Engine starts but won’t idle?

[cfriedman67]

I have a 1997 mustang cobra engine (fuel injected) installed that ran and idled fine last year during go carting. Today I went to start it and it started but will not idle. If I continue to give it gas it will run but as soon as I take my foot of the gas the engine stalls. Any ideas?

Thanks
Craig

[Joecobr]

I have the 98 cobra engine. Any work done on the engine since go carting? Any vacuum leaks? Bad gas?

[cfriedman67]

Nothing done. Just sitting, there was some gas in the engine that was in the tank through the winter .

[Gordon Levy]

Sounds like bad gas. You may have plugged up the sock on the filter in the tank. It might be a good idea to drop the tank and clean it out, replace the sock on the pump and put fresh fuel in it. Next year, staybill is your friend.

[CraigS]

Sounds like a stuck idle air control valve to me.
https://www.cjponyparts.com/idle-air-control-motor-gt-1996-9-5-2001/p/HW3420/?year=1997&msclkid=ee69c1723639149976419ffbf32f693c&utm_source=bing&utm_medium=cpc&utm_campaign=New%20Bing%20Shopping%20Ads&utm_term=1101201852105&utm_content=All%20Products
I haven't worked on this specific engine but have worked on Lexus/Toyota engines w/ a similar valve. These valves open up while the engine cranks to give a higher idle and then slowly close while the engine warms up. It's very obvious on a cold start but also happens to much less extent on a warm start. Some times they can be helped by removing and spraying out the passage w/ carb cleaner or gum cutter.
https://www.walmart.com/ip/Gumout-Carb-Choke-Parts-Cleaner-14-oz-800002231W/17128883?wl13=1221&selectedSellerId=0&adid=22222222222016740438&wmlspartner=wmtlabs&wl0=e&wl1=o&wl2=c&wl3=10364280044&wl4=pla-1103062142907&wl12=17128883_0&wl14=spray%20carb%20cleaner&veh=sem&msclkid=de4f979c576b139e4e4fc91591c5ca09
Brake cleaner usually won't do a thing.

[cfriedman67]

Thanks everyone for the advice. I found the problem. One of the vacuum hoses was very loose. Tightened it up and all is good.

[Joecobr]

Great feeling when you find the problem...more so when it doesn’t cost anything!