Recently got a '91 Montero RS 3.0 that had been sitting for 8 yrs. After changing all fluids, new tires, cleaning and coating rusty fuel tank, replacing fuel pump and filters my Montero ran great for about 1,000 mi. Now it starts up then dies after a few a few seconds. I pulled the fuel pump and it works fine. After reinstalling the pump I checked to see if it were getting power, the pump comes on and pumps when ignition is in start/cranking position but as soon as key is back in run position power to pump shuts down. As a result it runs a few seconds on gas pumped during start but as soon as it's burned it dies. Any ideas on cause would be greatly appreciated.

 

Have you been able to figure out the problem yet? I am currently working on a 95 montero 3.0 that is have the same problem. Was wondering what it might be. Thanks ahead

 

Two possibilities:
1. It is a sensor issue. When you turn on ignition, the PCM sends the signal to prime the fuel system. But once the engine is on, the PCM needs to tell the pump to pump fuel all the time while the engine is on. The trouble is that the PCM somehow doesn't recognize that the engine is running, i.e. one of the sensors is not signaling correctly.

2. It is also possible that it is some sort of relay issue. The priming signal could be coming through a different circuit and the main "run pump" signal is routed vial a non-working relay.

I would start by trying to find electrical diagram and trace the wires to see what kind of controls you see there.

 

I am certain the problem is a bad crank sensor or some other sensor telling the PCM that the engine is not turning in which case the fuel pump is shut down. (a safety issue for elec. fuel pump) . I bypassed the prob. by locating the fuel pump test plug, on driver's side firewall. It may be wrapped inside harness but it is there on my '91. If a lead from battery is connected to this plug the fuel stays on and the Montero runs fine. I ran a wire from bat. positive with an inline 20 amp fuse ($4) and a wire from test lead through the firewall, I then installed a toggle switch ($3) giving me manual control over fuel pump. I know this method bypasses safety cutoffs for fuel pump as well as you running the chance of forgetting to turn off fuel toggle when you leave vehicle but for myself it has worked fine with no issues.

Someday given time and finances I might do proper repairs but for now this is better than walking.

 

Ha, you just wired it like a race car You have to go through "Arming" procedure before each drive...