1998 MPV fuel issues
 

Hey guys. Joined this forum just to ask about this!

Picked up a '98 with a 3.0L and 220k on the clock because a timing belt had broke and they couldn't figure out how to put it back together. I got it home and had it running the next day. Not bad for $300!

Now I don't really remember why but for some reason I decided to check the timing. I think the p.o. may have had the dizzy out or something. Anyway, watched a YouTube video how to jump terminals at the diagnostic port to disable the ECM so it doesn't adjust timing, I think the video showed the wrong terminals to jump (or I'm an idiot) and I jumped the wrong ones. Now the only way I can get the dang fuel pump turn on and the van to run is if I jump the fuel pump terminal. Runs okay until it warms up then it starts acting sluggish. If I hammer it the van will take off like a rocket ship. What the crap did I do? I've check fuses and relays but I'm all ears as to which to check and double check.

It's really a sweet van but I can't drive it the way it is. Thanks in advance!

Still haven't figured it out. Was googling the issue again and found my own thread! Looking at some wiring diagrams and testing wires, I haven't determined much.. I can say, the pump is good, the main relay and the fuel pump relay are both good. For whatever reason, the PCM isn't turning the pump on. If I knew the logic of the PCM I would know where to look. Where does the PCM get the inputs that turn the pump on? That's the question..

Also, somebody sent me a PM but I don't have enough posts to look at it..

PCM will prime the pump when ignition is first turned on. Unless it gets a RPM signal it won't power the pump up to run.

Possible you have fried the driver inside the PCM.

So does it need an RPM signal to prime it or is that controlled separately? And then when it does get an RPM signal it turns the pump on continuously? Could be my crank sensor?

Thanks for replying by the way. Not a whole bunch of info out here on MPVs..

Priming is automatic whenever the ignition is turned on.

Without a scan tool capable of live data, its hard to say why its not working.

I do have a Snap-On scanner that does live data. Just don't know how to use it very well I guess.

So after watching the Youtube video again, I'm pretty sure what I did was ground the fuel pump wire at the DLC while it was running. Now, grounding that same wire is the only way I can get the pump to stay on. I have to think some more on it..