Fuel pump problem.

[88yota]

I was driving and my truck started starving for fuel. Pulled the tank down and two devices are in the tank. One the fuel pump and the other im assuming is the float for fuel level. To the small one (Gauge?) i have power going to. The big one (fuel Pump?) i have no power to. So i change what i thought was the fuel pump relay behind passenger speaker. and i still have no power to the pump. Any advice or help would be appreciated. Its an 88 toyota 4CYL EFI 4x4

 

[toyotafan]

ok, this is the first time that this has happened to you and it came on all of a sudden, or was it gradual? Does your fuel gague work? How are you testing the power to the fuel pump unit?

Plus remember to be careful when messing with a fuel tank, I probably don't have to tell you ... but just saying .... be careful.

 

[88yota]

Yes first time. and it came on all of a sudden. Yes fuel gauge works and i had a lil over half a tank of fuel. I unhooked the pump from the harness and put a test light on the female end of the connector with the switch on and it didnt have and power to it. Then i straight wired the pump and it does turn on and pump fuel. So that should tell me the pump is working fine. Power just isn't getting to the pump.

 

[toyotafan]

ok, I misread, I thought you were testing the pump itself, there is just no power going there. Hmm, is it running at all? Your first post said "starving for fuel" ... I had a fuel pump go out only one time on me and it was in a Ford Mustang and the thing just went from going 70 on the freeway to nothing and it coasted to a stop after about 1/2 mile.

 

[88yota]

it will start for a second but then quit. almost like my cold start injector is working but nothing else. I have looked over everything. im clueless

 

[tbplus10]

Are you getting power along with fuel to the infectors?
Whats the fuel rail pressure reading?
If I remember right that model truck has abot # fuses that power the injection system.
In addition to the fuel pump circuit theres an EFI fuse and the ECM fuse affects the system due to an ECM signal wire.

 

[88yota]

I am getting power to the injectors. I think i have narrowed it down to the computer going bad.... Will 2WD computers work with a 4X4? also will an automatic work with a 5SPD??

 

[tbplus10]

A 2wd computer can be swapped in place of a 4wd, their old enough the t-case doesnt impact operations.
I dont believe an automatic and 5 spd computer are interchangeable, the computer controls some trans functions on an automatic.
Kind of curious as to why the ECM is suspect?
If the ECM is bad the truck shouldnt start for even a second, just turn over and get nothing.
Have you checked for spark at the plugs?