My car only starts off starter fluid but runs fine after

My car has a 89 mustang engine swapped inside of it. it doesent want to start under its own fuel and needs starter fluid to get it running but runs fine after that. I have no clue what the issue could be but i need help badly

Is this a fuel injected engine? if so, this might help…

Testing for a failed fuel pump check valve - YouTube

how about some more info on this.
Has the engine ever started on it’s own with this 89 mustang engine? What engine is this? What car is this? What other modifications have been done?

this sounds like it could be a mix-match custom job, so advice of folks that can’t actually see the car may be a bit of a challenge.


Its inside of a 91 300zx and i believe its fully stock besides a switch for the fuel pump and the cold air intake, and the straight pipe with open headers. since i got it it has never started on its own without starter fluid but it runs perfectly fine and drives after, the second it turns off it needs starter fluid to go again. The only other issue is when i tap the accelerator its very slightly delayed of a response but that could just be how older engines are i have no clue

Does the fuel pump produce enough pressure? I believe it should be 40 psi.

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All I can add is does the pump turn on for a few second when the key is turned to run but not yet the start position? It should come on to prime initially and once the engine starts the pcm commands the pump to run.

Yet you bought it anyways. I’m not even trying, I’m out.


Hi @infogic2020_183170

This past thread may be of interest to you.

I’m not saying your car has the same problem, but you may want to test your CPS.

its a track car and i didn’t specify ask for your help to begin with so :wave:

ill have to get a kit to test the fuel pressure but from what i’ve seen thats most likely my issue

I’ll check for any similar issues I’m having in there, thank you!

its on a switch so i have to manually turn on the fuel pump regardless of the key being in or not

Since it’s a track car you probably have access to equipment and are capable of troubleshooting it yourself. Put a pressure gauge in line with the fuel line near the engine and see what the pressure is when you activate the pump. It’s always better to read near the center of the gauge pressure span. Use a gauge with a max of between 60 and 100 psi. I’m sure that you can do this and return the configuration to normal in way less than an hour.

Do you know, did they swap the proper engine control computer over when they transplanted the engine? Beyond the correct fuel pressure, I’m thinking some input sensor or cold start control isn’t quite right- coolant temp sensor, IAC function, etc. Just to be clear, it does this whether the engine is cold or hot?

I know they swapped the correct computer over with the car, that was one of the first things i checked

i just bought a fuel pressure gauge to check

Might be worth a try to ask helper to partially obstruct tail-pipe while you crank the engine as an experiment, to see if that helps the fails to start problem. Could be too easy for engine to move the air/fuel charge out of the cylinders at first w/ straight pipes, need a little exhaust system back pressure to keep it in the cylinders long enough to ignite.

Good idea to verify spark plugs are sparking during cranking as well. Some fords (my ford truck for example) use a different method to power the ignition circuit during cranking vs running.

George, don’t you think the closed exhaust valve would provide a little “back pressure” in the cylinder?

Is this how race car engines are stated in San Jose?

It’s ok w/me if OP doesn’t want to try it.