99 L31 Burb won't start

[SUBURBAN5]

If you just want to get it on the road, and burn some fuel out of the tank before you drop it, you could get a fuel pump for a 89 Ford van. Those are frame mounted inline high pressure pumps.
I did this temporary for a motorhome one time, hooked it in at the fuel filter.

Here's a picture from orielys to show you what they look like, usually in stock.

( Please don't flame me for Ford parts, it not made by Ford, just an application it fits)

Got a pic of the install?

 

[ralmo94]

Got a pic of the install?

No I didn't sorry. It was a get the motorhome moving so I could catch a flight kinda thing.

 

[SUBURBAN5]

No I didn't sorry. It was a get the motorhome moving so I could catch a flight kinda thing.

Gotta do what you gotta do

 

[Erik the Awful]

If you just want to get it on the road, and burn some fuel out of the tank before you drop it, you could get a fuel pump for a 89 Ford van. Those are frame mounted inline high pressure pumps.

If you go this route, mount the fuel pump lower than the tank. Fuel pumps push a lot easier than they pull, and a fuel pump set up to suck won't last long.

 

[ralmo94]

If you go this route, mount the fuel pump lower than the tank. Fuel pumps push a lot easier than they pull, and a fuel pump set up to suck won't last long.

If it's just temporary to get the tank empty so it can be fixed correctly, it probably doesn't matter to much as long as it's primed, but if in service for a while, I totally agree

 

[Erik the Awful]

If it's just temporary to get the tank empty so it can be fixed correctly, it probably doesn't matter to much as long as it's primed, but if in service for a while, I totally agree

Even for temporary use, mount it lower. The Air Force uses Holley electric fuel pumps on a piece of equipment, and several times I've seen a technician grab a pump out of benchstock to use to pump down a larger fuel tank on other equipment. About halfway done the fuel pump craps out, and they start whining about the pump being junk. Then I get to explain physics and chew their butt for wasting money.

 

[HotWheelsBurban]

Okay this is probably a dumb question, but it's late and there's no one I can call! When I use the jumper wire between the two terminals where the fuel pump relay goes, all that will do is tell me whether the relay is bad( assuming this procedure makes the pump activate?).
Obviously if the pump won't come on when I do this, my problem is the pump or the wiring down there. Does the key need to be in "on/run" to do this? Never had to do this before, that's why I'm asking.... thanks!

 

[ralmo94]

When I use the jumper wire between the two terminals where the fuel pump relay goes, all that will do is tell me whether the relay is bad( assuming this procedure makes the pump activate?).

Yes jumping the relay will run the pump without the key. Jumping the starter one will also I like to jump the starter after an oil change to build oil pressure.
And the 4 pin relay "should" work in place of the 5 pin. The extra pin is to energize a different circuit when there is no power to the relay. That being said my truck isn't near, it's in another state, but as long as it physically fits it should work.

If jumping doesn't work, I would definitely check for voltage while jumped. If you put your ear to the tank you "should" hear something, in my experience it pretty rare for a failed pump to make no noise at all, but quite possible.

 

[Pinger]

Okay this is probably a dumb question, but it's late and there's no one I can call! When I use the jumper wire between the two terminals where the fuel pump relay goes, all that will do is tell me whether the relay is bad( assuming this procedure makes the pump activate?).

If fuel presents, then problem is with the relay or upstream of it (ie, signal).

Obviously if the pump won't come on when I do this, my problem is the pump or the wiring down there.

If no fuel present, then problem is downstream of the relay (ie, wiring or pump).

Does the key need to be in "on/run" to do this? Never had to do this before, that's why I'm asking.... thanks!

'Hot at all times' - via fuse ECM-B.

 

[Dariusz Salomon]

Okay this is probably a dumb question, but it's late and there's no one I can call! When I use the jumper wire between the two terminals where the fuel pump relay goes, all that will do is tell me whether the relay is bad( assuming this procedure makes the pump activate?).
Obviously if the pump won't come on when I do this, my problem is the pump or the wiring down there. Does the key need to be in "on/run" to do this? Never had to do this before, that's why I'm asking.... thanks!

You remember when I had this issue since the beggining? I was blaming pump,but it wasn't it-it was the wire from ECU that controls the power.
So you gotta test the whole thimg first. This is the link,that will let you test the fuel pump. I posted it before. Just follow what he does. It also shows you how to jump the pump.

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Then, if that proves fine,you need to check control. You probably have the same fusebox as I do-bith vehicles are from 99. You will have to open the fuse box for it-please find my post on how to. On VCM under the hood(next to fuse box) you'll see 4 plugs-there's also designation-BLK ,WHT etc. As you can see at the bottom of the diagram(it's a diagram for 2 fuel tanks Silverado but it worked for me),it shows you which wires run from VCM to control pump relay.

1998-99 PCM Connector Pin Out Charts (GM 4.3L, 5.0L, 5.7L)

GM 4.3L, 5.0L, 5.8L Index of Articles

troubleshootmyvehicle.com

In this link you'll find pin out schematics from ech of the plugs-C1 to C4-you gotta take the C4 out(careful when removing plug-plastic is brittle by now) and check if there's a power coming out of the terminal(should be around 6 v if I rember correctly)-if you got power on VCM(key should be on for that-like when pump primes) your likely culprit is the wire(I think it's white/green). You may then want to then try to splice in another wire at the base of C4 plug all the way to the fuse box pump relay socket-if that works,this wire was a culprit.

But above all-check if the pump works by jumping it-I used a paper clip-just don't grab it with bare hand.

Our trucks are left overs from 98(at least mine is) so I always refer to 98 schematics-they wouldn't change things much (if any)for last year or 2 of production,with new truck already in the showrooms.

Also you may check C3-see if power from battery get's to relay at all.