Slow Going

[cap10]

I have a 1990 4x4 with a 3.0 that I have put togather from 3 different engines and I have some issues that I hope you guys can help me with.
It seems like its starving for fuel but I am not sure how to check the fuel pump pressure since there is no valve on the fuel rail like most engines.
Also,i have noticed that my fuel pump stays on whenever the key is in the "on" position. I dont believe this is right? That would not work out to well if the truck rolled over for instance. I thought the fuel pump will run for a few seconds with the key on and not cranking motor but then it shuts itself off right?
What could be causing the fuel pump to run all the time?

 

[Llowlife]

I'm not that familiar with the 3.0 but I'm going haphazard some guesses.

You will need to install a test gauge inline somehow

Most times a vehicle runs the pump for about 3 seconds and shuts off. It is possible but unlikely that Toyota shuts the pump off when it reaches a certain pressure. So I would pull the pump relay and see if it shuts off.

If it does shut off then you need to figure out if the relay is hot side or ground side switching. They are usually ground side controlled by the ecm.

If it doesn't shut off then you have a short to hot or more like.y ground depending on how the relay operates. There could be other possible issues as well but I'd start here.

Vehicles have a switch or sensor that detects a rollover iirc.

 

[mholme]

I have a 1990 4x4 with a 3.0 that I have put togather from 3 different engines and I have some issues that I hope you guys can help me with.
It seems like its starving for fuel but I am not sure how to check the fuel pump pressure since there is no valve on the fuel rail like most engines.
Also,i have noticed that my fuel pump stays on whenever the key is in the "on" position. I dont believe this is right? That would not work out to well if the truck rolled over for instance. I thought the fuel pump will run for a few seconds with the key on and not cranking motor but then it shuts itself off right?
What could be causing the fuel pump to run all the time?

What’s the history on the vehicle? Did you recently buy it and are putting it back together? There are diagnostic ports under the hood behind the fuse box on the front passenger side of the engine. It’s possible the Fp and B+ ports have been jumped together to force the pump to run when the key is turned on. It’s a troubleshooting method to see if the pump works, but sometimes gets left in place when people don’t want to find the root cause of the pump not running when it should. It is dangerous to have constant ON to the fuel pump, as you suspect. I would start there.

 

[64manx]

I had the same problem. The engine would idle fine but no power during driving. Plugged fuel filter was the problem. The fuel tank was very rusty inside and would plug up a new filter very quickly. I had to replace the fuel tank and that fixed it!
Good luck.

 

[cap10]

Yes… When I bought my runner it was not running. It had a motor that had a blown head gasket. I also acquired lots of parts in the buy.
I believe my problem might be in the Mass Air flow sensor ? A friend of mine lent me his from his "93 and when I plugged it in the fuel pump did not come on.
I suppose I will do some troubleshooting on the one I have and see what I can find out.

 

[cap10]

I was right about the Air Meter being the reason for the fuel pump staying on. I dug through all the parts I had and found another Meter that seems to work fine.
The only problem I am having at the moment is that its really slow to build up speed on the highway. Its weird because I get a fast response of my throttle when its parked but when I take it out on the open road it seems very sluggish.

You might be right 64manx. It might be a fuel filter. Or maybe a weak fuel pump? I will check tomorrow . Thanks for all the help guys.

 

[mholme]

What transmission? Tire size? Timing is set to??