I got spark and fuel but it will not start

[bmwracing_6]

I got a '91 GSX with a JDM motor and I have a spark and have fuel and the engine turns but it will not fire what could this be. I took the fuel line off to see if fuel was coming through and it was. It cant be out of timing cause it ran 2 hours earlier for about 5 mins and then I came back and it did not start. This car has not been on the road yet because we just got the engine to run recently. Thanks Justin

 

[LTUDSM]

1st thing is to check your plugs,after that check your compression,when you do this came back and post your results

 

[hopwoodp]

Here is a few things too consider: If your Engine coolant temp sensor is unhooked or just malfunctioning the car won't start(like when your car overheats, the engine shuts of), check coolant level, electrical connections, correct firing order and make sure you got enough juice left in the battery to crank the engine over. If none of those work, let us know and tell us what else you may notice.

 

[eclipsh]

Spark plugs and compression are good ideas but I'll throw a few more at you.

Internal combustion engines need three things to run: fuel, spark and air. Make sure your intake and throttle body are still working right, no loose cables or excessive fluid in the intake. A big puddle of something in a side-mount could prevent starting. It is not a likely factor but I would still pull the intake pipe off the throttle body and see if it starts temporarily. I'd also spray a little fuel into the intake at this point to see if you were running lean due to issue two:

Do you have a fuel pressure gauge? You may be getting too much or too little fuel resulting in the car not starting. It should read around 37 lbs while cranking. Our cars don't run the pump unless the engine is cranking or running, not just in the "on" position. If needed you can bypass this by feeding battery current directly to the pump to get your reading.

Have you checked the strength of your spark on all cylinders? It may be too weak to start the car or you may not be getting spark on all four cylinders.

If you have a data logger it will be invaluable at this time. It can tell you if the ECU has any error codes stored for you, such as not receiving a MAS or CAS reading.

Hope this helps!

EDIT: IF you are going to jump power straight to the power feed of the fuel pump, please do it with a 30A fuse in line in case their is a short somewhere.

 

[steve]

I got a '91 GSX with a JDM motor and I have a spark and have fuel and the engine turns but it will not fire what could this be.

So, Justin. What's different from the last time you posted this.

Did you fix up all the problems with your wiring harness?

Steve

 

[bmwracing_6]

Yes the wiring harness is good Steve cause it cranked up and idled however it was ruff but i did not have the vacuum lines hooked up at that time. But it does have a strong spark and it should be shooting a good amount of fuel because i can smell it when i start the car. I will see if i can do a compression test and post back up here tonight if possible. However i dont see why the compression would have changed for just idling for a couple of minutes. I also have another question about a vacuum line. There are 2 small vacuum lines coming from the intake manifold a red and black line I see the black one on the diagram but dont see the red one does anyone know where this line is going to?

Thanks, Justin

 

[bmwracing_6]

Well this weekend I was busy so I did not have time to work on it. However I do remember that when the was engine shut off for the last time (while shut off) I noticed some sounds smilar to cracking. Is it possible that the head may have cracked? Which could be causing low compression and making unstartable. I am just throwing it out there cause as of now it is the only thing in my mind that could be a possible senario.

Thanks, Justin