1986 mustang gt motor cuts out at 4000rpm, sometimes?
02-28-2011, 01:04 PM
#1
Thread Starter
Join Date: Feb 2011
Location: mississippi
Posts: 4
1986 mustang gt motor cuts out at 4000rpm, sometimes?
alright i have a 1986 mustang gt convertible that is all original. well that i know of, i bought it around 5 years ago and it sat for 3 because i was fighting over the title. when i first got the car it ran like a beast. i have never driven a 5.0 that runs like this on. after i let it sit now the motor acts like it has a rev limiter at around 4200 rpms. i have replaced fuel filter and only run 93 octane gas in it and put fuel injector cleaner in it religiously. but the thing is it doesnt alway cut out. it seems like if im driving at a constant speed at around 2000 rpm and then stop it will be idled up around 1300. i can take off and it wont act all stupid it will just wrap out like it should. im kinda stumped. i re timed it and it ran fine for like 20 minutes then started acting stupid again. ive put new plugs wires cap button. could it be the pressure regulator or the fuel pump? idk what to do anymore and i need advice please. i also have other problems with the car but i will post them later. this is my greatest concern at the moment. any advice is greatly appreciated
02-28-2011, 01:16 PM
#2
4th Gear Member
Join Date: Oct 2007
Location: Phoenix, AZ
Posts: 1,219
I would check the simple things first, like distributor cap, rotor and plugs/wires. I once had a rotor mess up the button on the cap and it would cut out off and on sometimes, not saying this is your problem, but just some ideas. Oh yea, that rotor was just a couple months old, so I now know that just because its "new" doesn't mean it not defective.
I would also check fuel pressure and run a KOEO/KOER test.
I would also check fuel pressure and run a KOEO/KOER test.
03-01-2011, 10:51 AM
#3
Thread Starter
Join Date: Feb 2011
Location: mississippi
Posts: 4
it was doing this already then i replaced all that once and it didnt help really. its like everything else ive done it will help for like 5 minutes then start the same ****. i already did the KOEO/KOER test on it and all it says is my temp sensor is out of range and my smog pump isnt working( i bypassed it) haha. where do you check the fuel pressure on these cars?
03-05-2011, 10:46 PM
#4
1st Gear Member
Join Date: Aug 2008
Location: GA
Posts: 139
there is a valve on the fuel rail, called a schrader valve where you can screw on a fuel pressure gauge available at any auto parts store...
maybe your fuel pump is headed south and can't maintain pressure under load at higher rpms.
maybe your fuel pump is headed south and can't maintain pressure under load at higher rpms.
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