Carb Problems?
Thread Starter
|
Freshman User
Joined: Apr 2014
Posts: 44
Likes: 0
Carb Problems?
I recently pulled out my 1983 F250 with a 7.5l 460 and a Stock Holley 4 barrel. It ran great at first, but now it spits and sputters and will only run for about 40 seconds. I've drained the gas completely out of the tank and changed all the filters and put new gas in with seafoam and it still has the same problem. I checked the choke and everything seemed like it wasn't sticking. I also know my fuel pump is good because when I drained the tank I tested it and it kicked gas out the line great. I'd appreciate any help I could get, thanks.
Moderator
Joined: Jan 2001
Posts: 56,950
Likes: 2,718
From: Virginia
After it runs for 40 seconds and won't start, pull the air cleaner off and look down the throat of the carb. Push back on the throttle by hand(engine off) and see if you see two strong streams of gas pour into the engine. If you don't, you still have fuel problems.
Senior User
Joined: Jan 2015
Posts: 383
Likes: 0
From: Stockdale, Tejas
Correct, you should have fuel inside your bowl. So that when you actuate your throttle linkage it will pump the gas (strong streams) out of the bowl and down the intake. I would imagine he is trying to see if your fuel pump is failing and only building up enough to pressurize the system to start and then loosing pressure.
Additionally if you have a intermittent problem with the oil pressure or oil pressure sensing switch it will cut power to both fuel pumps, and draining the bowl (30-40 seconds) without refilling it
Additionally if you have a intermittent problem with the oil pressure or oil pressure sensing switch it will cut power to both fuel pumps, and draining the bowl (30-40 seconds) without refilling it
Moderator
Joined: Jan 2001
Posts: 56,950
Likes: 2,718
From: Virginia
Yes, your carb works just like a toilet bowl in your house. It stores the fuel in a fuel bowl just like the toilet stores water in the tank. The fuel system is supposed to keep that fuel bowl in the carb full(to a specified height). That amount of fuel in there might be your 40 second run. When you crank the engine the system hot wires the pumps to prime the bowl. That may be all your running on.
Thread Starter
|
Freshman User
Joined: Apr 2014
Posts: 44
Likes: 0
It didn't have two strong streams. So now it should be either that oil pressures with or that pump? Thanks both for the help and franklin sorry for asking you a question on that other post haha I just was reading and that guy seemed to have the same problem
I actually found the oil pressure switch on the back center of the motor and tried 'hot wiring it' to the battery and the fuel pump did not come on. So what's next? Inertia switch? Where can I find this?
I actually found the oil pressure switch on the back center of the motor and tried 'hot wiring it' to the battery and the fuel pump did not come on. So what's next? Inertia switch? Where can I find this?
Senior User
Joined: Jan 2015
Posts: 383
Likes: 0
From: Stockdale, Tejas
Not necessarily, you may have a semi stuck float (or filled with gas) or needle, if your bowl isn't filling up it can be multiple things, your venturis can be clogged, a fuel filter can be severely clogged, your fuel pump may be going out.
I would start by removing, your fuel filter, get a container and a rubber hose, run the hose to the from the line you disconnected to the container and try starting it, and see if your even getting flow, if you are, then replace filter with a new one and take hose off at carb and repeat, if you get good flow to that point, then the carb needs to be rebuilt.
I would start by removing, your fuel filter, get a container and a rubber hose, run the hose to the from the line you disconnected to the container and try starting it, and see if your even getting flow, if you are, then replace filter with a new one and take hose off at carb and repeat, if you get good flow to that point, then the carb needs to be rebuilt.
Trending Topics
Thread Starter
|
Freshman User
Joined: Apr 2014
Posts: 44
Likes: 0
Replaced fuel filters already and I get a good flow but it doesn't seem to be constant only after the initial crank. I just pulled out the inertia switch and the white button at the top won't stay flush with the black and when I tip it upside down it free falls until it can no longer move. Should the button be flush with the top of the switch?
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
Ford Super Duty: 5 Things Owners LOVE, 5 Things They LOATHE!
Joe Kucinski
Every 2026 Ford Truck Engine RANKED from WORST to FIRST!
Michael S. Palmer
The Best F-150 Deal of Every Trim Level (XL through Raptor)
Joe Kucinski
Senior User
Joined: Jan 2015
Posts: 383
Likes: 0
From: Stockdale, Tejas
https://www.ford-trucks.com/forums/1...em-wiring.html
read above thread first, you can put a jumper wire to test if the switch is the problem, (in thread) test that first then go from there
read above thread first, you can put a jumper wire to test if the switch is the problem, (in thread) test that first then go from there
Senior User
Joined: Jan 2015
Posts: 383
Likes: 0
From: Stockdale, Tejas
, I would imagine where the ports "holes" where the two wires are going into, the switch closes the loop with constant pressure, hence why you can jump it, to close the loop
This is also a pretty informative thread
https://www.ford-trucks.com/forums/1...bed-460-a.html
Moderator
Joined: Jan 2001
Posts: 56,950
Likes: 2,718
From: Virginia
Why don't we back up, and make sure we are on the right track. Also if the truck runs like this, you can take it around the block and at least know it still runs and drives.
See that wire in the diagram below that goes to the starter relay(the starter solenoid on the fender). See if you can find that wire. I think it's on the "i" terminal of the solenoid. In the diagram below it goes to "fusible link T" which is blue, and then goes to a pink/black wire. If you can find this wire, take it off, and make a temp jumper and hook it to the battery + terminal on the battery. The pump should start running. See if the engine will start and run like this. This will make sure your fuel lines, fuel filters, fuel pumps, carb, and everything else is working. We will then know the problem is on the left side of the diagram below.
See that wire in the diagram below that goes to the starter relay(the starter solenoid on the fender). See if you can find that wire. I think it's on the "i" terminal of the solenoid. In the diagram below it goes to "fusible link T" which is blue, and then goes to a pink/black wire. If you can find this wire, take it off, and make a temp jumper and hook it to the battery + terminal on the battery. The pump should start running. See if the engine will start and run like this. This will make sure your fuel lines, fuel filters, fuel pumps, carb, and everything else is working. We will then know the problem is on the left side of the diagram below.
Thread Starter
|
Freshman User
Joined: Apr 2014
Posts: 44
Likes: 0
I figured out how to jump the switch by trial and error and it turned out to be the problem. What is the solution to this? I thank you all for the detailed and constructive help you've given me. You guys seriously saved the day.