No start

[72cut]

Still trying to diagnose why my 88 4.0 won't start. I pulled the terminals from fuel pump resistor, put jumper wire between the two, still cranks, no start ( does jumper wire have to be certain size?)

I pressed the schrader valve, no gas came out. I took off driver's side tail light to check ground, don't see it, I assume it would look pretty obvious attached to bed right? Looked under truck don't see any obvious wires hanging. What next? Is this it?

[cruiser54]

Do you know how to use a voltmeter?

 

We need to know if there is power to the fuel pump. Does the gas gauge work? 

 

In the meantime, now would be a great time to upgrade your fuel pump ground. 

 

CRUISER'S MOSTLY RENIX TIPS

IMPROVING THE FUEL PUMP GROUND

JANUARY 3, 2016 CRUISER54 60 COMMENTS

The fuel pump and fuel tank sending unit ground at a sheet metal screw up behind the spare tire on an XJ, and behind the driver’s taillamp on an MJ.

Not only is a sheet metal screw a lousy way to ground things, this ground path is long and travels through some connectors that are prone to corrosion and moisture.

Locate the black wire on  the HARNESS side of the fuel pump/sender 3 wire connector. Remove a 6″ length of the split loom covering. Strip back about 1/2″ of insulation from the BLACK wire.

Take your new ground wire, preferably at least 14 gauge and 12 to 18 inches long as needed, strip it about 3/4″, and wrap it around the exposed part of the harness plug wire.Solder the connection. Tape it up and reinstall the split loom covering.

At the other end of your new ground wire, add a crimp on eyelet. Attach the eyelet under a bolt that goes directly into the chassis. Be sure to clean the attaching point til shiny and apply OxGard to the contact surfaces.

[72cut]

1) I do not

2) it does

3) is there a video for this?

 

 

[72cut]

Just thought of something. Tell me if there is a flaw in my thinking. Can't I just unplug the fuel hose going into the filter, redirect it onto container, crank the motor and see if any gas comes out? If it does, pump works, if it doesn't, pump doesn't work. Is this a flawed idea? 

Now if gas does come out, I reconnect the hose, take off hose coming out of filter and do same thing. Gas comes out, filter is fine. No gad, filter is clogged.

[pizzaman09]

Yes your logic is correct, though the hoses can be challenging to get off at times.  You should be able to achieve the same thing by keeping the Schrader valve open on the fuel rail.