Update on 1991 Isuzu Pickup

I would drop back and look for something hooked up backwards. Check to make sure the fuel pump is hooked up to the right hose, the other is the return. usually the feed is larger than the return. I don't know if injectors will work on gravity feed. Have you replaced the fuel pump recently?

I agree, it appears to be that the pump is feeding the return line of the fuel rail. There is usually a pressure valve in the return line so that excess pressure allows fuel to return to the tank. I presume this also acts as a one-way valve, preventing reverse flow. Injectors usually need about 60 psi to atomise the fuel, otherwise you'll just get a dribble with no fuel/air mixture.

RRV

check the coil of the air bypass solenoid and ignition coil with a multimeter. maybe your timing belt snapped? it could be a engine computer problem too. Dont change the oil sensor! it is low after a oil change and when starting. Computer controlled cars usually let you crank with the pedal all the way down to clear extra gas out of the cylinders too. And one last thought is if it is cold, preheat your engine overnight.

G'day Tledoux, i don't know the vehicle but i would guess that the fuel line goes the other way. That is the front end is the in and the back end is the return to the tank. Injectors need a fairly high pressure to work and ther may be a kind of restriction in the back end of the rail to acheive this. A knowledgeable auto electrician once told me that the complicated side of modern engines is rarely to blame. Do all the old fashioned stuff first, i.e. check for fuel, spark, timing and compression.

I am guessing it is a throttle body, if so unhook the cold air intake at the TB & spray starting fluid or pour a bit of gas in. It should start. If so I would say you have a weak fuel pump or a plug line, you might have a floatie in the tank blocking the pump, but youll find that if you drop the tank to get to the pump...

Are you able to borrow a code reader maybe to pin point the issue?

Good Luck

Hi

In reference to your explanation, it was not state clearlly whether the problem is a Mechanical or electrical however I will advice you to check the fuel pump by disconnecting the hose after the pump and open the vehicle switch to see if its spraying, if it does then check the fuel filter the way it was position if correct. If both are correct then I advice you to put few fuel inside the carburator to the cumbustion chamber and crank your engine, if it start then the problem lies with the carburator, but if it does not start when you crank the engine, then its an Electrical. In that case Check your contact breaker setting point, and if power flows through

I hope this help

Aishaamadu

You can hear the fuel pump running but no fuel comes out, the thought that it is running backwards is a good one if some one has changed it out. If this is still the original pump I would think that the filter screen on the pick up tube is stopped up. Sometimes when you get fuel there filter system is not up to standard and you get the dirt out of the in ground fuel tank pumped in to your car.

Your best bet is to pull the fuel pump out and see why it is not pumping.

If you can hear the fuel pump running then the oil pressure sensor is not at fault. I would check what kind of pressure the fuel pump is able to build by putting a gauge in the line coming from the pump to the filter and seeing what kind of pressure is built with the pump dead ended into the gauge. You should see 80 to 90 psi from the pump. It has been a long time since I have worked on that old of an Isuzu but I believe that the line at the front of the fuel rail is the input and the line at the rear is the return. If the pump is unable to build enough pressure to overcome the pressure relief valve then you would see no fuel coming out of the fuel return. The 3 things that can cause this problem would be the fuel pump, the fuel pickup screen, or the pressure relief valve. Hope this helps.