Hey guys
My 90 montero v6 mfi will not start. I have spark. New fuel filter installed. Pulled the fuel pump to bench test. It will shoot a stream about 2-2 1/2 ft. straight out of the pump. I'm only getting 8-9 volts to the pump when it is mounted in the tank.
Is my pump bad, or is it a voltage problem? Don't want to put in a $150 pump/screen to still have the same problem.
Thanks.

Fuel pump should still work installed - even with jsut 9 volts. I'd have to take a look at the schematic to see if thats normal, but I would imagine 11V is probably the norm. I think systems rarely reach 12V, Most peak etween 10.5 and 11.5

Anyway, if you have spark and the fuel pump is working, sounds to be like bad/clogged injectors. i hate to say it, but the next step would probably be to remove the intake plenum and pull the fuel rail. You might be able to do this leaving one side of the injectors still attached, but you;ll at least have to disconnect one.

Once you have the fuel rail up off the intake, reconnect all removed injectors, place over a drip pan and apply bursts of 12V to your fuel pump - you'll probbaly need help with this!

This will tell you a few things. If you have:

a)clogged injectors
b)dirty injectors with poor spray pattern (not enough atomization)
c)electrical signal to the fuel injectors themselves.

Of course all this could also be caused by the ECM - it does after all control the MFI system as it's primary function.

It could be so many things, but I would still suspect a fuel delivery problem. Just difficult to narrow down the culprit.

A quick swap with a known good ECM might be the easiest thing.

MI-Mitsu

Hey thanks for the info.
A little more history: It wouldn't start last night. I put on a new cap and rotor. Started right up after the install and drove 10 miles perfectly. Parked it. Before going to bed went out and started it up several times with no problem. Now this morning, nothing. The new fuel filter didn't help.
With clogged or dirty injectors, wouldn't I be having rough idle, skipping, etc. before it just decided not to start?

Well, I'm no expert but this sure sounds like the way my fuel pump was reacting before it finally died. It ran fine during the day -- multiple start/stop cycles, but then when I was ready to leave work at night -- no joy. I could crank the engine 'till the cows came home and no light-off. Next morning armed with my trusty VOM to pull codes the engine would light right off. After having to call my wife twice to come and get me, I got the Raider home and in the garage, where it finally failed permanently. After replacing the fuel pump I haven't had any more problems.

I suspect your fuel pump is dying a slow death.

That being said, if you suspect the voltage, there is a test terminal up under the passanger side dash that you can apply 12v directly to the fuel pump, bypassing the fuel pump relay. If you give it 12V and there's still no light-off the "No Start Tests" document points very strongly to the fuel pump being bad.

Eric W.

That is what my rig was doing until this total death. I think I'm gonna gamble and put the pump on. Thanks. My wife is questioning the "Car won't start!" excuse for me coming home late after work.

Good luck with it! Fortunately for you it sounds like you've already pulled the pump, so putting a new one in will be short work. I suggest a new pump-to-tank gasket, but I'm betting you've already thought of it <img src="/forums/images/graemlins/kewl.gif" alt="" />

Eric W.

Update. New pump installed. Now she purrs like a kitten. Thanks for the help all.

Good work! <img src="/forums/images/graemlins/cheers.gif" alt="" />

Eric W.