94 bravada wont start

[jaffinator]

Hello,
This my first post here, but I think I got the hang of it.

The 94 Olds Bravada (4.3 vortec) wont start. (sisters car I know little about it)
It used to start intermitently and then not at all about every 2 to 3 days.
No check engine lights and It turns over just fine.
I assume is a fuel presure issue.
Ill begin with checking/replacing the air & fuel filter and fuel pump, and fuel pump relay.

Where are these parts located?


thanks
Jaffinator

[Chris Stewart]

Welcome to the site Jaffinator,
The air filter is in a fair sized box behind the drivers side headlight.
The fuel filter is on the fuel line between the fuel tank and the engine, you'll have to look.
The fuel pump relay is located behind the power brake boster/master cylinder, the one on the right on the firewall on my '92.
The fuel pump is inside the fuel tank.
Here's where you check the fuel pressure, the spec is 55psi+



Turning the keyswitch On runs the fuel pump for a few seconds and the pressure should hold for several minutes if the check valve is holding.
The fuel level sensor is terrible on these, it's possible there's no fuel in the tank.

[jaffinator]

Thanks C.S. Very helpful.

You mentioned the fuel level sensor. How bad could it be? Currently showing 3/8 of a tank parked on a slight up hill. Is it posible the level sensor is that far out?

Can the relay be tested with a multimeter for proper function? If so do you have specs for that?

With the key ON and/or the motor turning(not running) there is almost no presure there where your gauge is connected in the photo. Just barely enuff presure to dribble a few drops out, definately not 55psi.

thanks
Jaffinator

[Chris Stewart]

My fuel pressure is a little erratic at 1/2 tank by the gauge. Adding 5 gal. gasoline to the fuel tank at this time would take care of any possible error.

The dribble of fuel present suggests power is being applied to the fuel pump.

When you first turn the keyswitch on, for a few seconds, the light gray wire at the fuel pump relay should have 12 volts. This is voltage going to the fuel pump with no other stops or switches.

The orange wire is supposed to be always hot.

[jaffinator]

Awsome! Thanks again C.S!

For clarity, The dribble was only present when I initially depressed the valve. Such a small amount, I rather thought it was due to atmospheric pressures. Lacking any sort of rate of flow.

Also, I found these on the web, They did not have a year specific.
Do these look correct for the 94 vortec4.3 v6?
fuel_pump.gif

fuel_pump_connector.gif

Thanks again for all your help.
JJ

[Chris Stewart]

Yes I saw those and because there was no orange wire, I dismissed them.
Is the Check Engine/Service Engine Soon light on?

[jaffinator]

Also, not to doubt your wisdom, I did read that it was the inboard relay for the fuel pump.
Regardless, they appear to be the same relay.
What does the other relay do?
Can I swap them to to check for proper function?
Thanks again for all your help.
JJ

[Leeann94astro]

Originally Posted by jaffinator

Can I swap them to to check for proper function?
Thanks again for all your help.
JJ

Yes.

The outboard relay is for the fuel pump, the inboard is for the IMTV, or Intake Manifold Tuning Valve.

Can you hear your pump run when you turn the key (but not start the vehicle)? You might need to have someone else turn the key while you have your ear near the tank.

If the pump does run, the fuel pressure is incredibly low. Another quickie test is to spray carb cleaner into the engine and see if it'll start on that - if so, then it's not getting fuel.

[Chris Stewart]

[quote=Leeann94astro;6116200]
If the pump does run, the fuel pressure is incredibly low. QUOTE]

Is this from jaffinator's earlier post?

Those are some most cool attachments Leeann94astro

Just looking at the relays in my '92 manual. It looks like they'll swap but the light gray wire on the existing fuel pump relay should have around 12 volts for a coupla seconds after turning the keyswitch on.
I use a thin needle to pierce the insulation on a wire and access circuits with a meter. A dab of Liquid Tape or a fast drying sealant repairs the puncture.

[Leeann94astro]

[quote=Chris Stewart;6116688]

Originally Posted by Leeann94astro

If the pump does run, the fuel pressure is incredibly low. QUOTE]

Is this from jaffinator's earlier post Leeann94astro?

Those are some most cool attachments

yes, where he refers to the flow as a dribble.

Thanks :-)