my fuel problem

Try it with an open tank (cap removed) to ensure it isn't some vacuum issue. It might be blocked lines - both from the tank and return. You should be able to drive the pump straight from +12V (but via a 10A or 15A fuse just in case!) to see if it's a +12V supply issue, or pump/line issue. (Most pumps are +12V.) If that's fine, then trigger the relay. If ECU controlled, it's usually a ground signal. Airflaps may also be grounding (to turn the relay & hence pump on). If its charge or spark controlled, it's probably +12V to turn the relay on. (See also WireToFuelPumpWire-Fuse GetsVeryHot which refers also to the last post at the12volt.com/installbay/forum_posts.asp?tid=107789. Just ensure disconnection of the control signals first so you don't damage whatever is controlling the relay. Of course I should have asked why you think it's a fuel issue and not some other control? But before replacing the tank etc, I'd suggest a pro look at it. There is no point with a new tank if it's an O2, temperature or other sender, or blocked jets or injectors, or loose ballasts etc.... Or at least flush the tank in case someone has dumped balloon pieces etc. (PS - why the renewed fuel pump posts? Must be this hot weather eh?)

listing the type of car you are working on would be very beneficial.Kevin Pierson

Sorry.. I have a 94 cadillac fleetwood brougham....I took it to AAMCO and they brought in a specialist and they had told me that it was a fuel pump issue..but they wanted alot of money..I'm a student and starting school again and didn't have the money to get it down..so I been reading online and researching my self...I know its either the wiring within the fuel pump or the outside wiring..(pigstail)...also what i did was i connected a 12v battery stright into the + and - of the sending unit..outside wiring and gas comes out...so MAYBE it could be my ECM..??how can i get that check?? and how much are those??Fire310

I used to have a '94 Caprice wagon (dressed up as an Impala SS) and now have a '96 Roadmaster Estate Wagon....both of those are the same cars as yours. When the fuel pump on my '94 failed, I had it replaced at Pep Boys, as I was travelling, it was a Sunday, and they were the only place open. The first pump they installed was defective out of the box. The second pump worked for me to make the next 1000 miles of my trip, and then started to go bad shortly after that. When that pump did fail, it didn't stop working entirely. If the car was cool and left off for a while, it would work fine for about ten minutes of driving. Then it would drop pressure but still pump enough for the car to idle and move around a parking lot, but it couldn't build up any kind of speed at all. These cars are known for fuel pump failure as they get old. Look around on www.impalass.com and you'll see. Anyway........ So you've already tried manually wiring up your own power and ground directly to the pump? Well, that's not a bad place to start. Maybe you can temporarily run a toggle switch into the car's passenger compartment (don't forget to fuse at your power source!) and try driving around like that for a few days. If everything works perfect long-term with your toggle switch and wire, you can then start to suspect the car's wiring, fuel pump relay, ECM, and all that..........you'll need to get a wiring diagram for the car and start troubleshooting. On the other hand, if the jumper wire and switch still doesn't get the car to run reliably, you can be almost sure that the fuel pump is going bad. If you're in California, maybe the car's not too rusty underneath. A set or ramps, basic hand tools, and an afternoon and you could probably replace the fuel pump yourself.

Thanks Angel for the "why fuel" answer. So it's a bad connection but someone can con bulk money from you.. lol! Chris's great info supports the fuel (ie, pump) problem. Furthermore, it suggests finding an alternate quality pump. (Matching specs should be the same pressure (or higher is there is a pressure regulator elsewhere), same or higher delivery rate, voltage, internal pusher, or external pusher or puller (aka sucker), and the other physical stuff.) I was getting worried because pumps, filters and lines - fine, but a tank problem....?! But you should be able to fix this... With raw 12V (preferably fused) from battery direct to the grounded but otherwise electrically disconnected pump, an okay pump MUST pump okay (if lines, filters etc are ok). It sounds like that test is likely to fail. (Hopefully yes!) After that it's tracing back. But that's for later if needed. FYI - It is unlikely to be the ECU - its output/s should either work or not, though intermittents do occur - albeit often in connectors. TIP - for any electrical problem - disconnect and reconnect the connectors involved, and rotate same-sized fuses. This can re-make connections gone bad, and move intermittent fuses to another circuit.

When I connected my pump to an 18v batter off my cordless drill..it pumps..but i notice that at times it try to slow a bit...but i didn't want to leave it running cuz i might burn it....this is my second pump i bought..and it was a new one from autozone..paid about 100 bucks..Fire310

Wise move - 18V means twice normal power!! (Wattage, heat) It does sound like a faulty pump then? Just like Chris above... Though if the output was still connected to fuel lines which are blocked or kinked, it might slow its delivery...