Hello. I have a 1991 740 wagon with the Rex/Regina fuel system. I bought the car in mid summer to prepare for graduate school interviews. Long story short, the car stopped running months ago, and I have been trying to get it running since. The car gets spark (a quick shot of starter fluid will bring it to life for a moment. I tested the injectors with a light, they pulse. The fuel pump whirrs to life when I turn the key. I changed the fuel filter. I could easily blow through the old one. I do have the filter on the right way. I took the fuel line off from the fuel rail on the inlet side. When I turn the key on, a little fuel comes out, but just a small amount. I originally thought the old pump was weak (250000 miles on the odometer would make that possible). I replaced the pump today and nothing has changed. I added 4 gallons of fresh fuel, just for good measure (just put half a tank in the night before it broke down). The pump starts for a second when I turn the key on, pushing a little fuel out to the rail. While the engine turns, the pump keeps going, but the engine does not even try to start. A quick shot of starting fluid made it run for a moment. I am completely lost about what is wrong with the car. I am desperate to get it running, as I have been walking 6 miles each way to college since August and cannot afford to send the car to a garage. If anyone could point me in the right direction, I would be forever thankful.

 

I think I may have an idea of the problem, but wanted to see if this sounds correct. The in-tank fuel pump connects to the metal tube leading out of the tank by way of a plastic and metal intermediate coupling. This coupling has female orange rubber fittings that go over the male ends of the pump and the tube. When installing this piece, I gave thought to replacing it. Could I just replace it with 3/8 fuel injection hose and 2 hose clamps?

Other things I thought about:
Fuel pressure regulator, but there is very little fuel making it to the rail. Wouldn't a dead FPR just not bleed off excess pressure? Also, I took the vacuum line off and no fuel was present in the line. Lastly, how would the FPR affect the fuel pressure from the pump before the rail?

Relay. I have heard ad nauseum about the relay for the fuel pump, but the fuel pump is coming on every time. I have fuel to the rail, just with little to no pressure.

Unless if it is the coupling, the only thing I can think of would be a small hole in a line. Either one would seem to produce the same effect, like drawing fluid through a straw that is cut on the side (low volume and pressure, but some flow).

 

The rubber coupler in the hose can indeed fail. You can't replace it w/ regular fuel line sold at Autozone. Regular fuel line is only gasoline proof on the inside. The exterior will dissolve if immersed in gasoline for any long period of time. You must stipulate that it is for use in the tank.
So, it can't be the relay because it comes on every time, right? Assuming you know where the relay is, pull it out and, using a jumper wire w/ a male spade connector on either end, jumper the slot on the left closest to you and the one in the middle on the right hand row. You should get a spark when you connect the two, even with the key off. If your pump is good, the filter good, pump connector good...the car should start and run now. The jumper wire will make the pump run non-stop, key on or key off. It's not a band aid fix, it's a diagnostic tool. Not advisable to drive like that but if you choose to do so, make the jumper out of 12 gauge wire and keep it reasonably short. I've used a length of 16 gauge wire and it almost melted in just a few miles of driving. Oh...if the car will start and run...the relay is bad.

 

Thanks for the reply and the information on the fuel line. I will try to dig in and replace the line Sunday and post back with the results. I will also order a relay or two for the car. I know these often go out and it couldn't hurt to keep one in the glove box. Thanks again.

 

Having some issues myself with what I think are fuel problems. Looking forwards to your next post.

 

Why not go ahead and begin a new thread. Post what sort of symptoms/issues you're having. Maybe we can help...

 

Just replaced the hose. Now have fuel at the rail, but lots of air as well. I was getting next to nothing before. I noticed after multiple pump cycles, nothing but air seems to come out. It just dawned on me that I didn't have much fuel on the assembly when I removed it from the tank. I just put fuel in the tank the other night, but people regularly lose fuel around here to thieves. Also, when I listen at the filler neck while someone else cranks, I hear a strong air noise, like the pump is sucking nothing but air. I would have pulled the assembly again, but it is dark and late. I guess more fuel may help. I will let you all know if it does.

 

OK. I couldn't get fuel for awhile, because I only have a bicycle to ride (5 miles to the nearest station). I finally got a ride out to get fuel. I put 5 gallons in, turned the key, and the car came to life. All is well. Someone was siphoning my gas out in the wee hours of the night. I replaced the pump, the hose to the pump, and fueled her up. That is the recap. Thank you all so much. I am the happiest person alive!

 

I have the same car exhibiting the same symptoms. How difficult was it to replace the in-tank pump? (as in hours)

Where did you take off the fuel line to test for fuel? (before the FPR where it enters the rail or ...? )

Thanks for a reply

 

I removed the fuel pump more than once. It is really not that bad. The last time took 1 hour from the time I disconnected the ground from the battery to the time I turned the key to start. This assumes you have everything on hand. I would plan for 3-5 hours. There are many places online detailing the procedure. To test for fuel at the rail, I removed the hose with the nut fitting from the fuel rail. The rubber hose with a clamp is the return. Be sure to wear safety glasses when removing the line, as fuel will likely spray when the pressure is released. Be slow with the removal to bleed off the pressure. If the pump is good, the fuel pump relay is good, and there is fuel, you should get a spray when the key is turned to the on position. Be careful not to start a fire! (Let engine cool completely). As for the pump replacement, there is an access panel under the carpeted panels in the hatch. The carpeted panel has 3 nuts behind the back seats. Once these are removed, the panel may be stubborn. Pull it up. There is a black plate with 4 large hex head screws below the panel. Once the plate is removed, the fuel sending unit will be visible. From here, try to find a good tutorial on Google. There are a few, and this should be easy to find. A few key things: Be SURE to replace the hose between the pre-pump and the sending unit EVEN IF IT LOOKS GOOD (sometimes this hose alone will cause the problems seen for a bad pre/main pump). Also, Vaseline is your friend in getting that sending unit back in! Be sure to disconnect the battery before ever attempting work around the fuel system. Just as important, do not try testing the fuel pump when it is out of the tank (this could cause explosions out in the air where fumes are extremely dangerous!). Make sure the fuel pump relay or an empty tank is not the culprit. On the other hand, you should have less than 3/4 tank before removing the pump (otherwise, you may spill fuel). Let me know if you have any other questions. Good luck.

 

Look you did the same thing I did. When you put the sending unit back in you put it in at the wrong angle. Mine is not a Regina but when I put my sending unit back in I had the feed hose and return hose straight up. It kept running out of gas at around 1/2 tank. When I pulled the sending unit again I turned it and clunk it fell in to place and the hoses were to the right and down. Now I can go all the way to red and the light coming on. I was doing the same pressurizing air until I moved it.