that's weird.

do you mean, stays on for a second before dying out?
If so, then I think that's normal. Right?

I've never tried this, but it might at least eliminate a suspect key switch circuit:

Since the engine appears to start when the ignition key switch is turned to "START" - but dies shortly after - it could be that the key switch is not passing power in the "RUN" position. You could check the voltage on the switch, but for a quick read, crawl under the truck and have an assistant start the engine and hold the key in the "START" position. At the moment the engine fires, pull the solenoid connecter. If the engine keeps running longer than before, the key switch is not passing current when released to the "RUN" position.

It might be worth a try, but be careful.

Frank

check your grounds...

I think the pump runs while the key is in Start, and then only when the computer sends volts to a different solinoid in the MPI relay. I dont know how, but that is how the diagram looks.

What is the square with a slash symbol in the MPI relay? Should be a loop-de-loop solinoid symbol, but it aint.

oh...check for codes then and try unplugging sensors including the IAC.

then read the codes again

Rich.. by the rate you're going you might as well wait another week. I'll come re-do the timing belt job and get it running. <img src="/forums/images/graemlins/lol.gif" alt="" />

On the 89 V6 schematic, I see that the fuel pump is run by 2 coils in the engine control relay. 1 is controlled by the starting circut. The other is controlled by the ECU. Both are run through different fuses. I would check the main fuses & fusibile links near the battery. while working on the engine, something might have contacted ground & blown 1 of them.

Actually check them with an ohmmeter & also wiggle them while having an assistant try starting.

Cycle ALL electrical connections & insure no pins were bent or pushed out of thier sockets. While cycling ALL connectors, use grease to bar future corrosion. Silicone Di-Electric Grease is the best for the application, but regular wheel bearing grease will suffice.

Otherwise, the engine needs a signal from the ECU to sustain the power feed to the "run" coil. For that, a typical ECU takes a distributor and/or alternator signal.

If I remember right, some of the ignition connectors are similar. Unplug them all & make sure the colors match eachother.

I am guessing that you try to start the engine without all of the accessories connected... In that case it could be an alternator signal you are missing.

In the Haynes manual, I am seeing that the alternator is connected to the coil primary. It is also fed through the main charging wire to a fusible link. I would get some heavy duty jumpers to bypass the fusible links to check.

If the battery was not disconnected, or momentarily reconnected the feed wire could have gotten shorted & blown that.... *** My strong opinion *** & then is not feedcing a charge/ignition signal to the coil & then ignition is not feeding ECU to pull coil #2 in engine relay to keep the FP contact engaged.

If you check all of these, PM me & I can figger out a way to bypass & reverse feed them to help diagnose the run issue ***** At your own risk as I am just a hack like you *****


Ed

I haven't looked at the schematic, but I think the tach signal is what the ECU looks for to keep the fuel pump in operation when the key switch is in the "RUN" position.

As previously suggested, if all of the electrical functions are not connected, the engine may not run.

The idea to check the fusible links near the battery is good - also, the square plastic main fuses at the battery can be easily checked.

Frank

The ecu looks for a tach signal and if it doesn't see one (in ign run position), it kills the ground to the fuel pump relay coil after a delay of about a second.

I can't remember if the ecu tach signal comes off before the 'lectron doodads on the coil bracket that condition the tach signal for the the dash tach or after.

Does your tach show rpms for the little time it runs? If not, you've got connector issues at/around the coil bracket. One of the wires to one of the doodads has insulation that gets VERY brittle with heat and age and can break the wire by fatigue at a break in the stiff insulation. That's what happened to mine some time back. Check the connectors with one wire on the pside of the coil bracket that come off the coil - terminal.

Also check the ecu for a fishy smell...

Hi,

I just read this whole post so bear with me if this sounds too basic. When you remove the crank pulley bolt, it should come out first, then there should be a heavy, thick washer, then the harmonic balancer comes off. You should see a groove cut in the crankshaft nose that the harmonic balancer came off of. There is a small halfmoon-shaped piece of metal that rests in that groove. It's called the woodruff key. It should be a perfect halfmoon shape with no chunks missing out of it. After that comes out, there should be a thin metal disc that comes off, then the crank sprocket.

When you put it back together, make sure you are using the same order. Also, most importantly, are you putting that woodruff key back in the groove with a thin coat of copper anti-seize before you put the harmonic balancer back on? (also a thin coat of copper anti-seize on the crankshaft nose too) If you don't put it in the groove beforehand, the harmonic balancer will spin on the crankshaft nose and the engine will be out of time.

This is the only thing I didn't see in the troubleshooting tips so I'd thought I'd mention it. Hang in there! I've been in the same boat a couple of times before on the 3.0 V6. I had the exact same thing happen to me changing out the heads for a buddy of mine. After two weeks of messing with the timing and all sorts of troubleshooting tests including hooking it up to my MUT-1 scanner, it turned out that the fuel pump went south at the same time I was swapping the heads. It would run but just not with enough pressure to keep the engine running. It ran just like an engine that was out of time!

Pmontero

I am officially retarded... The problem is that I was being rushed by the owner, and I pinched the dizzy harness under the intake plenum. Thankfully Brendan noticed this and was nice enough to point and laugh for only a few minutes.

Thanks again Brendan. You always seem to be able to help this window licker out when in need! <img src="/forums/images/graemlins/cheers.gif" alt="" /> <img src="/forums/images/graemlins/cheers.gif" alt="" /> <img src="/forums/images/graemlins/cheers.gif" alt="" />

Edit: I am glad to say my timing belt job was done right at least... <img src="/forums/images/graemlins/lol.gif" alt="" />