Fuel pump help.

[Colby.325e]

Okay, so about a week ago my car died. Pushed it back home and started testing everything. I have spark, but no fuel. Relays and fuses are all set. I cannot hear the pump during start up. I order a new pump and received it today. I took the old pump out, and hooked the new one up, but no start. I can head it now, loud. I again checked for fuel at the rail - nothing. Maybe a clogged filter? I unhooked the line at the filter, but still, NO fuel during startup. Anyone got any ideas? I have power, and can clearly hear the pump engage, but it doesn't push fuel. What can I check next? Anything?

[berlow94]

Do you have a single or two pump system? If its dual then the pump in the tank is only your positive displacement pump. check your high pressure pump right next to the fuel filter. Disconnect fuel line going into this pump and test there. Very common on dual pump set ups for the wire connecting the pumps to fail (took me a whole day to figure out what was going on). If this is the case just get a high pressure in tank pump and convert to single.
Hope this helps.

[TobyB]

It'll only pump while cranking. (this is the 91, right?)

Unhook the line at the tank, and hook a bit of tubing up to it, and see if it'll
pump that way.

If not, and it's getting 12v, then you either got a bad pump

or are out of gas.

t

[Colby.325e]

Gonna try switching the pos and neg wires. I may have them backwards. Worst case I'll blow a fuse. Or the whole car up. Hoping option one.

[mr.vang]

Gonna try switching the pos and neg wires. I may have them backwards. Worst case I'll blow a fuse. Or the whole car up. Hoping option one.

If you switch the two wires chances are its pumping fuel the other way around. Once its run dry for awhile its going to burn the pump.

[Kozworth]

What I would do is extra confirm that you have 12v at the pump... I dont trust my ears, I trust my eyes. I would grab a dvom, key on engine off, and check for battery voltage at the harness. If thats good, try a fuel pressure test. Splice a fp gauge before the rail.

If there is no fuel pressure, it could be possible the pump polarities are reversed. I would visually inspect all the lines and see if I notice any leaks or smells. Check hard lines for crimping. Remember the rule of pressure.


X psi to rail [Filter] ~40psi from pump to filter

You will have the same psi on both sides of a crimp/blockage, just VOLUME will reduce. So the same pressure pushing the gasoline, just less gasoline on the post blockage side. It isn't too common that blockage prevents a car from my experiences.

If you had ~40psi or whatever rail pressure should be at the rail, I would say pull the injector harness and connect a test light between the prongs. The PCM should duty cycle 12v to open the injector. If there isnt any light, odds are the c191 plug is beat. Thats the crappy plug below the throttle body. Test for 12v pre and post the harness, and if its pre and the Test light is not lighting, cut the whole harness out and splice with male/female connectors.

[Colby.325e]

If you switch the two wires chances are its pumping fuel the other way around. Once its run dry for awhile its going to burn the pump.

That's my plan. I think I hooked it wrong. I haven't run it much. If I switch and it doesn't crank, I'll throw in the towel and get a new unit

[Colby.325e]

Koz, thanks for the advice. That will be my next plan of action if reversing the polarity shows no effect. I work until 7, but I'll update the thread and let you guys know! This is my first REAL issue with my e30 (I'm lucky as all get out), so I'm learning as I go. Never had a starting issue. Just some control arms and brakes. Very little electrical stuff.

[Colby.325e]

Swapped the wires, and it finally started. Took it for a drive around the block (which felt amazing - I don't remember it shifting so smooth), and the pump got progressively louder. Even in its quieter state, I can hear it above the engine idle. After driving for 2 minutes, it gets REALLY loud. Doesn't really sound like a "whine" as I've heard it described, but it's very irritating. It's the airtex fuel pump. Anyone have experience with these? I'm thinking I've probably burned it up by running it the wrong way for a little, right?

[dnguyen1963]

I bought an Airtex pump and it got so loud after only 3 months of use. Replaced with a tre pump and have been happy eversince. Note that I used a piece of fuel line to connect the pump to the fuel line instead of the funky coupler. The pump is a lot more quieter.