Sending Unit issues
Thread Starter
Melting Slicks
Joined: Jul 2004
Posts: 3,277
Likes: 32
From: Mission Viejo California
Sending Unit issues
Hi guys. So I have 2 sending units. One of them is in good condition and when I install it, the pump works fine. For whatever reason on the 2nd one, it is intermittent. I checked the voltage at the wiring harness to the pump prior to install. After install, nothing. Fuel pressure is at 0 at the rail. It did prime after key on, but afterward nothing. The car started, run for about 2 second good, then proceeded to die from no fuel.
Upon inspection, I'm seeing some burn on the harness where it meets the metal part that bolts to the car. I am running a large pump in tank (walbro 465).
My question is, can I buy upgraded, thicker wiring to replace the stock stuff? I bought a racetronix harness but forgot to ask about sending unit upgrades. Here are two pics:
Upon inspection, I'm seeing some burn on the harness where it meets the metal part that bolts to the car. I am running a large pump in tank (walbro 465).
My question is, can I buy upgraded, thicker wiring to replace the stock stuff? I bought a racetronix harness but forgot to ask about sending unit upgrades. Here are two pics:
Team Owner
Joined: Sep 2003
Posts: 25,394
Likes: 2,741
If the other (intermittent) is a ZR-1 sending unit then it will have provisions for the second pump and it's wired differently. A ZR-1 initially supplies voltage to both pumps and then switches to primary pump only until the second is called upon for required performance.
You could likely rewire for use in an L98/LT application but I don't know why you would want to. I don't believe I'd mess with/butcher the ZR-1 sender.
You can certainly rewire either of them and it's actually not particularly difficult. Some pump packages from Racetronics and others comes with what they want you to use for a harness.
Last edited by WVZR-1; Sep 6, 2014 at 02:11 PM.
Thread Starter
Melting Slicks
Joined: Jul 2004
Posts: 3,277
Likes: 32
From: Mission Viejo California
If the other (intermittent) is a ZR-1 sending unit then it will have provisions for the second pump and it's wired differently. A ZR-1 initially supplies voltage to both pumps and then switches to primary pump only until the second is called upon for required performance.
You could likely rewire for use in an L98/LT application but I don't know why you would want to. I don't believe I'd mess with/butcher the ZR-1 sender.
You could likely rewire for use in an L98/LT application but I don't know why you would want to. I don't believe I'd mess with/butcher the ZR-1 sender.
Thread Starter
Melting Slicks
Joined: Jul 2004
Posts: 3,277
Likes: 32
From: Mission Viejo California
did some more testing and it's definitely the wiring on the lt1 unit. I'm going to swap some of the wiring; the zr1 unit is in great condition compared to my beatup lt1 unit.
edit, upon disassembly, the ground is different on the two. It could be done but I'll contact racetronix and see if they have anything to work with my situation. If not, I'll buy a used one.
edit, edit.... I'm modifying the zr1 unit to work. I like it having two pins for the hot instead of one. I'm running a walbro 465 pump which is putting probably about 17-18 amps through the pin so I'll set it up to use both and then feed the positive wire to the pump. I removed the plastic part of the sending unit for the 2 pumps, and will attach the pump to the metal frame using clamps. I'll post some pics tomorrow.
edit, upon disassembly, the ground is different on the two. It could be done but I'll contact racetronix and see if they have anything to work with my situation. If not, I'll buy a used one.
edit, edit.... I'm modifying the zr1 unit to work. I like it having two pins for the hot instead of one. I'm running a walbro 465 pump which is putting probably about 17-18 amps through the pin so I'll set it up to use both and then feed the positive wire to the pump. I removed the plastic part of the sending unit for the 2 pumps, and will attach the pump to the metal frame using clamps. I'll post some pics tomorrow.
Last edited by qwiketz; Sep 6, 2014 at 06:20 PM.
Thread Starter
Melting Slicks
Joined: Jul 2004
Posts: 3,277
Likes: 32
From: Mission Viejo California
well, I went ahead and butchered the zr1 sending unit. I like this one because the current for the pump is passed through the bulkhead using two connectors instead of one. I'm not sure if I was running too much power through the old one or if something else caused it to fail, but it looks dead. Here's pics of the dead one and the new one and my final modified zr1 sending unit prior to install.
