Question about Cars & Trucks
I have a 1989 f-150,6 cyl, 5 speed manual trans,dual fuel tanks my problem is that the truck starts and runs for 1 or so mins than shuts down, here's what i've done replaced: low pressure pumps in both tanks ,new front tank,new hi pressure pump in frame rail, new distributor modjail, rotor,cap,wires, new coil, new fuel relays,new oil pressure shut off sender, sea foam in both fuel tanks. engine starts,fuel pressure @ the rail is 42 psi, runs 1 or so min that pressure falls to 12 psi eng stops, won't start for about 1\2 hour or so,than same thing. any one know anything else i can do?
If the fuel pump(s) run while the pressure is falling, replace the fuel pressure regulator and (although I'm sure you've already done this), replace the fuel filter. If the fuel pumps appear to be turning off by themselves, replace the inertia (fuel cutoff) switch.
Posted on Apr 14, 2014
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Posted on Jan 02, 2017
You are right. There are three pumps. It sounds like the transfer pump in the front tank is bad. The in tank pumps just supply the high pressure pump to keep it primed. You need the front pump.
Posted on Sep 21, 2009
Step #1 in any automobile diagnosis is "Isolate the system"
Switching fuel tanks may have seemed like a good idea, but it did not definitively determine whether the the fuel is getting to the fuel rails, so you are no closer to eliminating the fuel devery system than you were when the engine died.
If it does it again, you should do the easiest things first.
Pull a spark plug wire and check to see that you have good spark reaching the spark plugs. Good spark will eliminate the entire spark control system.
Only if you have good spark should you suspect a "part-time " fuel system problem. The Fuel delivery system can be eliminated if actual fuel pressure is checked at the fuel rail. (although you could still have injectors not firing for one reason or another)
You are losing one of these systems. (spark or fuel) only once you have determined which one, can you continue diagnosis to pinpiont the failure.
Posted on Oct 10, 2009
SOURCE: 97 GC 4.0 starts right
Well, aside from the O2 sensors, the throttle position sensor and temp sensor, looks very much like you have a totally new system there.
I assume you got codes for all those item from a system scan?
I suggest that you "ring out" the wiring harness and check every fuse in the engine compartment and in the passenger compartment. If you have continuity and no cross over in the wiring, pretty good chance that the engine computer is bad.
One thing...your fuel pressure seems to be a bit high...I didn't look it up but I'd expect it to be around 35psi to possibly 40? Do the plugs come out clean or black?
Posted on Dec 07, 2010
I You can get free fusebox layouts at Autozone.com by registering your vehicle.
Try changing the fuel filter. May be too much resistence is causing the fuelpumps to trip their limit switches.
If you have not used a scanner, someone may have one for this old style system. An bad O2 sensor can adjust the fuel mix too lean to run.
If you have a fuelpressure regulator, it may only cycle once for starting and then fail to trigger the fuelpump a second time to restart the fuelpump.
Check with FordF150blog.com or some of the 4x4 truck offroad sites for some pretty good info about problems like yours in the Backwoods and how to fix them.
I hope my solution is helpful.
Posted on Aug 14, 2012
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