Fuel pump question
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Dan’94
Joined: Feb 2018
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Fuel pump question
I know this has been asked a million times already but I’m still learning and any help would greatly be appreciated. I have a ‘94 4.9L I6 4x4. It’s got a single metal tank we’ve already replaced...we’ve also replaced the starter, fuel pump and solenoid. The truck will crank but the fuel pump won’t kick on. I just need help on where to start troubleshooting. Is it the relay or fuse or could it be the pump power wire itself? Thanks
Member
Joined: Jan 2018
Posts: 11,256
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From: Memphis, TN, Earth, Milky Way
When & why were each of those parts replaced? Surely you didn't replace a tank because the pump wouldn't run...
Start with the inertia switch.
(phone app link)
Then read all the OTHER captions in that photo album.
Start with the inertia switch.
(phone app link)
Then read all the OTHER captions in that photo album.
Thread Starter
Dan’94
Joined: Feb 2018
Posts: 11
Likes: 0
When & why were each of those parts replaced? Surely you didn't replace a tank because the pump wouldn't run...
Start with the inertia switch.
(phone app link)
Then read all the OTHER captions in that photo album.
Start with the inertia switch.
(phone app link)
Then read all the OTHER captions in that photo album.
Thread Starter
Dan’94
Joined: Feb 2018
Posts: 11
Likes: 0
I’m getting low voltage to my fuel pump. When I check my new fuel pumps new connector to the old harness, I’m only getting 6.7 volts. When I plug in the connectors I get no voltage going to the fuel pump. I’ve changed my eec and fuel relays, I’ve checked the inertia switch and can’t seem to find out what’s causing the low voltage.
Member
Joined: Jan 2018
Posts: 11,256
Likes: 1,770
From: Memphis, TN, Earth, Milky Way
I can't help without knowing EXACTLY where each meter probe is, and what the conditions are (battery voltage, which connectors are UNplugged, key position, meter settings...). Photos showing the meter & both its probes would help. Make sure the meter batteries are good, and that it reads correctly on a few known voltage sources.
Exactly how did you "check" the inertia switch?
Exactly how did you "check" the inertia switch?
Thread Starter
Dan’94
Joined: Feb 2018
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I put the meter probe on the pump power wire and only got 6.78 volts. Then I unplugged the connector on the inertia switch coming from the relay and got 6.5 volts so I figured it’s good because it’s passing all power it’s getting. All of that was in the key on position. Then with the battery hooked up and key off, we put the meter in the constant power terminal of the fuel pump relay and once again got 6 volts. Does this mean a computer problem?
Member
Joined: Jan 2018
Posts: 11,256
Likes: 1,770
From: Memphis, TN, Earth, Milky Way
Since you only mentioned one probe, and only for one reading, I have no idea. Remember that we can't see what you're doing. You either have to post LOTS of photos showing us, or use LOTS of words describing it precisely.
But no - the computer does not power the fuel pump.
But no - the computer does not power the fuel pump.
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Senior Member
Joined: Nov 2017
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From: Washington
If there's 12 volts at the source and you're only seeing 6 then something on that circuit is drawing current. That's a pretty big voltage drop. Could be a bad relay or partial short circuit somewhere. You should check everything that's on that circuit.
Thread Starter
Dan’94
Joined: Feb 2018
Posts: 11
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Since you only mentioned one probe, and only for one reading, I have no idea. Remember that we can't see what you're doing. You either have to post LOTS of photos showing us, or use LOTS of words describing it precisely.
But no - the computer does not power the fuel pump.
But no - the computer does not power the fuel pump.
Thread Starter
Dan’94
Joined: Feb 2018
Posts: 11
Likes: 0
Thank you I’ll look for that now...and I’ve replaced the eec and fuel pump relays