engine starts then turns off in 2 seconds...
 

brief history.. the car sat for 3 or so years, i installed a fresh rebuilt engine. ran great. drove it maybe 50 miles on back roads, everything cool, starts every time.. turn the engine on next day, warmed it up, everything cool... few days later, i try turning it on and it turns off right away and it's been doing it ever since...

i have no idea where to look at this point

it has code 26 (omp) and code 38 (warm up solenoid)

i ohmed out all 7 wires from omp plug to ecu plug, all good

tried 3 different omps, tried 2 ecus, same results.


it also backfires when dying.. so i guess computer cuts off fuel..

im also running premix.. other than that its 100% stock

code 38, im using JDM intake with no solenoid, i dont think it has to do anything with my problem..


it seems like the problem is CAS, but wouldnt it trow a code?

Hi,

what about your fuel pump ? It's like your fuel system has no pressure ... Enough to start the engine when you wait a bit ..

I don't think for the solenoid since you ran the car before without problem.

fuel pump works, but the ECU is turning it of after the engine starts..

i can start the engine lets say every 5-10 seconds, but it wont stay running for more than 2-3 seconds.. starts up every time tho..

You might try putting a jumper from the F/P terminal to the ground terminal in the Diag box then turn the key on. The pump should run and you should year fuel circulating. If that's OK then try to start the car and see if it continues to run. This will help isolate the problem if it continues to run.

i forgot to mention, but i already tried that. the pump turns on and the car starts, but it shuts off right away..

the odd thing is, why im getting code 26? OMP, ECU and all connectivity is good.

i searched for hours last night. on few occasions people get code 26 but always along with code 27, never 26 only.

im going to diagnose CAS, lets hope for better results..

Check all the wires running to the ECU especially where they connect to the ECU and make sure the insulation is good. Do you have anything piggy backing off of the wires that run to the ECU?

Make sure the EGI relay is working properly although w/o this working you should'nt have any pressure at all so that's probably not it.

Last resort. Try running a hot wire from the fp directly to the battery to bypass the ECU :) I wouldn't leave it like that until you figure out the issue but if it works you'll definitely know something is interfering w/ the power to the pump. I doubt it has anything to do w/ the CASs.

no, it's all stock, stock harness to the stock ecu.

the wiring looks good, although the wiring sat outside in the weather when i first pulled my old motor out maybe 3 years ago, for maybe a week. it ran fine, no symptoms..

i noticed yesterday that the exhaust overheat light was on, when key on, i dont remember if thats normal.. i guess it is..

im pretty sure it's a fuel issue, cuz it backfires when dying..

i still dont understand whats up with code 26... how do i get rid of this thing? it's there before i crank the engine..

Check the electrical lines from the OMP. Verify that they didn't rub on a belt and get damaged.

i'll do that. however, i have 3 different OMPs. it doesnt matter which one is plugged in, i get same results.. code 26 before cranking..

continuity between OMP plug and ECU plug is good. all 7 wires. 2 B/W at OMP plug get 12v from the relay as they suppose..

i have 2 ECUs, same thing... code 26..

bottom line, im not even sure, if the code 26 is reason, why my car is shutting off..


i'll go work on this thing, see u guys in few hours or so :)))))

As was suggested, the problem may be in the wiring. I've had instances where rubbing caused some of the wires to cross-talk. Follow the OMP wiring across the front cover and over the top and see if there is something wrong there. You might also want to make sure the wires didn't push back inside the connector which would prevent them to make contact when connected to the OMP. You're right though, 26 and 27 usually go hand in hand and even then, you'd think the car would go in limp mode but not shut down.

Here is a test you can do to verify all of the ECM connections are OK

Disconnect ECM connectors 1 and 4 and take a resistance reading between the following ECM harness points; they should all be 16-31 ohms.
1B and 4I
1B and 4J
1B and 4K
1B and 4L

Now leave ECM connector 4 disconnected and disconnect the MOP connector next to the power steering pump. Verify no continuity at ECM connector to ground as follows:
4I to ground
4J to ground
4K to ground
4L to ground

Lastly verify no continuity from the MOP connector pins A through F to ground

I think if this checks out you have a ECM problem as far as the code 26.

ok so i just installed another wiring harness, i bought yesterday for $400

code 26 is gone.

but the car still shuts off....

i'm moving and i need to move this car.


anybody got any ideas? ima gonna wire the pump and see what happens...

Pull the voltage at the pump to see if the pump shuts off when the engine does and if it shuts off due to a loss in voltage signal. If so, go with what Fritz recommended in post #6 as a temporary measure to help you move the car.

If you do lose voltage at the pump after the car starts, your problem is quite simple to rectify. Check out this thread, specifically post #23. This is the basis of a fuel pump rewire, but the diagram will help you go through the system. Again, this is assuming you have a fuel related problem and that will be established when you check the voltage at the pump.

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/how-increase-fuel-pump-performance-401691/

This same issue happened to me before and it turned out to be that my map sensor was connected. You could check that.

I had the same problem as WaachBack. After we compression tested my engine, it would start no problem, run for a second or two, then die. After going thru the same sequence a number of times, we found we had accidentally knocked loose the tube for the MAP sensor. After we put the tube back on, the engine ran fine. The MAP sensor is on the firewall next to the brake cylinder (on the engine side). It may not be your problem, but it's easy to check.

problem resolved, car runs excellent...

thanks to everyone who helped.

i cant believe i spend $400 for wiring harness, $80 for ECU, $75 for fuel press gauge, wasted 2 days and the problem was somewhere else...

lesson learned, at least now i have no check engine light and spare wiring harness and ECU to sell..

^ uhm, what was the cause of the problem and what did you do to fix it?

Was it the map sensor unplugged or fuel pump wiring .. or something else?

the map sensor, pump, ECU, wiring, everything was good.

it was like the stupidest problem ever.. im embarrassed to say...

ahh operator error? no worries.. im sure many others have similar "doh!" moments... for example, my car has an ignition kill switch, and I remember one late night, spending 15 minutes with a friend helping me no less, figure out why the car wouldn't start... needed to put the kill switch key in place and VOILA! It was like putting another quarter into the Super Sprint video game (very ol'skool), lol.. if anyone remembers that game, the animation would show the car would fire up and the guy sticks his hand out the window for a thumbs up!

That's exactly what this forum is for... If you did it, chances are someone else has or will so post up the issue so someone else doesn't have to go through the same headache (i.e. help someone who searches and finds this thread).

+1 on the answer, do it for someone who is having the same problem not yourself.

Glad you got it fixed, but inquiring minds need to know what it was....crossed fuel lines??? A plug somewhere that you might have forgotten to remove?

As others have suggested, there's always someone else who might benefit from our mistakes. I remember a forum member who was chasing a nasty vibration problem, blaming just about everything under the sun from using the wrong rotors, counterweights to bad mounts, plugs, fuel, ignition....and it ended up being a sheared key on the back end of the e-shaft which allowed the flywheel to assume a new angular position.

Interesting. I'm having the same issue. Every time I start it in the morning or rather for the first time in at least 24 hours it will start and as the revs are coming back down to idle it just shuts off even if I hold the revs above idle it still just shuts off in 2 seconds. However, unlike your issue, when I try to start it again after it dies, it will start just normally and run forever after. Even if I purposely shut it down and restart it runs just fine and starts just fine for the rest of the day. This all started when the cold weather came in.

I'm having RP tune the thing soon so I'll ask them to take a look at it, but it confuses me. I want to ignore it, but I know thats not a good idea.:dunno:

quit yer bitching texas man, come up here and see what REAL cold is like, we didn't break 0F until noon yesterday, it was -10 when I got to work at 10am today.

Lol... I need to know what he fixed. I probably did the same thing.