Fuel Pump Won't Shut Off

mike knight · #1 (**permalink**) 09-30-2006, 04:39 PM

Here are the facts:
Electric fuel pump (weldon 2025) which is easily heard at idle starts to rattle loudly. I drain the tank and pull the pump checking the brushes. Brushes show some wear but not excessive. I didn't want to lose any drive time this time of year in the midwest so I bought another pump. What the heck I put the new pump in service and it runs perfect. While test driving the car in my neighborhood the engine quits abruptly. I check the fuse and it's blown so i replace it. Pump is working again but it won't shut off when i kill the ignition.
I replaced the relay but that doesn't solve the problem. In order to kill the pump I have to pull the relay after engine shut down. This is becoming a big PIA. I put a meter on the disconnected battery to see if I have any draw down but the meter reads 0. Since there are only two wires coming out of the pump, one orange and one black and it's wired exactly as the old pump, orange to positive and black to a frame ground, I feel confident that I didn't wire it incorrectly.

Any ideas out there about what might cause this? I really don't like the idea of draining the fuel tank again as that is a huge PIA not to mention safety. I do have a 4 post lift so I can get under the car easily. The original pump is on its way to weldon for inspection and rebuild if necessary.
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strictlypersonl · #2 (**permalink**) 09-30-2006, 05:48 PM

It sounds like the relay is toasted. The contacts were welded together by some intermittant short before the fuse blew.

mike knight · #3 (**permalink**) 09-30-2006, 07:44 PM

I had the same thought and bought another relay and it acted the same way.If I plug the relay in with the key out of the ignition the fuel pump turns on. It never did this before. The only way the pump is not on is if the relay is removed from the plug.
Thanks,

Mike

Ron61 · #4 (**permalink**) 10-01-2006, 06:56 AM

Mike,

You might try this until you track down your problem. I have my fuel pump connected to a toggle switch on the dash so I can shut it off if I want to do some work with the key on. Much easier than pulling the relay.
As for what changed, try checking for voltage with the relay out and if you have it on the relay winding, find where it is coming from. Sounds as if the minute you plug in the new relay it is operating. Also measure through the relay contacts of the new one with an ohm meter to be sure they aren't welded together. If you haven't blown any more fuses, then they should be ok. It is possible that while your old pump was going bad, it drew enough current to cause a short between the winding lead and another lead that has power on it. I would start by pulling the relay and checking right at the relay plug terminals.

Ron

mike knight · #5 (**permalink**) 10-01-2006, 09:13 AM

Thanks ron, I'll try that today. If I can't uncover the problem I'll take er' out since it is an absolutely georgous day in chicago, 75d, low humidity,no wind and no clouds. I am going to drive today and hopefully the system will hold together until I can shut it down for winter inspections and work.

neverwouldof · #6 (**permalink**) 10-01-2006, 09:51 AM

What happens when pump starts to go bad? I believe i started having issues yesterday with mine. Guage usually sits at 6psi then it started twitching to 3psi and engine was running badly, before yesterday it would go up towards 10psi after driving awhile when running lower rpms. yesterday something quit and i was braking to turn into neighborhood and engine quit. I tryed to crank engine with clutch in while coasting and no deal.... had to push the rest of the way past the neighbors! Let everything sit over night thinking it might be flooded and tryed to crank this morning and nada.... starter while turning engine over sounded like it was under load and killing battery or something else went wrong.

any thoughts?

Keith

Jerry Clayton · #7 (**permalink**) 10-05-2006, 10:50 AM

Kieth

Change the needle seat assy on the seconaries of that carb
when a holley runs over the vent tubes with the engine not running and the throttle blades closed, it will run out around the throttle shafts

Check your fuel system for debries that is fouling your pressure regulator and needle seat assy

Flush all the hoses in the system, check all screens, set the regulator at 5-6 #, make sure your pump is shutting off

Jerry

Ron61 · #8 (**permalink**) 10-05-2006, 11:50 AM

Jerry pretty much said what the rest of us have been saying. He is correct about the fuel coming out around the throttle shafts if enough goes into the throttle body with the butterflies closed. Also while you are checking all the rest you might want to put what they call whistles in the carbs. They will keep gas from splashing up under braking and going into the vent areas. I had to have that done with mine and what a difference it made. If your pressure has been to great you could have the needle valves all messed up. My book on the 900 Holly I am running calls for just 6 to 8 pounds of pressure. My pump puts out 14+ so I have to watch it and make sure the regulator doesn't back off or the filter get full of crap. The gas out the muffler is just unburned raw fuel which has poured into some cylinders and is being ejected. Not good as some of it most likely went into the oil pan too. I would have both of the carbs checked out completely along with the rest of the stuff Jerry mentioned, and then change the oil and filter to make sure there is no gas in the oil.

Ron

neverwouldof · #9 (**permalink**) 10-05-2006, 12:24 PM

Ok .... will do . Thanks guys for your wealth of info!

I'll update once i get in there and see whats happening.

Keith