Could it be the cam sensor?

[dangeranger93]

Im looking to buy a 93 4.0 ranger and the guy says since he replaced the tranny when he starts it now it runs for a while and then looses fuel pressure and dies. He says it's the cam position sensor, because when he removed the tranny he says it hit the firewall.
What im asking would a bad cam position sensor cause it to run and then loose fuel pressure? or is it something else. Any help is greatly appreciated

 

[Bob Ayers]

The cam position sensor has nothing to do with the fuel pressure. Check to see if the fuel pump is still getting 12V (~13.8V if engine is running) when it
looses fuel pressure.

 

[dangeranger93]

he swears its the cam sensor, is there anything else that he could have done changing the tranny that would make it do anything like that?

 

[Bob Ayers]

he swears its the cam sensor, is there anything else that he could have done changing the tranny that would make it do anything like that?

Nope, it's not the cam sensor! Matter of fact, you can unplug the CAM sensor, and the engine will run without loosing fuel pressure! A more likely scenario is he smashed the fuel line that runs along the inside of the frame on the driver's side, limiting the fuel flow.

 

[Mosinman76254]

PURPOSE
The Camshaft Position (CMP) sensor provides camshaft position information for determining the position and stroke of No. 1 cylinder, which is required for fuel injection sequencing.

DESCRIPTION
The Hall Effect device signal supplied to the Powertrain Control Module (PCM) , is used for synchronization of sequential fuel injector firing. The input circuit to the PCM is referred to as the Cylinder Identification (CID) input or circuit.

OPERATION
The CMP sensor is a single Hall effect magnetic switch, that is activated by a single vane driven by the camshaft.

That should explain it... that's right from alldata.com.

 

[Bob Ayers]

PURPOSE
The Camshaft Position (CMP) sensor provides camshaft position information for determining the position and stroke of No. 1 cylinder, which is required for fuel injection sequencing.

DESCRIPTION
The Hall Effect device signal supplied to the Powertrain Control Module (PCM) , is used for synchronization of sequential fuel injector firing. The input circuit to the PCM is referred to as the Cylinder Identification (CID) input or circuit.

OPERATION
The CMP sensor is a single Hall effect magnetic switch, that is activated by a single vane driven by the camshaft.

That should explain it... that's right from alldata.com.

Without the camshaft position sensor, the injectors will still be fired from the crankshaft position sensor (along with the ignition) but not sequentially. The camshaft position sensor is also used to detect misfires.

 

[dangeranger93]

thanks, any other ideas on what the problem could be?

 

[dangeranger93]

does anybody know what would make the truck run and then lose fuel pressure?

 

[explorersportster]

you need to trace your fuel lines front to back, and if he was really banging on things, try to reset the inertia switch

 

[SMTGREG]

Fuel Pump!!!!!!!!!!!!! It has nothing to do with the trans being removed.

 

[Earl43P]

Could be a bad Fuel Pump relay, they are known to fail.

Do like Bob Ayers said in his first response, but check for fuel pump relay power at the inertia switch. Kinda impossible to get to the top of the tank unless you drop the tank or remove the bed. If you aren't getting power at the inertia switch, suspect the fuel pump relay. If you ARE getting the power, replace the fuel pump. Inspect for a crushed fuel line is good common sense too.

 

[explorersportster]

no the fuel pump doesn't have anything to do with the trans....but put 2 and 2 together...this was obviously not a good mechanic if he let the rear of the engine fall into the firewall...so what else could he have screwed up? the fuel pump has everything to do with fuel pressure..which is what the issue is....plus caused by a tranny job? when you lose fuel pressure, start with the obvious...fuel system components, especially the ones around where this guy was working

 

[AllanD]

I can say it isn't a cam sensor for one truely excellent reason... because a 1993 4.0 ranger doesn't have one in the first place.

AD

 

[martin]

clogged fuel filter can cause that.

 

[dangeranger93]

i havn't seen the truck yet, but i am going to. what should i look for to try and figure out what the problem is while im there?