Fuel pump?

[MY 85 GT]

Hi im new to this site...glad to be here..also new to the 5.0 world too...I have had a few turbo coupes in my day...i always wanted a 5.0 mustang now i have one it is an 85 GT 5spd stick and is all stock with 69,200 miles on it ..It was a 1 owner car thats why i bought it...My question is i have a block pump and its leaking so i just bought a carter performance pump and i want to replace it soon....But i was wondering besides it leaking would this cause an issue im having with it....The car runs fine if you drive it hard but just driving normal it stumbles/shakes not like a miss but like if it was running out of gas....also if i park the car let it sit for a few minutes then get back in it and try to start it, It just cranks i have to pump the gas to get it to start..i know i should do basics too like a tune-up that i will do also...but does that sound like the fuel pump is causing all these problems....thanks........

 

[Vipersix]

That certainly could be a contributing factor and I wouldn't rule it out. Swap out the pump and do a basic tune-up, if you're still experiencing the problem you will now have a good clean slate to begin from.

 

[MY 85 GT]

Thanks i am going to the pump then a tune-up so i hope its helps

 

[67&93 Stangman]

Check the carb

If the problem is still there after replacing the fuel pump, check the carb. It could be a choke issue.

 

[MY 85 GT]

You think? its the stock holley carb...still how can i check if its a choke problem? Another problem i have is that when the car sits after driving it for awhile then i go to start it bck up its takes forever to start i have to crank it and crank it and even have to pump the gas to get it to start.....

 

[67&93 Stangman]

Similar problem with my choke

I had a similar problem on my '67, it has an Autolite 4100 4 barrel carb. I did not have the rough idle at low speed, but I did have the issue with hard starting after sitting for a short time. I ended up replacing the choke spring (the bimetalic spring that controls how fast the choke opens up). I never had the problem again after that.

 

[MY 85 GT]

I didnt get a chance to put the fuel pump in yet due to the rain...But i checked the carb for problems...and guess what i never took the air cleaner off i just bought the car a few days ok i have a brand new edelbrock 1406 series on it so im guessing its not the carb thats the problem...It could be the fuel pump...But i had my Father drive it and he thinks its a miss, like a bad wire maybe a cap or rotor....maybe even the coil....Now when the choke is cosed it seems not to miss...weird huh? but when it opens it gets that miss back again...

 

[twistedwankel]

I didnt get a chance to put the fuel pump in yet due to the rain...But i checked the carb for problems...and guess what i never took the air cleaner off i just bought the car a few days ok i have a brand new edelbrock 1406 series on it so im guessing its not the carb thats the problem...It could be the fuel pump...But i had my Father drive it and he thinks its a miss, like a bad wire maybe a cap or rotor....maybe even the coil....Now when the choke is cosed it seems not to miss...weird huh? but when it opens it gets that miss back again...

You really ought to put a fuel pressure regulator in line. The newer pumps can overwhelm the carb. Only need about 5psi to work properly. Check on the Edelbrock website for that unit's rated psi.

Look for a vacuum leak.