jeffball610 Posted September 17, 2017 Report Share Posted September 17, 2017 I haven't confirmed a second dead pump yet, but the car falls on it's face as soon as it gets boost above about 4k rpm. I'm running a Mitsubishi 4G63 turbo with ECMLink, Walboro 255 on a Z31 fuel "bowl" setup, -6AN lines to and from, Denso 660cc injectors, and Aeromotive FPR. Several months ago, I brought my car to my friend's shop to help get a basic road tune to make it safer to drive and get to know the software a bit. We determined that it was running out of fuel under boost and checked the fuel pump. The pump was spraying fuel from a relief valve on the pump body itself, so we swapped it out along with the fuel line from the pump to the fuel pump "hat" that contains the hard lines and electrical connectors. After doing this, everything seemed fine, but my recent trip to the dragstrip was disappointing because the car didn't want to rev over 4-5k rpm. So I swapped the pump again thinking that was the issue. A quick spin around the block and I was back to boosted glory. Fast forward a couple of weeks to today. I was pulling away from a light in first gear, and the car fell flat when I tried to give it more than "cruising" load. This is the same feeling I was getting at the dragstrip. I can't imagine that I killed 2 pumps (maybe 3) from what little I drive it. The car has a total of about 1700 miles on it. I can activate the fuel pump with the motor off, and I get my set fuel pressure at the rail. I also get a noise in the fuel tank that sounds like returning fuel. Maybe more fuel than it should. It's possible that the relief valve is spraying fuel again, but what would cause these failures? The fuel sock looks good. My inline filter looks good. It makes the appropriate amount of fuel under cruise and throttle. What would cause a "partial" pump failure? I'm posting here for general help and knowledge, but will be posting in several places where people might have more specific knowledge of my components. 1 Quote Link to comment
G-Duax Posted September 17, 2017 Report Share Posted September 17, 2017 Hope you aren't buying the chinese knock-off Walbros. They copy them right down to the box, stampings on the pump, and instructions. The only way I ever buy a Walbro is through the US distributor, FuelPumps.net They have a whole page telling about the rip-off pumps out of chinkland. 2 Quote Link to comment
jeffball610 Posted September 17, 2017 Author Report Share Posted September 17, 2017 Hope you aren't buying the chinese knock-off Walbros. The current pump in the car is from Titan Motorsports. I could understand the issue with knock off pump, but to fail in less than 2 weeks is impressive. 1 Quote Link to comment
datzenmike Posted September 17, 2017 Report Share Posted September 17, 2017 Power supply wire to tank too small a gauge? Electric motor is on all the time trying to make minimum full pressure. Not sure if your fuel pump is intermittent duty or not. It should build pressure and then 'rest' till it drops below it's regulated pressure. Unless it is continuous duty it's pounding away all the time. 1 Quote Link to comment
G-Duax Posted September 17, 2017 Report Share Posted September 17, 2017 A true Walbro 255 can take continuous running. The current pump in the car is from Titan Motorsports. I'd call FuelPumps.net, and see if Titan is actually buying pumps from them. A lot of big name on-line people supplement their income by selling crap. FuelPumps.net would be a good place to ask about your problem. Oh, and I am less than impressed with a single plastic tie holding the pump on. You are asking for trouble..... 1 Quote Link to comment
jeffball610 Posted September 17, 2017 Author Report Share Posted September 17, 2017 Power supply wire to tank too small a gauge? Electric motor is on all the time trying to make minimum full pressure. Not sure if your fuel pump is intermittent duty or not. It should build pressure and then 'rest' till it drops below it's regulated pressure. Unless it is continuous duty it's pounding away all the time. My fuel pump has a dedicated power and fuse directly from the battery. It also has a dedicated ground to the battery along with several other grounds on the fuel cell. 1 Quote Link to comment
jeffball610 Posted September 17, 2017 Author Report Share Posted September 17, 2017 Oh, and I am less than impressed with a single plastic tie holding the pump on. You are asking for trouble..... The zip tie is mostly for piece of mind. The pump itself is stable with just the hose on there. However, it is also held into the fuel bowl and there isn't much room for it to move around. I suppose I could throw another zip tie on, but I don't see the purpose. I could also use a worm clamp, but again, not sure why I'd need it. 1 Quote Link to comment
datzenmike Posted September 17, 2017 Report Share Posted September 17, 2017 My fuel pump has a dedicated power and fuse directly from the battery. It also has a dedicated ground to the battery along with several other grounds on the fuel cell. Not what I said. The gauge of the wire is the queation. Too small for the current drawn through it, and there is too much voltage drop. Running a long ground wire is also bad. Use the body, can't get bigger than that. 1 Quote Link to comment
jeffball610 Posted September 17, 2017 Author Report Share Posted September 17, 2017 It is confirmed that the fuel pump has blown the "relief valve" just like the first one. My Aeromotive FPR can't lower the pressure below about 23psi. I am definitely getting return fuel into the fuel cell, so that eliminates a restriction that would cause high pressure. My thoughts are either the FPR is bad (not likely since my fuel trims look decent) or there is a restriction in the fuel line. Which is also not likely. Other thoughts are that the fuel pump is actually getting too much current since it is directly wired to the battery with an inline fuse and using the stock ECU wire as a trigger. Basically it's just the standard "fuel pump rewire" if the battery was in the trunk. What else would cause the pressure to be so high that it would blow the relief valve? I assume that's the correct term and diagnosis. It's the small hole next to the feed outlet. I'll attach a picture of the previous pump for reference. 1 Quote Link to comment
jeffball610 Posted September 17, 2017 Author Report Share Posted September 17, 2017 Not what I said. The gauge of the wire is the queation. Too small for the current drawn through it, and there is too much voltage drop. Running a long ground wire is also bad. Use the body, can't get bigger than that. Wire gauge is 10ga to and from the relay. The ground wire is only 16-18ga, but is only about 18" from the battery. The fuel pump hat also holds another 3 ground wires with 2 going to the battery and one going to the relay. It is possible that there is an issue there, but I would think it's causing too much current and causing the pump to run too quickly. 1 Quote Link to comment
datzenmike Posted September 17, 2017 Report Share Posted September 17, 2017 Seems like the power wiring would be sufficient but as current is the same in all parts of a circuit the ground must also be equal to the power wire. Impossible to have too much current flow but easy to get less.. Current (I) flow is a function of voltage (V) divided by resistance ®. Think of voltage as the thing that pushes current through a load. As the voltage is 12-14, and the pump (load) does not change then an increase in current cannot happen. The pump is designed to run on a car's power supply which is 12 up to 14v when running. The best you can do is ensure that it is getting the maximum voltage to it. To increase current flow you would have to increase the voltage or decrease the resistance. 1 Quote Link to comment
G-Duax Posted September 17, 2017 Report Share Posted September 17, 2017 The valve in the discharge is an anti drain back valve. 1 Quote Link to comment
jeffball610 Posted September 17, 2017 Author Report Share Posted September 17, 2017 I put a small 3mm machine screw in the relief valve of the old pump just to see if I could make it work.backgroundIt works. For about 2 seconds until the pressure is too great and it bogs down the pump. I took a quick video. This was after it had already build some pressure, so it bogs down even faster.https://drive.google.com/file/d/0B9b...ew?usp=sharingAfter that, I pulled it back out, and benched tested both the old and new pumps. I was surprised how much fuel stays in the pump itself. The old pump spit fuel from the feed like it's supposed to since the relief valve was blocked. However, the newer pump only spit fuel out of the relief. This leads me to believe either the feed is blocked in some way. I'm actually surprised that it could send 40psi to the rail with how little it tried to send fuel without pressure on it. 1 Quote Link to comment
datzenmike Posted September 17, 2017 Report Share Posted September 17, 2017 Is the pump bottomed out blocking the sock over the inlet? Assume this is the 'surge tank'? How does the gas get in? 1 Quote Link to comment
jeffball610 Posted September 17, 2017 Author Report Share Posted September 17, 2017 Is the pump bottomed out blocking the sock over the inlet? Assume this is the 'surge tank'? How does the gas get in? There is a rubber dampener that helps space the sock up from the bottom. That being said, it could possibly still be bottoming out. I'll try to do a better job when I install. The "surge tank" from the Z31 has a couple of holes around the parameter to allow fuel in. It also fills from the return line. The "maze" shape also acts like a baffle to hold fuel in the pickup area. 1 Quote Link to comment
Charlie69 Posted September 19, 2017 Report Share Posted September 19, 2017 Hope you aren't buying the chinese knock-off Walbros. They copy them right down to the box, stampings on the pump, and instructions. The only way I ever buy a Walbro is through the US distributor, FuelPumps.net They have a whole page telling about the rip-off pumps out of chinkland. Fuelpumps.net domain is up for sale so I do not think it is the go to place any more. Unless the Chinese hacked the domain. Quote Link to comment
datzenmike Posted September 19, 2017 Report Share Posted September 19, 2017 The Chinese have a 4 thousand year history of graft and bribery. There's nothing like ' fragrant grease' to smooth things over. Remember when Carter was president and the Iranian hostages? Remember the seal ? teams that were helicoptered in for the rescue? One helicopter had to be abandoned. It was the failure of a counterfeited part. Just look up Chinese counterfeit parts, and their government's failure to crack down on it. You wonder why replacement parts fail or are 'bad in the box'? 1 Quote Link to comment
G-Duax Posted September 19, 2017 Report Share Posted September 19, 2017 My bad, forgot the dash between 'Fuel' and 'Pumps'......... Correct address: http://www.fuel-pumps.net/ Quote Link to comment
distributorguy Posted September 20, 2017 Report Share Posted September 20, 2017 I'd move the return line away from the pickup. Its likely pushing fuel away fro the pickup, creating an eddy in the tank. I like the kick in your return line, but shorten it up to about half the depth of the tank OR extend it a few inches longer away from the pickup. Are you sure you're not just starving the fuel pump? What's your duty cycle like on the injectors at 4k? It may be a programming calibration and the pump is fine.They shouldn't be past 70% even with boost at 4k. Quote Link to comment
jeffball610 Posted September 20, 2017 Author Report Share Posted September 20, 2017 I'd move the return line away from the pickup. Its likely pushing fuel away fro the pickup, creating an eddy in the tank. I like the kick in your return line, but shorten it up to about half the depth of the tank OR extend it a few inches longer away from the pickup. Are you sure you're not just starving the fuel pump? What's your duty cycle like on the injectors at 4k? It may be a programming calibration and the pump is fine.They shouldn't be past 70% even with boost at 4k. I can move the return line a little. I don't know that it would cause too much of an issue, but that's a good thought. I haven't checked a log with the fuel pump to see what the duty cycle is. Immediately after replacing the last fuel pump, I did some pulls to redline, and it ran great. It seems to be starving for fuel when boost comes on, and the relief valve shouldn't be spraying fuel at idle. I don't have a way to check fuel pressure while driving. I'm checking for restrictions in the line right now. The new pump should be here by Friday, so I want to make sure everything is in order before then. Quote Link to comment
distributorguy Posted September 21, 2017 Report Share Posted September 21, 2017 Watch the duty cycle. If its starving, you'll be in the 90%+ range. Otherwise it may just be a bad tune under boost? Quote Link to comment
jeffball610 Posted September 22, 2017 Author Report Share Posted September 22, 2017 I've inspected the lines and blew them out with compressed air. I'm not finding any issues. The only thing I could think of is a clogged fuel filter. I'm running this one: https://www.summitracing.com/parts/tfs-23000/overview/ I thought someone told me years ago that I'd have issues with it, but I can't imagine why. It is advertised as fuel injection compatible and the housing is supposed to be good for 300psi. I don't see a rating or restoration for the filter itself other than stating it is 40 micron. I got a replacement filter today to see if there was an issue there. I also got an Autometer fluid filled pressure gauge in case the old one was bad. I had a crappy generic one that was falling apart. The new fuel pump should arrive tomorrow so I can do some testing. Quote Link to comment
distributorguy Posted September 25, 2017 Report Share Posted September 25, 2017 Any updates? Quote Link to comment
jeffball610 Posted September 27, 2017 Author Report Share Posted September 27, 2017 (edited) I'm still "testing". It did make a round trip from Vegas to LA on Sunday (around 500 miles) with some low boost uphill pulls (about 7psi). I haven't looked at the logs yet, but it seems to be working so far. I'm planning to get another fuel filter with a larger element. I'll be working with a friend on Sunday doing some road tuning to see if we have it ironed out. Edit: No updates. The system still seems to be working fine. I still plan to run a bigger fuel filter, but I haven't had any issues since the last pump replacement. Edited November 7, 2017 by jeffball610 Quote Link to comment
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