300 issue
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Tuned
Joined: Mar 2007
Posts: 485
Likes: 6
From: Timmonsville
300 issue
1980 F250. New kingpins tires, new brake shoes, new rubber brake lines, new fuel tank, new sending unit, new radiator, new plugs, new plug wires, Carter one barrel rebuild, oil and filter change.
Today was the first time I tried to go over 55 miles per hour. Up to that point I had driven a lot around 50 miles per hour. When trying to go 55 or faster the truck will sputter and almost stall. I would
depress the clutch and feather the throttle and it would recover and cruise fine at 45 to 55. Several more times while on the interstate I was able to recreate this condition. Your thoughts? My thoughts are fuel pump?
This fault required me in 4th gear trying to go fast to duplicate. When I got off interstate I revved it out in 3rd and not a single problem.
Today was the first time I tried to go over 55 miles per hour. Up to that point I had driven a lot around 50 miles per hour. When trying to go 55 or faster the truck will sputter and almost stall. I would
depress the clutch and feather the throttle and it would recover and cruise fine at 45 to 55. Several more times while on the interstate I was able to recreate this condition. Your thoughts? My thoughts are fuel pump?
This fault required me in 4th gear trying to go fast to duplicate. When I got off interstate I revved it out in 3rd and not a single problem.
FTE Legend
Joined: Jul 2010
Posts: 32,875
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From: Northeast, OK
Fuel and ignition can do similar things. But, my first thought is fuel. So here's what I'd look at first:
But, if it runs well in third and not in fourth then it might be ignition as a taller gear increases the cylinder pressure, making it harder for the spark to jump. So, it could be the coil, or some other ignition component is breaking down. But, the ignition module and pickup in the distributor usually just quit, so that isn't like them. If the fuel system checks out, replace the coil.
- Fuel Lines: There are several rubber hoses in your fuel system, and if they haven't been replaced they should be since they weren't made for today's gas with ethanol. I've had them ooze gas when the truck was off and allow air in when the truck was running, and that kills the pump's ability to move fuel. So, check/replace the hose from the tank to the hard line, the one from the hard line to the tank selector valve if you have two tanks, the one from the valve to the hard line, and the one from the hard line to the fuel pump. And make sure all of those connections are tight.
- Fuel Filter: Has it been changed?
- Float Level: If you got this too low the carb can starve for gas as the float won't let the needle far enough out of the seat to flow much.
But, if it runs well in third and not in fourth then it might be ignition as a taller gear increases the cylinder pressure, making it harder for the spark to jump. So, it could be the coil, or some other ignition component is breaking down. But, the ignition module and pickup in the distributor usually just quit, so that isn't like them. If the fuel system checks out, replace the coil.
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Tuned
Joined: Mar 2007
Posts: 485
Likes: 6
From: Timmonsville
Replaced fuel pump. Replaced soft fuel lines and fuel filter. The problem has gotten worse. The trunk will barely go 35. As a matter of fact when I got home I unloaded groceries and could not restart the truck. I shot ether to the air filter and still had a no start.Been reading up on DS2 trouble shooting. From fine to bad to worse to dead in 20 miles. Oh the joys of tinkering. The coil looks different than the one on the 84 302 I have. The boxes on the fenders well look the same. Was gonna try some parts swapping.Got tired.
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Joined: Jul 2010
Posts: 32,875
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From: Northeast, OK
Sorry to see that.
The differences in the boxes is denoted by the color of the grommet where the wires come out. If both of yours are the same color, probably blue, then you can swap them. And it does seem like that the problem is ignition since you've prettynwell eliminated the fuel system. The only thing still not confirmed is the float level, and it shouldn't have changed by changing out the pump, lines and filter.
The differences in the boxes is denoted by the color of the grommet where the wires come out. If both of yours are the same color, probably blue, then you can swap them. And it does seem like that the problem is ignition since you've prettynwell eliminated the fuel system. The only thing still not confirmed is the float level, and it shouldn't have changed by changing out the pump, lines and filter.
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Tuned
Joined: Mar 2007
Posts: 485
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From: Timmonsville
My fatigue must have clouded my vision. My 84 302 does have the coil with horseshoe as does 81 300. The both also have "blue" DS boxes.
One caveat, the 84 coil appears to have a condenser??? It is factory mounted and has plug to the horseshoe. The 80 coil does not. A condenser?????
Also read up on stator( aka pickup coil?) Cannot test that due to no start.
I am no mechanic, so parts swaps with known good will help eliminate. Will report back
One caveat, the 84 coil appears to have a condenser??? It is factory mounted and has plug to the horseshoe. The 80 coil does not. A condenser?????
Also read up on stator( aka pickup coil?) Cannot test that due to no start.
I am no mechanic, so parts swaps with known good will help eliminate. Will report back
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FTE Legend
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From: Northeast, OK
The condenser is because it is an 8 cylinder. See the lower right corner of Page 18 here: Start, Ignition, & Carb Circuits - ???Gary's Garagemahal. It is just for radio noise control, and really isn't needed.
Good luck!
Good luck!
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Tuned
Joined: Mar 2007
Posts: 485
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From: Timmonsville
Well after replacing ignition components with known good parts and getting same results we moved on to compression test.1,2, and 3 were 50ish psi. 4,5, and 6 were at 150psi. A dab of oil failed to raise compression in the low cylinders. So off came the head. Head gasket blown between 1&2 ,2&3.
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The condenser is because it is an 8 cylinder. See the lower right corner of Page 18 here: Start, Ignition, & Carb Circuits - ???Gary's Garagemahal. It is just for radio noise control, and really isn't needed.
Good luck!
Good luck!
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