Anyone ever experience this?

[rusty ol ranger]

I was out messing with my "new" B2 today. I replaced the postitive cable and spliced a new plug on the coolant sensor.

Anyways, last time when i noticed the screwed up postitive cable i noticed the fuel pump wasnt priming, and obviously wouldnt crank.

After i changed the cable it cranked great....but still no fuel pump prime. The wireing to the relay is pretty spliced togther (not by me) but i checked, had 12v to one plug, like 9.5 to the others, and 1 that had zero.

I took a paperclip and shorted the 12v terminal to the 0 volt one and the pump fired up. So i figured the relay was bad. I plugged the relay back in (so i wouldnt lose it)As i was heading in to turn the key off i noticed the damn negative terminal looked loose....so i twisted it a bit and the fuel pump kicked on. I looked down and noticed by where the neg hooks to the frame then heads back the wires are all exposed and corroded.

I wiggled the cable further down and got the pump to kick on a few more times then it wouldnt any more...also one time after the pump primed i tried starting it and it cranked fine....tried to start a bit...but wouldnt. It was after that i could no longer get the pump to run.

My question is....why...or what...would allow it to crank normally but not allow the pump to run...or actually start?

I ordered a new cable...but do i have another issue going on? Was it a fluke?

i dont understand electrical.

 

[RobbieD]

My first suspect would a bad, or failing, wire, especially on the ground side.

My question is....why...or what...would allow it to crank normally but not allow the pump to run...or actually start?

Case in point-
The starter is grounded through the engine block, to the battery negative via the thick primary grounding cable: the primary ground cable.
The fuel pump itself is grounded back to the battery negative through either the frame or body (I'd have to check the EVTM for which). This would be through a smaller secondary cable.

The primary cable on the early RBVs goes through a clamp on the frame before continuing on to the block. The body gets grounded through a smaller cable between the engine and the firewall (you probably know this already).

I would first thing on this truck, check and correct all of the grounding cables and wires, so that the engine, frame AND body are ALL well grounded back to the battery negative post.

Bonus tip: jumper cables can be handy for troubleshooting ground problems, by jumping the battery negative post to the part of the truck that's questionable.

Good luck!

 

[rusty ol ranger]

My first suspect would a bad, or failing, wire, especially on the ground side.



Case in point-
The starter is grounded through the engine block, to the battery negative via the thick primary grounding cable: the primary ground cable.
The fuel pump itself is grounded back to the battery negative through either the frame or body (I'd have to check the EVTM for which). This would be through a smaller secondary cable.

The primary cable on the early RBVs goes through a clamp on the frame before continuing on to the block. The body gets grounded through a smaller cable between the engine and the firewall (you probably know this already).

I would first thing on this truck, check and correct all of the grounding cables and wires, so that the engine, frame AND body are ALL well grounded back to the battery negative post.

Bonus tip: jumper cables can be handy for troubleshooting ground problems, by jumping the battery negative post to the part of the truck that's questionable.

Good luck!

It just threw me because ive had plenty not crank because of a bad battery ground cable...but not still crank and the fuel pump not run lol.

I did notice the ground that comes off down on the exhaust on the passenger side is gone...not sure what its for.

The one for the cab that goes to the head is intact.

 

[don4331]

I was out messing with my "new" B2 today. I replaced the postitive cable and spliced a new plug on the coolant sensor.

Anyways, last time when i noticed the screwed up postitive cable i noticed the fuel pump wasnt priming, and obviously wouldnt crank.

After i changed the cable it cranked great....but still no fuel pump prime. The wireing to the relay is pretty spliced togther (not by me) but i checked, had 12v to one plug, like 9.5 to the others, and 1 that had zero.

I took a paperclip and shorted the 12v terminal to the 0 volt one and the pump fired up. So i figured the relay was bad. I plugged the relay back in (so i wouldnt lose it)As i was heading in to turn the key off i noticed the damn negative terminal looked loose....so i twisted it a bit and the fuel pump kicked on. I looked down and noticed by where the neg hooks to the frame then heads back the wires are all exposed and corroded.

I wiggled the cable further down and got the pump to kick on a few more times then it wouldnt any more...also one time after the pump primed i tried starting it and it cranked fine....tried to start a bit...but wouldnt. It was after that i could no longer get the pump to run.

My question is....why...or what...would allow it to crank normally but not allow the pump to run...or actually start?

I ordered a new cable...but do i have another issue going on? Was it a fluke?

i dont understand electrical.

Probably the last person you want to hear from after the tow dolly, but..

Cavaet: I deal in newer Rangers ('98-00 primarily)

The computer (can't remember GEM or PCM) allows the fuel pump to run for short period, then shuts it down if the engine doesn't start -starter only get's to something like 200rpm, I want to say it needs to detect 500rpm to restart the fuel pump.

I understand electrical, I just hate troubleshooting it - especially when fighting the computer as well.

Then there is waiting period before you are allowed to try again. (Key must be returned to off, etc).

 

[Curious Hound]

The starter circuit has different power and ground paths, not shared by the fuel.pump.

 

[rusty ol ranger]

The starter circuit has different power and ground paths, not shared by the fuel.pump.

What made the pump run when i dicked with the negative?

 

[Curious Hound]

What I was trying to say is; the starter worked because it has good enough connections. But your connections going to other circuits are bad, causing intermittent trouble with the fuel pump and probably other things.

 

[rusty ol ranger]

What I was trying to say is; the starter worked because it has good enough connections. But your connections going to other circuits are bad, causing intermittent trouble with the fuel pump and probably other things.

Doesnt the fuel pump ground thru the ecm?.

 

[RobbieD]

Doesnt the fuel pump ground thru the ecm?.

The fuel pump relay is grounded from the ECM.

 

[Curious Hound]

Doesnt the fuel pump ground thru the ecm?.

What Robbie said. To expand on that; the fuel pump relay coil is grounded by the ECM. The fuel pump power circuit is grounded elsewhere. On my 93, it's the ground on the driver side inner fender in the engine compartment, right next to the starter relay.