Fuel System Issues After Supercharger Install

I'll try to keep a long story short:

Installed a Paxton 2200 kit on my 2005 Mustang GT, with FR 39/lb injectors, and Deatschwerks 340 lph fuel pump.

Car fired up, but had a fuel level error showing an empty tank. I have read about this happening due to sulpher build up on the sensor. Went to get gas as well as adding Chevron Techron to hopefully clean the level sensor. The car cranked but wouldn't start. Let the car sit for about 10 minutes then it fired up.

After doing multiple test hits/data logs, I was noticing a lean AFR, as well as DROPPING fuel pressure while under boost. The boost gauge was reaching about 8 psi near redline, and AFR was in the mid 12's. The fuel pressure in the logs was around 40psi at cruise, but going wide open throttle it would fluctuate from 32-37psi. I thought boost was supposed to increase fuel pressure so I was concerned. Contacted the tuner, they assured me the tune was all good for my setup and after looking at my logs. Changed the fuel filter but no help.

Now the fun part, I take the car on a trip to Ocean City MD, and while I'm pulling from a stop light in downtown D.C. the car shuts off. Car cranks hard but no start. Fuel is a bit low and does have a weird smell at this point but plenty to run the car. Long story short I got the car running the next day, I ordered a CarQuest factory style Fuel pump and put it in. No start... so I recheck everything and notice the DW fuel pump blew the fuel pump fuse when it died. So, I replace the fuse and the car fires up, I test the DW pump one more time and it is definitely dead.

So, I'm thinking, good to go I just need a replacement DW pump and I should be seeing safe AFR's. I did a few small pulls and the CarQuest pump was actually showing better AFRs in lower RPMS in boost, then of course leaning out up top as expected. Another note: while trying to fix the car in D.C. I went ahead and replaced the fuel pump drive module as well for good measure.

PART 2:

Once I get to Ocean City, the car is running great, other than a slight rough idle, the RPMS would drop down to about 500 then correct up to 800 or so, which never happened before. I was thinking maybe just different elevation or something. Car ran great all weekend, other than the slight hesitation in idle, occasionally.

The other BIG issue:

I'm headed back to TN from Maryland, and in VA the car sputters on the interstate and just shuts off. I try cranking a few times and it would start then die. So, I check the fuse and it's good. I start freaking as I'm in the middle of nowhere. I finally look down in the fuel tank on the driver side and notice NO GAS, BUT, there is gas in the passenger side????? The CarQuest pump does have a different looking siphon style to it to bring fuel over from passenger side. However, it was obviously not working. So, I'm thinking a possible clog in the crossover tube in the tank, partially because when I look down in the passenger side, there is DEBRIS floating in the gas, small particles and some large. I use a cup to transfer the fluids from one side of the tank to another to start the car. From there on, the car would drive normally, other than a slight hesitation at 70-80mph which seemed fuel related. At this point I'm thinking there is a clog in the system from that damn debris, or the CarQUest pump in on it's way out now. Data logging showed normal Fuel pressure duty cycle and pressure though. Had to fillup every 150 miles on the way home.

WHERE I'M AT NOW:

I'm working on cleaning the gas tank out of any possible debris, I'm going to replace the fuel filter again since seeing the debris, and I'm going to use compressed air in all the fuel lines if any debris. I'm starting to wonder if the Techron cleaner loosened the tank up and caused debris, or if I got a bad batch of gas in a small town. I still believe the orignal DW fuel pump I got was just bad from the get-go, as it had a lower fuel pressure with key on than the CarQuest pump, which is pretty sad. Key on showed the DW pump at 45psi rail pressure and Carquest at 65psi.

After cleaning everything, I'm going to install the new DW fuel pump. I wanted to use the CarQuest sending unit as it actually makes the fuel gauge work again, and has a PPRV delete, however, it doesn't seem to have the same connector as the stock unit. I'm thinking both incidents were not related. The first issue seemed like a weak pump from the factory that eventually just died. The second instance seems like a clog in the tank/lines. I'm going to tackle most of this, this weekend. What I'm hoping is the first DW pump was faulty and caused the fuse to blow. And then the tank got a little dirty causing my crossover to clog/slight hesitation at highway speeds since installing stock style pump.

I'm looking for any/all suggestions, tips.
Thank you

Fuel pressure should drop momentarily when boost hits but should go back to proper pressure. If it can't that's a problem, and I'd be hesitant of the tuner saying it's fine ignore it.

Not trying to get you to spend $ but for a 3v engine I'd recommend having lito here tune it.

Sorry maybe I wasn't clear. The tuner definitely didnt say it was normal the fuel pressure was dropping, they just meant what the tune was commanding for fuel and the other PIDs looked like the tune was working properly. When the fuel pump went out, they were not hesitant to send me a replacement. I have not tried the new pump but I will be this weekend.

I would recommend an oem hat as they are most reliable including their sender and siphon with a 400lph pump and upgraded wire fuse and relay to the fpdm to support the bigger pump and the increased current. Regardless of pump setup though you should be running a wire upgrade, that's the first step to getting more out of your setup and ensuring the fuel pump is getting the power it needs. I'm extremely confident this would solve all the issues your having after you clean everything up and your fuel pressure will be solid with plenty of overhead to support your boosted setup. The 400lph is my go to for a stock block boosted setup, its 600hp capable and much more robust under changing pressure and temp with the twin scroll pump design. I don't mess with 340s at all anymore except for a dual pump dual fpdm setup. Another great option would be a gt500 fuel pump setup. I have a custom one for sale in the classifieds as well. If you need any help with the wiring upgrade or 400lph pump install as well just let me know.

JeremyH said:

I would recommend an oem hat as they are most reliable including their sender with a 400lph pump and upgraded wire fuse and relay to the fpdm to support the bigger pump and the increased current. I'm extremely confident this would solve all the issues your having after you clean everything up and your fuel pressure will be solid with plenty of overhead to support your boosted setup.

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Yes I ended up using the OEM hat with the new DW 340 pump I got and it's hose. Are there kits you can buy with the upgraded wiring to the FPDM? And when you say upgraded fuse and relay do you mean the ones under the hood in the fuse box? I'm a bit of an electronics newb

Also, if I were to upgrade to a 400lhp pump, would that require a re-tune if I'm tuned for the 340?

Thank you

PaxtonGT05 said:

Yes I ended up using the OEM hat with the new DW 340 pump I got and it's hose. Are there kits you can buy with the upgraded wiring to the FPDM? And when you say upgraded fuse and relay do you mean the ones under the hood in the fuse box? I'm a bit of an electronics newb

Also, if I were to upgrade to a 400lhp pump, would that require a re-tune if I'm tuned for the 340?

Thank you

Click to expand...

Its a larger 10awg 30amp fused wire with a relay that feeds power directly from the battery positive terminal to the fpdm. It lowers current draw and pump duty cycle and provides more stable voltage to the fpdm during varying electrical loads while driving etc. Works and helps with any pump or bap setup.

The car will drive and run fine and be safe, short range fuel trims will likely be richer though since its a higher flowing pump so I would at least have your tuner look at it.

Shoot me your email and I will send you info on how to do the wire upgrade stuff.

Did the tuner tune for the fuel pump? I ask because there are (as reported here and by a few shops themselves) tuners who think the ecu will self tune for a different pump.

Yes I reconfirmed all my mods once I sent the datalog to them.

Update:

Once I put in the warrantied 340 pump, I also went ahead and deleted the PPRV. Well, monitoring my AFR gauge in Lambda, I'm still seeing about .85 up to 5k rpm or so, then it inconsistently creeps down to .83ish at redline. Definitely lean, so I looked at the logs and I'm still seeing FRP drop to about 34 psi or so the closer I get to redline. It stays at 39 psi until 4700 rpms. Starting to wonder if my factory hat has a corroded connection, cause get this, when I had the CarQuest pump in I got on it a bit, and saw .83 right off the bat! As low as 4500 rpms. Then it went to .87 near 5k. But with my stock hat and 340 its reversed. It starts up near .87 lambda then creeps down to .83 ish. What the hell is going on.

Oh, and I monitored commanded AFR and its .8 (lambda I'm assuming) at WOT after 4k rpms. Strange stuff. Can any of you fuel guys figure this one out? Lol. And as far as spark plugs, the porceline is very white after 2k miles no tan. Some black deposits not sure if carbon or detonation. Timing above 4k rpm stays around 17.5-19 degrees.

Ordered a fuel rail pressure sensor as well to rule that out. I had to be a little rough on it to get it off the first time.

And that wire upgrade is definitely sounding better at this point I'll keep you posted Jeremy. But I feel like other people have my setup and arent having the same issues so I really want to figure this out.

Edit: another test I did was unplug the vac line from the fuel rail pressure sensor at idle, FRP shot down to 29 then right back to 39 and idled normally. My boost gauge showed -2. The car still had the idle issue where it would bounce between 730-780 occasionally. And when this would happen Lambda would go from 1 to about 1.05. Unplugged each of the injectors and COPs, they all made a noticeable idle difference.

Hey Jeremy I shot you an email to go ahead and order the wire upgrade. Going to see how that goes. After that probably try a KB BAP I actually noticed it is recommended even with my bigger 340 pump on the site I bought the kit from.

I noticed your sig mentions an Autolite H1. If you mean HT1 those are the wrong plugs and you need the HT0 for a boosted setup. Then close the gap to somewhere between .030 to .032.

The lambda activity sounds normal for the parts you're using. The Carquest pump will start out rich and lean out as it runs out of breath. Whereas the DW will enrich the mixture as the engine demands more fuel with more rpm. It sounds like the added current of the DW pump is straining the stock wiring system, so doing the wiring upgrade should help. Remember to mount the relay as close to the battery as possible so you can keep your power & ground wires short.

Lastly I would double check that the pump is accounted for in the tune, as Bruce mentioned.

And it's too late for this now but keeping the PPRV might have been better for you. One of the drawbacks of this mod is the starting problems you were having. If your duty cycles aren't on the edge of maxing out there's no need to delete the PPRV.

46addict said:

I noticed your sig mentions an Autolite H1. If you mean HT1 those are the wrong plugs and you need the HT0 for a boosted setup. Then close the gap to somewhere between .030 to .032.

The lambda activity sounds normal for the parts you're using. The Carquest pump will start out rich and lean out as it runs out of breath. Whereas the DW will richen up as the engine demands more fuel with more rpm. It sounds like the added current of the DW pump is straining the stock wiring system, so doing the wiring upgrade should help. Remember to mount the relay as close to the battery as possible so you can keep your power & ground wires short.

Lastly I would double check that the pump is accounted for in the tune, as Bruce mentioned.

And it's too late for this now but keeping the PPRV might have been better for you. One of the drawbacks of this mod is the starting problems you were having. If your duty cycles aren't on the edge of maxing out there's no need to delete the PPRV.

Click to expand...

Hm I may need to check when I get home. I was going off memory so they very well may be HT0 as I bought them as a kit with the Paxton.

I believe you're right about the DW straining the stock wiring. Which could also be why the first pump ended up dying and blowing the fuse. Another reason I believe it may be a wire issue is sometimes I'll see as low as a .82 lambda near redline and other times it will bounce around a little higher so it's very inconsistent. Matter of fact with the CarQuest pump and it's lower power I would see lambda actually stay on a number for more than a second, now with the DW the number bounces around so much WOT I can barely read it.

Yeah the PPRV definitely effects the startup which kind of sucks, however my FPDC showed about 92% instead of the 95% or so before so I think it may have helped a bit in that aspect.

If the wire upgrade doesn't stabilize a safe AFR would the best next step be a KB BAP or a 400LPH pump in your opinion?

I don't think you should buy anything at all or replace anything until someone who really knows tuning gets into it and sees what is needed. For myself, my car has been on the dyno and done some really weird things, only to have it all be a tuning issue.

I've seen things like this be actual parts issues or tuning or both.

So best of luck to you.

Marble said:

I don't think you should buy anything at all or replace anything until someone who really knows tuning gets into it and sees what is needed. For myself, my car has been on the dyno and done some really weird things, only to have it all be a tuning issue.

I've seen things like this be actual parts issues or tuning or both.

So best of luck to you.

Click to expand...

Thanks, yeah it's been quite a headache.

PaxtonGT05 said:

If the wire upgrade doesn't stabilize a safe AFR would the best next step be a KB BAP or a 400LPH pump in your opinion?

Click to expand...

If the wiring upgrade and tune revision don't help, I would go with the drop in Walbro 400 or the GT500 pumps from Jeremy (mentioned below). Hopefully you won't have to troubleshoot that far though.

JeremyH said:

The 400lph is my go to for a stock block boosted setup, its 600hp capable and much more robust under changing pressure and temp with the twin scroll pump design. I don't mess with 340s at all anymore except for a dual pump dual fpdm setup. Another great option would be a gt500 fuel pump setup. I have a custom one for sale in the classifieds as well. If you need any help with the wiring upgrade or 400lph pump install as well just let me know.

Click to expand...

46addict said:

If the wiring upgrade and tune revision don't help, I would go with the drop in Walbro 400 or the GT500 pumps from Jeremy (mentioned below). Hopefully you won't have to troubleshoot that far though.

Click to expand...

OK. One more thing I want mention about the comparison between the CarQuest pump/hat and the DW pump/stock hat, the CarQuest would go .83 lambda immediatly on WOT, like as low as 4k RPMS, then creep up to like .87 as it ran out of steam. The immediate .83 seems normal to be but then it should go to the commanded .80. However, the DW pump/stock hat DOES NOT go to .83 immediately, sometimes I don't even see it getting that low over 5k rpms, it's more like - 3k rpms .90 lambda, 4k rpms .87 lambda, 5k rpms .85 lambda, then 6k rpms somewhere between .85-.82.

Even if the DW was running out of steam, even if the wires were not good enough to the FPDM, wouldn't the DW/stock hat STILL do what the CarQuest does by going to the commanded AFR as low as 3-4500 rpms? Any solid AFR I've seen in boost drops to like .8 and gets better from there, whereas I'm starting at .9 and slowly getting better. I feel like it's either the DW pump requiring too much power, or the stock hat has a connector issue. I think the tune seems okay as the CarQuest pump shot to .83 lambda immediately at WOT, I don't think a better pump would go to .90 lambda in the same situation... Wish I would've data logged with the CarQuest pump once.

The second warrantied DW pump is showing same weird AFR trends, and the 1st one died and blew the fuel pump fuse. So I feel like the same could happen to this one eventually as well. It's leading me to believe the stock hat is causing the issue either mechanical or electrical. Cause the fuse would only blow from drawing to much current right? So maybe the connector on the hat is freaking out the pump somehow. I'll be interested to see the wire upgrade's affect on all this.

MAF isn't pegging, it's around 960 counts at redline.

Some runs I did notice fuel pressure only dropping to 37psi or so with DW and others down to 32psi after 4,500 rpms but wierdly the lambda still slowly moves down but it bounces around as well, both scenarios caused the inconsistent AFRS, and not the steady .83 I was seeing with the stock pump at WOT.

Edit: I faintly remember on the first few pulls ever with the original DW pump and setup it would actually hold a steady .85 lambda immediately at WOT then dip to .83 lambda or so, after a few pulls though it started this erratic non stable AFR business. And even with the 2nd new DW pump I've never even seen it hold that .85 the original one did.

Possibly you're running out of pump...

When I was pushing 401hp/395tq I was at 89% duty cycle.. with a Walbro 400LPH pump.
What are you making for power?

06monera96 said:

Possibly you're running out of pump...

When I was pushing 401hp/395tq I was at 89% duty cycle.. with a Walbro 400LPH pump.
What are you making for power?

Click to expand...

I've been seeing 90+ duty cycle at 5500+ rpms, but even when the duty cycle is 80% I'm still not getting a good AFR. Where I bought the kit they said with the tune it should see 460-480 wheel hp. It makes about 9psi of boost near redline I have confirmed with a boost gauge. They didn't say a boost a pump would be necessary with the 340 unless I had cams or headers apparently.

It has not been on a dyno yet though.

The amount of fuel the injectors are pulsing is dependent on rail pressure and in turn dictates afr, so the afr issue is tune related or from excessive current draw by the pump.

The pump just moves the commanded amount of fuel up the injectors at delta pressure (base fuel pressure plus engine vac or pressure as measured by the frps) and in return-less the pressure is dynamic and constantly changing as the pump duty cycle is modulated. If fuel trims in the tune are out of whack with the specific pump then the pcm has trouble getting to the correct pressure it wants as easily as it controls the pump speed via the fpdm. Which in turn can affect afr. This can also be caused by a hot pump, the more current the pump motor draws the hotter it runs which affects flow and pressure output as well. When the pump cant actually support the flow at pressure, then pressure will drop rapidly and afr will go lean with it and that is the sign of a pump physically being maxxed out.

JeremyH said:

The amount of fuel the injectors are pulsing is dependent on rail pressure and in turn dictates afr, so the afr issue is tune related or from excessive current draw by the pump.

The pump just moves the commanded amount of fuel up the injectors at delta pressure (base fuel pressure plus engine vac or pressure as measured by the frps) and in return-less the pressure is dynamic and constantly changing as the pump duty cycle is modulated. If fuel trims in the tune are out of whack with the specific pump then the pcm has trouble getting to the correct pressure it wants as easily as it controls the pump speed via the fpdm. Which in turn can affect afr. This can also be caused by a hot pump, the more current the pump motor draws the hotter it runs which affects flow and pressure output as well. When the pump cant actually support the flow at pressure, then pressure will drop rapidly and afr will go lean with it and that is the sign of a pump physically being maxxed out.

Click to expand...

Great information thank you! Based off this information I'm thinking the DW pump or the fuel hat connection is drawing too much current, since the first pump physically died and blew the fuse, another tidbit the relay looks to have been getting hot as the prongs on it are blackish in spots like it got hot, I tried another relay since seeing that. That tells me the pump was killing itself or a connection on the hat killed it. If this is the case, I'm hoping the wire upgrade will fix the issue. But if it's an inherent flaw with the DW pumps (both I've had) with the stock fuel system then I don't see how running a bigger 400 would draw any less current. Unless I got two bad DW pumps. The tune was datalogged and while they did look at it and say their parameters were correct, they didn't offer much on the side of advice. Which I can partially understand since it doesn't seem to be an issue on their end.

Thanks again everyone for the help. Next step is new FPS/wire upgrade, look at fuel injectors for clogging, after that I will either try the 400 pump or BAP, if that fixes the issue but it's running rich then I'll get a Lito tune.

The wire upgrade will help with that stuff as well. It runs its own 40amp relay and 30amp fuse with larger wire for less resistance directly from the battery. So the stock wire and relay and fuse will see no current as its just run to ground to trigger the new relay and then supply power to the fpdm on the new better power wire. This is what lowers current draw of the pump, which means the motor runs cooler, improving pump control and flow, which can be seen from the lowering of pump duty cycle on a log.