Yet another problem with the 944S (fuel pump)

[armandodiaz]

OK, so I finally got everything sorted out and together. I tried to start the car and it just spins. I quickly figured out it was the fuel pump. I had replaced this pump 1 month ago before I started. My first guess, faulty pump, right. I had an old pump laying around so I plugged it in and it started!
I take the pump back to the parts store 2 days later and they replaced it. I went home and decided to start the car again...
no start.
I checked and there's power and ground going to the pump, and the pump is hot.
What can be shorting out the pump? I don't what to hook up the new, new pump so I don't short it out.

BTW: I have no history on this car, it's been sitting for 7yrs.
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[Brando]

Did you replace the filter with that pump? If it's sucking air or sludge it will burn out. I'd say take the filter off and replace it, also see about taking the tank out (after draining) and have it cleaned and re-coated. This was a suggestion made to me. So far a new pump and filter and she was roadworthy after that.

Also, that little line from the bottom of the tank to the pump inlet might be clogged up. It's short enough you can replace with some rubber hose from a FLAPS and be ready to go. That or your in-tank filter might be very very dirty.

[armandodiaz]

The filter is new and it did run for about 5 miles the first time I replaced the pump and 5 minutes when I put my old pump in. But you might have a point about the in-tank screen. I'll have to ask the owner how old is the fuel in there.

[SoCal Driver]

Maybe a golf ball rolling around in the gas tank? Rolls over the siphon and no gas to the pump!

[Brando]

Originally posted by SoCal Driver
Maybe a golf ball rolling around in the gas tank? Rolls over the siphon and no gas to the pump!

Acutally I was thinking a sock might be the culprit...

Yeah, gas over a year old, i'd "dispose" of it and replace with new gas. Especially if the car has been sitting for that long... I'm sure it's separated and you possibly pulled the not-so-petrol chemicals from the tank and into the fuel lines... I hear water isn't combustible, and vinegar is barely so...

[Razorback1980]

What Brando suggested is the first thing to look at, but also check the fuse to make sure it's the right amp. If it's pulling too many amps, it should blow a fuse. Probably good to check the ohms through the ground wire as well.

[armandodiaz]

Posted: Thu Mar 16, 2006 8:10 pm Post subject:

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All right, I talked to the owner. He's not sure how old the gas is but says it's definately more than a year(not good). I plan on draining and flushing the tank, screen and hose this weekend. I'm still a little sceptical about it being bad gas. Last time I ran the car it was with my old, working pump and it was only for about 15min.
I looked through the wiring diagram and discovered the power to the fuel pump(grn\sw) also powers the O2 sensor (#2 terminal) with no fuse in between. What are the chances of a bad O2 sensor burning up the pump?

[Razorback1980]

It's just a guess but I don't think the chances would be very high. I think if the O2 sensor was shorted, it would blow a fuse. Electric motors tend to quit running because of heat and heat is caused by it drawing too many amps because the work load is too high or it isn't getting sufficient power or ground. I think I would go with the pump is burning up because it is working too hard. Check all lines and make sure they were totally open and the fuel pumps job is very easy. Check the amps to make sure it isn't pulling too many amps but if it were, you would think it would blow a fuse unless the fuse is not the correct one. I can't believe that bad gas would cause a pump to fail as it doesn't care about gas quality. But I really like Brandon's idea of the screen being plugged and would probably be my first theory as well. I would also check the fuel pressure at the fuel rail and again at the hose going back to the tank to make sure there is nothing blocking the flow. That's the route I would take. What I'm not saying is that the gas doesn't need to be changed as indeed I do think it does but more for the engine's sake than the fuel pump.

[armandodiaz]

Update:

I pulled the screen off, this weekend. First off, it came off in two pieces. The parts picture shows it as a one piece unit(the nipple and screen). Next thing I noticed was that it was all sticky and gooey. The bottom of the tank was the same way. Third thing I noticed was that it looked as it was collapsed or sucked inward.

Last thing I notice was while I was looking at the DME relay it seemed as if the blades of the relay were discolored as if had overheated.

My next step is to buy a screen assy, new relay and a whole lot of carb cleaner. Does anyone else have any ideas on how to clean the tank(without removing it)?

[Razorback1980]

I would do whatever it takes to clean it right. The sticky goo is just going to transfer to the injectors and then they will be the problem along with the gas tank if that hasn't been done already. By not cleaning it right, you will just take a simple problem and make it into two or three more complex ones. IMO You've already seen at least one of the effects of not having clean fuel with the fuel pump. If it's worth doing, it's worth doing right.

[armandodiaz]

What is the correct way? I was planning on using carb cleaner and spraying the inside of the tank, as much as possible. I was also going to take the cap off the injector rail and I was going to shoot some carb cleaner and blow it out. Do you have any better ideas?

[Razorback1980]

I've never pulled a tank, but if I could I would take the tank out and then you can use whatever cleaner you desire and not hurt anything. You would also be able to make sure it's completely clean before you put it back in operation. I know that may be a lot of work, but it's the best way. I would also flush the lines and replace the filter. If you really want it to run the way it should, it may even need to get the injectors repaired. Someone put a link on here of a place that specializes in that. It will probably run if you did something short of that, but it will run the best if you clean everything. You just don't know where all that sticky stuff went to but it had to make it all the way to the injectors or the car would have never run. How much it messed up the injectors is the real question.