Help! Gmc suburban


#1

My husband and I have a 96 Gmc 5.7l 2wd suburban. A while back we had to have the waterpump, radiator, and intake gaskets redone. After we got the vehicle out of the shop and back home my hubby did a tuneup on the thing.
Well before we got the stuff to do the tune up the truck would crank run a few feet and stall out. We could restart it and it ran fine. So we did the tune up thinking that this would fix all issues. We were wrong we got the tune up done and it won’t start he took some gas and pour it in the top and it started no prob but naturally after the gas burned off it died. So we thought well it’s the fuel pump replaced the fuel pump and nada. So then we went and looked at the fuses. Noticed that the Relay didn’t look quite right and so we replaced it. Still Nada. Does any one have any other idea’s.


#2

Bring it to a reputable local shop to get diagnosed. Before replacing the fuel pump, hubby should have tested for fuel pressure at the line. If there was none, he should have checked to be sure it had voltage. If it did, he could have checked to see if the old pump was operating. These are really basic troubleshooting steps, and with all due respect if hubby lacked the knowledge to do these tests before replacing th epump it may be better to let a qualified tech look at it.

If he put gas down the throttle body and it started, that pretty much says it’s a fuel delivery problem. If my guess is correct, the fuel on that is delivered via a throttle body injector, and that injector may not be opening. It opens and determines its pulse width based upon signals received from the crank speed sensor (or cam speed sensor…I don;t knwo which that engine uses) and some other “engine demand” sensors. If that crank/cam speed sensor has failed, the injector won’t know to open. A shop can check for these types of things.


#3

We are trying to do as much as we can ourselves. Like everyone else Money is tight right now just trying to get an idea of what it is so we can do it ourselves.


#4

When it does not start see if you can hear fuel pump,have seen wires going to pump have bad connections and work only sometimes. A volt meter helps to follow to see when the 12 volts stop


#5

He says he can’t hear the pump says that the old pump worked but wasn’t very strong so I’ll get him to check the connectors


#6

There should be a ground bolted to the frame back by the tank. Remove ground and clean terminal and frame.


#7

thanks we’ll check that.


#8

I’m not an expert but if the fuel pump runs, that pretty much rules out the fuel pump. There should be a test connector under the hood with a green connector on it. You can hook a test light up to that to tell if power is getting to the pump. If the light goes on, the computer is signaling the pump and the relays are being activated. If the light goes on and the pump doesn’t run, then there could be a wiring or connector problem.

You should do a pressure test also which will tell you if the pressure regulator is doing its job. One thing to check is to make sure a vacuum hose wasn’t taken off or knocked off. Also check the fuses to the engine computer since that has to tell the pump to run after cranking. Don’t know anything about the fuel solenoid.


#9

My wife posted this, and there are 3 wires going to the plug for the fuel pump and only one of them is showing power. I checked with test light. There is a black with white strip and a gray wire and another that goes to the pump that I have seen. The relay under the hood is new, just replaced it, new pump, new tuneup kit.


#10

I’m going to bow out pending a real mechanic before I hurt someone. But I believe there should be two wires going to the pump. A ground and a hot. There also should be two going to the sender, unless they combined the ground. There also could be a secondary hot wire that would be coming from the oil pressure sending unit so that in the event of a relay failure, the pump would still be energized but this should be a hard connection and not a separate wire. Guess you really need the wiring diagram. Might be available from Autozone on line if you sign up.

First question would be whether the pump runs or not. If not and the connector is hot, could have just a bad connection. I even had one car hardwired because of a connector problem. Had another one with a connector that really had to be roughed up. Car wouldn’t start at all. If it runs, then you’d want to check the fuel pressure to eliminate a blocked filter, bad regulator, etc. If the pump runs and you have good pressure, then I’m at a loss.