Fuel pump issues? Please read..

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This is going to take some explaining, so please bear with me here, since I'm stumped.


S14, SR20, ID2000, E85, Link G4 ECU, Walbro 450 lp/h pump, Fuelab FPR, stock lines & Z32 fuel filter - those are the relevant parts here I think.
The battery is in the trunk, the pump is wired to a relay in the trunk as well.

Engine was just built, so this is with the base map, slightly adjusted for better idle etc, so this is just me starting to drive the car. I've started it and let it idle a few times prior to this, with no issues.

So yesterday, I'm going to take it out on the road for the first time, and try getting on some boost to see what happens. I let it idle for like 20 minutes, and it's hot out, so it gets warmed up quickly etc. Take it out on the road, do an easy pull to get up to about .5 bar/7-8 PSI in second gear, no problem. Throw in third goes well at first, but then it cuts out, like dies as if I turned the ignition off.

I clutch, rev and it is alive, but this happens all the time now - when I drive with a steady throttle, it does this - if I keep the throttle at the same position, nothing happens, I have to take my foot off the pedal, and throttle again. Sometimes it does "come back" if I don't take my foot off, it's just random.

Go back home, and I immediately see on my AFR-gauge that it's a bit more rich now.. Turn the car off, then turn the ignition back on - the fuel pump keeps priming/running and the relay for it in the trunk, keeps clicking.

I disconnect the pump, and it's still clicking. So I try this - I bypass the relay and connect the pump directly, and now it almost never cuts out - I've taken it up to 1 bar/14-15 PSI without it cutting out at all, but it is running lean instead (14-15 AFR on boost). It will still, sometimes cut out as above, but not as often at all, and not as bad, ie I don't have to clutch kick and rev it, but it still happens, and I don't know why..

The lean on boost may be due to the tune, but then again, the base map should be very safe in terms of richness etc.

Anyone with ideas/help will have my deepest grattitude, and if someone solves it outright, I will f*cking Paypal you some dough! I am really that desperate.

[TheRealSy90]

A basemap is just to get the engine running and idling. It's not meant for running the car in boost at all. You need to get it tuned.

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A basemap is just to get the engine running and idling. It's not meant for running the car in boost at all. You need to get it tuned.

Oh that I do know, I have a full day of tuning booked on friday, but I was hoping to solve my fuel pump issue before then, so that I don't have to use up my time on the dyno to look for it. Reason I am driving it before is to find issues such as the one I'm having beforehand.

[Josh@Fuelab]

If the relay is clicking w/o the pump even being connected, I would tend to think it's a bad relay. What is the amperage rating on your relay? Is it possible that the pump is starting to draw more current than the relay is supposed to handle? How is your relay being triggered? I've had several customers that have tried to use a factory fuel pump signal to fire a relay for an aftermarket pump and had all kinds of problems. I'm not really sure what the cause is (every brand of car seems to be a bit different it seems). In my experience, it's best to come up with your own switched signal rather than using the factory pump signal.

It may not have anything to do with your problems, but are you sure the pump is not cavitating or overheating? I'm not familiar with the size of the fuel lines on these cars, but most cars have a fairly small line size- especially for the inlet side of a pump as big as a 450. Pumps do not like to work for fuel (Walbro, Bosch, Fuelab, Aeromotive, etc.). They can push through with no problem, but they don't like to "suck". That can damage the pumps. Ingesting air and/or cavitating them can cause somewhat erratic behavior like you are experiencing as well (although, that doesn't explain the relay clicking back and forth).

Like mentioned above, I would certainly stay out of boost at all costs. A base map is just to run the engine in a bit before it ever sees boost.

[sqd]

If the relay is clicking w/o the pump even being connected, I would tend to think it's a bad relay. What is the amperage rating on your relay? Is it possible that the pump is starting to draw more current than the relay is supposed to handle?

It may not have anything to do with your problems, but are you sure the pump is not cavitating or overheating? I'm not familiar with the size of the fuel lines on these cars, but most cars have a fairly small line size- especially for the inlet side of a pump as big as a 450. Pumps do not like to work for fuel (Walbro, Bosch, Fuelab, Aeromotive, etc.). They can push through with no problem, but they don't like to "suck". That can damage the pumps. Ingesting air and/or cavitating them can cause somewhat erratic behavior like you are experiencing as well (although, that doesn't explain the relay clicking back and forth).

Like mentioned above, I would certainly stay out of boost at all costs. A base map is just to run the engine in a bit before it ever sees boost.

First off, thanks for the info and reply!

Yes, I got a new relay today, a 30 amp one, and some thicker wires, just to make sure. Will install them tonight to see what happens! What the current relay is rated for, I don't know to be honest, was installed a long time ago, but worked fine with the Bosch 044 I had previously.

And absolutely, I just wanted to make sure it ran, I haven't been on boost for more than 4-5 times, and no full throttle either. I am aware that base maps aren't for running around with, and I keep a very close eye on all values (AFR, oil pressure/temp, water temp, knock and so on). But yeah, come friday it will be tuned, at least if the pump is working correctly that is..

[Josh@Fuelab]

What are you using to trigger your relay- factory fuel pump signal or some other switched source? I've ran into several customers that use a factory pump signal to trigger their relay, that have had many different odd issues such as yours. Granted, I only deal with my pumps (Fuelab), but I'd venture a guess the issue could be the same with a standard brushed pump such as a Walbro, Bosch, Aeromotive, etc. If possible, I would try a different switched source then the factory signal just to rule that out. I have little experience with your type of car- but I've had that problem with things ranging from a BMW to a Cummins diesel.

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I believe I've fixed it! An almost hidden cable was a bit damaged, and one crimped end was not snug at all, so I could just pull it off.. Fixed those, replaced the relay and ran a new thicker ground for it, and now, it doesn't cut out at all!

Thanks for the help and info Josh, very much appreciated :)

Sent from my Galaxy S3

[Josh@Fuelab]

Crimped end failures- those are always tricky to find. Any new build/new wiring job that I do, I solder the end after I crimp it to keep it from loosening up over time.

Overall- I'm just happy to see that the Fuelab regulator was never at fault. :naughty:

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Crimped end failures- those are always tricky to find. Any new build/new wiring job that I do, I solder the end after I crimp it to keep it from loosening up over time.

Overall- I'm just happy to see that the Fuelab regulator was never at fault. :naughty:

Haha, yeah no issues with the FPR so far :) Let's see how it stacks up on friday, with 30 PSI of boost :D