300 six dying in 4L offroad
02-18-2018, 05:07 PM
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300 six dying in 4L offroad
1989 F-150 300 CID 4x4 5-speed. Lost power repeatedly, offroad, steep climb in 4x4 low range. Would re-start after a few minutes, but only run another 1/4 mile or so and die again. Acting like a fuel supply problem (like accumulating enough fuel in the carburetor - but it is EFI). When I finally got down the mountain, it ran fine around town and home. No indication of overheating. Ideas? Frank in NM
02-18-2018, 07:11 PM
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Welcome to the site!
How full was your tank? Wondering if between steep angles and sloshing around, air was intermittently being pulled up into the fuel line?
How full was your tank? Wondering if between steep angles and sloshing around, air was intermittently being pulled up into the fuel line?
02-18-2018, 07:44 PM
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fuel quantity query
Fuel quantity was almost full. Although the problem began when I was climbing in 4L first gear, it continued as I was descending. I turned around when it first developed and started back down. It ran for a while then stopped, ran for a while then stopped. When I got back down (after several starts and stops) and on the highway, it ran OK. So I started up another trail again, 4L first gear. It was fine for a while, but after a mile or two, the same thing happened. I started back down and it acted as before. I wanted to check this forum to see if this is common problem before paying for diagnostics to someone who may not know old Fords.
02-18-2018, 10:22 PM
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Most technicians today don't know these old trucks any better than their owners. If you have to pay for this kind of diagnosis, you'll end up selling the truck to pay the bill. It's not a complicated system, once you take the time to learn how it works. Read this caption, study the diagram, and then follow the appropriate link:
(phone app link)
The ethanol in modern gas affects these old systems badly. But those captions explain how to repair or bypass the problematic parts.
(phone app link)
The ethanol in modern gas affects these old systems badly. But those captions explain how to repair or bypass the problematic parts.
02-19-2018, 03:00 PM
#5
Martin
I would guess that it's getting a little hotter than temp gauge shows. If you've had the truck for any length of time you'll understand how susceptible these generation trucks are to just a bit to warm, doesn't have to be boiling over. Best way to tell if fan clutch is working is if it locks for a few seconds on cold start. If it's not doing the cold start lock it's working good enough to climb around in double low. Not much natural air movement at 5-7 miles an hour.