Help with no start

[03Mach1]

Tomorrow I will finaly be able to look at my brothers truck. Up till now I ahve been trying to help him over the phone.

Here is the deal, the truck - 95 EB with the 4.0 OHV, cranks but will not start.

So far there is no fuel pressure at the rail so says the schrader valve.

Fuel pump fuse is good, switched the fuel pump relay with the AC relay, still nothing.

Not sure what he is listenening for my brother has not been able to 100% tell me if the pump kicks on or not when the key is turned.

I have been searching here for a good bit and have yet to come across what I am looking for.

Is there a way to 100% determine if the fuel pump is working or not. For example on my F-150 a wire came into contact with the exhaust and shorted the PCM. The PCM would not turn on the Fuel pump. Is there a way to jump the fuel pump, like run a wire from the battery to an accessable wire in order to get the pump running?

If I can do that and the pump works I know I need to look for something else, If I do it and the pump still does not turn on then I can replace the pump and that should fix the problem.

I saw this post

http://www.explorerforum.com/forums/showthread.php?t=187484

Where Dash stated "Test lead from OBD I connector grounded", which if I read right should activate the fuel pump but I am coming up dry on where the test lead that needs to be grounded is.

Also according to my brother there is no CEL showing up either.

 

[jlsparky7]

Replace the fuel pump and fuel filter. 95% chance one of the 2 is the problem. Assuming the battery is strong.

 

[03Mach1]

Not to be a ##### but 95% is not enough for me to wast the time and money replacing a possibly good pump. Thats kind of like saying, my throttle response feels a bit sluggish so I will just replace the whole engine, never considering the tranny could be at fault.

 

[budwich]

go to the inertia switch... disconnect the plug.... take a meter and measure the resistance on the wire going to the pump (ie. resistance to a KNOWN ground). You should get some reading if the pump is good. Further run a lead back to the battery on same said wire. The pump should run and you should "see" pressure at your schrader valve.... careful though how you "see" the pressure... ;-)

That should give you some "feeling" about the fuel side of things.

 

[03Mach1]

thanks bud, thats what I was looking for.

2 questions.

Once the plug is disconnected stick the probes from the DMM, 1 on each connection, if the pump is good I should get something other than a 0 reading.

As for hooking +12v up to the plug from the inertia switch, does it matter which of the two I hook the 12v up to?

thanks.

EDIT: I tried hooking the DMM up to the inertia switch on my Mach which has a known good pump. The wires were green and red. I out the red DMM lead to the red wire, the black lead to the green wire. Turned the DMM to read ohms(resistance) and got nothing. I also tried grounding the black lead and putting the red lead on the red wire and still nothing.

I was rushing so there is a chance the ground I used for the black lead was not good enough. I am going to try it again on my Mach and on my brohters Ex tomorrow. So for clarification should I put both leads from the DMM into the socket or ground one lead and put the other lead into the socket?

 

[budwich]

Please read my instructions carefully.... "RESISTANCE ON THE WIRE GOING TO THE PUMP (ie. resistance to a known ground")... there is only one wire going to the pump from the switch.

And of course, the next statement about connecting up a voltage supply only makes sense then. Hope that is clear. The wire in question is PK/BK at least in 96... ymmv for your year.

Lastly, zero isn't any good as this is then a short (again... if you measure to a KNOWN ground)..... and would have probably blown a fuse. High resistance is probably equally as bad as this means you have an "open circuit"... hence the statement... "some reading".

Hope that helps a bit more.