troubleshooting fuel flow
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From: florida
troubleshooting fuel flow
After recently replacing in line fuel filter on F-150 (1990) I had problems starting the truck. Fuel filter is placed in proper direction and truck was running for about 15 minutes after being placed. Radiator was recently flushed (after fuel filter placement) and some water may have spilled onto components in engine. At this point fuel pump doesn't sound as though it's properly pumping at initial turn of key. Truck turns over but won't start. Please provide insight and or troubleshooting possibilities. All responses are appreciated. Thanks
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From: florida
Yes, I just checked to see if gas was pumping from either rear tank by disconnecting rear fuel filter and turning key and engine several times. No gas came through and no noise could be heard from either fuel pump. It appears that gas is not flowing from either tank at this point.
Forgot to include before:
1990 F-150 4X4 , 302 with 156K miles
Thanks for your response.
Forgot to include before:
1990 F-150 4X4 , 302 with 156K miles
Thanks for your response.
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From: florida
Further info on fuel flow problem....
After further investigation problem appeared to be in fuel flow relay. Upon replacing fuel flow relay, fuel pump could be heard immediately at turn of key. Truck started within seconds, but now fuel pump won't shut off without pulling new relay.....is this a bad relay or is there another cause?
thanks
After further investigation problem appeared to be in fuel flow relay. Upon replacing fuel flow relay, fuel pump could be heard immediately at turn of key. Truck started within seconds, but now fuel pump won't shut off without pulling new relay.....is this a bad relay or is there another cause?
thanks
Last edited by dtpax; Mar 9, 2004 at 12:21 PM.
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Happy ending....
Turns out my fuel flow relay was bad....the frustrating thing is that when I replaced the part with a brand new one from an auto parts store it was 'too' good! Instead of fuel pump not working it wouldn't shut off.
When I first inspected my relay I gave it a shake and there was a rattle sound that could be detected. I figured that she rattling indicated a bad relay switch and asked for one that didn't rattle at the parts store. Oddly enough it took 3 or 4 of them before I found one that didn't rattle. Now I know that the one that didn't rattle was apparently stuck in on position and kept the fuel pump from shutting off at all.
After a return to the auto parts store I requested a relay that I had previously refused and finally made it to work this week. Hopefully this helps anyone that might have a similar problem.
Still loving my 90 F-150...dtpax
Turns out my fuel flow relay was bad....the frustrating thing is that when I replaced the part with a brand new one from an auto parts store it was 'too' good! Instead of fuel pump not working it wouldn't shut off.
When I first inspected my relay I gave it a shake and there was a rattle sound that could be detected. I figured that she rattling indicated a bad relay switch and asked for one that didn't rattle at the parts store. Oddly enough it took 3 or 4 of them before I found one that didn't rattle. Now I know that the one that didn't rattle was apparently stuck in on position and kept the fuel pump from shutting off at all.
After a return to the auto parts store I requested a relay that I had previously refused and finally made it to work this week. Hopefully this helps anyone that might have a similar problem.
Still loving my 90 F-150...dtpax
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From: florida
My relay was located under the hood above the left fender.....slightly behind the overflow for your coolant and in front of your brake fluid. There might be a plastic keeper which houses two test ports and an additional relay (not sure what that's to). It's pretty easy to snap out but you may need a flathead screwdriver. Senior uses could give you more information but hopefully that helps. Good luck.....dtpax
Sorry didn't get back sooner, but have been out of town.
Sorry didn't get back sooner, but have been out of town.
