I'm having issue at least when it comes to the electrical part of things. My 1991 4.0L Ranger started to die from time to time last fall and then while I was on my way to the junk yard died completely... it will try to turn over just fine but I can't hear the Fuel pump trying to turn on. I've replaced the pump with a brand new one... I replaced the fuel pump relay and the 30A fuse directly above it... and I checked the Inertia fuel switch and it appears to be functioning properly... however I did shove the prongs of an amp reader into the plug going to the inertia switch and I'm not picking up hardly any readings. It did register 1.5V but I'm not sure if it's suppose to be that low or if I was getting some sort of phantom reading.

My understanding is that the flow of power starts at the battery, proceeds to the fuel pump relay switch, to the inertia switch and then to the fuel pump. (If I got that wrong someone tell me please)

If no power is making it to the inertia switch and the fuel pump relay has been replaced what then would be the problem?!? I'm almost wondering if the relay switch I installed was defective. Is there a test I can do to figure that part out... and how would I do it.

 

Welcome to the site..

Is the pump relay clicking?

You might pull the fuel pump relay and check for good power distribution on/at the connector.. Should be a 'Hot at all times' leg, one 'Key On' power (all 12v), and a ground.. The remaining leg is the 'load' or the inertia/pump feed.. If you have a meter, you can ID the leg and check for continuity from the relay output leg of the relay connector to the inertia..

If you 'add' 12V to the PK/BK wire leading out of the inertia with a test lead will the truck start?

Next, if the trucks starts with 12v added to the DG/Y wire going into the inertia then the switch is closed.. You can also check for power 'up to' the relay connector (load) if the test lead is still installed which would show 3 12v legs if the key is on.. That will help prove out the inertia and a pump run test.. If the connector tests show low voltage then you may need to dig deeper.. If its a relay ground control issue, you can try wrapping a thin copper strand wire around the ground leg of the relay (being careful to not short against the others) and install it.. Use a test lead and ground the other end..

Let us know what you find....

 

Yes I do hear a clicking noise when I first turn the key but before the engine starts to turn over. I never really new what that was.

 

In the winter I have no problem what so ever. But now the weather is warming up, my truck is acting up again. Changed the fuel pump today. It will occasionally get power to the pump, but as soon as you shut it down, it takes hours to start again. How does one trace it from the power distribution box to find out if it is a melted wire?

 

Just a suggestion. When you said it becomes a problem in warmer weather I immediatly thought of vapour lock. Dont know where you live but if you have winter grade gas (ethers in it) this gas can become a problem when the weather warms up.