Kaajot
Micro Machine Manager
Another stumper-
I cannot keep this truck running reliably. Every 2-3 months the system goes down to a rough idling, stalling, POS. It's a great truck if it would just run -- all new parts, etc. Restored minus needing some rust cut out on the rear fender wells now and replaced with a nice pair of guards.
I don't have the two fault codes (used a snap on, it read in English for us and it's -10 deg out so not in a rush to find my ODB blink tester!) and received two fault codes for fuel pump ground and MAP ground.
The truck is running rough. The MAP sensor is probably broken again -- we've warrantied/purchased 4 now in 2 years. Is there a good way to bench the MAP whenever I get this problem figured out to see if it's good or not?
Anyway, I benched the three relays with 12vs and checked -- got an audible signal on the continuity and you could hear the clicking of each relay closing its circuit, so the top part of my fuel pump/engine control is good. I've not detached the box to inspect the wiring harness on the back side yet.
I just replaced the fuel selector switch about two months ago. We had a no-start situation when that blew. Again, thinking a ground is shorting out all these relays and switches.
Fuel pumps WILL push fuel, but voltage is dropping. If at times I let my foot off the pump and the alternator/rpms gets low, then the truck begins spurting to stall. Sometimes I can recover with a rev, sometimes not. In order to get into gear or switch I'm doing the wrong thing and keeping the RPMS high (1500-2000 is my best guest minimal) in order to go from one gear to another (P-R, R-D, D-R, P-D). Switching gears causes the voltage to drop and stalls the car most times if not boosted with additional current from the alternator.
Battery is strong. It's getting abused just like the transmission, but it's less than a year old and should be working as intended. Always above 12.5V. Probably would be hanging above 13.0V if this problem wasn't sucking it dry.
MAP is offline and disconnected, but vacuum tube is still connected. The truck is shifting rough in drive from first through third. Fourth and OD are a little less bumpy, but overall it always has a "bump" or a rough hit at all transitions up gear. Down gear nothing noticeable happens, but a full stop is liable to wind up in a stall unless you break and add gas at the same time to keep voltage up (not a good idea, particularly in snow and ice right now).
I haven't checked the inertia switch yet -- believe I have one behind my right kick panel in the cab from what I've read? I guess testing that voltage would tell me if the ground is before or after it even if it is not faulty itself. Or it could be faulty? Since it just sends signal I think its more likely a ground out and not that component that's failed, plus I don't want to buy another switch for $50 if it's a ground. The last impact on the vehicle was a 12 pt buck in 2013 -- worked fine for years, so I don't think the inertia switch is going to be the problem, but any pointers on that or where else to look is appreciated.
I noticed in a 87 or 88 Ranger video on YouTube that they had voltage drops at a fuel pump and also lights flicker/dim and blink too fast. I do have some wiring harness issues on my tow and aftermarket license plate illuminator (custom bumper, required).
Does a 1992 F-150 4.9L (my vehicle, VIN Y) have a ground that's shared with tow, fuel pump relays, and map sensor?
EDIT:
PS: The truck often runs rich I think and a smell of rotten eggs/sulfur occurs occasionally. Believe it's just fuel pump controls going wonky, but wanted to throw in that symptom. No blue smoke out the tail pipe. White smoke is evident, but it's really eff'n cold and could be condensation?
I cannot keep this truck running reliably. Every 2-3 months the system goes down to a rough idling, stalling, POS. It's a great truck if it would just run -- all new parts, etc. Restored minus needing some rust cut out on the rear fender wells now and replaced with a nice pair of guards.
I don't have the two fault codes (used a snap on, it read in English for us and it's -10 deg out so not in a rush to find my ODB blink tester!) and received two fault codes for fuel pump ground and MAP ground.
The truck is running rough. The MAP sensor is probably broken again -- we've warrantied/purchased 4 now in 2 years. Is there a good way to bench the MAP whenever I get this problem figured out to see if it's good or not?
Anyway, I benched the three relays with 12vs and checked -- got an audible signal on the continuity and you could hear the clicking of each relay closing its circuit, so the top part of my fuel pump/engine control is good. I've not detached the box to inspect the wiring harness on the back side yet.
I just replaced the fuel selector switch about two months ago. We had a no-start situation when that blew. Again, thinking a ground is shorting out all these relays and switches.
Fuel pumps WILL push fuel, but voltage is dropping. If at times I let my foot off the pump and the alternator/rpms gets low, then the truck begins spurting to stall. Sometimes I can recover with a rev, sometimes not. In order to get into gear or switch I'm doing the wrong thing and keeping the RPMS high (1500-2000 is my best guest minimal) in order to go from one gear to another (P-R, R-D, D-R, P-D). Switching gears causes the voltage to drop and stalls the car most times if not boosted with additional current from the alternator.
Battery is strong. It's getting abused just like the transmission, but it's less than a year old and should be working as intended. Always above 12.5V. Probably would be hanging above 13.0V if this problem wasn't sucking it dry.
MAP is offline and disconnected, but vacuum tube is still connected. The truck is shifting rough in drive from first through third. Fourth and OD are a little less bumpy, but overall it always has a "bump" or a rough hit at all transitions up gear. Down gear nothing noticeable happens, but a full stop is liable to wind up in a stall unless you break and add gas at the same time to keep voltage up (not a good idea, particularly in snow and ice right now).
I haven't checked the inertia switch yet -- believe I have one behind my right kick panel in the cab from what I've read? I guess testing that voltage would tell me if the ground is before or after it even if it is not faulty itself. Or it could be faulty? Since it just sends signal I think its more likely a ground out and not that component that's failed, plus I don't want to buy another switch for $50 if it's a ground. The last impact on the vehicle was a 12 pt buck in 2013 -- worked fine for years, so I don't think the inertia switch is going to be the problem, but any pointers on that or where else to look is appreciated.
I noticed in a 87 or 88 Ranger video on YouTube that they had voltage drops at a fuel pump and also lights flicker/dim and blink too fast. I do have some wiring harness issues on my tow and aftermarket license plate illuminator (custom bumper, required).
Does a 1992 F-150 4.9L (my vehicle, VIN Y) have a ground that's shared with tow, fuel pump relays, and map sensor?
EDIT:
PS: The truck often runs rich I think and a smell of rotten eggs/sulfur occurs occasionally. Believe it's just fuel pump controls going wonky, but wanted to throw in that symptom. No blue smoke out the tail pipe. White smoke is evident, but it's really eff'n cold and could be condensation?
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