Walbro 255 random shutoff

[jon95dsm]

Hey guys. I'm having an issue since upgrading my fuel system and didn't see anything quite the same using the search function. This started after installing a Walbro 255 and an Aeromotive fpr.

A few days after installing the pump and fpr I was cruising and my afr pegged lean then a few seconds later the car shut off and would not restart. I let it sit for about 20 minutes and then it started up normally on the first try. This happened again a few days later, wouldn't restart immediately but did start normally 15 minutes later. I hadn't done the pump rewire yet and was thinking maybe there was too much draw between the pump, aftermarket fans, and amplified audio so I drove it to the shop and rewired the pump with the STM kit. Everything worked fine for about a week and then yesterday the same issue. Shut off, wouldn't restart immediately but would later that evening. When it happened yesterday I waited about 5 minutes then moved it to a parking lot and let it sit there idling. I listened to the pump and I could hear it slow down for several seconds before cutting completely off. To clarify on that, it didn't sound like the pump shut off and was just slowing down. It was more of a slow deceleration (like if you put a load on an electric motor) for several seconds before turning completely off.

Any ideas what could be causing it to do this? The only thoughts I've had are possibly a faulty pump, it could be an electrical connector issue (although I would expect the pump to cut off immediately if it lost connection instead of slowing down for a bit first like I could hear the last time), or possibly an installation error. I went through the VFAQ instructions before installation and have reviewed them again as well as youtube videos since the issue started and everything looks correct as far as installation goes.

I'm at a loss here. Any help is appreciated.

Extra notes:
Car profile is up to date if you need to see everything that is done.
Pump was bought from extremepsi so it should be genuine.
Pump and fpr were purchased new and only have a couple of weeks use.
I have inspected for leaks several times and do not see or smell any.

 

[joemamma]

when you put the pump in did you repace the filter on the bottom of the sending unit? When was the last time fuel filter was replaced?

 

[jon95dsm]

when you put the pump in did you repace the filter on the bottom of the sending unit? When was the last time fuel filter was replaced?

Yes I got the Walbro installation kit as well so the only reused part is the plastic spacer on the pump outlet.

 

[bling5tatus]

I had to re-run a new (larger gauge) wire from the harness plug to the pump to trigger the relay. The stock harness wire was old and crappy and I didn't feel like trying to figure out if it was the problem for sure but after a lot of f'ing around replacing that wire made my similar issue go away completely.

 

[jon95dsm]

I had to re-run a new (larger gauge) wire from the harness plug to the pump to trigger the relay. The stock harness wire was old and crappy and I didn't feel like trying to figure out if it was the problem for sure but after a lot of f'ing around replacing that wire made my similar issue go away completely.

You're referring to the factory power wire that triggers the relay, not the little bit that remains as a power wire after a pump rewire, correct? I can give that a shot.

The only part that doesn't clear up is that I was having the issue before doing the rewire as well. I did read that some people had issues with their oem relay after installing a bigger pump but I'm not very familiar with that part of the system.

 

[joemamma]

you may need a higher amperage rated relay

 

[boostdawd]

My money is on the pump being faulty/defective.

 

[joemamma]

if wiring is up to snuff and relay too i would also ave to say the pump as i have gotten many new parts that were defective over the decades

 

[jon95dsm]

I'll check out the stock relay and run a 12 gauge signal wire to the rewire relay. My money is on faulty pump as well. I was planning on getting an ethanol rated pump later this year anyways its just a huge annoyance if a name brand pump is failing within a week of use.

 

[bling5tatus]

When mine had a similar problem it was shortly after installing a new Walboro 450 pump. I pulled my hair out trying to figure out why it wouldn't work. It ended up being the factory wire that triggered the pump rewire we did. This is on a fwd 1g so doing this wasn't as easy as accessing the hatch. Also, I went through the trouble, thinking the pump had failed, and removed it and hooked it up to power to see if it still worked properly. The pump had no issues and I would like to warn you if you try this that you could create a spark very easily and start a fire so I'd work very carefully or use long jump wires far away from the bucket where the pump would be.

In any case, after checking many things I determined that the factory relay was ok, but the wire that was originally used to power the pump (and is now used to trigger the relay/rewire) had somehow toasted itself. I'm not sure how and I've not measured the resistance or removed it from the car since then. Once I ran a new wire in place of it, however, the car worked fine and hasn't had the issue since. Simply doing a standard rewire didn't fix the issue for me as I thought it would because the original factory wire triggering the rewire was still the problem. It left me stranded so it wasn't fun.

 

[jon95dsm]

Yeah it's definitely not fun getting stranded. Thankfully I was only on a main road one of the times it cut off. Also that I have a second daily for when my race daily does this haha. The pump does work. I'll drive it for a couple of days without issues and then it just randomly cuts out. I wasn't sure if there could be certain conditions that would cause a minor defect in the pump to surface. I should be able to change the wire in the next couple of days and we'll see how she does. Hopefully a larger wire fixes the problem. If not, guess I'm starting on ethanol parts sooner than expected.

 

[ThunderChild]

As long as the wire isn't compromised or corroded heavily, it only takes 150ma to turn on an automotive spdt relay, so I suspect the wire or the relay more likely. I'm running a 340 stealth and 12 gauge wire from bat->relay->fuel pump. I am relocated and have monitored voltage and amperage at the pump feed and see no significant changes, even after drag passes. For a rewire from the front of the car, 8 gauge should be sufficient.

So I suspect the relay may have a coil that's heat soaking or internally shorted, unless the turn on wire is really corroded.

 

[jon95dsm]

Hey. I'm just updating this thread in case anybody else has a similar issue and is looking for a resolution.

I replaced the Walbro 255 with a DW300 and there was no change to the issue. At this point I'm assuming the pumps are fine.

I think the problem was that I had finally exceeded the capabilities of the stock alternator when I added the fuel pump. I had the alternator tested and it was in good working order but on a log I would see dips down to the mid 12s in battery voltage. My battery was gradually losing charge as well (it's a red top that's less than a year old). I charged the battery back to full and installed a Galant 90A alternator. There are still dips in voltage but that is just at really low rpm. The overall voltage is much better now and it hasn't shut off on me yet. I'll be driving it this week so we'll see if that fixed it or not.

 

[jon95dsm]

That last post was actually wrong. I finally managed to catch the problem on a log. MAP sensor is having issues. Problem solved.