Stalling after smog pump delete and x pipe

dscolastico07 · Sep 5, 2021

Just removed smog and added catless x pipe on 95 mustang. Car cold starts fine ans drives great but when restarting, car stalls unless i feather gas for a few seconds. Never had this problem untill removing smog and adding x pipe. Car is stock other then 75mm tb, cai, and now x pipe . Any ideas?

Chythar · Sep 6, 2021

Did you remove the rest of the smog equipment, like the hoses and such? There's a metal pipe going to the back of the heads that adds air into the cylinders at startup, I believe. If you don't block off the pipe you'd be allowing unmetered air in to the cylinders. I don't know exactly how the added air at startup affects how the engine runs, but it's possible you may need to get a tune. Hopefully someone else will chime in that has more info.

dscolastico07 · Sep 6, 2021

Yes. I removed everything . I plugged heads with thermactor plugs and propely capped off the 2 vacume lines coming off the old smog equipment. Also used high heat jb weld to plug the smog on x pipe. I dont think its vacume related becase the first start up is fine it will idle all day the way it should. Its only if i shut it off and restart. Seems computer related. I just want to know why

General karthief · Sep 6, 2021

Check the fuel pressure, you need to know what the pressure is when it will not start.
Don't ignore the possibility of a vacuum leak.

dscolastico07 · Sep 6, 2021

Fuel pressure is a good point actually. I just got in from driving it for a few hours and it didnt do it at all untill i was almost home and stopped at the store. Stalled 3 times untill it decided to idle. Im going to need to put a Guage on this. Anyone know what fuel pressure should be on a stock 302?

General karthief · Sep 6, 2021

32-4 ish psi at idle with the regulator vacuum line plugged in and 44ish psi at idle vacuum line removed

dscolastico07 · Sep 7, 2021

UPDATE: just bought fuel pressure testor at harbor freight. Koeo fuel rail red 32 pounds. Took vacume line off regulator, it spikes to 39 pounds. Let it sit and idle and get up to operating temps next thing you know the guage is at 21 psi. After that i was getting reading of 10 psi. I would cycle the key a few times it would get a little higher but not much. Kinda want to get a second gauge on this. I dont know if i trust a gauge thats less $20 dollars.

HemiRick · Sep 7, 2021

You fuel pump is dying....it needs a new one, no better time to replace the filter too.

dscolastico07 · Sep 8, 2021

So i bought a new fuel pressure testor today . Idles at 32 with vacume line on but what i noticed is when i give it throttle, the gauge didnt really move no matter how much throttle i gave it. As i was doing that i got a backfire come out the intake. I continued to let it warm up shutting it off hear and there but could not get it to stall unfortunately. I checked the guage again and now the fuel pressure goes up as i give it throttle. Also at cold koeo the rail would read 32psi. At hott, it would only read like 10-15. I could cycle key few times tho and get it to read higher tho. Could this just be a clogged fuel filter this whole time? I mean every bad fuel pump ive had i needed a tow truck. It eather worked or it didnt.

General karthief · Sep 8, 2021

Replace the fuel pump.
You got a psi reading at warm, idle with vacuum line off regulator?

dscolastico07 · Sep 8, 2021

Idle with regulator line off jumps up to 39psi

WhiteCobra95 · Sep 8, 2021

There are three primary items in play here: 1) fuel pump, 2) pressure regulator, and 3) fuel filter. If it were me, I would start with the cheapest / easiest thing first. Then work my way back to the most likely or expensive / difficult thing to replace. However, fuel pump failures are fairly common on these cars.

dscolastico07 · Oct 12, 2021

Update: so i replaced fuel pump, and fuel filter. Along with gas tank and sending unit. Everthing seemed to be good for a while untill today. Starting stalling today after warm again

mattys91gt · Jul 6, 2022

dscolastico07 said:
Update: so i replaced fuel pump, and fuel filter. Along with gas tank and sending unit. Everthing seemed to be good for a while untill today. Starting stalling today after warm again

is it common for the fuel pump to keep making a sound while driving I'm not sure what brand or flow amount the fuel pump is I have a new aftermarket pump but just stock flow of fuel I'm not sure what it is

1994FiveO · Jun 23, 2023

I have the exact issue OP is facing, it it is only when warm. Can't figure it out either.

My fuel pump is 340 Walbro brand new. PSI at prime engine off is 40.

I am thinking it is the EGR that has been deleted causing issues...no idea.

WhiteCobra95 · Jun 23, 2023

Was the EGR plugged correctly after it was removed? If not, the EGR path can be a huge vacuum leak.

Stalling after smog pump delete and x pipe

dscolastico07

Might be a little more then a crack.

Chythar

Recently finished repairing my rear

dscolastico07

Might be a little more then a crack.

General karthief

wonder how much it would cost to ship you a pair

dscolastico07

Might be a little more then a crack.

General karthief

wonder how much it would cost to ship you a pair

dscolastico07

Might be a little more then a crack.

HemiRick

I'd be looking at jacking under the house

dscolastico07

Might be a little more then a crack.

General karthief

wonder how much it would cost to ship you a pair

dscolastico07

Might be a little more then a crack.

WhiteCobra95

dscolastico07

Might be a little more then a crack.

mattys91gt

Active Member

1994FiveO

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WhiteCobra95

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