fuel pump?
10-20-2012, 07:07 AM
#1
1st Gear Member
Thread Starter
Join Date: Mar 2012
Location: New Jersey
Posts: 122
fuel pump?
I was doing some reading lastnight. 5spd 1985 mustangs had factory 4bbl. Autos had cfi. So if this is correct it answers a few questions but still not. I have a starting probem. I noticed thismorning i didnt hear the fuel pump wine when i turned key on only a "click" i have to pump gas alot to get it to fire. It has stock dist. But with msd cap n rotor n blaster coil and plug wires. I see a stock duraspark ignition box on driver fender. Could ignition box need upgrade? Also if it was carb why do i have o2 sensors on it?
10-20-2012, 03:17 PM
#2
6th Gear Member
Join Date: Nov 2006
Location: Spfld, MA
Posts: 9,240
I suppose the answer to your question(s) all stem from what this vehicle actually is.
What were the factory options you believe it had, and what did it have when you actually bought it. Without those answers it'll be hard to piece together the clues.
What were the factory options you believe it had, and what did it have when you actually bought it. Without those answers it'll be hard to piece together the clues.
10-24-2012, 07:33 AM
#7
5th Gear Member
Join Date: Jul 2012
Location: ohio
Posts: 3,628
If its a carbed 302 you have a mechanical pump. If its hard to start when cold you may want to check out the choke to see if its operating correctly. Also with a carb a vacuum leak will make it hard to start because the fuel is sucked from the bowl by vacuum . It may just need to have the carb rebuilt the kit would come with a new accelerator pump also.
Also with a carb the engine is not really relient on the fuel pump to start . The fuel pump only supplys the carb with fuel as it is needed . The actuall starting is dependent on fuel available in the bowls of the carb. If the choke is not choking off the air to the carb then it will take a lot of pumping to get enough fuel into the engine to make it fire. The choke richens the mix when cold in a couple ways First it allows less air to enter the intake second it allows more vacuum to pull fuel from the bowl. This richens up the mix quite a bit for a few seconds allowing the engine to start when its cold.
I bet if you manually operate the choke to close it off it will start right up. Have a buddy hold the choke closed while you start the engine.
Also with a carb the engine is not really relient on the fuel pump to start . The fuel pump only supplys the carb with fuel as it is needed . The actuall starting is dependent on fuel available in the bowls of the carb. If the choke is not choking off the air to the carb then it will take a lot of pumping to get enough fuel into the engine to make it fire. The choke richens the mix when cold in a couple ways First it allows less air to enter the intake second it allows more vacuum to pull fuel from the bowl. This richens up the mix quite a bit for a few seconds allowing the engine to start when its cold.
I bet if you manually operate the choke to close it off it will start right up. Have a buddy hold the choke closed while you start the engine.
10-24-2012, 04:11 PM
#8
Join Date: Sep 2012
Location: maryland
Posts: 15
I had the same problem with my '91, ole' girl shut off on me at a light i made it back home and turned the key to hear the fuel pump acting crazy...I replaced the fuel pump, fuel filter, fuel pump relay the next day and it fixed the problem. auto zone sells a fuel system kit for like $100 if you were to go stock of course. but to answer your question it def sounds like the fuel pump is bad, I changed it all just to be safe and do some preventative maintenance, you might benefit from the same.
10-24-2012, 04:17 PM
#9
5th Gear Member
Join Date: Jul 2012
Location: ohio
Posts: 3,628
I had the same problem with my '91, ole' girl shut off on me at a light i made it back home and turned the key to hear the fuel pump acting crazy...I replaced the fuel pump, fuel filter, fuel pump relay the next day and it fixed the problem. auto zone sells a fuel system kit for like $100 if you were to go stock of course. but to answer your question it def sounds like the fuel pump is bad, I changed it all just to be safe and do some preventative maintenance, you might benefit from the same.