Virginia Posted May 1, 2016 Share Posted May 1, 2016 I turn the key to the on position and can hear the pump buzzing but the engine won't start. I'm 99% positive the leads on the pump are hooked up correctly. I disconnected the feed line on the tank side of the external fuel filter and turned the key to on but nothing came out. If the pump leads were hooked up incorrectly, the pump wouldn't run, right? Or would it run backwards and if that's the case, what would happen? I really don't want to drop this tank again. Link to comment Share on other sites More sharing options...
HOrnbrod Posted May 1, 2016 Share Posted May 1, 2016 Yes the pump will run in reverse (backwards) if polarity is reversed. When you turn the ignition key ON (not to START) does the pump run for a few seconds then shut off? If it keeps running it's not building up pressure indicating it's probably wired up backwards. Link to comment Share on other sites More sharing options...
Virginia Posted May 1, 2016 Author Share Posted May 1, 2016 It does run for a few seconds then stops. What else might help...There's over 3/4's of a tank of gas so the pump should be fully submerged in fuel. I've jumpered the the fuel pump relay and can hear the pump running but didn't leave it jumpered long. Should I do that again? And if so, how long should I let it run? I've opened the schrader valve and got almost nothing out of it but haven't hooked a fuel pressure guage up. Should I do that? Link to comment Share on other sites More sharing options...
HOrnbrod Posted May 1, 2016 Share Posted May 1, 2016 Bummer. If you had the fuel pump running with the fuel rail Schrader valve stem out and no fuel comes out, it's either an obstruction in the supply line or the pump is bad. Try a set of gauges but I doubt you will read anything. Next step would be to remove the sender/pump and check the supply line for obstructions. If everything looks okay carefully try a bucket test. You can use diesel or even kerosene for a short test. I had a bad Bosch pump right out of the box once that wouldn't pump. What were your original symptoms that caused you to replace the pump? Link to comment Share on other sites More sharing options...
Virginia Posted May 1, 2016 Author Share Posted May 1, 2016 There were no symptoms. Original owner had the pump and everybody said may as well replace the pump while you have the tank down. I'm not familiar with the bucket test. Link to comment Share on other sites More sharing options...
HOrnbrod Posted May 1, 2016 Share Posted May 1, 2016 Wire up a battery charger to the pump for power and hook a temp hose on the pump discharge port to empty into a bucket. Then lower the pump into your fuel bucket with a rope, power it up and see if it pumps into the other bucket. There's even a flow volume test writeup in the FSM where a healthy pump should pump at least one liter of fuel per minute. It's normally done on the vehicle but since you said there's no fuel coming out of the fuel rail.......... Link to comment Share on other sites More sharing options...
Virginia Posted May 1, 2016 Author Share Posted May 1, 2016 OK. Will work on this tomorrow and at this point, I may just put the old one back on. Link to comment Share on other sites More sharing options...
1987Comanche Posted May 2, 2016 Share Posted May 2, 2016 Did you use a new chunk of rubber fuel line when you replaced the fuel pump? If the pump is running but no fuel is coming out the hose could be kinked, torn, etc. You need fuel hose rated for submersion (SAE 30R10). Standard hose won't hold up. Link to comment Share on other sites More sharing options...
Virginia Posted May 2, 2016 Author Share Posted May 2, 2016 Yes. We used what came with the new pump. Link to comment Share on other sites More sharing options...
HellCreek Posted August 7, 2016 Share Posted August 7, 2016 I have a similar problem. I replaced the fuel tank and pump on a 1991 with a 4.0L. I have 30psi at the rail. The engine turns over fine, but it will not start. I tried starting fluid in the throttle body, and it will run only as long as fluid is squirted. I attached a noid light at the injector connectors and they are receiving pulses. Any suggestions? At first I thought that it might be the CPS, but it wouldn't run even with ether if there was no spark. Link to comment Share on other sites More sharing options...
HOrnbrod Posted August 7, 2016 Share Posted August 7, 2016 Tom, when you turn the IGN key on does the fuel pump start, then shut off when it reaches ~30 psi? Was the replacement tank and fuel pump new stuff, or used from another vehicle? If so, what year vehicle? I'd try the flow test into a bucket I mentioned above to see if it's pumping enough volume - that will eliminate the fuel pump and regulator if good. Link to comment Share on other sites More sharing options...
DirtyComanche Posted August 7, 2016 Share Posted August 7, 2016 I have a similar problem. I replaced the fuel tank and pump on a 1991 with a 4.0L. I have 30psi at the rail. The engine turns over fine, but it will not start. I tried starting fluid in the throttle body, and it will run only as long as fluid is squirted. I attached a noid light at the injector connectors and they are receiving pulses. Any suggestions? At first I thought that it might be the CPS, but it wouldn't run even with ether if there was no spark. Did it run before you replaced the tank and pump? Link to comment Share on other sites More sharing options...
HellCreek Posted August 7, 2016 Share Posted August 7, 2016 Hi, Don, Yes, the fuel pump runs then shuts off normally. The tank and pump and brand spanking new from the parts store. I also flushed the fuel lines from the rail back to the tank (with the hoses disconnected. Dirty, It ran when I first got it; then it sat up for about 10 years. The tank and pump were ruined, so I replaced them with new parts. What bothers me is that it will run on starting fluid sprayed into the throttle body, so I think that would eliminate, spark, timing and pretty much anything not fuel related. Also, on the starting fluid, it starts up on the first revolution, so -- not hard starting. I suspected the injectors were not firing so I got a NOID light set and verified that they were. It might be clogged ingectors, but all of them? Link to comment Share on other sites More sharing options...
DirtyComanche Posted August 8, 2016 Share Posted August 8, 2016 Is the pump actually running while you're cranking? If the fuel in the lines and rail was really that bad, there is a good chance that multiple injectors are plugged, and the regulator is gummed up. You could keep trying it and they may flush themselves out enough to function, or they may not. Even if you're down two cylinders it's really hard to get the engine to start. Check fuel pressure while cranking, look for it bleeding down. Link to comment Share on other sites More sharing options...
Virginia Posted August 8, 2016 Author Share Posted August 8, 2016 My problem turned out to be the pump wired backwards. When we changed the wires, it worked fine. Link to comment Share on other sites More sharing options...
HellCreek Posted August 8, 2016 Share Posted August 8, 2016 Thanks, I will try these things and let you know. Link to comment Share on other sites More sharing options...
HellCreek Posted August 9, 2016 Share Posted August 9, 2016 Hi, Virginia, I bought a complete pump and sender assembly, so mine had a pigtail with a plug that attached directly to the wiring harness -- no wiring involved. Dirty and Don, i removed the schrader valve from the rail, attached a hose and pumped gas into a coffee can while I cranked the engine. No problem there, but I removed the injectors and the fuel rail and flushed them anyway. The injectors were a little dirty, but seemed to function o.k. They shot a stream when activated. The rail, however was another story. When I flushed it, flakes of crud came out. It took a large can of carb cleaner to flush it completely. I reassembled everything, switched the key about 7 times to prime the system, and it started on the second revolution. I was thinking of adding a can of Seafoam to about 10 gallons of gas in the tank to finish cleaning out the system. Does anyone know if that is a good idea or of something better than Seafoam? Thanks for all of your help. This forum is AWESOME !! Link to comment Share on other sites More sharing options...
buckwheat Posted August 10, 2016 Share Posted August 10, 2016 Personal Opinion Only: Use Marvels Mystery Oil. I like the results I have gotten from it. Link to comment Share on other sites More sharing options...
Virginia Posted August 12, 2016 Author Share Posted August 12, 2016 Use it how? Link to comment Share on other sites More sharing options...
buckwheat Posted August 12, 2016 Share Posted August 12, 2016 My response was for Hell Creek;s question about Seafoam. But now to answer your query: This is a quote from Marvel Mystery Oil's website "How much Marvel Mystery Oil® (MMO) do I put in my gasoline tank? Marvel recommends using 4oz of MMO for every 10 gallons of gasoline." MMO can also be used in the oil, in motorcycles, as a fuel stabalizer, etc. One of those nice things to keep on hand. Again, just my opinion. Link to comment Share on other sites More sharing options...
Virginia Posted August 12, 2016 Author Share Posted August 12, 2016 Great! Thanks Link to comment Share on other sites More sharing options...
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