99 L31 Burb won't start

Pinger · Sep 21, 2022

HWB: Both Dariusz and myself thought we were going to have to drop the tank but were spared when we found the problem in the wiring. C'mon and be the third!

Going slightly left-field.... you had PassLock deleted. Any possibility that that coding has a bug and is messing with the pump signal? If suspect, can you swap the PCM from Rawhide into the Burb to check? (Probably not the case but anything rather than dropping the tank to find the pump is fine).

ralmo94 · Sep 21, 2022

can you swap the PCM from Rawhide into the Burb to check? (Probably not the case but anything rather than dropping the tank to find the pump is fine).

If the problem is in fact at the vcm connection, simply plugging in another could temporarily solve it and give a false positive. Just thinking out loud while reading.

Dariusz Salomon · Sep 21, 2022

ralmo94 said:
can you swap the PCM from Rawhide into the Burb to check? (Probably not the case but anything rather than dropping the tank to find the pump is fine).

If the problem is in fact at the vcm connection, simply plugging in another could temporarily solve it and give a false positive. Just thinking out loud while reading.

Good idea,but if it's in the wiring,it won't help. If however it turns out,that there's no power from VCM then by all means it may be another step.

HotWheelsBurban · Sep 22, 2022

Swapped relays and still no start. So I guess I get to crawl under it and look at wiring near the tank....

Dariusz Salomon · Sep 23, 2022

HotWheelsBurban said:
Swapped relays and still no start. So I guess I get to crawl under it and look at wiring near the tank....

Relays don't go bad that easily,tho I do keep a spare one. It must be wiring. Did you do the video checks?

HotWheelsBurban · Sep 23, 2022

Plan to tomorrow, it was just too hot to do much yesterday.

L31MaxExpress · Sep 24, 2022

I have a computer friendly logic probe that also has a power probe function. Obviously, the power probe portion is not computer friendly. Comes in handy at times with diagnostic work. Back probe the connector with a T-pin, hit it with the power probe and ZAP it either works or doesn't.

HotWheelsBurban · Sep 25, 2022

Okay, I made a jumper wire and put it into terminals 30 and 87 in the fuel pump relay, where it plugs into the underhood fuse/power block. Banged on the tank again. Nothing, nada, zilch.
I can feel the loomed wiring harness for the pump, in front of the tank, along the top of the crossmember flange. Loom feels good and secure, no breaches, feels good and firm like nothing is loose. To actually get to it though, I would have to be standing under it, with it on a lift. Even with the body jacked up on the trailer hitch, there's not enough room to get to anything. Between rear axle and the tank, there's very little room....
Any ideas?

SUBURBAN5 · Sep 25, 2022

HotWheelsBurban said:
Okay, I made a jumper wire and put it into terminals 30 and 87 in the fuel pump relay, where it plugs into the underhood fuse/power block. Banged on the tank again. Nothing, nada, zilch.
I can feel the loomed wiring harness for the pump, in front of the tank, along the top of the crossmember flange. Loom feels good and secure, no breaches, feels good and firm like nothing is loose. To actually get to it though, I would have to be standing under it, with it on a lift. Even with the body jacked up on the trailer hitch, there's not enough room to get to anything. Between rear axle and the tank, there's very little room....
Any ideas?

Did you check fuel pressure at the rail with a fuel guage?

HotWheelsBurban · Sep 25, 2022

No cause I don't have one. But there's no gas at the Schrader valve, it just smells like old gas. And the pump makes no noise whatsoever.

99 L31 Burb won't start

Pinger

I'm Awesome

ralmo94

I'm Awesome

Dariusz Salomon

I'm Awesome

HotWheelsBurban

Gotta have 4 doors..... Rawhide, TOTY 2023!

Dariusz Salomon

I'm Awesome

HotWheelsBurban

Gotta have 4 doors..... Rawhide, TOTY 2023!

L31MaxExpress

I'm Awesome

HotWheelsBurban

Gotta have 4 doors..... Rawhide, TOTY 2023!

SUBURBAN5

I'm Awesome

HotWheelsBurban

Gotta have 4 doors..... Rawhide, TOTY 2023!

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