Project: The Anal Probe

[Galane]

An electric fuel pump not running is most likely the pump gone bad, but it can also be other things.

The way most are set up, they run for a bit when the key is turned to Run, then shut off. That's to pressurize the fuel system. When the key is turned to Start, the pump is supposed to turn on again.

When the key is let back to Run, one or more engine sensors are used to signal that the fuel pump shall continue to run. Some systems use the oil pressure sensor. Others use the crankshaft or camshaft sensor.

Something quite a bit less expensive and easier to change than the fuel pump, and just as likely to go bad is the fuel pump relay. The relay is most often under the hood somewhere near the left or right side, typically in or next to the under-hood fuse and circuit breaker box.

What's rough on fuel pumps is running around with the tank nearly empty. The pump motor uses the gasoline for cooling. Some vehicles (mostly GM for American makes) have a porous foam sleeve around the motor to wick up fuel* when the tank is nearly empty. Some others (like a 1998 Chrysler Sebring convertible) have nothing like that, and replacement motors aren't available, just the whole bleeping $200 pump assembly.

*Which didn't stop the pump in my 1986 Cimarron from quitting and leaving me stuck in the middle lane on a five lane road.

What's really frigging annoying is in-tank electric fuel pumps just love to die right after filling the tank. Can't go *poof* when there's just fumes in there, too convenient.

[skyking]

Sven, don't bother rewinding an alternator for less power. It really only uses as much hp as is needed by the loads you put on it. Reduce load = reduce hp needed.

[Sven7]

Galane, I have to look up which relay does what and figure out a way to test them. The car is honestly a really low priority in my life right now. More concerned about maintaining my bicycle, which gets much more use. I've been riding the bike all over town and the only reason to have my car is to drive 15 minutes up to a friend's house in Troy.

[Ultra-Orange]

Love your thread! I'm doing similar work to my Metro and have referred to your thread on several occasions!

Quick question. When you did the paint job did you attach your mods differently or Paint over the tape? Looks really clean in the pictures. I don't see the tape but the mods don't look like they have been changed.

anyways. *clears throat* great job and keep up the good work!

[Sven7]

Thank you. I buffed (~600 grit?) and painted the coroplast red before attaching it to the car- spray paint does not stick to duct tape. When I did the camo thing the masking tape pulled up the red paint underneath so I now have three colors of duct tape: red, white and black. For touch-ups

[HyperMileQC]

This is a great thread, usually, i'm not really liking the american cars... But your probe is fantastic, keep up the good work Sven7

[johnunit]

I doubt hotter plugs will gain you anything. In general, the stock plugs are best for stock engines. Motorcraft (Ford) copper plugs are quite good.


Hotter plugs will also limit your ability to advance the ignition timing before encountering detonation. I'd experiment with more timing, for sure. Keep an ear out, but you MAY not even need to step up to premium fuel. You may be able to advance timing by enough to make a difference in fuel economy before encountering ping. However, if you don't have the equipment to tap into the factory detonation sensor, and the exhaust leak makes a tapping/knocking sound... You can probably see where I'm going here. My personal experience has been both a 4.0L OHV Explorer and a 5.8l Carbed Crown Vic saving gas (even in terms of dollars per mile) with advanced timing and premium fuel. Whether that translates to a Probe? No promises.

[Sven7]

QC thank you- I'm not especially enthusiastic about American cars either but this is a Mazda underneath after all!

John, the more I think about it, the more I do not want to touch the timing at all. Too much to go wrong and this is a daily. The farthest I feel comfortable going right now is an alternator on/off switch.

If the fuel pump doesn't work I might be seriously looking at this.
92 Geo Metro Limo READ ENTIRE POST

[skyking]

OMG get it now!

[Sven7]

Hehe that thing would be perfect.