete write up on how that system works on my Mini site somewhere but would take a while to find. Actually found it very quickly by paging back about 4 pages in one particular problem thread. JS

Lots of good stuff above.
And yeah, the 'twinkie' is only OBD0, OBD1 and beyond dont use this.

Going back to the main relay option... while its doing the fuel pump side of things correctly, it does tell the ECU to do things too.
It for one supplies power to the ECU. Have you confirmed there is 12V on both of the ECU power pins, and ground on both too? +12V is A25 and B1 (using normal OBD1 counting, not your crazy diagram counting ), and ground is A23 and A24. You should also check that D1 has +12V also, and this is a constant power (not ignition switched). D1 is the ECU Voltage Backup pin.

B9 is powered via the Main Relay when you crank the engine, it tells the ECU when your cranking, and to start injectors, fire the spark etc... might want to check that this isnt intermittant...

A7 is grounded internally to the ECU when you prime, and then disconnects (open circuit) when priming is complete. Then when you crank the engine, it will ground internally again and should stay grounded from this point I think. It knows to do this via the B9 pin that you are attempting to crank it etc. I am 99% sure it will ground and then open circuit for priming, and then ground and stay grounded for running, so the pump stays running constantly. Again, something to check...

A21 is the signal that goes to the dizzy to fire the ingitor... you should check that this does goes +12V when you are cranking the engine. You may have done this from the dizzy end already though.

Injectors. These are powered directly on one side, and are grounded via the ECU on the other side. The ECU controls the firing of them by switching the grounded side. The positive side should all be connected together, you may have checked this voltage already - but I think you said its fine and wont effect your spark anway.

Just a few things to ponder..

Edited by strudel, 16 May 2010 - 11:18 PM.

[Old School REX]

Thanks a lot for the responses guys... I'm going to look into everything you mentioned either tonight or tommorrow evening; ill report back my findings.

[Gabe87CRX]

Thanks a lot for the responses guys... I'm going to look into everything you mentioned either tonight or tommorrow evening; ill report back my findings.

I hate to chime in like a moron but.... the fuel pump is only an inline pump on these cars... and those posts on the pump DO get corroded and icky...

Have you removed the pump to check it?