For the past couple weeks the 97 rover is starting up with no problem and at other times won't start I replaced the fuel relay same issue. Could it be the fuel pump? I excluded it as the culprit because when it doesn't start I press the nozzle in the fuel rail line and fuel spurts out what could it be? Could it inded be the pump is weak or faulty, fuel pressure regulator? Maybe even mass flow sensor? I bought a fuel pump but haven't installed it yet until I'm sure it's what's been causing the problem.

 

On the right track, there is a fuel volume test as well.
I would see what is not happening at the time of the condition, ie, having the gauge hooked while trying to start, checking for spark, cam signal, etc.

 

How do I do a fuel volume test?

 

No start you mean no start no crank? well you need a fuel pressure tester to see if its the fuel pump pressure is good.

 

What would the tester be hooked up to? I know the question sounds dumb. What about the fuel pressure regulator? Vehicle is trying to start it is cranking

 

There is a little valve on the fuel rail around the intake chamber. Just get a tire pressure gauge and hook it up, should be somewhere around 15psi.

 

Ok if it's not exerting a pressure of 15 or so, it's the fuel pump that's at issue?a

 

I replaced the pump section of the pump with another pump, problem now is that the gas light remains lit and I have to crank the truck multiple times before it cuts over the pump definitely is working.I forgot to disconnect the battery before I changed the pump. Could this be the reason the truck thinks the tank is on empty, I was thinking to disconnect the battery for a few minutes hoping this will somehow reset the sensor or whatever needs to be reset. Will this work to get the fuel gauge working properly?

 

You probably disrupted the sender while rebuilding the pump, which will cause the gas gauge to malfunction. 15psi is just what mine registered as, idk what the normal range is. If you are getting like 3psi, I'm sure you have an issue. Anywhere around 15, your probably fine.

 

I am assuming Rover HSE ?
The fuel pressure for it should be 35 - 38 psi at idle.
( also dependant upon vacuum present )
Too, there could be an injector hogging all the pressure, I would assume you do not have a tester for it, but the spark plug is like looking at a heart, and it should spell problems within the system
( light tan, ok - black - carbon fouled, oily - bigger issue internally, or what we are looking for, clear and wet or tan of course - clear and wet either no fire, or too much fuel there )
Mitchell did not have a volume test calculated, sorry, just pressures.


Also important besies what exactly we are working on is:
Is there a intermittent no-crank condition or a no-start condition ?
Important as there is a TSB relevant to the no-crank.
On the fuel pump, what I have found is a harness needed for a specific VIN range. You must have not needed that harness extender.

Are there any trouble codes present ?

New fuel filter too, and installed with arrow in right direction ?

No leaks ?

Sender disturbed ( agree with LRScott ) or also maybe plug in damaged or not plugged in ? Issue not there until said repair ?

Let us know, but too, there are other questions we all have to assist better.