lortech

Hi everyone,

New to forum. I have a case where I am working on a 91 4runner 3.0 v6. The engine does not start. In two of ten cases, the engine atempted to start on one cylinder revolution but did not continue and acted if there was no fuel to start.

I have checked everything.

MAF meter switch for open circuit relay good continuity and I think checked for voltage and is good.

EFI/Open circuit relay. Both click when starting and checked continuity on both relays. Both good. Back probed both outputs of ECU to injectors got a good pulse on my fluke meter.

Good strong ignition secondary pulse to ground.

timing is at TDC for #1 cylinder Distributor cap terminal


So now it comes down to the fuel filter fuel pump or fuel pressure regulator.

I cracked the bango nut to the fuel line and cranked the engine and got fuel squirting out of the fitting. After tightneing that up, checked fuel return line by disconecting it. When applying a vacume to fuel pressure regular, recieved no fuel flow from return line when cranking. When leaving fuel pressure regulator line open to the atmosphere, recived no fuel pressure comming out of return line when cranking the engine.

Owner said he was driving the truck and it suddenly died. He had it towed to his house, then re replaced the fuel pump. Still no start.

IS there something that I could have missed? It has strong spark in the ignition system, has good pulse in the injectors and timming is right on.

IF the owner put in the fuel filter in backwards could that prevent the truck from starting? Does it have a one way valve?

Some one in another thread said if the ignition does not ground the open circuit relay circuit, then it would be a no start. Have defective ignition switches been known to cut out and contribute to a no start on these trucks?

I do not have a fuel pressure gage to troubelshoot this problem. I will however be buying one in the future to do more of these trucks and japanese vehicles.

Thanks for your help

vital22re

iTrader: (2)

you may have an issue with the circuit open relay. it may prime the system when you turn the key on. But if it doesnt' get the signal from the maf meter it wont leave the fuel pump runing. try puttin 12v to the fuel pump and see if it starts with continuous power there. just an idea

lortech

I dont know if you read in my thread, but when I crack open the bankjo bolt just enough to let fuel out, I can attempt to start the truck and fuel does squirt out of the banjo fitting.

Any other ideas?

I did not however, short B+ to FP and attempt to start the truck. I did though, do this just to see if the fuel pump does run and it did.

What are your feelings on the fuel filter being on backwards?

Lastly, there was three relays above the ECU. One smaller that was metal and round and two black above the metal one. Those were black and plastic and taller. No indication which was the open circuit relay. When starting the truck, one of them clicked just dont recall which.

What about the idea of the fuel filter stuck backwards? I hate the idea of going to the guys house and back to this laptop so want to get as much info and find the solution so the truck can start.